Question for you guys. I have been inquiring about chaning out my t3 compressor for a t4 but now I'm wondering, could my turbo be flattening up top because I'm too rich? I am running an 8:1 fmu and an inline. I DO NOT have a VAFC or anything else, and I do notice a lot of black soot on my back bumper, so now I'm just wondering if my t3 with the .60 ar on the compressor side can still make power past 5000, or is it in fact too small. Any help or insight would be great, and how much hp can a VAFC actually help me make by adding and subtracting values!
thanks again guys

 

whoa! Flattening + FMU = equals too much fuel press, and locked up injectors. You are overboosting and that flattening is dangerous. I'm guessing your running small injectors? and trying to boost too much.

 

well, as it stands, I'm using a garrett t3 off of a merkur Xr4ti and it has a compressor housing ar of .60. I have an obd1 h22a using stock injectors an 8:1 fmu, and an inline fuel pump. I believe the stock injectors are about 320 or so. Anyway, when I talk about flattening, I mean that my car doesn't pull anymore past 5000. It kinda well...flattens out! haha. it pulls pretty hard up until 5000 but I was guessing that either the compressor is too small, or I'm just running too rich up top, so I just wanted to lean it out up top to try and get closer to a 12:1 ratio.

 

oh ok I thought you meant a flattening "noise" or something. Prelude stocks I think are 270cc's. If the car looses power when you build max boost then you maybe right about running rich, the best to find out is to install a A/F gauge, they are not 300% accurate as some may say but it sure is better than guessing. You could also try lowering your calibration to a 6:1.

*sigh* I remember those FMU days.

 

yah, my car is a 94 so I'm pretty sure they're in the 300's. anyway, as for the running rich issue, I have an autometer a/f gauge, but I don't want to place too much trust in it, but all I know it goes straight green and doesn't move unless I let off the throttle. But what i am gonna try is to use my friend's jrsc fmu. it's a 5:1 rise rate so maybe that will lean it out, but hopefully not too much

 

ok good luck with it but if the 5:1 leans you out too much, you could always play with your base pressure. From what you said about the A/F gauge your definately running overly rich.

 

I'd visit a dyno and straighten out your fuel before you question the max capabilities of the turbo.

 

what's the a/r on your t3 turbine? I know the compressor a/r is 60 but what about the turbine. It could be your turbine being too small as well as being too rich

 

yah, it seems pretty small. Is it on the turbine somewhere, cuz I didn't see anything when I installed it. Anyhow, it spools quite quickly and like I said, there's a lot of black soot at the back everytime I boost hard so I'm assuming that I'm getting enough fuel, but reallyl, if I am running too rich, how much hp can I be looking to gain from merely leaning it out?

 

i'm not FI yet, but based on searches i've done i've seen about a 10-15 hp gain when they have corrected their a/f

If you are spooling at 2500 rpm or below, then i would assume its a .48a/r..if you are spooling around 3000 or higher than probably a .63a/r....based on you having stock internals


[Modified by symba, 5:59 PM 10/31/2002]

 

I believe it's a .48 then cuz it starts to spool around 2000 or so. So that's 10-15 to the wheels I take it?