BRAAP

Wrapped the aluminum cover for the EGR port plug on my LS1 intake. After the picture was taken, the screw received faux anodizing, via Sharpie.

Someone just turned me on to this site, no idea how established or safe it is, but looks like a possible venue for buying and selling LSx bits. http://www.lsxmarketplace.com/ .

Here are pics of both style mounts. I am not sure what the cut off is for the early vs late rear mount on the 260. The 260 was the year Nissan used to empty their parts bins of the 240 body components and they did, (either 5 or 7 different plants these cars were being produced in), they would then use the 280 bits. Have seen 260's with the tiny front bumper and large 280 style rear bumper, etc. I would guess there is no cut and dry date, production number etc that would determine early vs late, just have to crawl under the car and see where the rear sway bar mount is attached, on the frame structure or cantilevered forward of it. EARLY rear bar mount, picture is of a '73 240-Z; LATE rear bar mount, picture is of a late '74 260-Z; Hope that helps, Paul

That bar is referred to as the 280 bar. It will only fit the "late" 260 and all '75-'78 280 cars. Body mount for that bar is cantilevered forward of the frame rail structure. The early 260 bar has a dogleg in it where it attaches to the body, (see pic). The early 260 and even the '73 240-Z have rear sway bar mounts directly under the frame structure vs cantilevered forward of it as on the late 260 and '75-'78 280-Z. The '73 240 came with the mounts on the car, just no bar so the early 260 bar is direct bolt on for the '73 240, (I seem to recall that some if not all the '72's also have that mount? I could be wrong...) In short, that bar will fit late 260 and all 280 cars. I have Z's here with both style mount brackets on them, I'll try and get pics.

I have found that for machine tooling, quality is one of those that follows the rule of you get what you pay for. An entire set of taps and dies for for only $29?! They will probably work, but will lose their edge quickly, more importantly are prone to breaking, vs a quality tap. Even quality taps can break and must be handled with care, the cheapos are just that much easier to break. Last thing you want is to have to take your block back to the machine shop and pay them to extract your broken tap. Wont be cheap and in some case will require helicoil or bush and rethread. The thread chaser kit rejracer mentioned is great kit, the thread files are very handy for cleaning up boogered threads on bolts. Another technique commonly used by budget DIY types, for chasing existing threads are still in good condition but just need a clean up is to make your thread chaser using a bolt. Cut flutes along the threads to capture the debris, add twist tot he flutes while can help extract the debris. 2-4 is flutes with a thin air power part off wheel, or thick dremel part off wheel, or even a steady hack saw blade. Tool trucks such as Snap-On, MAC, Matco, Cornwell, etc are great for standard hand tools and quality brand name tooling, but definitely do NOT purchase machine tooling from them. Been there done that, Snap-On's taps and tap handles, Machine tooling on the parts trucks is one area where the quality is not there for repetitive use, even their prices are reflect such tooling compared to genuine quality machine tooling. If you are only going to use them a hand few of times through out your life, then yes, that cheapo set from Northern might work but use extreme caution if they start to bind as they are will break easily. You can get the same sets from Harbor Freight as well. If you want to use your taps more regularly and for actually tapping metals for fab projects and/or just prefer to have quality tools for the job, I recommend staying way from tap "sets" and buy the taps individually from a machinist outlet such as MSC, etc and as Pyro mentioned, HSS will get you further than carbon steel. You shouldn't need any dies. A thread file like those in the kit rejracer listed is a good investment. If ordering individual taps, common thread sizes on the L series engines are, (All threads are metric in mm); 6x1.0 (Valve cover, cam thrust plate, cam oil spray bar, timing chain inspection cover, front cover, dizzy, Timing chain guide and tensioner, water pump, oil pan, crank case breather screen holder) 8x1.25 (oil pump, front cover, water in, thermostat housing, carb intake mani, exhaust mani, cam towers, mech fuel pump) 10x1.25 (EFI intake mounting) 10x1.5 (mains, head bolts, bellhousing, engine mounts) A few of the the not so common sizes, you most likely will not need taps for these; 12x1.25 (Flywheel) 16x1.5 (Damper bolt) 16x2.0 (Cam sprocket bolt) Hope that helps, Paul

