I recently picked up a '94 rx7. The motor was rebuilt and street ported by Atkins. At the same time a pair of Pettit hybrid turbos were also installed. The previous owner removed the boost pills from the wastegate lines as he was using this setup in conjunction with a Power FC.

Now the car is running a stock ECU, the pettit turbos are running just off the wastegates so they boost something like 7-5-7 pattern. What is the MAX boost I could run with this setup? My only other mods are downpipe and apexi N1 exhaust.

 

Since you're running the stock ecu, 10 psi.

 

erm not to over-rule you, but i think the straw analogy is in order here. 10psi on the stock turbo is less than 10 psi on a ported/clipped/etc. turbo

 

10 psi at the intake manifold is10 psi.

Q of air is a function of press, density, and crosssection area. the intake is a fixed cross section, p= 10psi in both case, and density will be the same if the air is the same temp..

Now if the big turbo is more efficent it may have not heated the air as much, thus increasing its density and thus mass of air; but I wouldn't expect the density to be too different. The bigger gain such come from say 12 psi at turbo is needed to create 10 at intake rather than say 14 to get 10.

 

Seeing as how the stock ecu is right around 10:1 AFR above 4000 rpm with a downpipe and exhaust, I doubt stock turbos that are ported and have clipped turbine wheels are going to be an unsafe combination.....

 

Ok 10 psi. Thanks guys!

 

Get a power fc or other standalone, and you should be able to run 16 psi.

 

From what I hear about Atkins motors, you have bigger problems on your hands!