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Does anybody think that an IRTB setup would work with the stock ecu if I made a custom plenum that hooked up to the stock AFM? Or would the restriction of the sensor negate the throttle response of the irtb's? otherwise i dont see why it wouldn't work, considering that the sensor would still be metering all the air going into the engine.
 

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I like it! I learned at an early age there is no problems only solutions.
Just sometimes we like to make things more complicated then they need be.
 

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Does anybody think that an IRTB setup would work with the stock ecu if I made a custom plenum that hooked up to the stock AFM? Or would the restriction of the sensor negate the throttle response of the irtb's? otherwise i dont see why it wouldn't work, considering that the sensor would still be metering all the air going into the engine.
BMW M cars have been running ITBs with a plenum and MAF for a while now. I think if you make the plenum pretty large, you won't lose to much response.

Chris Chu was also running a plenum on his ITB setup, ducting cold air from the bumper arean (I think).
 

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I honestly wouldn't muck around with the AFM if you were going ITBs. removing intake restrictions and increasing airflow is what makes them function so well. Stuffing a restrictor (afm) onto them.. negates the gains.

On a side note... I do have gsxr 52mm throttle bodies for sale... with piping and a honda cut flange... could be good DIY start ;)
 

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The IRTB's would work fine sucking through the AFM. In fact, the limited edition Mazdaspeed B-spec II car does it exactly like that- IRTB's breathing through the MAF mounted in the stock location. (It's a NA8, hence the MAF instead of AFM)



NOW, I have read somewhere that there is an inherent problem- the throttle bodies are closer to the engine than the MAF is to the throttle bodies. Hence the engine is responding to the throttle movement before the MAF can respond. That's the reason why the Mazdaspeed kit has such a a small plenum- they are trying to minimize this delay problem. Too small a plenum will choke off the power obviously. Hence the inherent problem.

Oh yeah- last time I brought this point up on M.net a bunch of people jumped down my throat :(, so I'm not claiming I have the last word on this.... but it sounds reasonable to me ;)
 

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I'm not smart on the MAF on later cars, but the MAF on a 95 is pretty restrictive at high engine speeds. The MAF in my RX8 is a hot wire setup between a couple of screens, instead of a large bullet in the middle of the 95 MAF. I think it is just an issue of finding a MAF that isn't a restriction. How about a MAF for a big V8? They must flow a lot of air.

Bruce
 

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Discussion Starter #15
1 more question; If using a turbo with this setup wouldn't it be easier to tune than an NA car with itb's? Never mind a stock ecu though, even with a good stand alone, it seems it would be easier to meter the air at one point (before the plenum, with a turbo setup) than having the ecu try to guess how much air is going in through 4 separate throttle bodies via throttle position vacuum sensors and whatever other tuning voodoo your irtb's need. not sure if that made sense......

1 more thing that is just an assumption on my behalf, but it must be slightly easier to make reliable with a turbo, beacause every car i can remember coming equipped from the factort with irtb's was also turbocharged
 

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What factory turbos also have ITBs? (not to say you can't do it, ive just never seen it in a production car.)

The few factory cars and sport bikes I know of with individual throttles are all N/A.
 

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Skyline GT-R RB26DETT
Pulsar GTI-R SR20DET
I think the new BMW 335i also is Turbo ITB.
I'm not sure about the 335. I'll look into that. It seems that it's a standard single throttle setup from the pictures i've seen, but I can't seem to find any documentation talking about its actual design :? Silly Germans...

People have been boosting M3s for a looong time now with no issues (except that they want more POWAR)

http://www.youtube.com/watch?v=Oe-eJeHT1Bk Only ~400hp :cry: Dat's ok, there's a 600hp turbo variant :twisted:
 
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