Gollum

I agree with all JohnC had to say, and tend to agree with the old farts around here. That said: I find it CRAZY how poorly most people around my age (25 currently) can't find useful info. I've worked as a freelance computer/network repairman since I was 15 and if there's ONE thing I've learned, it's that in this day in age, all the information possible is available at your finger tips. This should lead one to conclude that the best worker isn't one who can remember the most information to pass a test, but the one that can best find information and put it to use. I'm paid $100 when I walk into a business to fix a computer problem not because I know everything, but because I know how to find everything, and how to apply that found knowledge. All the same principles apply here at hybridz. It's never about knowing enough to fit in, it's about knowing how to find information to learn to see things the way the experts do. My goal in life isn't to understand every detail of everything, but to know how to find the applicable details of what I need at the moment. Luckily I have a decent memory and CAN do quite a lot of different things without references all the time. I'm a jack of all trades guy. My mother in law actually said just a few weeks ago after finding out I had a photography gig "Is there anything you don't do?" This isn't because I'm a genius, I'm not. It's because I know how to find people of high caliber and LISTEN and PAY ATTENTION. And that's what I've been doing here since I was 14. Reading!!!! I lurked for over a year before a became a member and I wish more young people would do the same.

Ideal conditions don't include a heat that will be having massive heat management issues at 700rwhp. Ideal conditions don't include intake temps over 150F, nearly impossible on most 700hp setups. Ideal conditions don't include imperfect cylinder to cylinder tuning, which I've seen few people account for. Ideal conditions are just that, fantasy that few will ever see into being a reality. Another factor that people don't talk about is "under what stress" and "for how long?". There's quite a many 1000+ HP 2JZ motors out there, but how many of them will LIVE at WOT? I've seen motors making 300+HP per liter that do it all day long without breaking a sweat, while other 150HP per liter motors blow up on a hot day. Ideal conditions rule out this factor, since the question is just "how much power can the stock pistons make". It's a fairly arbitrary question but yet it seems to be the one everyone tends to ask, as it makes something "real" in our minds and gives us something to talk about. I'm honestly not surprised that Jeff is making about 500 to the wheels on a stock bottom end. I'm somewhat surprised more people haven't done it. It's obviously quite possible. I don't know of anyone who's broken the 600hp mark at a stock bottom end, but I don't think Jeff's setup is the most exotic ever seen and I think it's certainly a goal worth shooting for.