That is a production piece, several were made. At least two different companies were making those IR mechanical injection manifolds. Individual runner/throttle blade Mechanical injection manifold, not Electronic fuel injection. They all were cast with the carb mount bolt pattern. They were designed and built for boat racers running the Datsun L6, not for use in the cars. The runners of the Kinsler are HUGE in diameter, not even remotely close in comparison to flow vs the stock EFI intakes, would not be good for anything other than full tilt 9000+ RPM race engine, Boat, Drag, Bonneville racer, etc. The other version, (I think it was Vetters) has smaller ID runners, but still much larger than the stock EFI. More comparable to triple carbs. I purchased the other version a few years back back from a gent that races Datsun L6 powered boats, his L6 powered race boat pictured below, who was selling a couple of the bent Kinsler styles in that ad as well, with intentions of adding bosses for Electronic fuel injectors. Ended up scrapping the project, 1 fast z bought the intake from me, he also has one of the Kinsler styles. The bent style requires custom horns/extensions to clear the hood, the Vetters doesn't, but also doesn't allow much room for an air cleaner, which race boats don't use. The Vetters Manifold mocked up in my race car.

I'm with this guy... errr... I mean, I agree with him...

Is your radiator secure to the core support/body structure on the passenger side? Is the radiator core separated from the mounting surround that is attached to the core support? Pull on the radiator to see if it is loose. Hard to tell from the pics but it looks like the radiator took more than one strike from more than one fan blade in that one isolated region of the radiator indicating the radiator moved rearward, into the fan, or the engine moved forward into the radiator.

I wont shed this so long as the topic remains on the path it appears to be headed, not so much a "what's best" discussion but a technical discussion as to the affect of Air temp, pressure and density altitude, humidity, etc on engine performance and/or temperature and humidity effects on available traction for various tires and tire compounds. For power production! As cold and dry at the lowest possible elevation as possible. Scenario, death valley during a high pressure front moving through, -20 degree F, 0% humidity, you'll make big power. Problem with that is depending on the tire type, compound etc, available grip might not be ideal, but that's what tire warmers and burnouts are for, right? Not to mention the discomfort of trying to perform pre-race chores in that enviroment.

Between doc visits, a trip out to Verona/Madison WI, (went the Packers-Bills game on the 19th and visited the EAA Air Venture museum while there), enrolling in some A-CAD classes, etc not much progress has been made on the car. There hasn’t been much to do any how as the headers are still being sorted out. I think my last substantial update was back in April or May? My how time flies watching grass grow. Once the headers get sorted and finally built, then it’ll be gangbusters to get it on the road, probably wont stop to update the build thread till it’s on the road and I can breathe again… For now, just another pittly little update. Started in on the wiring, reconfiguring pin out and inserting pins back in the circular BMW connectors I picked up for the ABS relocation, (just made and extension harness, didn't have to cut or splice the car or ABS module), in the middle of routing the LSx harness. Thank you to Pzary for his advice I spent a couple days building a cheesy little PCM desktop tuning bench, now I can access and tune the PCM outside of the car, on the bench/desktop. Made a couple adjustments to the PCM tonight including Throttle Cracker, Throttle Follower, fuel cut parameters, will be massaging the VE table and ignition map to better match the Vette cam, etc. (PCM is '02 Avalanche), bench tuned a few others PCMs as well for other swappers, (delete VATS, skip shift, set tach signal, tire size/gearing, hi-lo speed cooling fan set points, etc). PCM tuning bench extracting data; BMW Oil pressure sender is installed on the LSx. Spent more time scratching my head with hand full of fittings trying to figure out how I am going to do this. Almost just drilled and tapped the 16x1.5mm adapter to directly accept the 12x1.5mm oil pressure sender, but couldn’t quite bring myself to do that as the wall thickness would be quite thin and the last thing I want is to shear the head off the adapter leaving its threads in the block of an assembled engine. Using another 1/8 NPT fitting I drilled the female end and tapped for 12x1.5mm to accept the BMW oil pressure sender for the idiot light, robbed the LSx oil pressure sender crush gasket and installed the mess. There has to be an oil pressure switch out here from another OE application that is 16x1.5 mm threads. Sure would make that a whole lot easier. While watching the Grass grow I thought I’d play a little more with my 3M Di-NOC faux carbon fiber, (used it on the PCM tuning bench), and covered the aluminum plug cover for the EGR port on the LS1 intake. Don’t like the shiny screw head, may have to faux anodize that, black sharpie.

