ITB's on a 24v project, Dyno results Post 136!!!

[Wanganstyle]

What's the size of euro s50 ITB for comparison?

S54 is 42.5mm if you want a comparison.

It's huge as its 42.5mm x 6

Euro s50b32 wont be much different; anything above 36mm would be adequate for a s52 NA.

A supra mk4 has a 60 mm throttle; it's ok for a 600rwhp. Cut that in half for a NA application and multiply by 6.

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[golde30]

What's the size of euro s50 ITB for comparison?

[digger]

Once the maps are adjusted to account for the rush of air lower in the RPM's, think the 45's will be fine. The parent company wanted to start with larger throttles, I wanted 45's as they are a good "middle-of-the-road" size. They should work well on a stock engine and have room to grow. So far, there has been ZERO interest on b25's, never mind stock anything- so all the more reason the test engine is nice to be a b25, as gains on a modified engine will be exponential.

jenvey thought i should use 48 on my M20, what nonsense on anything that you want a good VE in the midrange from rather than a dyno queen.
you can make 500bhp with 50mm ones. sizing based on hp/cyl is a good guide as it gives velocity so 45's are good for 400bhp this gives plenty margin for M50/52 based engines.

ive chosen 42mm for my next build but not jenveys, couldn't be bothered figuring out linkage etc

[ForcedFirebird]

i would think 10" to 12" from head to trumpet inlet will function well. the only question is if 45mm throttles requires a pretty heavily worked motor to get the best from. im interested to see results i suspect it will be fine since they are further upstream and the runners are long.

Once the maps are adjusted to account for the rush of air lower in the RPM's, think the 45's will be fine. The parent company wanted to start with larger throttles, I wanted 45's as they are a good "middle-of-the-road" size. They should work well on a stock engine and have room to grow. So far, there has been ZERO interest on b25's, never mind stock anything- so all the more reason the test engine is nice to be a b25, as gains on a modified engine will be exponential.

[digger]

Stock m50 with muffler only. 200,961 miles to be exact. Have s50 cams and some other items we will be adding to the car.



No, I have not cut a stock manifold. They fly off the shelf for OBD2 cars coming in for manifold swaps.

We made them as long as the chassis would allow. The e30 24v swap kits will have to be 28mm shorter.

i would think 10" to 12" from head to trumpet inlet will function well. the only question is if 45mm throttles requires a pretty heavily worked motor to get the best from. im interested to see results i suspect it will be fine since they are further upstream and the runners are long.

[ForcedFirebird]

So you have to run a MAF delete to use this set up? What kind of engine management are you running/recommend?

Using a stock ECU and tuning it around the MAF right now. An air-box could be made to use the stock MAF, we will be making them in the future.

[rzerob]

Air-boxes are in the plans, we have vacuum manifolds/blocks that allow the brake booster, IAC, FPR, and CCV to be utilized.

So you have to run a MAF delete to use this set up? What kind of engine management are you running/recommend?

[ForcedFirebird]

Very curious, pending results. Is the test motor/intake/exhaust 100% stock for good benchmarking?

Stock m50 with muffler only. 200,961 miles to be exact. Have s50 cams and some other items we will be adding to the car.

hey thanks i meant overall length but i can work it out

150mm + 118mm + 40mm = 308mm which is pretty good. when you compare to the dbilas which is woefully short for a mild engine it should be alot nicer without any penalty

have you ever cut up a OEM manifold to measure size at the start of the OEM runners to see how much taper they used?

No, I have not cut a stock manifold. They fly off the shelf for OBD2 cars coming in for manifold swaps.

We made them as long as the chassis would allow. The e30 24v swap kits will have to be 28mm shorter.

[ForcedFirebird]

Have the whole thing bolted back on the car. Idles like a rock, but off idle and stabbing throttle bogs pretty bad. Was hoping to go to the dyno tomorrow, but will need to re-write all the maps to add fuel sooner. Rolling on the throttle, or once the fueling catches up, this thing is a rocket.

[digger]

Same as stock meeting the head (1078mm^2), 45mm round (1590mm^2) with a smooth taper in a ~150mm length



Air-boxes are in the plans, we have vacuum manifolds/blocks that allow the brake booster, IAC, FPR, and CCV to be utilized.

hey thanks i meant overall length but i can work it out

150mm + 118mm + 40mm = 308mm which is pretty good. when you compare to the dbilas which is woefully short for a mild engine it should be alot nicer without any penalty

have you ever cut up a OEM manifold to measure size at the start of the OEM runners to see how much taper they used?

[ForcedFirebird]

you get a better transition from round to oval with a longer manifold adapter. which is less likely to upset airflow especially given proximity to where fuel is injected

how does the cross section vary compared to stock M50 manifold? ie what is the equivalent runner diameter for the plastic OEM at the start and end of runner and for this setup? also how does the length compare for both?

Same as stock meeting the head (1078mm^2), 45mm round (1590mm^2) with a smooth taper in a ~150mm length

Very curious, pending results. Is the test motor/intake/exhaust 100% stock for good benchmarking?

How does idle control work with these?

What are you doing for a plenum / airbox?

-E36 guy, want a setup like this for Nasa TT build on S50.

Air-boxes are in the plans, we have vacuum manifolds/blocks that allow the brake booster, IAC, FPR, and CCV to be utilized.

[Bimmerman325i]

Very curious, pending results. Is the test motor/intake/exhaust 100% stock for good benchmarking?

How does idle control work with these?

What are you doing for a plenum / airbox?

-E36 guy, want a setup like this for Nasa TT build on S50.

[digger]

you get a better transition from round to oval with a longer manifold adapter. which is less likely to upset airflow especially given proximity to where fuel is injected

how does the cross section vary compared to stock M50 manifold? ie what is the equivalent runner diameter for the plastic OEM at the start and end of runner and for this setup? also how does the length compare for both?

[Nisse Järnet]

The throttle bodies are tested to 6bar :)

I think im ok with that :D

[ForcedFirebird]

Ok cool, i might get itbs on my M50 turbo :)

The throttle bodies are tested to 6bar :)