I have a set of turbos from COSMO 13B RE, the seem identical to the ones from my previous FD. For this project the car is going to get a computer which can't run sequential turbos. So I need to convert them to NON sequential. I have searched far and wide and found much info about the conversion and the wastgate porting, but there is some conflicting information. Specificly it is what to do with the turbo pre controll. Some say to cut it out and plug the shaft hole, some say weld it open, and some say weld it shut.

What is the reasoning on this, anyone please?



The other question is regarding wastegate overporting. I have allready over ported the wastgate into an oval shape so that the stock flapper covers about 90% of the hole and cant get stuck in. This is well above the 75% rule, but I am wondering if anyone has replaced this flapper with a larger washer or possibly piston engine valve, if so it could be oppened up into a much larger oval withought removing to much structural material. Has anyone done this, and is it worth it?



Thanks allot,,,,

the wastegate flapper should cover 100% of the hole. If it does not, you'll have VERY slow buildup of boost. If you can find a larger washer that can stand up to the heat, I would do that.



Pre-control is easy. Cut it out and weld/plug the shaft hole. If you don't cut it out, it needs to be held open with some safety wire on the outside.

this thread explains why I overported,



http://www.rx7club.com/forum/showthread.ph...honda+wastegate



I have never actually driven a car with an over ported wastegate, my previous FD was ported right to the edge, it was sequential and it still had boost creep depending on the exhaust. after reading this thread I did buy the book.

The cosmo turbos may look the same but they are not. Fd turbos flow about 12% more . More or less blades on turbine and compressor, and the fd ones spin at higher rpm.