Fast Burn DreamsWhen we first tested DM using the GM Performance Parts cast-iron Vortec cylinder heads the results were outstanding. Then we thought about running GM's Fast Burn aluminum heads, which were based on the Vortec castings, but with some radical changes. For one, the Fast Burn heads have a much larger 210cc intake runner, which, in hindsight, might have been just a bit too much for the little Mouse. Second, we tried a new COMP Cams Xtreme Energy hydraulic roller camshaft that also may have been too big for our needs. In the end, the Fast Burn heads worked well, but power was down when compared to the other set of aluminum heads we'd ran before, which had smaller 195cc chambers. We think this really points out the importance of properly matching components to your application. And that going too big is still not the best way to make power today.
T26: GMPP Aluminum Fast Burn heads (9.2:1 cr, 62cc chambers, 210cc runners, 2.00-inch hollow stem intake valves, 1.55-inch Sodium filled exhaust valves), GMPP single-plane intake manifold, Speed Demon 750 carb, COMP Cams Xtreme Energy hydraulic roller camshaft XR-282-HR (230/236 at .050, 282/288 adv, .510/.520 lift, 110 LS). GMPP 1.5:1 aluminum roller rockers, 36 degrees total advance.
Lasting ImpressionsOur last set of tests for DM included swapping out the 750-cfm carb for a Holley Street Avenger TBI system we had lying around our office. This test did not go too well and we were plagued with failure almost from the start. The engine wouldn't make anywhere near the power it had been making before (compare T26 and T27), and it turned out that our Holley parts had sat in our offices for way too long before we tested them because we learned too late that Holley had updated them since. Our EFI fuel map was wrong for the throttle body we were trying to run so we had a tuning nightmare all day long and when we finally got DM to run, it was almost too late. Since these last tests were such a bust, we've decided to rebuild DM and equip it with the newest Holley components and a smaller set of cylinder heads to make sure it'll run correctly next time out.