Aftermarket/Replacement Cylinder Head Rule Change - Page 2

SS734 · 12-13-2017, 04:52 PM

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?

Dwight Southerland · 12-13-2017, 05:13 PM

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.

CWhitney · 12-13-2017, 08:30 PM

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?

james schaechter · 12-13-2017, 09:49 PM

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.

Stephen & Horace Johnson · 12-22-2017, 12:52 AM

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

Paul Merolla · 12-22-2017, 08:21 AM

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

PJ305 · 12-22-2017, 09:53 AM

Quote:

Originally Posted by Paul Merolla

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

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?

Michael Beard · 12-22-2017, 10:03 AM

Quote:

Originally Posted by MR DERBY CITY

Nice, and you guys think that there are NO crate motors in NHRA....

Quote:

Originally Posted by Chris1529

Give everyone a stock replacement aluminum intake too and there you go.

You mean like the LD340?

jmcarter · 12-22-2017, 10:07 AM

Looks like Dwight is going to be busy!

SDT1DYI · 12-22-2017, 10:27 AM

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.

12-13-2017, 04:52 PM	#11
SS734 Junior Member Join Date: Apr 2016 Posts: 27 Likes: 5 Liked 4 Times in 3 Posts	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?

12-13-2017, 05:13 PM	#12
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,980 Likes: 52 Liked 724 Times in 177 Posts	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. __________________

12-13-2017, 08:30 PM	#13
CWhitney Junior Member Join Date: Feb 2008 Location: Sun Valley,Ca Posts: 85 Likes: 2 Liked 8 Times in 5 Posts	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?

12-13-2017, 09:49 PM	#14
james schaechter VIP Member Join Date: Dec 2004 Location: Cumming GA Posts: 1,928 Likes: 1,066 Liked 1,212 Times in 249 Posts	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. __________________ James Schaechter 3163 STK

12-22-2017, 12:52 AM	#15
Stephen & Horace Johnson Senior Member Join Date: Jul 2007 Posts: 949 Likes: 323 Liked 148 Times in 46 Posts	Re: Aftermarket/Replacement Cylinder Head Rule Change 5hp off only for aftermarket head..... __________________ Stephen Johnson #2162 Horace Johnson #2167 SS/D 427 Ford Fairlane NHRA-IHRA

12-22-2017, 08:21 AM	#16
Paul Merolla Senior Member Join Date: Dec 2001 Location: Papillion, NE Posts: 596 Likes: 194 Liked 232 Times in 57 Posts	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

12-22-2017, 10:07 AM	#19
jmcarter VIP Member Join Date: Dec 2008 Location: Richmond Hill GA (and Port Ludlow WA) Posts: 4,121 Likes: 1,976 Liked 2,702 Times in 852 Posts	Re: Aftermarket/Replacement Cylinder Head Rule Change Looks like Dwight is going to be busy! __________________ Jim Carter 2340 Super Stock 2340 SST/2340 Stock

12-22-2017, 10:27 AM	#20
SDT1DYI Member Join Date: Nov 2016 Location: Indianola Washington Posts: 354 Likes: 0 Liked 394 Times in 124 Posts	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.