Thought I'd offer something more on the initial topic here. The thing about detonation is that it's poorly understood by most hot rodders, tuners, car builders, what ever you desire to call them. The mere fact people even car about the octane number of alcohol or LNG. It took me quite a lot of searching to find the answers I was looking for on the subject, but the most important thing I learned was that the whole octane rating system was NEVER designed to compare horsepower, or even compare gasoline to other fuels. It's SOLE purpose was to evaluate how different PETROLEUM BASED FUELS would run in comparable engines. Basically, it was to make sure you didn't damage your engine, and bought an appropriate grade fuel. The most important thing to realize is that the octane rating was done in a test engine, just like an engine in your very car, only it's a single cylinder engine with adjustable compression ratio. There's two models of testing, the more prominent of the two you keep the ignition timing at one point and then increase compression till detonation is detected. In the other method you adjust timing with compression, but it's still a static timing setting for each compression level. If you've dealt with any alternative fuel to petroleum gasoline you should already see the issue. Not all fuel bases have the same burn rates, thus not all fuels have the same "timing requirements" to make peak horsepower. Remember, the goal of power is never to run as much timing as you can, but to place the peak moment of force just past TDC to allow as much energy as possible to be transferred to downward motion. This test method then is ONLY useful to compare similar fuels against each other, or if you're checking a fuel for a wold in which you can't adjust timing of an engine. Yet, for years hot rodders have thought "more octane means more power!" which couldn't be further from the truth. If this were the case, then petroleum based gas over 98 octane would be able to out perform E85, but that's not the case. In fact, even if you factor in the fact that E85 is lower energy density, but also factor in the extra fuel you're running to reach stoich or even "peak rich torque", E85 is still making even more power than it should in THAT calculation!!! This isn't to show how "great" ethanol is, but to show how broken our understanding of fuel, power, octane, and detonation is. So, lesson #1. Detonation is a burn characteristic. Don't confuse it with a timing issue or a mixture issue. Even though both of those things in our world "SOLVE" the problem, that doesn't mean that's what detonation is. #2. Detonation is NOT preignition. There IS a serious difference. If you compression gasoline vapors in oxygen enough it would combust all on it's own without any help from a spark. This is preignition. What we're talking about killing motors is detonation. Detonation is what happens when an even like preignition, where the fuel does combust on it's own accord, is started by a previous spark event. Detonation happens AFTER your spark plug fires, preignition happens before, or without the spark plug firing. So, knowing just these two things, which you can go much further in detail on, you'll be able to deduce that what we're dealing with is chemical stability, or burn stability. When you start ignition in a sealed chamber pressures rise throughout the chamber, long before the flame reaches all the fuel molecules. This very pressure increase can be enough to send the another strain of fuel molecules into combustion. Now you have multiple flame fronts in one chamber. This is detonation. Ask a chemist how to prevent detonation and they'll most likely say "remove the heat". This leaves us hot rodders saying "well... we... ummm... lower compression!!!" because even the beginner hot rodder understands that compression = heat. Hot rodders, especially of old, know that heat + HP and thus begins the never ending battle of HP versus compression versus timing which is the VERY thing we're actually talking about in this very thread, even though it hasn't been directly discussed much at all. But, as you might know, there's a plethora of ways to remove heat from the chamber, all of which are things attended to by real race teams, especially formula 1. First and foremost is cooling your cylinder head which forms a good portion of the overall chamber. Next you want to cool the piston as much as possible. There's two ways to cool each. The piston is cooled by oil, it's very lubrication, and the cylinder head is cooled by water, and also oil to a minor extent. The block is cooled by water as well, and there is heat transfer there between the piston and block, but I'd argue it's insubstantial, ESPECIALLY when we consider the other main contributor to temperature control.... ...Atomization!!!!! What's the biggest difference between a cold engine and a hot engine? One runs absurdly rich, and one can run a wide range of fuel ratios. A cold engine needs to run huge excess amounts of fuel because it's gasoline VAPORS that burn, not liquid and the liquid needs HEAT in order to atomize and become vapor. Until the engine is warmed up a bit we need huge amounts because so little atomizes. But there's another factor at play here. Basic physics: Every action will cause an equal and opposite reaction. Just as it takes heat to atomize fuel, the atomization process actually REMOVES heat through "latent heat transfer". This is a huge reason direct injection motors can be more aggressive with timing and compression, as they can remove more heat from the chamber. When you inject fuel pre-valve you're removing heat from the air, and also the intake and intake valve itself, which hardly matters at all. The extra heat that's being removed from the intake can be removed from the piston and cylinder head when utilizing direct injection. Besides just those basic cooling aspects there's also other forms, such as material engineering. Using a material that can handle heat better and has a higher transfer of heat will reduce detonation tendencies. Why do you think that though iron heads can handle detonation nicely, they also tend to not allow as aggressive of timing? Let's not also forget about another huge area of breakthrough: Coatings. I'm actually out of time and will continue this later.

It's funny how many people don't like the front end. I'm not a huge fan, BUT, the aero of the stock front end sucks big time and if you look at that front end with that in mind it does a pretty good job of closing up the front without looking like you just shoved something in the front end to block it off.