The doors and the internals of the doors are NOT interchangeable at all! Bumpers, dash, taillights and EFI can be swapped, but require a little ingenuity. Of course the wiring become more complex for the newer cars, so using harnesses and bits of any harness is not direct plug and play. Most of everything else can be transferred, or at least being as you have both cars in possession, it should become plainly obvious if a part can or can not swap over just by looking at it or trying it. If you have mechanical aptitude, don't be afraid to dive right in and find out yourself. Do keep in mind, this forum is an extreme performance Z car forum, hence the name HybridZ, not really a Z car 101 forum nor a replacement for a shop manual. Getting comfortable with the Haynes manual, (or whatever shop manual you have for your cars) and then tearing into both your Z cars will take you along way towards learning on your own what can and cannot be swapped over, then when you get a stumbling block, we'll be here.

All US market L6 heads are drilled and tapped to accept factory carb intakes, from the first '240-Z up to and through the last L6 powered '83 280-ZX and '84 810/Maxima. Have even installed the early SU's on a Z car N47 and Maxima N47 head, bolts right no, no mods. Now if you want to install a factory EFI intake on an L6, it must be a '75 or newer head, Z or 810/Maxima. It wont bolt on to the '70-'74 heads, unless you drill and tap it and have the injector slots machined. Where did you read that the N47 head is not tapped for the carb intakes?

Exactly. If he finds a cam that is large enough to crash the stock valves and pistons, the stock bottom end and stock unported heads wont be able to make use of that cam's RPM capabilities and power potential.

I'm sure you probably already traced the fuel lines back and forth under the car to locate the fuel pump, this is just for others in case it helps. Nissan mounted the fuel pumps in two locations throughout the '75-'78 run. No idea why other than it depends on what factory the car was manufactured I guess, (cant remember but it was 3, 5 or 7 different factories the S30's rolled out of). As pictured, one location is on a bracket just behind the passenger half shaft. Other location was mounted on the 45 degree slope just ahead of the passenger half shaft.

Bump.

And the fun begins.

Very cool, looking forward to seeing that info. For the budget DIY crowd, especially in the era pre MegaSquirt, that sort of info opens up possibilities for tuning around cams and intakes.

