65,
I asked and received from NHRA a reduction of all 1970 455's in Super Stock. They are now rated 335HP. We normally double that number to see what HP is required to make a SS car go 1 second under the index as a general rule of thumb.
This means 670HP so it is up to you. The 428 is similarly is 320 rated only requiring 640HP. NHRA listed the 428 as a flat top piston, but we all know the truth. This resulted in a combo that has a MAX CR with no valve reliefs at 13.2 to one compression. With valve reliefs more realistically 12.5 to one way higher than the 70 455HO
428 is the softest Pontiac in SS due to two huge mistake by NHRA. A much better combo than the 1970 455 currently. The 455 will have a stroke that is much more limited on intake port size than the 428, and much less compression.
As to the HP, I am not privy to everyone's dyno sheets, but I just listed who the fastest cars are as they are listed in the public domain.
Lynn
Last edited by NHRASuperStock455SD; 03-04-2007 at 11:54 PM.
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