Chevy Engine Build Part 26 - The Pinnacle Of Performance

More Camshaft Gives DM 580 Hp And 514 Ft-Lb TQ!

Mike Petralia Oct 1, 2004 0 Comment(s)
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Last month we started out by saying "it's been a long time since Danger Mouse (DM) has seen gains this big with only one bolt-on." Well, this month we're saying it again because the gains were even bigger than before, and we did it with fewer bolt ons this time too! In fact, this month's power gains were so impressive that we feel we've reached the pinnacle of normally aspirated performance for DM and we're going to go in a radically different direction from here. Yep, for a while at least, we'll be stepping it back, looking at power made with some really streetable combinations. Although finding this much power has truly been a fun experience, we need to get back into the real street game.

In this month's test, No. 43, we made almost as much power normally aspirated as we did with a blower way back in DM Pt 10/Test 20 (July, 2003). Back then we installed a Weiand Pro-Street mini blower and made 602-peak hp. Of course the blower added lots of torque as well, with DM making almost 575 lb-ft back in that test, all of it on 100-octane unleaded pump gas. Jump back to the present and we figured it would be fitting to return to Weiand, and its parent company Holley Performance Products, to see if we could make almost as much power without the blower now. We wanted to experiment with a combination that few people ever use on the street, but one that can make a lot of power.

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Last month we felt that our cam choice was not quite in sync with our intake manifold/cylinder head package. So we asked Lunati to modify one of their catalog grinds for us and it turned out to be the perfect match.

Test 42 from last month was our first trial with an out-of-the-box Weiand Hi-Ram, and the results were good, (see: DM Pt 25/Test 42; September, 2004). We knew the ramming effect of the long-runner Hi-Ram would make more torque, but we'd also expected more peak horsepower. When that extra top-end power didn't arrive, we consulted with George and Bob Vrbancic to select a new, more appropriate cam matched to DM's Hi-Ram intake manifold.

We also felt strongly that, although the valve springs on DM's Edelbrock Victor Jr. cylinder heads might still be in good shape, (a quick check in the valve spring tester confirmed they were holding up just fine), the entire valve train might be moving around a bit near our very high 7,000 rpm redline. So we dusted off some parts from DM's past that didn't work too well the first time out, but saved the day for us this time.

Way back in DM Pt 3/Test 08, (November, 2002), we tested a COMP Cams stud girdle to see if there would be any power added to the very mild combination we were running at the time. Power fell off, and we placed the girdle into semi-retirement. But, like any old pro, when the going gets tough, the coach needs something he can call on to shift the tide and the stud girdle was it. We bolted it on and were rewarded with more top end power and no losses down low.

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Speaking of perfect matches... When we removed the Weiand Hi Ram to swap cams, we noticed that the Fel-Pro 1206 gasket was barely sealing. Notice the impression showing the top of the intake not even covering the silicone bead on the gasket.

Heat Affects Power
Today was the first of June, and the heat in Speed-O-Motive's dyno cell was staggering. Hovering above 95-degrees most of the day, the air going into the engine was not conducive to making power. The problem was that with DM's new cam increasing cylinder pressure, all that hot air did was make DM detonate. If this had been a cool day we easily could've gotten away with running this test on pump gas.

But conditions forced us to run 105-octane VP race gas, which was a first for DM while running normally aspirated. Even when we tried to pull ignition advance out using MSD's timing computer, the power fell off and the detonation lingered on. There was no way around it this month, but heck, what'd be the fun of doing this thing the same way every single time?




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