Datsun OE EFI intake manifolds Cleaned up, shaved and customized L6 intakes. Start out with my personal list of items that I typically delete and retain; This example is an intake swap with a 60mm TB conversion I completed recetnly for a local customer. Local customer sourced a non-EGR N-42 intake, 60mm TB, Pallnet fuel rail and TB spacer kit then dropped those goodies and the car off for me to install and tidy up similar to what we have done for many others, including rerouting the EFI harness along the firewall and under the fuel rail instead of over the middle of the plenum, A/C delete, etc. After the intake swap and clean up, the car runs great, just as it did when it came in, other than the deleted air flow regulator as described below. Other than that, no different! This is a bone stock L-28 EFI. Items deleted; 1) EGR, (This is a ’75 car registered outside of CA) 2) Air Flow Regulator (for a cold idle speed that the engine will idle on its own without holding the gas pedal, a "warm" idle speed has to be approx 1000-1200 RPM on a properly tuned L-28. If a warm idle speed of 650-800 is desired, then you’ll have to hold the gas pedal to keep the car running when cold till the car warms up, or reinstall the Air Flow Regulator.) 3) Coolant by pass that ran under the Air Flow Regulator. 4) Cold start injector and Thermo time switch. Tapped the cold start injector hole for 1/8" NPT, brass pipe plug installed. (left the Thermo-time switch in the thermostat housing, just deleted the wiring.) 5) A/C equipment in the engine bay. Items rearranged; but still functioning as OE! 1) Carbon Canister vacuum line has new port drilled and tapped into the back of the plenum and vacuum line rerouted along passenger frame rail and across the lower firewall. 2) Fuel Pressure regulator relocated to the firewall, fuel rail plumbed in a pseudo dead head style arrangement, (before anyone jumps on the “dead end EFI fuel systems cant be done” bandwagon, SEARCH! It can, has, and is still being successfully done, by the OE and tuners such as myself with NO ill effects NO vapor lock etc). Vacuum port of the FPR also has its own new dedicated vacuum port added to the back of the plenum next to the canister port. 3) PCV is now drawing fresh air, K&N filter on valve cover. (This caused the engine to ingest "false air" as the air being drawn in through the PCV system is no longer being measured by the AFM, yet the engine is breathing that air, i.e. “false air”), as such I will be fine tuning the part throttle tune with a combination of the water temp resistance and AFM adjustments, todays project. For those new to the stock EFI or EFI in general, just leave the valve cover breather plumbed to any port between the Throttle body-butterfly and the AFM and you’ll be just fine! 4) Removed the EFI harness and removed the outer sheathing from the harness that resides in the engine bay. Deleted the Thermo-time switching wiring back to the splice, also deleted the cold start injector wiring. (Just leave the wires cut, but protected from grounding/shorting. The computer doesn’t know the difference nor does the engine.) Separated the injector wires and the water temp sensor wires of the AFM and TPS wires into two separate runs. Retaped those as 2 runs. Reinstalled harness, routed the injector and water temp wires along firewall and then under the fuel rail, (can’t even really see them in this photo below, but they are there) and routed the AFM and TPS wires back in the stock location. Customer wasn’t ready to for a shaved intake, so this one was just painted and installed. Original fuel pressure regulator port plugged as well as a couple other deleted vacuum ports. Here is the picture, below that is a diagram of the dead-head fuel rail system. Boot between TB and AFM is not secured in picture, it needs to be secured! Here is brief run down and how I tackle cleaning up these intakes. With the intake removed from the car and ALL the ancillary parts removed, I jet wash the manifold, (just take it to your local automotive machine shop and ask to have it jet washed or tanked, they’ll take care of it from there). Now for the aggressive removal tactics. Mark ALL the bosses that you won’t be using and wack them off. You can use a Saws-all, hack saw, cut off wheel, or you can just gnaw them off if you have really good dental insurance. I prefer to clamp the intake down on the table of a milling machine and use a ¾” end mill and just GO FOR IT!!! (My oldest daughter enjoys performing that machining operation for me). Then I use the die grinder with assorted non ferrous carbide bits to “rough in” what’s left. Then I use a finer carbide bit in the die grinder to smooth out the scallops left behind from the more aggressive bits. Then I’ll use a sanding roll in the die grinder to smooth out all the grinding marks. Now, mark all the holes that will be getting filled in, i.e not used any more. Now, depending on whether the intake is getting polished or painted, that will determine how I tackle the holes and divots left behind. If it is getting painted, I will tap all the holes for SAE pipe plugs and thread in solid brass pipe plugs into the holes and then carve the protruding remnants of the plugs down flush. I have been known to use JB Weld as filler in the divots left behind, but I won’t 100% admit to that. If the intake is to be polished or the customer prefers the intake to be all aluminum, I’ll make small aluminum plugs from scrap billet that fit the larger holes and have a competent welder weld the plugs in their respective holes and also fill in all the remaining divots, (I don’t weld, so that portion is outsourced). When I get the intake back, I then get out the die grinder again, and start all over on the welds till the entire intake is somewhat smooth. Then I attack the intake with a D/A, then it gets a final cleansing and paint. If it is getting polished, I get it “roughed in” so to speak and take it to a polisher to let him/her finish the job. Oh, before it gets painted/polished, I will set the intake up on the mill and “face” the throttle body mounting surface and if the head mating surface received any damage, I’ll surface that as well. The Throttle body surface ALWAYS needs resurfaced if the cold start injector boss was removed/plugged, especially if the cold start injector boss was welded shut. When filling the holes that used to house the cold start injector, whether I use the pipe plug method or have it welded, the throttle body mounting surface will distort. Welding severely distorts it. Better off to just resurface it so there is no chance of a vacuum leak. That about covers it. Each person will have their own techniques that work best for them, so use what works best for you if you so choose to do this on your own. Die grinder and bits; Intake ready for plugging; Here is an intake pictured above just prior to paint. Note the Brass plugs and if you look close, you can make out some of the divots left behind from the old boss holes, grinding divots, etc. Component location; The Fuel Pressure regulator is attached to the fuel rail itself. 1) Large is Brake booster, smaller is FICD, factory A/C controls etc. 2) Mount for A/C idle speed boost. 3) Fuel Pressure Regulator port. 4) Mount for Air Flow Regulator. 5) Port for Carbon canister. 6) Cold start injector. 7) Fuel rail mount pads.

