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Performance Turbocharger Setup Questions - Off The Wire

From Canada with Love
First off, I want to say that I love the magazine and it's the only one I've ever subscribed to. I own a 1994 six-speed Z28, so naturally I love to see LT1 tech in the mag. However, I realize that the LSX owners far out number the LTXs and that there is way more to high-tech GMs than fourth-gens. I read every mag from front to back, including the Turbo Buick and Cobalt articles.

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Lately I've seen letters to the Editor thanking you guys at the mag for the increase in females gracing the pages. Now don't get me wrong, attractive women are great, but this is a magazine that teaches people how to choose the right cylinder heads for their new stroker project, not a tuner mag that teaches people which stickers add the most hp to their fart-can-equipped Civic. Please leave the women in the tuner mags.

Lastly, I must say that I have always thought that catalytic converters zap huge power from any engine, and living in Canada, I am not in danger of having my car pulled off the road for not passing a sniffer test. We do, however, have visual inspections stations that have started to appear here and there. I believe that more than a few of your readers would love to see a test where you show a stock engine with and without cats and possibly a modified engine, just to show that the loss in power (if any) increases, the more power an engine puts out.
-Joshua Kehler
Via email

Cats are the least of your concern, a "dirty" versus a "clean" cam could be 20 to 50 rwhp easily. Our emissions-legal CT project made about 75 hp shy of what you would typically expect of a heads/cam LS1 F-body (due to the CARB-legal LS6 cam), but that is why man created forced induction. And don't worry, model shoots would never take any edit pages from the tech section. Hopefully the one or two per year we do is a nice enough compromise.

Turbo Tech
I read the excellent article "Records Meant to be Broken" in the November 2009 issue of GM High-Tech Performance. The car is remarkable. I wished the article had been more expansive because the car is obviously extremely well thought out. For instance, I wondered why a hydraulic roller was used instead of a solid roller. I also wish more emphasis had been laid out about the electronic versus fuel strategy, for example I am told that these days drag race turbos send some rare fuel in to the exhaust and ignite it there so as to spool up the turbo quicker but then again, maybe that would be an excellent auxiliary article for you to write?

Also, the article spoke, on page 25, about "using an octet of 160 lb/hr injectors", how is it that 8 injectors are used on a six cylinder engine?

Anyway, the specific reason I am writing is because the article mentioned the car runs 37 psi of boost and that is a huge amount; I am wondering how they keep head gaskets in the engine and what else they do to keep this engine together. You have a great magazine!
Thank you,
-Kevin Lambert
Via email

That sounds like some good fodder for a tech article or a turbo buildup, might want to start harassing Mr. Cesler, our resident tuning expert and lover of turbos. Tony uses VP Q16, which is part of the new generation of oxygenated fuel. I don't know that using this particular fuel helps spool up, but often fattening up the mixture is known to help. Choosing the correct converter, using a transbrake, and a high-dollar billet wheel turbo also help. As for the "octet," you are correct, that is a misprint. While some have been known to use extra injectors in custom intake manifolds for additional fueling, I don't believe Mr. Gomes employs this method. As for keeping the engine together, consider that this a very stoutly built motor using a TA Performance block. Copper head gaskets and O-rings are very common in a high-horse turbo build of this kind, but mainly I would attribute the credit to both RPE (who built the engine) and tuner Cal Hartline as well as sound maintenance and attention to detail by the owner.

Please send all letters to:, or mail to: GM High-Tech Performance, 9036 Brittany Way, Tampa, FL 33619. All letters are presumed for publication and GMHTP reserves the right to edit all letters.




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