I'm in the process of converting my Z28 from a T-trim Vortech to a PTE-76 GT-S. The car has a 383 with 8.3/1 compression, AFR 210's, 224/236 - 14 cam, a TH-350/4000 stall, etc and has run 10.40 at 133 with 13 psi boost at 3800 lb.

I'm fab'ing up the kit myself and have a queston about the exhaust pipe leading to the turbo. My plan is to place the turbo where the centrifugal was, but with the compressor inlet facing forward. The turbine inlet will point up, with the turbine discharge pointing rearward.

I will use a 1 3/4" shorty header on the passenger side and a 2 1/2" crossover pipe under the motor. The pipe will travel up the rear driver's side of the engine, run forward along the head (picking up each cylinder as it passes, aka "log"), then turn down at the #1 cylinder into the turbine. The "log" was originally planned to be 3", but would be MUCH easier to fabricate and clear everything if it were 2 1/2".

My thinking is this: Heavy cars have run 150 mph in the quarter and made 800+ rwhp with the 76 GTS and 3" downpipe. The whole idea behind a turbo is that it expands the exhaust gas through the turbine wheel. If the gas goes from 30 psi in the header to 5 psi in the exhaust, then it expanded about 2 times it's original volume. So, the pipe leading to the turbine could be half the cross sectional area of the downpipe. This logic says that the pipe leading to the turbo could be 2 1/4" for a 3" downpipe and be OK.

Am I crazy, or does this make sense to anyone?

Mike

 

You probably allready know, but turbo technology's street system is almost identical to what you described.

If you're going to go through the trouble of fabricating it yourself, why not build an individual tube manifold for the drivers side instead of a log?


To answer your question though, IMO 2.5in would work for the log, and making it out of 3in would do little for increasing efficiency/power potential, especially in comparison to changing the design.

 

Believe me, I would like that better than a log. But, on a scale of 1 to 10, 10 being most difficult to fabricate, I give the log a 7 and a header a 9.5. Also, I'm trying to ensure I have access to the header bolts, sparkplugs, turbine flange bolts, and clearance to all heat-sensitive items. The 4th Gen / LT1 doesn't give much room for this.

How much power has the Turbo Technology kit been proven good to?

Thanks,
Mike

 

Now that gets my vote for understatement of the year.

Looking under the hood of these cars makes me want to scream "Get the kit!" as making your own kit would certainly cause one to question one's own sanity....

 

Walk in the park