Big mouth/Large bore Throttle bodies. As mentioned, the stock EFI manifold port runners have only 53% the area of the L-28 intake valve!… Even armed with this knowledge, some guys are still fixated on wanting to install larger throttle bodies on their EFI L28 as a first mod. You spend all the money, time, and effort you want on big throat throttle valves, but until those restrictive runners are opened up, exhaust system opened up, optimize the ignition system including advance curve, you will NOT be realizing the engines full potential with any over sized throttle body. Braaps recommendations on where to concentrate ones efforts for building more power from their L6 engine in order of priority… 1) Exhaust, Ignition, (quality spark and “tuned” mech curve), Induction, (including getting rid of that AFM!) 2) Cam, (but ONLY after exhaust, ignition, induction upgrades including an aftermarket standalone EFI) 3) Light weight flywheel. 4) Head work. In regards to HUGE throttle valves, here is a thread that discuses the details with good arguments from both camps; http://forums.hybridz.org/index.php/topic/54034-big-throttle-bodies-why/ Hope that helps...

Intake manifolds, runner sizes; Of the factory OE EFI intakes used on the L28, they are very similar from a “power producing/air flow” stand point, (we are not discussing the visual aesthetics here). There are two style of plenums, full length open box style for the early N/A and Turbo intakes and the necked down plenum for the later N/A plenums, necked down toward the rear of the plenum. Another difference is webbing between the runners. Early intake had no webs, later intakes have the webs. The Jury is still out if the webbing acts as a heat soak affecting IAT or acts as a heat shield reducing IAT, too many variables between different L-6 installations, engine bay air flows, exhaust manifolds and heat shielding etc for there to be a definitive answer. Regardless of the webbing, due to the restrictive runners of the OE EFI intakes, the discussion of which OE EFI intake is most ideal for performance, in my not so humble opinion is inconsequential. I say either use the one you already have or find the one that you like to look at when the hood is open and will still pass Emissions, (if you need EGR or not), and use that one. Seat of the pants you will NOT feel any difference switching between open plenum and necked down plenums with the N/A manifolds. The runners are so choked down that any difference the plenums could/would yield in how then engine produces power is negated, not being realized. On the dyno, the necked down plenum vs open plenum N/A manifolds will perform the same! With runners capable of allowing the engine to breathe, those plenum differences would be small, and the consensus seem to favor larger Plenums, though there is some argument for smaller plenums in some applications. Now the Turbo intakes have just slightly larger ID runners, (see information below), and as has been covered elsewhere on the forum, the runner ID of the factory EFI intake manifolds is only 53% the cross sectional area of the intake valve itself, ie.. the runner IS the restriction and any other changes including larger than stock throttle bodies will not yield any gains, till the restriction is no longer a restriction, i.e. the runners of the manifold! The Turbo runners are only slightly larger than the N/A runnners and should yield approx 2 maybe 4% more power over the N/A, again, nothing you could feel seat of the pants, and there is FAR more power to be gained in dialing in the tune, i.e. AFR’s, ignition timing and getting the ignition system up to snuff, i.e. Quality wires, (Taylor plug wires are NOT what I'm referring to when I say quality wire. Jacobs, Nology, and Magnecor ARE!), NGK spark bolts with projected tip for N/A engines. As of late, there has been a few members here making an effort to improve air flow with EFI manifolds, building their own manifolds and also carving up OE intake manifolds in an effort to open up the runners to allow the engine to breathe more freely. Those folks are on the right track. One particular discussion regarding perceived advantages of the Turbo intake over the N/A intakes fired me up to spend an afternoon measuring a few EFI intakes that we have laying around the shop and posting those results. Mind, you I only measured 4 manifolds. 2 of them are Turbo intakes, the other two are N/A. One of the N/A is a non EGR P-82 off a friends 280-ZX, the other is a NON EGR N-42 intake manifold. I have no idea what years the Turbo intakes are, sorry. I’m sure measuring all the EFI intakes that Nissan used would be more accurate, but I strongly feel the results I acquired are good enough for the intent of this thread, i.e. I don’t think measuring them ALL will reveal anything not found here. Also, keep in mind, these are cast parts, and as such, there are some pretty drastic differences between manifolds, let alone within each runner due to the casting molds etc. I started out also measuring the runners horizontally as well as vertically, but the casting part line was skewing the measurements so much, and being as the runners are, for the most part round not oval, I just used my vertical measurements. In summation, yes the Turbo manifold has ever so slightly larger runners, yet that difference, in my not so humble opinion, is not worth any effort to replace any other existing OE EFI intake that you may be already using. (I take back all the statements that I made previously in other threads in regards to the Turbo intake manifolds being a worthwhile upgrade). ALL of the OE EFI manifolds ARE restrictive, period! No real gain in power will be had using one over the other. There are much bigger performance gains to be had in just dialing in your ignition timing and Air Fuel ratios than switching to a Turbo Intake manifold. If a real marked performance gain is your goal, make sure that none of the OE EFI manifolds are on your engine. They can be made to look real pretty and will perform respectably, but more power can and will be had by switching to an aftermarket manifold with larger than stock diameter runners. Extrude hone is an option as well some of the extreme preparation others have done to open up the stock runners. I would agree that if the runner could be safely opened another .100” using that process, that would help. Realistically, opening it up another .200” would make it worth while, but I’m not sure there is enough material in the runners to safely remove that much using the extrude hone process. Also, the cost of extrude hone for a little gain is something that you’ll have to weigh against your bank account. For some, it might be more cost effective to spend a little more for a custom intake which would allow the rest of your performance parts and modification to do their job to the fullest, not just partially. Here are the details of the afternoons measuring session on these manifold runners. I measured all 6 runners of all 4 manifolds and I measured each and every runner in 3 different locations along the length of the runner. I was using my machinist snap gauges and Mitutoyo 0-12” dial caliper. First measurement point “A”, is 4 ½” from the head flange. Point “B” is 2 ½” from the head flange. Point “C” is at the head flange, ¼” in from the flange surface. Top pic shows the manifolds that were measured. Second pic shows the locations at which the measurements were taken, “A” “B” and “C” respectively. Third pic is each and every measurement taken at all three points in all runners of all 4 manifolds, to within .005”. Average runner diameters per location, avg per individual runner, and avg overall. At the bottom is the square area of the averages and the % of difference between the two N/A vs the Turbos, (I used 1.308” Sq/in for the Turbo Reference). Keep in mind, if using the stock ECU and wanting to take advantage of what larger intake runner has to offer, much like bigger cam, the stock ECU will not play well with a freer flowing intake. An example of a custom built larger runner intake; http://forums.hybridz.org/index.php?showtopic=51825 Just a little food for thought. In researching intake manifolds and power produced from those that have ran their cars on the Dyno, was able to find quite a few for the Turbo guys, and a handful for the N/A guys. Essentially all of the Turbo guys running the OE EFI intake manifold are making great torque numbers, but the HP to Torque relationship is reminiscent of the mid ‘80’s GM TPI engine or like turbo diesel HP and torque numbers. Huge torque, but it falls off early in the band. Others that are running similar set ups with the only difference being a different or altered intake manifold, their HP numbers fall in line with the torque numbers respectively, i.e. if they are making 500 ft lbs of torque, they are also making in the neighborhood of 500+ HP. The OE intake guys making similar torque figures are typically making mid 300 to low 400 HP. For the N/A EFI crowd, a similar situation holds true. You will find that the fast EFI N/A guys are running some intakes other than the OE intake! (hmm… seems to be a trend here… ) The throttle valve being used, whether it be OE or the monster 90mm Q-45 unit is irrelevant. Good read for designing induction systems; http://www.themotorbookstore.com/engine1.html Good source for intake manifold and EFI fueling components.; http://www.rossmachineracing.com/

