Super Stock Piston Compression Heights

boydw2000 · 02-03-2024, 12:13 PM

Working on engine design and build for NHRA Super Stock. I was trying to find out if there are any restrictions on piston compression heights. Rule book states: "Replacement pistons permitted, provided they do not increase stock compression ratio and retain overall design pattern as
specified by automobile manufacturer." I have searched several forums and websites, not finding anything on this. I know the rods have to stay stock length, so could some of the Super Stock engine/racers help me with this info. (Can the pistons compression height be shortened.) I have had the heads, intake, crank, and Jesel rockers with belt drive for this build sitting here for a good 10 yrs now and what to restart the build. Heads and intake were done by the late Dave Layer, things may have improved since then. Thanks for any info you can provide, would like to order the block, which the heads and intake need the block decked to fit the top end.

Regards,
William

Alan Roehrich · 02-03-2024, 12:54 PM

Quote:

Originally Posted by boydw2000

Working on engine design and build for NHRA Super Stock. I was trying to find out if there are any restrictions on piston compression heights. Rule book states: "Replacement pistons permitted, provided they do not increase stock compression ratio and retain overall design pattern as
specified by automobile manufacturer." I have searched several forums and websites, not finding anything on this. I know the rods have to stay stock length, so could some of the Super Stock engine/racers help me with this info. (Can the pistons compression height be shortened.) I have had the heads, intake, crank, and Jesel rockers with belt drive for this build sitting here for a good 10 yrs now and what to restart the build. Heads and intake were done by the late Dave Layer, things may have improved since then. Thanks for any info you can provide, would like to order the block, which the heads and intake need the block decked to fit the top end.

Regards,
William

Stock compression height is not required in Stock or Super Stock.

Be aware that some good tech inspectors will look down upon radical milling of components (blocks and heads) and how legal it is.

Paul Precht · 02-03-2024, 02:50 PM

Quote:

Originally Posted by Alan Roehrich

Stock compression height is not required in Stock or Super Stock.

Be aware that some good tech inspectors will look down upon radical milling of components (blocks and heads) and how legal it is.

There is a minimum CH listed for Stock replacement pistons but not for SS that I can find.

boydw2000 · 02-03-2024, 10:36 PM

Thanks guys, appreciate the replies.

Dyno · 02-03-2024, 10:47 PM

As long as your deck clearance is correct and head gasket thickness measures correct, the pin height does not matter in SS. If your deck height is short , you can make up the difference with a thicker head gasket or the other way around. Make sure your CC"s are correct for the chamber volume and your runner volumes are equal or less than listed. Watch either dome height or dish volumes.

02-03-2024, 12:13 PM	#1
boydw2000 Junior Member Join Date: Oct 2012 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Super Stock Piston Compression Heights Working on engine design and build for NHRA Super Stock. I was trying to find out if there are any restrictions on piston compression heights. Rule book states: "Replacement pistons permitted, provided they do not increase stock compression ratio and retain overall design pattern as specified by automobile manufacturer." I have searched several forums and websites, not finding anything on this. I know the rods have to stay stock length, so could some of the Super Stock engine/racers help me with this info. (Can the pistons compression height be shortened.) I have had the heads, intake, crank, and Jesel rockers with belt drive for this build sitting here for a good 10 yrs now and what to restart the build. Heads and intake were done by the late Dave Layer, things may have improved since then. Thanks for any info you can provide, would like to order the block, which the heads and intake need the block decked to fit the top end. Regards, William

02-03-2024, 10:36 PM	#4
boydw2000 Junior Member Join Date: Oct 2012 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Super Stock Piston Compression Heights Thanks guys, appreciate the replies.

02-03-2024, 10:47 PM	#5
Dyno Senior Member Join Date: Dec 2002 Posts: 870 Likes: 920 Liked 605 Times in 177 Posts	Re: Super Stock Piston Compression Heights As long as your deck clearance is correct and head gasket thickness measures correct, the pin height does not matter in SS. If your deck height is short , you can make up the difference with a thicker head gasket or the other way around. Make sure your CC"s are correct for the chamber volume and your runner volumes are equal or less than listed. Watch either dome height or dish volumes.