runner volumes??

[gmonde]

i am a amc guy and i will be checking my combo before going to battle and i will let you how the numbers play out gmonde

[Dave Layer]

Junior

The current S/Stk runner volumes basically ARE the old Stock numbers. For years the NHRA runner volumes were listed as "Cylinder Head Volumes" and were used for both Stock and Super Stock. Several years ago NHRA quit ccing Stock heads and the new title for the same runner volume list was (and still is) titled "Super Stock Cylinder Head Volumes". NHRA's tech dept.reasoning for no longer ccing stocker heads, at that time, was your not allowed to modify them so why should we have to check them? And we all know what has happened since.

I don't believe that there are that many Stocker heads in use that are larger than the S/Stock volumes. We have been (and still are) doing alot of good running Stocker heads that will pass the cc rules. HP and Torque come from air flow and air speed not big holes.

Dave Layer

[SS Engine Guy]

Originally Posted by Dave Layer

I don't believe that there are that many Stocker heads in use that are larger than the S/Stock volumes. We have been (and still are) doing alot of good running Stocker heads that will pass the cc rules. HP and Torque come from air flow and air speed not big holes.

Dave Layer

From Greg Hill's post awhile back: 1/5/09
In teardowns over the first part of last year on stock eliminator heads, 59 heads were poured and 48 of them were found to bigger that the super stock volumes. Of that number only three racers were disqualified. If you think your heads are okay you might be surprised. One set of heads that was poured was 17 cc's larger on the intake runner and was passed. If any of you are thinking about going to National events this year I suggest you take your heads off and pour them to see where you are.

Greg

48 out of 59 sounds like a high percentage to me. I agree hp comes from air flow/speed/lack of drop out and large ports don't always equal performance. Maybe the srac wasn't given the correct numbers? I don't know..........sounds like a mess to me seeing that the SS runner specs were gathered quite a few years ago on mostly already modified heads.

[Greg Hill]

That number came from a reliable source.

Greg

[SS Engine Guy]

Thank you Greg. As I stated, there seems to be quite a lot of stock cylinder heads that are larger. Of course I don't have as high of a data base as a sanctioning body, the numbers that I have poured in house seems to back up the 48 out of 59 numbers.

[novassdude]

What is the chance that the heads were to large because they had been modified? I know only a few were tossed but we all know that alot of heads pass that should not have.

[Bill Edgeworth]

I’m really surprised at those numbers. I was one of the people who had their heads poured and not just once, three times last year. My heads came up 3cc under on the intake and 8cc under on the exhaust. I did not see anyone getting a hard time about their runner volumes in any of the “Teardown Parties” I was at. Maybe the Pontiac stuff is the exception to the norm. I did see some very close attention being given to the short side of the runners on a number of people’s heads. Maybe being over the published numbers is going to be the trigger for them taking a closer look.