zredbaron

Haha, I love stumbling upon these comments unexpectedly... Thanks John and to everyone else who contributed their setups. Great thread!

I take it you finally got a chance to test the LCAs then... good stuff? How much different is the ride, ie is it undriveable anywhere other than the track? I still test and tune my carbs on country roads before each race, and I'm hoping that full-race LCAs add more of an instant response than an absurdly harsh ride. (never ridden in a car with spherical mounts for rod ends)

Leon's right (again? lol) -- a 3.9 and a lightened flywheel alone will make any car considerably zippier than it was before the changes (you're trading top speed for acceleration in the lower gears, hp is obviously not increased). I personally don't know enough about stock EFI or SUs to advise a proper comparison beyond "food for thought," *BUT* I do know that SUs are very capable... capable of much more power than your listed combinations will produce. Check out what Dave Rebello has been able to accomplish with them: Amazing! I have no idea how modified these SUs are (or are not?)... simply pointing out capability when attached to an obviously full race motor. Unless they are installed on a 100% stock 240Z (and even then!), some tuning will obviously be in order. I remember back in 1998 I was VERY surprised when I removed triple DCOEs (40s, with 28mm venturis) and put SUs back on (I kept and still have the DCOEs), that my power, engine responsiveness and overall fun factor went UP once I put the SUs back on a 100% stock '72 2.4L 240Z (except for headers/muffler/distributor). That car was so zippy it probably even ran better than my first evolution of a 3.1L stroker with a "performance head and cam" and Electromotive HPV-1 ignition (again, the whole engine has to be on the same page! my 3.1L was obviously not at the time). Bottom line, do you want a computer to handle everything for you, or do you want to tinker with carbs on occasion and be directly involved in every aspect of a nostalgic car? (Much less tinkering on SUs than on triples, of course.) Initially intoxicated by being so manual, I've gotten over the nostalgia factor and want ITBs for ultimate NA performance, but we all have different goals, uses, and budgets that we're willing to devote to our hobby. The beauty of HybridZ is that there usually is no consensus (heck look at the differences between the V8, RBxx, turbo and NA groups alone!). When we all come together, we offer different perspectives from different styles of car-building, and through our collective brain-storming, we equip each other with enough experience and know-how for the thread-starter to figure out how they want to proceed. You obviously can't agree with everything that we've posted on your thread. At the end of the day, it's your car, so it's your personal preference and budget that will decide one way or another. You seem torn. I suggest from personal experience that you sleep on it as long as you need to, perhaps even consult a local shop or two (especially if you plan on involving any of them in your project) and see what their take is independent of our suggestions. Again, grain of salt. My shops often criticize what I've done with the car or what I'm asking them to install, but that's ok; my money is usually still green, and I love my car so that's what matters. I can share that in both the car show and autocross racing worlds, people love nostalgia when it has a personal style to it. As long as it's your style, you'll be proud of it and other people will be drawn to your car no matter what that style is. Especially true for things like "cars and coffee" get-togethers that seem to be sweeping the country and also low-budget performance groups (ie who can get the most performance with the least budget). Very cool groups btw. Learn from fellow HybridZ members, ask your questions, we obviously all love talking about Zs, but hold off on purchasing anything until you figure out how you envision your hot rod! Also, try to discern advice from people who have learned the hard way (like me) and the true subject matter experts (like the engine builders, suspension shop owners/fabricators, etc) and apply our perspectives accordingly. Oh, and when you do figure out what you want and hit the GO button, start a project thread and show us what you're doing, perhaps even send a PM with the link to whichever members on this site that were most influential for you. Good luck!

Isn't that what we're supposed to do on HybridZ? Spend your money for you? For "more pep" and without braking the bank too much, the basics like a K&N air filter, bigger throttle body, perhaps a little more cam (not too much), and 3-2-1 headers with a Magnaflow (personal preference, any straight-through should be fine) muffler should provide some extra zip (and a wonderful sound, which gives the illusion of speed) without braking the bank. A stock ECU, although not ideal by any means, I agree should be able to handle the upgrades (ie balance the AFR ratio for the changes). You can always save the programmable ECU and basic port job (with another step up in cam) for a later date if you decide you want a even more pep. Messing with the head, CR, etc is very expensive, and you don't get a return on your investment unless you align every other aspect of the engine as well. FWIW, what sold me on Electromotive initially is it's spark energy and spark duration has a considerable advantage over CD designs; 2 coils are charging while the other is discharging, not to mention capacitors simply can't compare to inductors in terms of amperage (current), which in my opinion is much more important than voltage. I remain loyal for these reasons and also because they keep adding new features and improve their designs every couple of years.

Cool! I went to their site hoping to read more about it and found no mention of it. TERRIBLE website btw. Luckily google helps out: http://www.mondello....atalog_pg09.htm Unfortunately, the article is a sales pitch to other engine builders and doesn't really say anything particularly useful. From what I gather the idea is to see where the liquid tends to gather, and try to experiment with the port shape to maximize even dispersal...? It does throw around "turbulence" a lot, contrary to our discussion about pulsing, but as you said, Tony, it's a flow bench after all. I *assume* that by "wet" they mean mostly air with an amount of moisture added that's fairly comparable to an ICE's A/F ratio? It doesn't come out and say it directly. An interesting approach, regardless. I suppose if it's worth any salt it will catch on. Good share, Tony.

I've had hit or miss moments with him too. Like many shops, they're usually tinkering too much to mess with email (rightfully so!). I've called and placed an order over the phone on two separate occasions and my parts were shipped immediately. That said, I didn't receive a receipt for either purchase! Anyone else have that problem? I keep meaning to call him, but I can never seem to remember within business hours...

Fantastic compilations, guys. Thanks so much for sharing!

I think in Josh's head the triangular shapes are also appear consistently slightly offset. Anyone else think so, or is this another case of seeing what I want to see? This is either a result of parallax error or perhaps minor inconsistencies (all are done by hand, after all, perhaps the result of a dominant hand and dominant eye combination?). I suggest this as a possibility in my own head, too; if it were a deliberate swirling, one would think it would be more pronounced. I would think, anyway... Those Watanabe heads are probably some of the finest examples of hand-made detail I've ever seen. Hard to believe anyone could be so good with a dremel, regardless of design / performance considerations. Those ports and combustion chambers are incredible!