CAMS and the OE EFI system; The OE EFI will NOT tolerate larger than stock cams, (large enough to make any difference one would spend money and time to swap out), and there is no “reasonable” way around it. If you desire a cam for EFI L28, do yourself a favor and steup to aftermarket Engine management which will allow you to tune around the new VE curve the cam delivers and also delete the AFM from the air stream. The stock Z car EFI isn’t tunable enough to compensate for an altered VE curve. I’m sure someone could hack the resistors and caps in the ECU, but with Mega Squirt being so inexpensive and readily accessible now… The OE EFI will barely tolerate extreme exhaust mods and minor head work, (those two items with the stock cam and stock EFI intake manifold don’t alter the VE curve too much and what they do alter we are able to compensate for with a variety of methods). The OE EFI will not tolerate freer flowing intake manifolds. Both of those alter the VE curve drastically enough that there is no reasonable way to keep the part throttle cruise AND WOT in balance. You will have to sacrifice one for the other and at that, if you spend too much driving around in the compromised region of the tune, the tune could be far enough out to actually foul plugs, which means that when get back into region that is correct for the engine, it wont run right due to fouled spark plugs. In summation, if you have the stock EFI, keep the stock cam and stock intake manifold. If you desire an intake manifold and/or cam change be sure you also have an alternative engine management system that allows the end user to tune and make use of what the cam and intake manifold brings to the table in performance gains. Paul