dieselman88

I currently have the on3 76mm turbo on my car, and apparently they have a small exhaust side which builds up back pressure. I was thinking about switching it out to help it breathe better. I seen cx racing has some turbos, and they seem to have a bigger exhaust side. I have a t4 flange and a 3in v-band down pipe, just didn't know if it would make that big of a difference

JoeNova

Call up On3. They can send you a larger turbine housing for your turbo.

dieselman88

Is it the actual housing that is smaller? I thought maybe it was the turbine and all. Be a simple swap?

JoeNova

It depends on which A/R your housing is. If its .96, its the biggest i think they have to fit the 65mm turbine wheel.

The A/R might be cast into the inside of the turbine inlet.

LJMSJohn

Depends on what you have... if you have a 65mm turbine 76... call On3 and buy one of the 7675's....

wheel diameter will make more of a difference than the housing. when you have a backpressure issue, swapping to a bigger A/R housing is a pointless thing to do. It affects the overall flow capability of the turbine very little.

JoeNova

It depends on which housing he has. If he has the .68, he will gain flow with the .96. Those .68 housings are tiny. The inner flow volume on them is probably less than that of the inlet/outlet flow area.

But Like John said, at some point you hit diminishing gains. You can increase the inner volume of the housing with a larger A/R, but only so much air can still flow through the inlet and outlet, and the problems get compounded when you have a tiny wheel doing it.

On3 sells as 7875 that is a healthy step up from the 7665. Its not too expensive and most of your stuff should swap over pretty easy.

dieselman88

It has .80 ar stamped on the compressor/boost side of the turbo housing