Fantastic input, Leon. Thank you for helping lift some of the fog for us as these concepts all tie together in a *practical* use with ICEs. When you're right, you're right. I myself even acknowledged the pulsing nature of the 4-cycle pump, but I failed to apply my own recognition to the way I was conceptualizing everything. Glad to take a step back and recalibrate my perspective. I still would argue that laminar flow does occur, just exclusively within small pulse widths, ie as the wave is passing by, there is a (very small) period of time that is laminar, which is of course preceded and followed by turbulence. Splitting hairs, I admit, but I'm stubborn and I still think designing flow paths to promote laminar flow is a relevant performance goal, despite the fact that I agree that the pulsing action generally speaking is not laminar by definition. 260DET, I just poked my flashlight around my intake ports (head is completely off at the moment) and you might be onto something with Sunbelt's triangles imparting an angular momentum. Maybe. However, looking at the head in person, I initially was going to object to your theory until I noted that every single cylinder has an *ever-so-slight* offset of the triangle to the valve guide. This curious consistency is why I think that your theory is plausible. *If* a measurable angular momentum is imparted, it is *very slight.* I will caveat all of these observations that I may simply be seeing what I went looking for, and had I not been looking for it, I may not see it this way at all (a bad scientific approach to observations). Bottom line, you're theory is not disproved in any way, and if correct, this effect is *very slight.* If this very slight angular momentum is by design as you suggest, then you're right, this is some very tricky work indeed! Regardless, it's a very interesting theory! I would suggest, however, that these triangles are nothing new in the world of race-quality port jobs. I personally don't think that by looking at pictures, or even a shop studying the head in person, would be enough info to truly understand the how and whys gained from proprietary R&D, and therefore attempting to duplicate may not work out well at all simply because it all depended on a certain detail that well, was proprietary. Just my opinion. I totally agree, and I think ultimate HP would also go to ITBs for the aforementioned reasons (the head loss incurred by the venturi). There is zero doubt that power under the curve goes to ITBs. What I also want to know is, since my flow bench test gives cfm numbers for steady flow (not pulsing like a real engine), is the cfm rating for carbs or ITBs also rated using steady flow, or is it talking about a "for real" cfm flow of an actual four-stroke cycle's pulsing flow patterns? A good point, it will get gunked up anyway, and this gunk will no doubt have an orange peel texture at the very least. From a strictly theoretical standpoint, a rough surface will cause a boundary layer of localized turbulence across the rough surface. If laminar flow is near this turbulent boundary layer, it encounters less drag than a slick surface would (golf ball effect). Less drag (head loss), more flow, regardless of the flow being textbook laminar or the pulsing pressure waves of an ICE or what not. Less head loss is less head loss. They obviously went out of their way to polish the surface. I wonder why?

When in doubt, just keep clicking! FAIL.

EDIT - duplicate post - is HybridZ slow lately or is it me?

Damn good two cents! I hadn't thought of laminar not doing any mixing and turbulence helping the mixing / atomization. Excellent point! Surely there is a happy medium between the two, because too much turbulence would get in the way of the fuel/air behind it in my mind. I would think deliberate turbulence would be more important for carburetors than for ITBs / EFI, since jets produce crude droplets of fuel relative to the finer spray produced by injectors (assuming the injectors aren't too big) due to the higher fuel pressures. Perhaps the expansion after the venturi is enough relative turbulence (anything flow following a restriction is "unhappy" until it steadies out again) for this mixing? What about direct injection? You mean to say that the intake manifold would be deliberately turbulent on the way in so that when the injector sprays fuel it's turbulent / primed for mixing, or are the injectors just that good? I would think that ideally you could cram more air/fuel through the port by designing an injector that sprays so finely it doesn't require the turbulence for atomization (which of course means high fuel flow for high RPM power would take the hit). I thought that with ITBs for example, the long runners with injectors not being too close to the intake ports allowed the distance the mixture has to travel do the work to atomize the fuel along the way, and in this case, heat is good to help atomize, so long as the heat is post-injector. Right? Wrong? I've seen ITB setups that have two stages of injectors for this reason -- one for the fine sprays, one for the high volume sprays. This really only makes sense to me if you want a high hp motor that's also a daily driver and fuel economy matters. Or is there a reason a race motor would want the fine spray, too? (if memory serves, I think the finer spray was the furthest from the port, which is opposite of what I would guess, but again, if memory serves) (I'd like to get a better grasp on this for when I start making design choices for my switch over to ITBs in a year or two.) With exhaust, we agree that a bad bend would incur a pumping loss (head loss) and is therefore restrictive, but I still think that turbulence in this case is always bad. Why would it have nothing to do with laminar flow? That statement seems contradictory to me, so I'm not quite sure I'm reading it right. Or are you saying that after the scavenging portion of the exhaust it simply is irrelevant whether it is laminar or turbulent so long as head loss is minimized?

More like 5 million words ago! Turbulence has a HUGE affect on fluid flow, more than I ever would have thought before I was taught to respect turbulence. Turbulence literally has vortices (eddies), which means some of the fluid travels in reverse before its path returns to the direction you want it to go. Laminar flow is more compact and goes one direction only for the most part, therefore you get more bang for the buck. This is why mandrel bends in intake and exhaust are so crucial. If we *really* wanted to be accurate for what's *really* going on, we would flow-test mass flow rate in addition to volumetric flow rate. What flows well with one density (proportional to pressure) will not flow well at another. Also, what flows well at one speed (venturis / tapers) will not flow well at another. Everything has a bell curve. Your idea of smoke and what not like they do in aero tunnels is a great idea, but is likely so cost-prohibitive that it's only practical for the budget of a manufacturer and used in an R&D fashion rather than tuning a personal race motor. As for the spinning fluid part, great idea to explain the disparity, and it's plausible, but what would impart the rotation to begin with? Our intakes, carbs/ITBs, and ports are not rifled in any way. I can't think of a way that it would begin spinning outside of "nature wants to spin" because of earth's rotation and reference bathtubs draining and hurricanes. That level of theory is beyond me. Additionally, throttle plates at WOT are literally a horizontal plane, which would resist any fluid rotation and attempt to straighten it back out. As for why it makes so much of a difference, I have a guess (exactly that). The only comparison to radial flow (outward from a center vice spinning) I can offer is from helicopter aerodynamics, but again, there is obviously some spinning going on with helo aerodynamics and it doesn't quite compare. Back to the flow bench, I believe it's wholly adequate for how it's used. Ok, so it doesn't perfectly simulate what's really happening (hell, pistons go up and down on a four stroke cycle, so it's pulsing like the pump it is, not a constant flow like a flow bench provides). To the point, it's a relative test. It allows you to take a baseline, port the head, and note that you made a 33% improvement or what not. If you figure out that putting a triangle in works well, or going HUGE and shiny like JDM works well, again, it's relative to what you started with. You incorporate a change, and if it was a bad one, your flow will go down or plateau, and with a good change the flow will go up. I imagine that a port job is much better on the torque band if the builder stops porting just as it plateaus. If you keep porting and don't increase flow, by removing more material, you have a larger radius, larger radius means slower speed going in. Not ideal in my understanding, but again, I'd still like an engine builder to comment on the practicality of our discussion. More flow is easily accomplished by bigger ports or valves, but even after reaching the limit of port size, they can continue to increase the flow by shaping the ports / turns more efficiently (more laminar). It's for these reasons that I stress the need for a practical perspective. The practical perspective is actually more relevant than the theoretical. There are no doubt hundreds of theoretical great ideas for F1 cars that are tossed out every year because when they took it to the dyno or the track, it didn't produce a benefit, despite the fact that all the engineers thought it would. At the end of the day, it's the lap time that matters, not theories. (In my mind I don't type to hear myself talk, but rather in response to the questions / discussion at hand. Anyone feel differently about said dissertation(s)? I'd hate to be "that guy." Hah. )