Well even though the threads of the L31DETT all died I'd say it's safe to say the stock rods will reach 700rwhp. I personally think the pistons MIGHT survive that if the condition were right: 1. Cylinder temps need to be LOW LOW LOW. 2. Intake air temps need to be under CONTROL, sub 150F 3. Big aspect: The head needs to flow well enough that you're not needing to run 30psi to get to those power levels. The more boost you're running the more heat your fighting, and you'll already have enough heat from the horsepower to deal with. So really there's two questions in that one you ask. 1. How much power will stock pistons take with the stock head? 2. How much power will the stock pistons take with a modified head, but let's add a 3rd just for the hell of it, 3. How much power will the stock pistons take in a theoretical perfect world? The other huge question in all this is "what fuel"? Not all fuels burn the same and exhibit the same loading forces on the piston. It's a minor detail, but it's these minor details that kill you if you just guess and figure "well it's good enough"...

Anyone with just a little grinding experience and a steady hand can see HUGE improvements over stock without going "all out" on a race ready head from someone like Robello, Paul, Brian, or Peter. This is in no way to devalue what these guys do. But thanks to the resources available on this site ALONE, let alone others out there, there's enough info to properly unshroud the valves, lift the intake ports as much as practical, reshape the bowl, and modify the cooling passages. All of which can get you quite a lot of extra power for very little coin, other than your time. And honestly, having a CNC to port the heads with is such a small aspect of cylinder head prep. Like Peter said, it saves his arm and cuts down on time. It's not like some magical cure to making power. No such thing as a magic bullet.

In some ways it applies to both motors in question though. But really pharaoh, the way some of your statements are worded can be quite misleading. There's pushrod V8 drag cars running 13:1 compression ratio running 20+psi on ethanol.... Compression doesn't limit boost, it limits timing. Timing CAN limit power, but you have to understand the whole picture to figure out how much power you're "losing" from added compression. Just throwing a turbo on a NA engine without ANY other supporting mods probably WILL break some parts, but that has NOTHING to do with the turbo, but EVERYTHING to do with the tune. And you don't EVER lean an AF ratio because of compression. If you're trying to play it safe and keep the detonation at bay you enRICH your AF ratios. Adding excess fuel does a few things to reduce chance of knock. 1. Causes a slower total burn that can often push back the timing of peak pressure of combustion, 2. Cools the air charge as there's more fuel to be atomized, and in doing so transfers more heat from the chamber. 3. Causes the mixture to be harder to ignite (goes hand in hand with #1). When you start to look at the WHOLE picture you see that timing and mixtures are a dynamic duo. You can't change one without affecting the other. The leaner you run, the less timing you NEED to run for peak power (not CAN run before peak power, there's a difference, think about it). The richer you run, the more timing you CAN run, or CAN get away with as some people tend to tune. Most people get knock, so the add fuel in that area. That's ONE way to fix it. You could also pull timing in JUST that spot and see what happens. Oh, and personally..... If I were running a turbo on a P79 w/flat tops combo (read, quench heads, not open chamber) I'd run as THIN of a head gasket I could, PERIOD. That would REDUCE my chances of detonation, because though I might be adding a .1-.2 compression over factory, for that marginal increase I get much improved quench, and the more you can improve quench the better. The "perfect" setup for huge boost would be to run a MN47 with a dish piston that matched the shape of the MN47 chamber, to keep the quench areas flat against the piston, and keep the chamber spherically pancaked, hopefully landing you around 8:1 compression. That'd be "ideal" for someone wanting to run anything from pump gas to race gas. I personally want to build a MN47/flat top combo as a turbo motor for E85... And probably run 15+psi... And on a stock bottom end.

If you're talking about JUST THE CHASSIS, then the difference will be 25-75lbs depending on which 240Z and which 280Z chassis you're talking about. All the difference between the two curb weights is in everything bolted onto the chassis. My 280Z weighed in at 2560 with a L28ET with the interior stripped. I still had a full layer of dynomat which is a heck of a lot heavier than carpet, so really this is nearly "stock" weight. The car is now quite gutted and my goal is 2300lbs with no fiberglass body parts. Once I have the money for a fiberglass hood I'll go even further and shoot for 2200. In that second stage that includes fiberglass parts I also plan on converting my 280Z back to a R180 and doing a CLSD R180 subie conversion. You have to realize though, the 240Z underwent a LOT of changes just from '70 to '73.

