67 or 76mm turbo on my drag car?

[blackvette101]

What do you guys think would make more power on my 306. It's a built 306 with a trickflow top end kit. However I am still using the stock block so I am limited to 10 psi. I've heard that at such a low pressure ratio the 76mm will make less power because it will be below its efficiancy island. I'm not too worried about the lag since it will be a drag car with a 4000 rpm converter but I will not go with the 76 if it will make less power. What do you guys think I should run?

 

[Wildcard]

The 76 should be better. Match it with a smaller turbine a/r if you are worried about lag , but with 4000 rpm being your launch rpm you shouldn't have a problem if your running a .68-.81 a/r backside. If you want specifics pull out the compressor maps of both turbos and check to see sheets what the turbo would look like on your engine.

 

[Shaunk]

Unless your planning to go with an aftermarket block later the 67 will be more than enough for your needs.