If my memory serves, this is the gauge I went with (different face, same guts). I still used a resistor in parallel to slightly shift the readings. As far as getting close to empty goes, the gauge will get down to a certain point and never get lower. For my car, this is at 1/4 tank. Not knowing when I'm about to run out of gas, and always keeping the car fairly empty for autocross renders the gauge completely cosmetic. Did you have similar results?

I second this with a *foot stomp* in recognition that not everyone agrees. When selecting primary size for my recent purchase of Stahl headers, I emailed Stahl directly to see if their opinion matched some of the advice I received here on HybridZ. It did. The larger primaries allow higher peak hp, and smaller primaries allow a wider torque band. (Note the careful word choice of "allow" -- the rest of the engine is crucial.) The only time you want large primaries is if the engine is primarily used at WOT -- drag racing and road racing. Step it down a notch (or two, depending on cfm numbers and cam) for autocross or a high performance street rod. From the horse's mouth (Jere Stahl): The bold part is of course a profound statement if his experience is on point. His company is recognized nationally by many as *the* header upgrade, and he only offers exhaust for dedicated race cars. That makes his experience rock-solid in my book.

Great advice on all counts. Going to a dyno should be automatic after every set of changes you make a change to your engine. Keep in mind that changing a cam won't change as much as you think it should unless you port the head to enable the additional flow to take place (or to maximize it, depending on the head or one's perspective). Also, unless you're hell-bent on nostalgia and either want to learn how to fiddle with carbs or are already a carb master, EFI is the only logical choice, especially since you already are running it. It's hard to do one or two upgrades to an engine and stop there. It won't make the additional power/torque you think it should simply because another aspect of the engine becomes the choke point instead of whatever was upgraded. In my opinion, unless you are *very close* to a manufacturer's OEM engine AND have no desire to upgrade anything further, not getting a fully programmable ECU is a disservice to yourself and also to future upgrades. "Good enough" is only good enough if the topic of discussion isn't important to you. In other words, are you trying to build an engine that is well-tuned and balanced, or are you trying to build a powerful one? Better to buy a programmable ECU once and be able to re-tune it on dyno day after any mod you could possibly think of for the engine. ~$150-300 for the dyno tuning is among the cheapest horsepower one can find. If you're intimidated to tune an ECU, you can simply pay the dyno shop to tune the car for you. If they're competent, it's not an issue. Megasquirt is one of the most popular ECUs (good for consulting those who have gone before you), but Electromotive is often overlooked. I'm personally very loyal to Electromotive. If you go to their site and download the .pdf of their operating manuals, you will probably see why, as they are unassuming of experience level and explain everything initially in layman's terms and then get in the weeds and show you how capable their product is. (Megasquirt's documentation may also do the same, I haven't seen it.)

IMHO a diesel cam couldn't possibly be worth your time... different fuel, different compression, NO spark, etc. The old adage "you aren't going to out-engineer an engineer" comes to mind. I almost always defer to experts in their own field (I say almost because some "experts" are nothing of the sort) -- cam design being aligned with actual use of the engine is *crucial.* That said, if the mission is simply curiosity, count me in!

