Blow through AFM on 3SGTE?

[Ako]

Okay, found something weird with the wee car this weekend. Was looking at the pipework and wondering why the injectors were pre - turbo. Then it occurred to me that noones that daft, and besides, the pipework was all the wrong shapes.

So.. The AFM on the wee car has been placed between the intercooler and the throttle body, but before the extra injectors. Also amusing to note it ran no BOV, depsite the TD06-25g hanging on the side of it. Has a tial 50mm now, should be nice and rowdy.

ANYWAY - question is, can the toymota AFMs work happily in this manner? Or should I just sort it so it goes to pre - turbo, like a normal setup should be.

[CozmoNz]

go for gold, the air goes through it one way or another

alot of the afm 4agze boys just run the afm just before the throttle body (also allowing a vented bov BEFORE the afm (no over compensating)

i dont get what you mean by the injectors..

alot of extra injectors are mounted before the throttle... and only turned on via a switch etc anyway, and youll be at full throttle then ANYWAY (same as nos)...

hold on... PRE turbo? as in injectors firing into the turbo? that seems very silly :S

[Malcolm]

well I actually used to run my AFM between intercooler and throttle body, here's a pic:


when I originally did this, I was under the belief that the AFM measured mass air flow, which is constant throughout the system, however from what I've read since then, it seems the AFM measures volumetric airflow, which of course changes greatly when the air is pressurised, so for instance at 1bar of boost, the AFM will be reading HALF the amount of air that is present.

So, to summarise, it worked fine for me, but I think I just got lucky and the engine probably would have crapped out sooner or later, and I wouldn't do it again.

[IH8TEC]

as in like what i have on my car? look in the bottom right pic.

it works very well, and the extra injector is between the afm and t/b too

[CozmoNz]

your kidding right all_fours?

if you were only getting HALF the fuel (half measured air), your be running HOW lean again?

your engine wouldnt live... .. at all


im not sure about the "air going through" bit, but i do disagree with the half fuel idea.. if thats true, there wont be many if any 4agze afm turbo's without converting to link (orrrrrrr obviously afm before turbo)

[Ako]

go for gold, the air goes through it one way or another

alot of the afm 4agze boys just run the afm just before the throttle body (also allowing a vented bov BEFORE the afm (no over compensating)

i dont get what you mean by the injectors..

alot of extra injectors are mounted before the throttle... and only turned on via a switch etc anyway, and youll be at full throttle then ANYWAY (same as nos)...

hold on... PRE turbo? as in injectors firing into the turbo? that seems very silly :S

Nope, mine are controlled properly - you can adjust their own timing, and they are activated by RPM and boost.

Anyway, to clarify for cozmos benifit - its set up just like the 3SGTE in the pics above. Nice downpipe by the way!

My thinking was the same as yours all_4s, wasn't sure how the toyotas measured air flow. I'll move it to pre - turbo, not worth taking the chance on. I know (well, think) some afms measure air volume, needed to see if the toyota one will actually measure compressed air properly or not.

Silly japanese people doing funny things to my car!

[Dell'Orto]

So you're saying it never had a T67? Was only a TD06? Geez that had some oddball stuff alright! Flag the extra injectors and do it properly anyway

[Ako]

Bear in mind the designations trust use for turbos are still mitsi turbos. T67 is a td06 front cover, and td07 rear, for example. A 25G is still a very large turbo for a 2L engine, the evo boys pull 450hp out of it EASY.

That said, the majority of things I THOUGHT this car had to start with, were wrong once I actually doing my own hunting around on it. i.e the 262 cams which are actually 274 (according to the machiney thing at kelfords), the turbo, blah blah.

And doing it properly... Nah. I'll get it running, get it making a little power safely, then sell it on. I've got a cefiro here which is far too amusing to pass up, and resale on the mr2 wont get any better if I spend more $$ on it or not - your car is testament to that.

[Dell'Orto]

Yeah, and as you can see, no-one wants to buy MR2's, so you're stuck with Pinky forever, might as well modify the shit out of it

[Malcolm]

your kidding right all_fours?

if you were only getting HALF the fuel (half measured air), your be running HOW lean again?

your engine wouldnt live... .. at all


im not sure about the "air going through" bit, but i do disagree with the half fuel idea.. if thats true, there wont be many if any 4agze afm turbo's without converting to link (orrrrrrr obviously afm before turbo)

Well I certainly didn't say it would have half the fuel, because I'm sure the ECU knows quite a lot about airflow based on RPM and throttle position (some race-based ECU's only use RPM and throttle position for fueling, I've heard), and I'm almost certain that the AFM showing half the airflow would not mean the car would only get half it's required airflow. And if you wonder how lean it was running, when I took the turbo off it was WHITE, same with the spark plugs. I also can't comment on how the airflow meter reacts to pressurised, and thus denser, air. It seems reasonable to suspect the extra mass of the air might force the flapper further open, but it wouldn't be enough to account for the change in air volume.

I certainly wouldn't risk running it like that again. I would be very suprised if most people doing 4AGZE turbo conversions put the airflow meter anywhere other than between air filter and turbo, where it's supposed to go.

[vvega]

ive seen a few people do run it that was
bazda was one of them

his motor worked very well like that
v

[IH8TEC]

i have his old i/c setup, seems to work very well for me too,

[Malcolm]

well mine worked well too, I mean it was good enough to make me the fastest gt4 in the world on stock ecu according to alltrac.net (now gtfour.ca and I think others have beaten me now), but I certainly think it's unwise as the AFM isn't a mass flow device (like a hotwire or similar type sensor)

[Mr Revhead]

bazdas set up also used a few tricks to alter the fuelling.....

[IH8TEC]

yeah, change the afm to give it more fuel, + the extra injector.

for the afm http://www.mr2sc.com/websites/tech/Adju ... 20Fuel.htm