Vortec Cylinder Heads - Head Games

Danger Mouse Part 6

Mike Petralia Feb 1, 2003 0 Comment(s)
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We installed a set of Denso Iridium Power spark plugs (PN IT24). Notice the cast-in hump above the plug in this photo. According to McKenzie's Cylinder Heads, this is a foundry reference point and can be radiused smooth without hurting power if you're porting your heads.

Last Month's Power RecapIn DM's fourth bash on the dyno last month we made some mistakes and tried a set of cylinder heads that were too big for the little Mouse to play with. DM ended the day with a maximum 379 hp and 417 lb-ft of torque. The average horsepower and torque figures were 303 and 399, respectively (see: Test 13). That was down a little from the factory iron camel hump castings we'd ran before, but the power loss was most likely due to too large of a combustion chamber and too big of valves in the heads we tried.

For DM's fifth dyno test we thought we could do a little better by installing a set of Vortec cylinder heads and trying some different-ratio COMP Cams Magnum roller-tip rocker arms. We were once again rewarded with more power, and after all testing was completed, DM clocked in at a new 416 peak hp and 440 lb-ft of torque. Average horsepower and torque also increased up to 333 and 417, respectively (see: Test 15). As usual, if you feel you've got a better idea for us to try, send it in and we'll tackle it in the upcoming months.

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5th Series Of Dyno Tests
We'll number every series of tests consecutively, starting with the last number of the previous month's tests. We'll also list the last test from the previous month so you'll have something to which to compare the new tests. This month our first new test is number 14. Unless listed, no other changes were made for any test.

We used a set of Mr. Gasket's MLS (Multi-Layered-Steel) head gaskets to seal the Vortec heads. So far, we're very satisfied with their performance.

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SDPC machines the Vortec castings to accept larger valvesprings and cuts the valve guide bosses down so you can run a cam up to .550 lift.

Test 13: Last test from last month. S/R Torquer cylinder heads PN 042660-2 67S (67cc chambers, 170cc intake runner volume, 2.02/1.60 valves). Edelbrock RPM Air Gap manifold, Speed Demon 750 carb, 1-inch open carb spacer, COMP Cams XE262H cam (262/270 adv duration, 218/224 duration @ .050, .462/.469 valve lift, 110 lobe separation) straight up.




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