HAHA! Love the pic of the star trek idiots! (What was that race again?) Where does love go? A soul? Can I touch them or put them in a bottle? HAHA. Pressure is the combined forces of all the particles slamming into the surface that is resisting it (ie the air is "pressing" on the surface, a balloon presses outward on the rubber barrier as you blow air into it). This is true of fluids and gases. In air, this includes water vapor and inert gases other than Oxygen. Psi is of course lbs per square inch (pounds are actually a force, not a mass -- grams are mass -- lbs assume we're on earth with a G-force of 1 [gravity]). Metric is better! As temperature of the air goes up, kinetic energy (a relationship of mass and velocity) of the air particles goes up, and pressure goes up. (tempurature is defined as the average random kinetic energy of a system) So, the faster particles move (tempurature), the more pressure. Also, the more air particles there are (either in a container, or in a column of air) the more pressure. In a pure vacuum, there are zero air particles, and it only exists in theory. Space is very close, but there are still gases present, just not enough to be anything more than negligible, trace amounts. In a relative vacuum, the pressure doesn't go anywhere, it's still there. Take a piston in a cylinder, since this is what we're really talking about. Let's "pause" time / flow and make it a closed system so it's easier to explain/visualize, ie, seal off the intake and NOT let air come in. "Vacuum theorists" claim as the piston moves down, a relative vacuum is the result, right? Obviously there was *some* amount of air in the combustion chamber before the piston draws down, right? Let's just say there are 1000 air particles in this tiny space, let's call it 10ccs, are at some pressure, let's call it 1 atmosphere and assume there was no compression and the valves just closed, too. Nevermind the actual volumetric expansion math. As the piston draws down, let's say the 10ccs became 1000ccs by the time it reached bottom dead center. This larger area still contains the same number of air particles, but now instead of 1000 air particles occupying 10ccs, 1000 air particles are occupying 1000ccs, which is 100x the volume. There's more to it than this mathematically, but the relationships are the same: as volume goes up, pressure goes down. The 1000 air particles, instead of bouncing off the *surface area* of the 10cc container, 1000 air particles are now bouncing off the *surface area* of the 1000cc container. So, *per square inch* (for the psi pressure unit), there are very few air particles bouncing off the container *relative* to the 10cc container. The pressure is still there, it's just been spread thin to the point of being somewhat negligible compared to when it occupied the tiny container. This relative vacuum is very trying on the container, so much so, that outside air will try very hard to force it's way in (just like water tries to force it's way into a boat's hull -- exact same principle, only with water the density is for all intents and purposes constant). Open the valve, and air rushes in from outside the head, just like opening some fresh-sealed foods hiss and let IN, also similarly, opening a can of beer let's air OUT. Ambient (outside air) pressure is again the result of the cumulative weight of a column of air from the surface up to infinity. At 4000', you have 4000' less in this column AND the bottom parts of the column are also the most DENSE due to the weight of the column above it quite literally compressing it closer to the earth's surface (due to gravity). We didn't even talk about density of the outside fluid (air), composition of the air (inert gases, humidity, dust / pollutants), all of which significantly affect flow performance. You can't ever stop going deeper in the weeds, really. An NA internal combustion engine (ICE) in space doesn't fail because of a vacuum... it fails because there is no oxygen for combustion. Yes, we're both saying the same thing, but well, if an NA motor were at altitude (4000' lets say) but in *pure oxygen* instead of "air," it would significantly outperform an NA engine at sea level running on "air" (assuming the engine were tuned for the change). It would be more along the lines of running on pure nitrous full-time. Also a totally different ball of wax, but the performance comparison is similar. As for the ITB/venturi discussion, 36mm venturis aren't remotely comparable to 45mm ITBs in my opinion. Nevermind the jets and venturis vs. injectors, air being shoved through a 36mm orifice can't possibly be compared to air being shoved through a 45mm orifice. Not a fair comparison; one is moving very fast and one is not. We agree carbs need a venturi, so we would literally have to flow test whatever venturi could keep up with a 45mm ITB. This would have to be flow-tested, because as already pointed out, the venturi incurs significant head loss and the ITB just doesn't restrict the flow as much. Sure, it tapers, but tapering is NOT a venturi. A venturi narrows and expands again by definition. Literally, a flow restrictor in and of itself. It's for this reason that I glossed over intake for JDM vs domestic L6s. If you *properly* supply the head with the airflow it is capable of (by proper ITB / venturi size), it then is simply a matter of achieving an optimal AFR for every throttle position / load / RPM combination. If you accomplish this, well, you're intake is no longer restrictive. The only way to accomplish this as far as I know is through experimentation on a dyno. You can get "close enough" if you are a carb guru, but with modern engine control (ie the computer for injector and ignition control) you can literally map out data points (for AFR and spark advance) for every permutation of throttle position / load (vacuum) / RPM (and even MPH in the case of Electromotive, and this matters because with cold air intake a measurable ram effect is experienced), and even further refine your starting points based on a temperature sensor in the [cold] air intake plenum and utilize the required feedback of an O2 sensor in the exhaust. There's just no way a mechanical device can compete with that, which is what makes a well-tuned motor powered by carbs so appealing. It's just that much more elite. There are of course intake design factors like how much to taper (ie 50mm air horn down to 45mm throttle body tapered down to your intake port diameter) across whatever distance (how steep is the taper angle?), how far the injector is from the port, injector size, etc. and well, I know of these concepts but I have no *practical* knowledge and have not studied how one affects driveability (torque) vs. hp or WOT flow, all with respect to RPMs. I might be able to talk to it based on what "makes sense to me," but it would be theoretical ONLY, not checked by any personal experience in the industry. We totally jacked this thread btw. I'll admit it. Sorry guys!

Strictly speaking, both are true, so long as by vacuum one means 'relative' vacuum. The piston creates a relative vacuum (ie pressure differential) which allows/causes atmospheric pressure to fill the cylinder. The only time this statement would be incorrect is if someone says the piston "sucks" or "pulls" in fuel/air. Vacuums do not suck up dirt; ambient air shoves itself into the vacuum because an air pump is creating a vacuum, and it the incoming air collides with dirt (loosened by a revolving brush) and the dirt goes with it, just like a plastic bag gets shoved around by the wind. My 2 cents when this topic comes up over scotch: don't ever let a pretentious person get away with saying "sucks" or "pulls." Short of artificial gravity or an atomic lasso cast via nanobots, you cannot *pull* on an air particle. Sarcasm aside, thanks for the practical knowledge, Tony. Hadn't thought of the flow restrictions ("head loss" is the term, and it's not referring to a head, but rather resistance to flow) encountered in the intake (before the port) and it makes sense to factor that into what pressure differential you choose to approximate atmospheric. Glad to hear my test was "standard" even if my mind has an asterisk wanting to know more about the temperature, humidity, etc. I had no idea that EFI operates on such a drastically less amount of pressure differential at WOT. Makes sense of course (no exaggerated venturi, but rather air horns or tapers), but I didn't think the difference would be so significant. This leads me to wonder why peak hp numbers via EFI vs carbs for the same motor aren't all that different. Makes sense for partial throttle positions (larger pressure differential), but WOT... hmm... [Highland? Islay? Haha.]

