Smurf STI

A question for the collective:
Almost every setup I've encountered that is fuel injected, is also a blow through. I have not seen a single draw through setup.

Can anyone here provide insight as to the reasoning?

RobsyUK

iTrader: (2)

I'm going to guess it uses more energy to pull rather then push

John 37

Virtually all modern engines use multi point injection with an injector per cylinder. A draw through system has one air stream before the turbo so dedicated injection is impossible.
Draw through was popular with carburetors. By putting the carb before the turbo, it only sees the engine at atmospheric pressure. The problem is the float chamber. Blow through carbs become much more complicated. They have to either pressurise the float chamber or put the whole carb in a plenum chamber. Since carbs only run about 2psi fuel pressure, that has be linked to boost pressure too.

Smurf STI

I understand the reasoning in the case of a carburetted application.

However in an EFI application blow through, where fuel delivery is not a problem. Would a suck through be a better option? Let me explain...

Turbo lag is stereotypically the thorn on a turbo set up, what happens when you pull a vacuum on the compressor side of the turbo? You reduce gas density, there by allowing the turbine to maintain momentum. Instead of choking it through a small bypass Circuit...

Thoughts?

John 37

So you're referring just to the throttle location. I see your point about maintaining turbo speed and it may well work. A down side is the throttle now has to pass unpressurised air so needs to be larger.

lockheed

iTrader: (1)

I don't know or remember ………… but David Vizard did a few tests on this subject although a bit dated .