I need some help diagnosing a problem. The car is my 86 Civic Si with a Turborex kit (Garrett T3) on a stock motor. The car is used only for autocross, so it doesn't get driven much. Recently, it has started smoking at idle after a run. I typically try to let it idle for 2 minutes after each run to cool things off a bit. Now, after about 1 1/2 minutes at idle, it starts pouring blueish smoke. If I give it just a little throttle, like 1500-2000rpm, it quits smoking. It seems to be running fine, and isn't fouling plugs, so I thought that my turbo was going bad. The turbo was also leaking oil, so I decided to get a new (rebuilt) one. I put the rebuilt one on and raced it today, and I'm getting the same thing - smoke at idle only. I replaced the drain line when I did the turbo. The only other thing I have done recently is I installed a new exhaust right before this started happening. I went from a 2 1/4" crush bent system that exited at the rear of the car with no muffler to a 2 1/2" straight pipe that ends right behind the driver, in the center of the car, with no bends at all. Has anyone ever heard of an exhaust that has too little backpressure causing a turbo to smoke at idle??? Since its the end of the racing season, I'm going to do a leakdown and compression test anyway, but I'm pretty sure that the turbo is where the oil is entering the exhaust and burning. Any thoughts or suggestions would be appreciated.
Thanks - Chris

 

your turbo is prolly blown check if your oil drain has a kink in it

 

that's weird if its only doing it at idle only..hmmm

 

probably the rings.when boosting the cylinder pressure forces the oil back into the oil pan,when idling the manifold vacuum pulls the oil up into the combustion chamber .

 

Yeah probably the rings and the boost blows it back down the cylinder walls. I bet when you tear into that one, you find **** loads of blowby down the piston skirts.