Big preface: I'm not an engine builder, but rather a guy that's learned the hard way and asked questions along the way. Since this is a mostly theoretical thread, I'll share my education as it applies to head flow. This is common knowledge to engine builders, but there are those that could benefit and I don't mind. The theoretical flow knowledge is the combined result of college and military flight school ( helo pilot - more sub-sonic aero theory than fixed-wing guys). Theoretical knowledge and practical knowledge don't necessarily always agree. Engine experts, please chime in if I'm out to lunch or what not. No, I don't know why they would do it without the plug. Two theories: either a.) they weren't supposed to and the supervisor caught it (and I just so happened to receive both numbers) or b.) same reason a dyno shop would turn SAE correction off -- to have bigger numbers and make the customer happier / shop seem better. Numbers without plugs would obviously be useless for calculating ITB / injector size, etc. The only reason I pointed it out, is because well, you never know what a shop does unless you're looking over their shoulder. Sometimes not even then! Haha. Also, in case anyone was wondering, flow numbers are per cylinder, not the whole head. This really gives you an idea of the performance when a 350 cu. in. V8 is often fed by a 450cfm-750cfm Holley carburetor. If I had one of those feeding my head, the head would still be theoretically *very restricted* (at WOT / full lift) and they are found happily feeding an engine ~twice our displacement. Hence why 40mm DCOEs really only belong on 100% stock L6s, even if the carbs are equipped with maxed out venturis. Head jobs of this caliber also take the time to ensure flow numbers between cylinders are comparable. Standard port/polish jobs don't ever go to a flow bench, so no one ever verifies if the cylinders are even, they're just eyeballed. This is why full race jobs cost so much. It's painstakingly detailed, gnat's-ass work. And an art tempered by theoretical know-how and a lot of R&D and experience. As for the disparity of flow between with/without plugs, if you look at the combustion chamber of an L6 engine, you notice the plug is between both the intake and exhaust valves, and is slightly offset. Plugs protrude into the combustion chamber, and as a fuel/air mixture flows around a valve, it wants to do so symmetrically 360 degrees around the stem. If there is a protrusion on one side, then part of that circulular flow pattern is disrupted. Not a perfect analogy, but for visualization purposes: Imagine a sprinkler flow, but a full 360 degree spread. If you were to stick your finger near the tip, you would get a flow disruption. (If it helps you visualize, think about the instant the valve begins to open -- it will "spray" just like a sprinkler will. As the valve opens, it becomes more like your garden hose nozzle on a "full" setting, only with a TON of lift to the point that it probably looks more like a fire hose) In sprinklers, it the spray looks uneven, and would look even more exaggerated than this: In the case of a sprinkler, the flow is still the same, it just sprays unevenly. This is because it's pressurized, and unless you contain the pressure (ie a shutoff valve closing), it will simply flow in a different direction. This is how a nozzle can spray a jet stream long distance. Same flow, small hole; it has to speed up. This is also known as the venturi principle (not to be confused with a venturi, which speeds up [narrows] THEN slows back down [expands]), which is not just for carbs or merge collectors, but even aircraft wings (known as camber, which is how they produce lift). Obviously camber in this case is unrelated to camber in wheel orientation. In a head, you don't have the same kind of pressure that a water pipe does, all you have is atmospheric pressure that PUSHES ambient (outside) air into the vacant space cause by a piston being pulled downward from top dead center. (Suction is NOT a real force.) Air is PUSHED by the pressure of the air behind it, which is why turbos and superchargers are so effective. They PUSH more air because they are at a higher pressure. This is why they have a gauge for boost, so you can see how much pressure (above ambient) is being utilized to SHOVE air into the head/cylinders. This is why Tony D's comment about being at 4000' is significant. At altitude, the pressure is less because the air is thinner. Thinner air, less *resistance* to flow, but most importantly, less oxygen available for combustion. In other words, 400hp at altitude is >400hp at sea level, just like 400hp in the summer is >400hp in the winter. Same car, different air, different performance. This is why dynos have an SAE correction, so that guys in the mountains can attempt to compare numbers to the guys in San Diego. *Attempt to compare.* This is why carburetors must change jets as the weather changes. Unfortunately, it isn't so simple as what altitude you are at / what the [barometric] pressure is. Pressure is literally how heavy the air above the sensor "feels" (imagine a column of air up to infinity). This "weight" or pressure also includes humidity. Humidity is always bad, not just for corrosion, but for oxygen content. H20 displaces O2, and instead of an extra O2 molecule, you might have one or two H20 molecules instead. This not only restricts combustion (less oxygen to ignite with the fuel) but also drastically affects flow characteristics. Aircraft wings HATE humidity, and aircraft engines hate it even more (turbines have thousands of spinning airfoils / tiny wings spinning around 20-50,000 rpm depending on the design). Not to mention water (in liquid form) is incompressible and tries to stick to surfaces and create drag. Bad. "Standard" atmospheric pressure is defined as 25 degrees Celsius at sea level. Again, this is PRESSURE, not air density. Pressure feels the sum of all airborne particles, not just oxygen. This includes water, nitrogen, carbon dioxide, etc. Aviation also uses a term known as "density altitude" that is essentially pressure (ie altitude) corrected for temperature. As temperature goes up, density altitude goes up, but actual density goes down. For example, if you take a balloon and heat it up, it will expand and eventually pop. Inside the balloon pressure goes up and density goes down, but the number of gas molecules inside the balloon is constant. Again, neither pressure altitude nor density altitude tell you anything about humidity content, carbon dioxide, etc. Even *IF* you somehow had the same pressure altitude, same temperature AND same humidity from one town to the next, your carbon dioxide content and other atmospheric gases can't possibly be the same (smog? lots of plants?). You can see why this is so complicated, and now you can see why fuel injection is so important. A computer senses if enough fuel was sent based on *oxygen alone* and simply adjusts it's output for the next stroke (and even does fancy things like adjusting for load, throttle position, temperature, etc). A carb could never compete with that. Ever. Even IF you could tune it perfectly, it would only be for THAT DAY. Hell, that hour. Comparing carbs to fuel injection is like comparing the drivetrain of a GT-R to the drivetrain of a peg-leg manual. No comparison. All this air stuff is why people say dyno numbers are only useful at the same shop on the same day. Plus the machine calibration factors. To the point, in a NA engine, without that extra push found at higher pressures (lower altitudes or boost), every little bit of turbulence matters (inhibits flow), which is why port jobs are so important and therefore ultimately "all power is made in the head." It's more important that the internal turns (horizontal runners turning downward towared the valve, also how it goes "around" the valve) encourage laminar flow (smooth and straight) rather than turbulent flow (disrupted, swirling eddies and what not). *Theoretically,* I do not approve of the JDM port jobs, because they don't encourage laminar flow "around" the valve stem, and because they are polished (again, reference golf balls). The Sunbelt pics I shared show a triangular shape right in front of the valve guide/stem to encourge the fluid to start turning *before* it runs into the stem and therefore minimizes becoming turbulent once encountering the valve guide/stem. Again, I stress theoretically, because the rest of the port is obviously HUGE and therefore may overall flow more despite the turbulence. However, if the flow isn't laminar, then at partial throttle positions, the volumetric efficiency (VE) would drastically be reduced. Again, the JDM heads are for dragsters, which know WOT only. The video of that red S30 sounds nasty and pulls hard, but below ~4.5k, it sounds like an F1 car and just runs like $#!+. Sexy, but not good. Back to the plugs, if a plug is adjacent to the valve stem, the flow is disrupted for approximately one hour of a clock position (1/12). The turbulence around the plug affects the adjacent areas, as well. How much, who knows, but evidently it's about 25cfm. (VERY SIGNIFICANT.) At this level of being "in the weeds" fishing for performance, indexing the plugs becomes an important factor, which is why I commented that I don't know the depth or orientation of the plug. I personally orient my plugs with the open spark facing the exhaust valve. This is for two reasons: it puts the external electrode (ground electrode in NGK v-groove example below) toward the cylinder wall AND less than perpindicular to the intake valve. I want the ground electrode less than perpindicular to the intake valve for two reasons: put the "finger in the sprinkler" in a minimal damage direction but most importantly, to have the center electrode bare and toward the exaust valve. Whew! Now I want the center electrode bare and toward the exhaust valve for maximum flame front propagation, and this propagation is completely uninhibitied toward the exhaust valve, which is where it has to go eventually anyway. Sure, most of the cylinder may not care about that last bit, but the little bit if fuel/air that remains within the vicinity if the spark plug now has nothing in the way between it and the exit. Why not put the ground electrode away from both intake and exhaust valve? It would be *too* close to the cylinder wall, and the flow inhibition and flame front inhibition would likely cause a small dead spot between the electrode and the cylinder wall, especially at higher RPMs when there isn't as much time for the flame front to reach every little nook and cranny for a complete burn. I pick an in-between to balance the pros and cons. This is in the weeds. My Chevy V8 will not benefit from indexing the plugs, but my race motor on race gas will. Also in the weeds, the NGK v-groove design causes the spark to attract toward the outside(s) of the ground electrode, encouraging flame front propagation in both directions (and therefore around the ground electrode as opposed to directly through it. Again, my Chevy will not notice, but my race motor with race gas, will. I for one would appreciate an engine builder confirming the indexing orientation theory. Obviously we know indexing is better than not, but optimal orientation and the why, well, I'd like a confirmation if anyone's got it. For the above reasons, the below type of plug (quad ground) is about the worst idea EVER in terms of flow and flame front propagation. Perhaps a reliable spark in difficult conditions such as extreme cold, but I wouldn't ever put it any of my vehicles. And finally, 28" Hg (mercury) is NOT a standard atmosphere. 1 atmosphere (sea level @ 25 degrees celcius) = 14.7 psi = 29.92" Hg 28" Hg = .94 atmospheres = 13.75 psi 28" may or may not be the "standard" test, I have no idea, but it isn't a standard atmosphere, that much I do know. 15psi of boost equates to an NA engine just driving around as if they were at approximately 30,600' below sea level! (1" Hg per 1000' thumbrule) Now you know why some view turbos/superchargers as "cheating" and many NA engine aficionados regard NA engines as "pure." This extra boost "only" produces an extra 25-50% horsepower, depending on the engine. In some cases, boost can well more than double the power output, but you really have to get into the weeds on the turbo side of the house to do that. I better stop typing before I get too delirious. Very overdrawn on sleep!

