pacesetter header, individual throttles, estimated outputs ?

[SSS]

Sorry, i should have mentioned those simulations were based on a KA24E, not the DE.Although it's only an engine simulation program, it's far far more accurate than desktop dyno 2000, which i have used before. It's not the easiest program to use Insanity, took me a while to get the hang of it.

It was only meant to illustrate a point i was making regarding cams and intake manifolds, you can't solely place 100% of the blame on the intake manifold. A properly designed intake manifold can make increases everywhere, but you really need cams to accentuate these gains.

For instance, i did generate a run using stock KA cams, very short runners and a plenum 50% of the engine's capacity, and the results were terrible; torque dropped everywhere with only a small peak power increase.

[s1ndicate]

Could you upload your engine file for the KA?

[SSS]

Try this one, it should have all the data for a stock E.

[InsanityInc]

Sorry, i should have mentioned those simulations were based on a KA24E, not the DE.Although it's only an engine simulation program, it's far far more accurate than desktop dyno 2000, which i have used before. It's not the easiest program to use Insanity, took me a while to get the hang of it.

It was only meant to illustrate a point i was making regarding cams and intake manifolds, you can't solely place 100% of the blame on the intake manifold. A properly designed intake manifold can make increases everywhere, but you really need cams to accentuate these gains.

For instance, i did generate a run using stock KA cams, very short runners and a plenum 50% of the engine's capacity, and the results were terrible; torque dropped everywhere with only a small peak power increase.

What's "very short"? You can make them too short and at that point you won't do anything great because you've designed it to run above your redline. For the DE, the ideal length for stock redline is about 10 inches or so. Also, you're not suddenly going to make peak power at 9000 by doing this, but the stock 240/248 cams have MUCH more potential than a torque peak of 4300 and a power peak of 5600.

[PandaS14]

Insanity, Ideal length of runners at 10" is for a KA with a plenum. Nobody's been able to determine the ideal length for ITB's yet. And to complicate things, as you said, cams make a whole lot of difference too. So for one person, ideal lenght might be 11". yet someone else with different cams migh have an ideal length of 9". Personally I wish I could have made my runners like 5" long and done all of the runner length tuning with velocity stacks.

[InsanityInc]

Insanity, Ideal length of runners at 10" is for a KA with a plenum. Nobody's been able to determine the ideal length for ITB's yet. And to complicate things, as you said, cams make a whole lot of difference too. So for one person, ideal lenght might be 11". yet someone else with different cams migh have an ideal length of 9". Personally I wish I could have made my runners like 5" long and done all of the runner length tuning with velocity stacks.

Well, considering I'm talking about a stock-cam s13 KA24DE with a plenum...

[SSS]

What's "very short"? You can make them too short and at that point you won't do anything great because you've designed it to run above your redline. For the DE, the ideal length for stock redline is about 10 inches or so. Also, you're not suddenly going to make peak power at 9000 by doing this, but the stock 240/248 cams have MUCH more potential than a torque peak of 4300 and a power peak of 5600.

Short as in 3.5-4" short.It didn't make any power after 5900rpm, just dropped off like a stock intake manifold (for the E).

[Nismo_Freak]

It wasn't a comparison.

Obviously it was, else you prove nothing by introducing the two.

I was using it as an example to show that the length of your runners does affect the operating range of your engine.

Yes, but you failed to introduce the differences of the two runner lengths on the SAME engine. The SR20VE will have vastly different volumetric efficiency due to the differences in head design, and cam flow.

Why would nissan change the manifold for the VE if it didn't?

Emissions requirements for one, sizing constraints for two, and differences in applicable market.

There are MANY reasons why they modify manifolds. Look at the differences in the USDM SR20DE's, there were manifold and cam differences made throughout the years to adhere to ever tightening emissions requirements.

For all intents and purposes, the VE is the exact same engine with different cams.

Bottom end is the only similarity in the VE and DE. They have the same stroke and bore, that is it. Head, manifolds, cams, are all different.

SR20DEs have almost the exact same cam configuration as an S13, yet they have a power peak at 6400. If you look at the dyno of an SR20DE, the torque does the same thing as it does in a KA, just slightly later, and if you look at the intake manifold of an SR, the runners are also slightly shorter.

Volumetric efficiency is dictated in large part by the head design. The manifold has the same design, and the runners are not that much shorter.

You also have to understand that rod ratio (albeit kind of a age long arguement), and overall vacuum points help to dictate mach flow around the valve during variations in valve opening degrees. The KA's long stroke aids in lower RPM cylinder filling due to a higher piston speed, and greater TDC dwell to make use of that torque.

Remember the engine operates on vacuum as the sole source of inlet flow. You need to maximize the pulse length while maintain a critical flow point in the head (essentially port velocity and valve flow mach numbers)

Cams also don't share the same valve opening points even with the same duration and lift. This is because of differences in LSA, and valve opening mechanisms.

Stock cams on my NX2000 (high-port B13 engine) are as follows:

Intake - 248 deg. / 10.0mm liftExhaust - 240 deg. / 9.2mm lift

Different from the strongest KA OEM's which are 240 / 248

Just FYI the later model low-port engines have a 232 deg. / 8.6mm intake cam and when you switch to the OEM B13 "hot cam" you should see a gain of around 6whp or so.

Also, the SR20VE VVT cams have roughly the cam specs of the JWT KA cams. So obviously there's something fishy going on, and all signs point to the intake manifold.

Head design is just as important. You can't compare two similar cams with dissimilar heads and assume the manifold is the difference.

Also, who said you can't throw up your dyno? I just said it didn't prove d!ck. Not to mention that KAs and SRs are not that different. 10mm of stroke isn't going to completely change how an engine can breathe.

10mm of stroke, 3mm of bore, two variations of head design, cam design, valvetrain design, exhaust manifold, intake manifold, quench area, ignition timing, intake length, pistons, piston rings, frictional losses, exhaust backpressure variations, valve timing, etc. etc. etc. etc.

That will make a difference, obviously more than you assume.

Similar parts does not mean it works the same, everything must be in tune.

So you have proof of this? Oh wait. You don't. And everyone besides you with an ITB setup says the engine feels far more powerful on the high end.

Also, your engine does not make 140ish@6000. It makes 140ish@5700, and you have nearly the same power at 6000. I have yet to see any non turbo KA making peak @ or above 6000, besides the NISMO one.

Until there is conclusive evidence, ie. dyno. I think we are all just guessing and assuming results.

[InsanityInc]

Why are you so hung up on absolute VE? That's not what I'm talking about at all. I'm talking about where you GET that VE. Also, all nissan DOHC engines have very similar head designs, so no major differences in flow are going to be realized there. And valvetrain design? Please, that doesn't mean **** for how an engine breathes. The SR having rocker arms instead of buckets isn't going to change the flow at all. Piston design, piston rings and frictional losses have effects on overall power production, not breathing ability. There are going to be differences, but not to any massive degree. You are severely underestimating the importance of the intake manifold. Everything else in your engine matters very little if you can't get air through your intake properly, because everything else in your engine comes after that point.

Quote »Until there is conclusive evidence, ie. dyno. I think we are all just guessing and assuming results. [/quote]Well, considering everyone who's done ITBs (except for Julian) says it's made a massive high-end improvement, and many engines that suffer from a similar problem have realized large gains with just changing the intake manifold, and the fact that intake manifold design is a massive part of any kind of performance engine building regardless of the subtle variations in head design or stroke. While you're right, it is a "guess", it's also a guess that has a very good chance of being right considering all the information used to make it.