Two choices for B17, T3/T04B .36 turbine, .63 compressor, or T3/T04E .48/.63 (I think). Which would you chose? I know the B would spool up fast, but would it run out of steam before redline? I'm a noob to the whole A/R thing.

 

It depends on what you want; What is the car's purpose? Drag, AutoX, etc. Do you want midrange power, or do you want good topend?

What boost level are you planning on sticking too? Small Turbos start to get inefficient when you get into higher pressure levels. But the bigger turbos are inefficient at the lower boost levels. It's all a big compromise.

Personally, I'd go with the T3/T04E .63 A/R turbine side, and .50 A/R on the compressor side.

 

^really? wouldn't a .63 a/r on the turbine side be laggy? i was under the impression that you should have a smaller number on the turbine side than on the compressor side....... but you have it the other way around..

 

The idea works for both sides of the turbo, but the effects are more dramatic when you change your turbine housing. A .63 A/R can be laggy, I guess it just depends what your definition of lag is. Lag can be a good thing as well.

 

Just want the car to be enjoyable for spirited driving. I've been I/H/E for almost 4 years now, and while the B17 is fun, I want something a little more fun than I'm used to. Boost pressure would be low, 7-8psi and really wouldn't go higher than that. I guess if it came down to it, I could swap snails out later if I wanted higher boost, etc.

 

If you go too small on the turbine A/R you will find your self in the surge region of the compressor. Check the compressor map of the compressor you want to use to see how close you can get to the surge region and then choose the best turbine.

 

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