addition stahl exhaust pics (AKA porn): these are to compare the arrived Stahl race headers to Monza / MSA performance headers and the aforementioned octopus headers. I was immediately impressed that everything here is hand-made. Even more impressive, the merge collector and headers were made at different shops, but slid together like a glove. Remarkable. You can really see how impressive the difference in merge points are between "performance" headers and "race" headers. Also, my Stahl headers are NOT the largest primaries, and my merge collector has a smaller merge diameter than road race engines. This is for torque down low at the cost of high RPM power. Bottom line, the octopus headers are really flipping crazy to look at, but so are these. These are tuned, the octopus headers don't seem to have as much detail in that particular regard. Again, WOT vs. torque band.

Wanted to update some of my posted head flow data and throw some additional "food for thought" in the mix. I received the official printout from when I had my head flow tested, and it also included flow performance WITHOUT spark plugs installed. The previous (above) chart is how it flows WITH plugs installed. Note that these 'without' numbers bear a striking resemblance to other "all-out" head jobs. Also, I have no idea how deep the plugs were (they weren't my plugs), if they were indexed, etc. etc. Here's the additional data, comparing WITH vs WITHOUT. The food for thought is this: flow numbers should be taken with a grain of salt, just like dyno numbers. Numbers are somewhat arbitrary unless comparing head improvements on THE SAME BENCH with THE SAME AIR. That is to say, unless specified, we don't know whose numbers have plugs and whose do not. We're also assuming flow pressure is the same (standard?). Pressure DOES NOT equal density, as humidity and temperature are very significant factors, and fluid density and composition will greatly vary airflow characteristics, even if on the same head and same bench. Case in point, as I review my dyno plot, I notice that they turned the SAE correction OFF for the printout. I have the raw data files, so I now know the truth: my 264rwhp was a result of it being a cold day. The SAE corrected was 250rwhp, which is what I'll need to use when I return to the SAME DYNO once I get my car all back together. They obviously wanted me to see the bigger number, so they gave me the raw hp, not correcting for having good air that day (at sea level). I digress. Again. And lastly, the head shop was *extremely* impressed with Jim Thompson's work. (Again, he no longer does L6s, sorry to say.) They were so impressed in fact, that they kept the head and studied it, photographed it, etc. in hopes of duplicating its flow concepts on future race heads (unknown type). They really went on and on about it. I'm sure there are other shops out there that still do this level of work (Rebello). You usually really DO get what you pay for. If you don't curse that the price of your head costs as much / more than most complete V8 crate motors, then you aren't getting a full port job. It takes that many hours of detailed labor to do it right. Again, the power is all in the head. (I'm still not even close to unlocking mine -- race headers this year, ditching the "street carbs" next year.)

And on my end, now that I see how *ridiculously* long my post was (really?), I can't believe how bad we're theorizing this exhaust to death! Now that I re-read it, I wonder if it's just a bunch of hot air... whirlpooling exhaust seems like a bit of a stretch! Haha. I do still think the ultimate WOT volumetric flow rate of the octopus header will be measurably greater, just like it's torque band will be worse than that of a 3-2-1. Also, to set the record straight, I wasn't suggesting proprietary secrets (wherever that line is drawn) be shared, in case it came across that way at all. I don't feel like anything I shared could be duplicated arbitrarily based on a pic and a couple numbers for a cam, and is therefore merely for discussion / comparison purposes. Oh, and the 3-2-1 merge collector details (distance from exhaust valve, etc) should be taken with a large grain of salt since it was based on a single conversation with JohnC on the phone, and I may not be remembering it accurately. I sure as heck didn't design it, the point was that exhaust is as tunable as every other aspect of a car, unfortunately it's one setting only: installed. Again, I'm a paying customer who enjoys learning about what he's doing to his engine, not someone who actually knows what they're talking about.

I agree with Jon/others who suggest you don't need a ton of truck, our cars are light. Make sure you get a 4x4 if you don't get a dually, you never know when a track wants you to tow your trailer across a mud lot! I still tow my Z with my '98 Chevy 1500 5.7L which has more than enough power, but gets 8 mpg while towing on the hwy. If you put enough miles on a trailer, perhaps diesel is the better option. Also depends if the truck is your daily driver like it is for me. That said, on the road you would be *safer* stepping up a notch from say a F150->F250 or equivalent. Perhaps it depends on how many miles you think you'll tow a year, what kind of highways and roads you're on. Oh, and if you get an enclosed trailer, get extended side-view mirrors! Next go-around, I'm stepping up the truck a model or two, if that's worth anything. Yes, it's enough, but it's old and it isn't that safe. I agree with others that safety is a concern, why not protect your car on the way to the track, too? I keep hoping to run into someone who went with a new Ford with an EcoBoost engine and tows with it. I don't think I'd like it (I think you should be able to hear if your truck is running, but that's just me!), but it's a sweet setup regardless.

