slimtastic
yea dude...I rock
- Joined
- Aug 9, 2002
- Messages
- 741
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SignUp Now!You can't flip the factory manifolds like the LS people do to face them forward?[/. F or w body. Wouldn't work. This is easier.
NIce build thread! I know its tons of hours and work to do so props to getting the LC2 accessories and everything working on the newer engine. I chewed on this a long time ago when I built Codys GN but didn't have the ability at the time to fab the intake and a few other things that I can do now. He had a fairly new 3" downpipe from Gbody parts I believe so I just modified it a bit to move the turbo up a little and worked well, but when you are building it all from scratch that really helps and opens a lot of doors. I thought it would be great to be able to use the same existing downpipe but wasn't that simple. Looking good so far and hope it finished up great for you.
Tune wise- if you need assistance let me know. I built a hybrid GTP/Fbody file for my L67 86 Cutlass so I can use all the common L67 engine side tables and 2 bar map sensor and also run dual bank 02 sensors and 4L60E transmission. I originally just used a 98 Fbody pcm which works ok, and also what is still in Codys car and hasn't caused any issues- you are just stuck with a 1 bar map sensor. The 2004+ Supercharged Grand Prix used a smaller map sensor like the NA engines, only 2 bar, so it will clip right into that style intake.
You'd be better off spending the time trying to get the turbo spooled and then trying to keep the exhaust pressure as close to intake manifold pressure as possible. There's huge power to be had in doing so. The valve timing and piston position relative to tdc is what will determine flow direction for a given cylinder more so than the header tube location and design. You're still dealing with much higher ex pressure on almost everyone of these little turbo applications. The flow is going in the direction of least resistance which happens to be backward into the intake as the piston approaches tdc on the end of the ex stroke and the beginning of the intake stroke. The piston has to go far enough down the bore to let the intake charge begin to fill the cylinder. Till this happens there is no positive flow into the cylinder and the air that's about to enter is diluted with the back flow. Reducing the ex pressure not only allows the positive flow to begin sooner but will also reduce pumping losses at the end of the ex stroke.I have a few in this thread.http://turbobuick.com/forums/threads/turbo-header-log-vs-collector-vs-ta-style.413682/
The thing I was talking about is referred to as a anti reversion cone. By allowing the primaries to stick into the 2.5" tubing instead of notching creates this anti reversion wall. The exhaust gas travels out of the motor like pictured, down the center of the pipe and then fans out and back into the combustion chamber.