Can somebody be more specific about what 2 cars we're talking about? I only see a S30 mentioned...

I love VG equipped S30's, but that's 100% about weight, placement of said weight, and packaging size. YES, it's more difficult to fit a turbo + exhust into the engine bay, especially without steering linkage modification. YES, the L motor is better all around. Revs higher dollar for dollar, has less oiling issues, YES, the L motor has proven to make more NA power time and time again. BUT!!!! Not only is the VG a bit lighter (not by more than 50 pounds by most accounts), but it's HALF the length, AND it's a V motor keeping the center of gravity LOWER. That's what I like about the VG, but same could be said about nearly ANY V6 between 2 - 4 liters. I also like that the VG has commonly available turbo parts and a stock ECU and injectors will take you to 300+whp just fine, and you CAN tune it if you so desire. The VG is also dirt cheap. As the VQ becomes cheaper and more readily available then I'll say the VG should just be left alone, but that day isn't here yet. A quick and dirty VG versus VQ will be less than half the swap costs. That's hard to argue. Now..... All that said... Unless you're setting up your car for hardcore HPDE racing, the S30 will handle JUST FINE with a L motor in there, and then all the benefits of the VG I mentioned just went out the window. The L engine is very capable. So it's really up to you.

Now you do... http://www.harborfreight.com/garage-shop/portable-garages/10-ft-x-20-ft-autoshelter-portable-garage-68772.html Or http://www.northerntool.com/shop/tools/product_200471112_200471112 Your welcome.

Woohoo! Congrats. Gotta love the hybridZ community. I hope 280zex got a beer or something out of this at least.

Barn find? Lets see proof

Behind my grille is probably a few megatons of earth... it went to the land fill years ago now. I run no grill. But if I were to have a grill, the only thing between it and the radiator is just the few necessary wires to go to the driver's side headlight and turn signal.

Q: Have you tried using any sort of starting ether to get it running? Get someone else on the ignition switch and give it some spurts and see if it's much more ready to cough. If timing is close, and you have good spark, you should even be able to get the engine to run for a bit just on starting ether if you keep spraying it. If this is the case, and you get it semi-running but stops once you stop spraying ether, then you definitely have something going on with your fuel supply. Then from there you can check for fuel pressure at the carbs, then from there verify you don't have something obviously wrong with the carbs.

huh.... I'd never thought about that, but that REALLY makes sense. Quite a cheap and elegant solution if you think about it. My .02 cents I was going to add to this thread was that I USUALLY don't really like superchargers on inline engines because packaging is usually just odd. But considering that we DO have a readily available 4 barrel carb intake manifold the rest of the process isn't too complicated. So, I must say.... I support

brian ~ yes If you had a 5.0 v8 versus a L28 RPM for a given speed and gear would be identical if the same trans, diff, and wheel size were used.

Answer: Very much A lot higher than we're talking, that's for sure!!! Only a mere 5100 fps.

Xnke, from what I'm guess you're looking at figures pointing to around 3800 fps (feet per second). From most of the people I've talked to, and literature I've seen on the subject that's about the figure you'll find for OEM cast pistons with factory cranks. The OP in this thread is having his crank dynamically balanced, hopefully by someone who knows what they're doing. And hopefully he's smart enough to be buying NEW cast pistons, and hopefully hyper cast types at that. I've met and seen plenty of people with experience building bottom ends suggest that the limit for a setup like this should be more around 4500/4600 fps and be "just fine". Remember, main issue with a stock L28 revving high is due to crank balance issues, not cast pistons deciding to just fly apart. My only point is that even cast pistons (done right) can be WELL beyond the RPM territory most of us will make power. Plus the OP is also building a 2.4, which should net him a good 500-600 RPM at the top of the RPM range to meet the same mean piston speed, plus he'll have longer rods keeping acceleration and side load forces on the piston lower.