First of all, wow, this is a wonderful thread Josh, thank you for the tremendous time and thought you've put into this, and to all who have contributed. I've come a long way over the years thanks to HybridZ, but I'm still learning, and like many of us have an insatiable thirst for maximum performance, both theoretically and practically. That said, I'm just stumbling on this thread now, and my big-picture conclusion with the mythical JDM 400hp dragsters is that they're more hype than hope. I don't doubt that they may edge more ultimate hp out than our own L6s, but agree our road racing and autocross engines are built for area under the curve. I would have to see their engine on the dyno right after I saw an established engine on the same dyno, same day in order to believe 400hp with gasoline @ 12:1. It's too good! That would be nearly 130 hp/L! The Ferrari Enzo produces 110 hp/L with similar fuel/compression at 7800rpm. I just don't see the VE of 2 valves per cylinder with carbs and premium gas going against an Enzo's VE. Need to see that one in person, or hear from those who have. I agree with others that have defended the reasons development goes in certain directions or doesn't. ZR8ED, had some great VE comments, concur. Ultimately I would never want a JDM motor for a bunch of reasons, but this isn't about that. Yet. For shared knowledge purposes, I'd like to point out how similar my Jim Thompson / Sunbelt head is to some of the JDM head info you compiled. We agree power is made in the head, so let's start there. To my knowledge Jim no longer does L6s but works on BMWs. Sunbelt no longer exists, but merged with Kinetic Motorsports. I feel no moral obligation against sharing my head's information; I bought the head, I bought the cam. I'm allowed to share what I know about it if I want to, maybe other members with fancy heads from shops other than Sunbelt feel the same way... Disclaimer: I'm someone who got incredibly lucky and fell in line about seven years ago behind JohnC, who paid for serious R&D for his N42. I'm not an engine builder, however I do have some data about the E31 head Jim built for me. Also, I know there are other L6s builders out there, and I nothing of how they build heads or cams. Just sharing the one I own. And a lot of hot air. HEAD: -early E31 in style of JohnC's N42 -37cc chambers -44mm/35mm valves -pictures of ports below, very different around valve guides -208/134cfm in/ex @ .565" lift (recently tested, no details on bench) -202/145cfm in/ex @ .525" lift (according to Sunbelt as shipped, Flow Prow bench) Also according to Sunbelt: "200cfm on a Flow Prow bench is 225cfm on a Super Flow bench." I know nothing! These pics are from 2004 when I received the head from Sunbelt. Note how different the combustion chamber shape is (E31 head) with similar cc numbers. Also note how different his valve guide approach is. I also add that this cam is designed with a single set of springs (outer only) whose length is between that of typical inner and outer springs. This cam is profiled specifically for these springs and uses 25% less seat pressure. Or so I'm told. So that's a variable. Also note the texture isn't shiny. It's my understanding that polished actually increases surface friction, and a slightly textured surface has less drag (head loss) along the surface of the ports (dimpled golf ball effect). I'm surprised the JDM heads are so shiny. (Seems to me the old SSS / Nissan Competition valves were "swirled" for this very reason.) Okay so obviously the main difference thus far is port profile, texture, valve size, valve guides and peak flow numbers. And seat pressure. Lol. Isn't that just about everything except the cam!? .530" lift isn't necessarily so small if your entire engine is tuned for it... JohnC had .534" lift, Dan Baldwin had .550" lift in respective posts in 2004. Both Sunbelt-built, both powerhouse NA L6s. It isn't size that always counts, it's what you do with it. Or so I hear! Definitely not true with my tires! Contrarily, I had .525" lift in a head built by Jim, and I only put down 195 whp at the time. Street performance intake and exhaust, street compression, poor fuel, etc. Rebuilt in '08 to 12:1, race cam, maxed-out 40 DCOEs, and race fuel and put down 264 whp. Still more out there. Same head all along. Tune, tune, tune. For *your* head, for *how* the car will be used. my 2nd Sunbelt cam: .565" gross lift (Arbitrary? Nope! More on lift vs. flow below.) seat duration is 326º/315º .050" duration is 290º/275º lobe separation angle 104º Torque from 3500-7000 Power above 4000 (up to 7700, outer spring advertised maximum). Asymmetrical lobe, 104º separation. Note that the exhaust lobes are more asymmetrical than the intake. Has nothing to do with minimizing overlap; it's just to sound cool. (Haha!) I really hope this doesn't upset anyone. There's so much more to cams than basic specs. Any attempt to replicate would be a fail as far as I know. I say 2nd cam because the head originally was originally delivered with a cam with .525" lift and 290º/275º total seat duration. Hmm. I also very recently had my head flow tested. Different numbers than what Sunbelt provided (more on that in a bit). Here's a graph from the numbers I have this go-around: Note that for Jim's port/polish, there is a diminishing lift performance between .550" and .600". Again, no coincidence, .565" lift peaks the flow chart. I'm not saying Jim Thompson is the only one who has built a head/cam this well tuned, but I am saying that it's been done on this side of the pond. Just not with their oversize++ valves and somewhat radical headers. I would LOVE to know more about Dave Rebello's heads. I'd love to see pics of the ports, cfm numbers vs. lift, cam selection, etc. Suspension knowledge isn't proprietary, why does engine-building have to be? People are still going to go to well-recognized shops and order race motors to be built. EXHAUST. I honestly don't see how exhaust can come anywhere near supersonic speeds, no matter what kind of nozzle you create. But damn, look at those headers! Haha! I mean look at the damn things, they look like a waterpark ride! Our race primaries are mandrel and equal length too, so what? When I saw the octopus headers my first thought is that they appear to have fairly equal angular-distanced primaries, too. (Total degrees of bending each pipe does, at the same radius even.) This allows about as equal / laminar flow as one could hope to achieve comparatively between six primaries. I'd like to have equal angular distance in my own headers, even if just for my own warm fuzzy, but I really don't see it making much difference except for WOT at higher RPMs. I have yet to read an in-depth explanation of *why* 3-2-1 has better scavenging/torque than a 6-1. While the 6-1 might theoretically out-flow a 3-2-1 (less friction / head loss), the 3-2-1 will out-scavenge the 6-1. The only in-the-weeds thought I have is that in the 3-2-1 design, only 3 cyls are shared for a given collector. As the pressure wave reaches the merge point of these primaries, it sees a junction; an big pipe turn going the same direction down a 2.5" pipe AND two sharp u-turns backwards up the other two primaries toward the head. As the wave propagates past the merge point, low pressure is felt behind it, which is felt upstream toward the two exhaust valves via the other two primaries. This low pressure is shared by the two primaries. In the 6-1 design, this low pressure is shared by 5 primaries. 