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Mike Volkman · 02-07-2022, 01:21 PM

Aluminum or replacement heads - Some received a 10 hp adjustment and others 5. On our 318 combo we petitioned NHRA for the 5 hp like our Chevy bros recd and we got it. Noticed some bb chevy also recd 10. Not sure the thinking with NHRA. Typo?

All the engine gurus i talk to say the aluminum head loses 15 hp apples to apples. I'm thinking untouched that is probably correct but with the better combustion chambers etc who knows.

So if an aluminum is untouched there could be a hp reduction under the then current factored rating. I know our 340 aluminum ss cant compare to the steel head factor. +17 hp difference on aluminum, not 10 or 5.

02-07-2022, 01:21 PM	#6
Mike Volkman Junior Member Join Date: Nov 2020 Posts: 80 Likes: 32 Liked 508 Times in 51 Posts	Re: Access to AMA Shipping Weights? Aluminum or replacement heads - Some received a 10 hp adjustment and others 5. On our 318 combo we petitioned NHRA for the 5 hp like our Chevy bros recd and we got it. Noticed some bb chevy also recd 10. Not sure the thinking with NHRA. Typo? All the engine gurus i talk to say the aluminum head loses 15 hp apples to apples. I'm thinking untouched that is probably correct but with the better combustion chambers etc who knows. So if an aluminum is untouched there could be a hp reduction under the then current factored rating. I know our 340 aluminum ss cant compare to the steel head factor. +17 hp difference on aluminum, not 10 or 5. Last edited by Mike Volkman; 02-07-2022 at 04:33 PM.