DEFINITELY start by verifying timing. 1. Pull valve cover. 2. Rotate engine to TDC that has front #1 cylinder cam lobes pointing up like rabbit ears. 3. Pull dizzy cover. 4. Check which plug wire the rotor is facing towards. 5. Verify this wire goes to #1. 6. Configure plug wiring in order from there, going counterclockwise from #1 you established. I spent the better part of a day getting an L motor running and if I'd not ASSumed anything and followed these steps I'd have had the engine running in well under 15 minutes. Turns out my oil drive shaft was 180 degrees out, woops. It's EXTREMELY easy to get the oil pump drive off just a tooth which can make it EXTREMELY difficult to get the engine running right, or running at all in some cases.

I'd go even further and say cast is fine for ANY NA engine that won't live on a track. I wouldn't hesitate to take cast pistons to the track as long as I knew it was built right and hasn't exhibited issues. Brian Blake, aka 1FastZ, one of the best L engine builders of the NEXT generation (read, he's not an old guy who's been doing this forever, but a young up and coming), PREFERS hypereutectic pistons in many of his builds. I've owned cars with forged pistons and know plenty of people that do. They're not "fun" and most certainly this is true when you've built the bottom end to take 200+hp per liter. For what it's worth, brian used cast pistons in his 3 liter that he revs to 8k on a regular basis. I really don't see RPM as a huge issue for cast pistons in a 2.4. As long as your bottom end is well balanced the only thing to break a cast piston in a L motor should be mean piston speed, or detonation. Detonation will be unlikely at 7k or above, unless something is severely wrong, and mean piston speed of a 2.4 would be pretty high when comparing to a 3 liter able to run to 8k.

Truer words are hard to come by.

Because it's the only bad thing we can say about the 3.9/turbo combo. Otherwise the only "issue" I see is 5th gear cruising RPM, which I personally see no issues with as long as you don't mind INSTANT boost when you stab the throttle.

What was your car's trim level letitsnow? My '75 was fairly gutted, and will now be completely gutted. I'm not even running side glass. Before, I was at 2560lbs and I could easily just let the clutch out in 2nd gear (not pop, just minor slip) and be rolling just fine. I really don't see the point in having a 1st gear if I'll spend as much time shifting out of it than I will in it. I'm still not certain what exact clutch I have in my car as I've never pulled the tranny, but I DO know that it grabs PLENTY hard at ANY rpm without noticeable slip, but is still very streetable and easy enough to feather. I'd assume it's just an aggressive organic clutch. Having very little weight in the car with a stock flywheel helps though. And as any drag car should exemplify for all of us, is that the more power/weight you have, the less you need your shorter gears to go fast. Most of the 1,000+hp cars I've seen in person either had two or three speeds in them. Of course most were auto, but some were manual still. And never once have I seen a quad digit car (in person) that had rear gears over 4.00. Maybe once I get my car back up and running I'll take some video of 2nd gear pulls, both racing launches, and tame driving roll offs.

My EFI was also running absurdly rich, which helps turbo spool. And yes, only making 10 psi by 2400 in 5th sounds like something is amiss. My wastegate line once came off in a spirited run and all of the sudden I was reaching 14psi in quick 2nd gear pulls to 3,500, yikes! I also had huge 3" exhaust with a straight through muffler. I didn't have a better downpipe though which I'm sure would make a difference. I also ran NO intercooler, and don't plan on it myself. I never had a LSD, which I suspect would help a LOT, but in 1st gear I could easily burn both tires at will. Getting a good launch wasn't hard but 1st gear sure went by fast, and at only stock power levels I can't image what it would be like running closer to 300whp.