Volume III, Issue 6, Page 17

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Max Chevy covers all automotive things Chevy. A new issue of MaxChevy.com is published on the 15th of each month and is updated throughout the month.


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roject cars being the recalcitrant churls that they are--devices whose fate is obviously controlled by creatures wearing tin foil hats somewhere outside our dreamscapes--there will be no installment of the flaky-foont Biscayne this month.

Except for a couple of letters we’ve gotten on the enterprise, both of them from Biscayne fan Mike Perrault, who is putting his ’66 B-body back together the way I should have done mine, it seems that none of you could care less about my overweight unpopular champion. That’s cool. I’m sure I’d like your car, too, but I really don’t care if it runs or rots because it isn’t mine.

There is a matter of philosophy at stake here, one that coincides with foolhardy notions and one that has to do with when you reach the saturation point, when enough really is enough. We used to do certain activities until we dropped, passed out or got arrested. Way too risky these days, brittle bones and all that. And it hasn’t got a thing to do with maturity (I figure I stopped doing that when I was about 20). No, it’s more about feelings of self-worth, gratitude, and propriety at a certain stage of life. Remember, I’m just going on what I’ve read about and been told, what those thoughts and goals should be, but I stopped maturing way too early, so all I really have to go on is hearsay—that and about 45 years of menacing myself and keeping fairly quiet about it. Like kids do when they play in the woods alone.

As I’ve probably said here more than once, the 453-inch LS-type is a mild street engine composed of some very expensive parts: Lower end worth about $7,500 and the crankshaft is a Hank the Crank billet piece of which there is exactly one. The compression ratio is also mild, averaging 10.7:1. With CNC LS6 cylinder heads and a GM Hot Cam, and an LS6 intake manifold, the nugget makes more torque than horsepower—which was exactly the goal.

It was a collective between Mark McPhail, then a special projects engineer at GM, and Katech Performance, one of GM’s not-so-silent partners over the years who provided many winning engine combinations, mostly of the road-race variety, and a lucky car writer who was in the right place. So despite its billet arm, CarriIlo connecting rods, and CP pistons, the stuff of many NASCAR qualifier engines, this one was built more for reliability than bestial response.

As tuned with the early FAST XFi engine controller and matching eDist electronics, it starts easily (hot or cold), has a very crisp throttle response, and pulls like a mother until the mid-5,000s when it begins to run out of air. They thinking here is that it needs more fuel/air to make more power that is now latent and waiting for more of that pure breath that makes it grow.

I made several inquiries about applying the inexpensive L92 truck cylinder heads (developed for the 403ci) that needed larger intake parts and valves. On the exhaust side, they flow less than the CNC-hogged LS6 heads that are already on the motor. The first person I asked about his was Nicky Folwer, Scoggin-Dickey’s LS-engine master.

“Ro, whatever you can think of doing to one of these engines I have already done,” He told me at the PRI Show two years ago. “You’ll pick up about 100hp and 100 lb-ft. The L92s are perfect for a big-bore engine like yours.”

I got another opinion from Mark McPhail, now an application engineer at GMCOPO (www.gmcopo.com), a growing concern composed of ex-GM engineers who market stuff ranging from electronic controllers, to manuals, to engine swap information, to sensitive measuring equipment and how-to installations. Its repertoire is growing steadily.

“I have not been impressed with the L92/LS3 heads for street use. They kill off low-speed torque and response. They are more knock limited than the ported LS6 heads that you have (you cannot run as much spark timing before knock). I would use a FAST inlet and a 90mm mechanical throttle body to tune-up your ride. This project is complete, move on to something else.”

Mark, I’d love to but I have already a pile of parts that can’t be returned. I have the utmost regard for your how-to knowledge and development skills, but I’m going to piss you off this time--and you did remind me to hold onto all parts that I removed from the original form.

Matt Hilton at HPS Cylinder Head & Manifold Development in nearby Tarpon Springs, (www.hpscylinderheads.com), will port-match the exhaust side and do some bowl and bump smoothing but nothing radical. The L92 heads are cheap and I got a couple of bare ones that Matt will fill up with Manley stainless valves and Crane valve springs and related equipment. These pieces are now available with a complete CNC experience, from GMPP but the ones they put on the 6.2L trucks don’t have any of that stuff and that’s what I wanted to put on the 453.

The head modifications will appear first. As tuned by Cal Hartline (www.hartlineperformance), baseline dynamometer runs produced 460 hp and 498lb-ft of torque at the wheel. We’ll see what effect just the heads have on this combination and retune the new program, and spin it up on the wheel dyno. I guess what I’m looking for is 500hp. It’s just a stupid arbitrary number. I’m also excited to feel the expanded power band. The engine pulls very hard to 5,500, but completes the scenario by slithering around in 0.62:1 at 1,500rpm, no chugging, no gagging, no stumbling. It purrs.

Am I going to screw up the perfect storm? Probably. If all goes “as planned,” hardy-har-har, we’ll have an installment on Matt’s cylinder head treatment in next month’s MaxChevy and an installation and testing the month following. Best not be holding your breath, though. For a preview of HPS’ expertise, check out this issue for the 5.3L truck heads Matt did and flowed for a serious supercharged engine. Yes, LM7, small-valve castings that most people consign to shelf duty for perpetuity.

As for that maturity thing? It’ll have to wait a little longer.