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Originally Posted by Turdinator
ITBs are always expensive. In fact, as has been mentioned several times before, NA mods are always expensive for the HP gains. I don't see why they'd be hard to control as long as you are using a suitable ECU.
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I can't think of an aftermarket racing-type ECU that can drive two electronic throttle valves on their own, without some kind of piggyback setup. If you find one under $5000, let us all know.
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I was thinking last night that perhaps a twin throttle setup would be easier than ITBs.
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They're actually very similar to ITB's in terms of the way they are physically driven. On ITB's for electronic throttle, you have all the throttle valves for a bank driven on a common shaft. There has to be software learning to calculate and compensate for differences in airflow between cylinders. So if you have two banks with ITB's, you have two electronic throttles essentially. In one sense that's the same as two upstream throttle valves.
Some engines have an upstream throttle before the plenum and then ITB's right at the intake port, like the Lexus LFA engine.
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We could use two stock throttle bodies and just splice the signal from the ecu to each in parallel. Although i don't know if that electronically feasible.
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Never say never I guess, but you do realize that each electronic throttle module has two throttle position sensors on it used for feedback? So how is the computer going to compensate for variations in throttle valve deposits if you are feeding it a dummy signal to drive the DC motor? The electronic throttle learning won't be accurate for the other throttle. I suppose that matters a lot less in a racing environment with very little part-throttle driving, but I just don't see it being feasible on a street car.
Nobody has addressed my point about the lack of variable valve lift. On Celica 2ZZ or basically any Honda engine, you have more than one lift profile. That allows you to have some semblence of low speed torque. If you can succeed in going with a very aggressive camshaft design you will lose a lot of your low-end torque on this engine.