Chevy Small Block Part 17 - PT. 17: Fresh Off The Old Block

DM Is Rebuilt and Ready for a New Year

Mike Petralia Feb 1, 2004 0 Comment(s)
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With a new year usually come new promises. New commitments are also often made, only to be broken later on. But Danger Mouse (DM) will not be broken, nor will we break our promise to give you the best real-world dyno tests with it this year. Although we've got big plans for DM, rest assured that everything we do will still be in the scope of things you can duplicate yourself, usually for just a little extra cash.

When DM was first envisioned, we planned to test any and all combinations that could be thought up, in order to see what worked and what was a load of you know what. Some of our tests have worked very well, and DM peaked has peaked with 480 hp on pump gas last year using an off-the shelf EFI system from F.A.S.T. and no power adders. Sure, we also made over 600 hp with a small Weiand blower, but the main scope of this project has always been motor-only power. We'll stay that way for most of this year, but there are a few HUGE surprises in store later on.

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Back in DM Part 14, we first tested Holley's Street Avenger Throttle Body electronic fuel injection (TBI) and got results that were less than we'd hoped for (see: SC, November 2002). After that test was done, and following a string of steady power losses we'd been experiencing in the last few tests, we'd decided that DM had to come apart for inspection and rebuild. You might think that rebuilding a street engine after just one year of use is unnecessary, but keep in mind that DM lives on the dyno. And the dyno cell is a very harsh environment.

What we mean is that dyno pulls are made at wide-open throttle and there's usually nothing but idling in between. Imagine how your engine would feel if every time you warmed it up, all you did was mash the throttle and raced it for about 10 seconds and then idled around only to mash it again and again. Now try doing that about 1,000 times in a 12-month period and you'll understand why DM needed a rebuild.

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Speed-O-Motive Takes Control
Along with our decision to rebuild DM this year came a deal we struck with our friends over at Speed-O-Motive, who're installing a new DTS engine dyno as this is being written, to take over all the maintenance and testing duties for DM. That frees up time for our staff to pursue other life-affirming goals, like getting a life. The crew at Speed-O, from which now on they'll be referred to, were eager to accept the challenge, and rebuilt DM in less than 2 weeks to keep us on schedule. But, Speed-O's dyno was not ready for a test, so for the first test of 2004 we returned to Vrbancic Brothers Racing and bolted DM onto their DTS dyno to maintain consistency in our testing regime.

Before We Begin
Before we jump right into DM's latest test results, we wanted to go over the rebuild specs for you. DM had seen a lot of dyno pulls last year and its bearings showed it. So a new set of Speed-Pro bearings, along with a fresh set of file-fit Speed-Pro moly rings, were installed. Also, to correct the deck clearance problem DM has had since its beginning, (the piston pin height was too low, so the original set of pistons sat .050-inch down the bore, leaving a huge quench area), we installed a new set of forged Lunati pistons with more pin height to give DM a true "zero" deck.

Then a new set of World Products Sportsman II iron cylinder heads were bolted on and a new Lunati hydraulic roller cam was installed. We reused the same COMP Cams roller lifters, pushrods, and 1.6:1 rocker arms that'd become a stable of DM's past testing. To top things off, a new, coated Holley Street Avenger manifold (PN 300-36S) was installed and topped off with the same Holley HP750 carb we'd used back in Part 14. All of this was to give the Holley Street Avenger TBI fuel injection system we planned to retest a better chance at making some power gains.

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