high-power 16V NA

[Luke]

I've heard of people adapting these throttle bodies to other cars... they come stock on some suzuki motorcycles.


http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=016&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=260105167750&rd=1,1

I think it would be really cool to adapt something like this to 16v with later heads, high compression pistons, cams and megasquirt.

[allessence]

I had thought about doing the individual throttle plates but decided it was way to much work to fabricate from scratch.

But, this looks like a viable way to go depending on throttle bore diameters.

[99Super]

I thought of doing the same thing, only w/ some big GS1100 42 or 44mm Mikunis. I have an early 2.3 head w/ a very short manifold peice still attached that could be used OR just cut the plenum from a standard mani and go from there. Looks like you have the higher tech solution!
Don't forget, if it's going in a 99, you have to figure out a header system to get all that air out efficiently!

john

[Crazyswede]

Keep in mind also that its a non turbo car so you may want to put some though into the intake manifold design. Just putting throttle bodies on the side of the head wont give you optimal performance.

[Luke]

Yeah I didnt mean to imply bolting them directly to the head. Best bet would be to cut off a stock manifold and weld an adapter plate to it. For runner length just mimic about what saab had on the orginal 16V ems.

[paulh]

hmm definitely interesting, might have to keep an eye out for a cheap set of those.

Paul

[DeLorean]

well the stock manifold for sure isn't optimum, but I think that some dyno results would be needed to see what sort of gains a set up like that would net. Personally, I think the plenum size combined with the small TB is probably where a lot of the restriction is coming from, which those would fix. My idea was to weld an aluminum drum to the stock runners to increase the plenum size, then use an NG-900 Throttle body bolted to that approximately where the stock TB is located. That would be nice because the TPS is correct for not only Megasquirt, but LH 2.4.2 as well.

[allessence]

has anyone came up/ran with this idea far enough to figure out throttle body bore sizes needed? The throttle plates themselves could be fairly small. 40-42mm? This being based on manifold runner diameter?

I'd be game for some R&D. Put a T7 head on a 2.1 with about 22lbs boost running thru seperate throttle bodies with secondary injectors, sounds about right to me.

[Crazyswede]

Jennifer,

Charlie north runs this setup on several of his cars or cars that he built. I believe he is using the throttle setup off of a hayabusa.

[Luke]

Well the venturis on side draft webers for a saab engine are typically in the 38-42 mm range, so that probably close to what we want for ITB's too.
Im not sure there would be much advantage of ITB's for a turbo motor though.

[paulh]

Well the venturis on side draft webers for a saab engine are typically in the 38-42 mm range, so that probably close to what we want for ITB's too.
Im not sure there would be much advantage of ITB's for a turbo motor though.

agreed, turbo with ITBs is just getting complicated, you'd have to build some sort of crazy secondary plenum for the backs of the TB's. plus even after all that hassle, you probably would see little to no gains from it.

Paul

[allessence]

wouldn't you gain some off boost power do to better flow dynamics?

better spool, better flow, better power?

[max]

Hmm... Luke you might have to do a high powered NA rally car, after you do your twin carb factory replica historic rally car.

[Crazyswede]

i disagree with the turbo with ITB remark. I have seen several turbo cars with ITB setups and they didnt do anything to fancy. I believe the 16v test cars ran itb setups. As I understand it, running appropriately sized ITB's with a properly designed intake will improve throttle response and can make it easier to design the plenum as all 4 cylinders draw equaly from the plenum vs having the intake at one end and cylinders drawing from different ends of the plenum.

As far as intakes go, I seem to remember you want long thin runners for Hi rpm and short fat ones for low. There are some cars out there that run both and use a butterfly valve to vary the air flow from one runner to another depending on throttle position and rpm.

[Luke]

Short fat runners are preferred for high rpm and long thin for low rpm. The thin diameter keep the velocity up at lower rpm and the long length is to accommodate for the longer duration between intake valve events. The idea is that pulsating waves are created as the intake valve opens and closes and air that is being drawn into the valve slams up against it. There is a reversion in the flow and a pressure wave is sent back up the runner, this pressure piles up in the plenum and then bounces back into the runner. If everything is timed right it does so right as intake valve is opening again, thus it makes sense that a longer runner would be better for low rpm because the time between valve openings is longer and the greater distance of the runner allows the pulse to arrive at the correct time. OEM manufactures can use this to give the engine a power boost at low rpm for drivability but usually it has a trade off at high rpm. I have a book around here somewhere that explains all this very well.