5 primaries, 4 strokes, you do the math... sometimes two valves are open vice one. It can't possibly scavenge as well in my mind. (I totally admit that I'd have to track out the 4-stroke cycle for all 6 cyls for verify the 3-2-1 setup never feels a pulse with two exhaust valves open. Not going to think that hard.) Torque, not power, is affected most by scavenging, right? Then that's it. Drag racing doesn't care about torque as much as power. Ultimate peak flow potential. An octopus header is a work of art for WOT only. Road racing cares about torque. Autocross does even more. The street even more. These Stahl header photos are courtesy JohnC. I believe in this pic they are 1 3/4" primaries (equiv of 45mm) for road racing applications. They run 45-48mm out there, we run ~42-45mm here for autocross / road racing respectively. Again, trend respective to how the motor is used. Note the three dimensional reverse-coning on the left collector. Looks similar to cyclone shapes on some household vacuums. Not to be confused with cyclones, this air isn't spinning, but note the gradual coning / venturi effect. Very nice. You can see these deliver two 2.5" collectors. I don't have it in hand yet, but JohnC is sending me a custom merge collector that sounds pretty damn cool (there's still one more merge with a 3-2-1 design of course). If I recall correctly, I wanna say it's a 20-degree merge angle (pretty steep!) where both 2.5" collectors merge to a single 2.5" pipe. At this point in time a pressure wave will scavenge the other collector tube, alternating strokes. Smooth. Then I think JohnC said it will even nozzle slightly (to narrower than 2.5") then expand to 3". He was very specific that this will be exactly 36"-38" or whatever it was from the exhaust valve. No idea why it was so specific, but I would theorize that it's the distance that draw torque out the most and was discovered experimentally. Perhaps he'll chime in. From this point on (i.e. the middle of a 3" pipe), the 6-1 comes back strong. It's an exhaust race! Haha. No, seriously. [in terms of transmitting a change in throttle position to the drivetrain, the 3-2-1 wins. In terms of ultimate WOT flow, the 6-1 wins.] "And they're off!" In the lead we have 3-2-1 that just seems to have been sucked away at tremendous speed by the previous stroke! It's hit a sharp bottle neck at this "merge collector" and now it's home-free with nothing but 6' of 3" mandrel pipe! 6-1 is way behind, BUT at this point from the exhaust valve both are traveling at the same speed (both are in 3" diameter pipe, similar displacement, similar head flow). The pulsing motor's exhaust is less dense (less time allowed for flow), therefore at steady state WOT, once both motors are up to speed, THEN AND ONLY THEN does the 6-1 design win the race. It has fluid density. The exhaust is traveling at the same speed as the 3-2-1 at this point, and it nears the muffler then it accelerates out. I have a theory for their velocity nozzle muffler, but I admit it doesn't quite feel complete. The revolver-style merge collector induces a rotation to the exhaust, right? Slightly cyclonic? Whirlpools flow faster than pulsing bubbles. Watch your bathtub empty itself and you'll see a whirlpool. They're whirl-pooling their exhaust, and this effect only takes place at steady state WOT... any transitions in throttle input will disrupt the flow enough to temporarily cause the flow through that funnel to be turbulent and run like crap. This ONLY would be applicable to a cyclonic exhaust flow, which would only be created from a 6-1 header with a revolver style collector. Again, I'm thinking this results in piss poor driveability / throttle response. One might argue that the exhaust is going one-way (whereas with a whirlpool, water and air are trading places), and that a whirlpool would therefore be fruitless. However, it's pulsing don't forget, so the air in front of and behind the pressure waves do funny things, especially when narrow, and just might be happiest to swirl and not fight. Like the air and fluid in this picture. Idiot check: what does Formula 1 do? Not a swirl! After their graceful merge collector, they aren't swirling -- they're in the weeds fishing for aero crap (I would argue that hot gases will only piss off their wings -- but aero is another discussion!) Back to the point, they're doing aero stuff, NOT spiraling their exhaust and funneling it out some magical orifice. Neither is NHRA. That's all the common sense check I need... a magic exhaust tip will not make my car go faster. If it would, you would see spiraled headers on Top Fuel dragsters that look like Dyson vacuums! That kind of thinking (tips will make me go fast!) is what gives JDM / RICE a bad name in the first place. And no Josh, that wasn't aimed at your theory. Basically I'm suggesting we have a comparable level of tuned exhaust performance they have across the pond; they are tailoring to peak flow/power and we are tailoring to scavenge for usable torque. Whew! Man, that's about as much hot air as I've ever typed. By all means, please put me in my place if I'm out to lunch! Found this video. Shows how much of a pig it is down low, as predicted, but god, does it that motor sound MAD! It's the red motor in the red S30 we've seen a few times in these JDM threads. INTAKE: Not much discussion, rightfully so. Pick the right intake to match the flow / usage of your head, tune it on the dyno, the end. BOTTOM LINE, they are too far in the land of diminishing returns for my wallet. No one would dispute that our autocross and road race motors' area under the curve would have a tremendous advantage over the JDM dragster, which is how we use them. Put their motor in our cars for our events and we'd get beat for a lack of driveability! Reverse is also true of course, we would lose at the drag strip. Note that the Kameari $6500 head claims 320hp, not 400. That looks like it has the potential to actually be a get-what-you-pay-for item, unlike the hardware. I'd like to know what Kameari claims that head, the one pictured, actually flows when delivered. Okay fine, this thread is about the engine, not its use. They only use their best ~3000rpm power band at WOT and that *is* their purpose. Fine. On dyno day add up the *area* under each engine's best 3000rpm band and compare them (peak too, why not). I would claim that percentage-wise, on the same dyno on the same day, there would maybe be not more than 5% better numbers on the JDM best vs. our best, whatever L6 that would be. That's my claim, maybe that's me being an American and defending our ways, but it's also my honest assessment with what I think I know at the moment. One of us would have to skip the pond to find out. Hats off to them for their peak hp achievement, though! And God, I loved the sound in the video of the red Z on track! Most people aren't willing to pay twice as much for a proven part in the search for that last bit of power. But hey, some people have too much money to spend. Luckily most of them go for "Porsh's." For the rest of us, I agree Tony D, send the money to a shop like Rebello and wait for a crate. Best option I see at the moment. Anyways, I'm rambling at this point and have probably embarrassed myself enough. I like my autocross motor, it's awesome. The end.