What kind of issues would I see with a turbo with to small of a an AR on the turbine?

[jet1]

Running 2 60 mm compressors at 1000 hp with ex turbin AR of .68. seems very touchy for tulipping valves. It is a 260 ci running e85 @ 15 lbs @ 7200 rpm.

[Orr89rocz]

Hard to say without more info.

What size motor? Rpm range? What size turbine wheel? How much boost?

Any backpressure readings?

[jet1]

Ya sorry got pulled away and didn't realize that I hit post. Edited it. I do not have any back pressure measurements but will be doing that. I guess wondering what I should be seeing at the turbo flange?

[Orr89rocz]

Thats doing well on just 15 psi for 260 inches. But i dont think you would have issues with those turbos assuming turbine is in the high 50’s mm low 60’s mm or bigger.

I ran 60mm compressors with 65 mm turbines and .68 ar on my mild 400 sbc and only turned 5500 rpm making 800 hp crank 640 whp. 14 psi. No issues

[jet1]

Thanks, that is good to know. Ya the power is decent if I could keep it together. it will be going back on the dyno in a month, so I am just trying get things to look at. timing is another thing which seems high to me at 32 deg all the way up to 22 lbs.