Re: Aftermarket/Replacement Cylinder Head Rule Change
 

Guys you are missing the point here.


Aftermarket heads are already accepted with a HP penalty. There is talk that they will become "replacement" heads and this result will eliminate the different factors of OEM vs. Aftermarket heads for the combos that currently have them.
Trying to find out "if" this does go through, what will happen to the two hp factors that are currently different?

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

Conceptually, when you place a different hp factor on an engine because of the use of replacement heads (aftermarket or OEM), you have essentially created a new engine for the books. The problem is the way that classification is calculated since it uses a weight break of one rating and then the weight of the new hp factor. Eliminating the differential of ratings will simplify the calculation for the guys in the field, which is always a good thing since it helps eliminate confusion and mistakes.

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

So does this mean that if a combination has been factored 20 HP now its gonna go back to the OG HP rating??

Example 396 Iron head is 375/385
396 Alum head is rated at 405HP

Both heads go back to 375?

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

It makes sense to me that there would not be a penalty in superstock. heads can be modified extensively. Stockers should keep the penalty for the aftermarket heads. My opinion anyway.

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

5hp off only for aftermarket head.....

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

Boy, I didn't see that coming...aftermarket heads for SBC in Stock. With a 5hp penalty.

NHRA Tech Department makes updates/corrections to the Stock Car Classification Guide
Jan. 1, 2018



The NHRA Technical Department recently made changes to the Class Guide.

Buick 98-99 added missing pages to website

Chev 62-79 added SBC replacement heads for Stock

Chev 2015 Camaro 376 365 corrected shipping weight Stk/SS

Chev 1969 Corvette 350 300 separated auto/man transmission

Ford 2010 330 500 added Stock weight breaks

Ford 2012 330 510 added Stock weight breaks

Plym 1968 Barracuda 426 425/505 separated from non SS/AH

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

I looked up one of the Edelbrock heads for a SBC and it listed 185cc intake runner, the others were 172cc to 175cc intake runner. NHRA specs are 172cc intake and 65cc exhaust, how in the world can a stock racer use replacement heads that are so far out of whack from each other?

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

You mean like the LD340? :rolleyes:

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

Looks like Dwight is going to be busy!

Re: Aftermarket/Replacement Cylinder Head Rule Change
 

Does Edelbrock then make a SBC head with intake runners 161-165 CC's? Edelbrock is the only approved head? All I have seen is 180 CC and up.

Steve Teeter STK 6380.