OK, I need help with something...........

[Xplantdad]

I'm thinking if that 74 Trans Am is an SD455 it could be a close race depending on the driver

[MosportGreen66]

Was going to say the same thing. If the car happened to be a super duty, the torque on the thing must out-number that of the L72. Also, correct me if I am wrong, but doesn't drag rading have a lot to do with the driver? If the Yenko's driver was subpar compared to that of the TA, then that might be the answer to your question.

[nuch_ss396]

Bruce,

Those '74 SD-455's were rated in the upper 300's as far as HP, weren't they?
It just looked like the Yenko driver
pulled off the power and let the Trans-Am pull away. Are
those races staged? Anyone know who's Yenko was featured
in this segment?

Steve

[MosportGreen66]

Horsepower ain't everything though.

hp and Torque, weight ratio, rear end gear, transmission... all factor into overall speed

[BBIGG BLOCK 396]

Maybe that Yenko Driver missed a gear!Or maybe he had some type of malfunction such as clutch,busted the distributor cap,could be a number of things.

Bobby Dodson

[Xplantdad]

[ QUOTE ]
Bruce,

Those '74 SD-455's were rated in the upper 300's as far as HP, weren't they?
It just looked like the Yenko driver
pulled off the power and let the Trans-Am pull away. Are
those races staged? Anyone know who's Yenko was featured
in this segment?

Steve

[/ QUOTE ]

Colin or Charley might have an insight on whether those races are staged or not. But from what I remember, the SD's HP rating was VERY conservatively estimated (insurance purposes). If I'm not mistaken...weren't the ratings near to or the same as a hemi (425 +/-)? On unleaded gasoline no less and with less compression?

[Bill Pritchard]

By '74 they were using net HP ratings, so numbers were way down from 70 and earlier. Not sure but I would guess a 74 SD455 would have been somewhere around 300 hp as rated from the factory

[1970Bluel78]

A good friend purchased a 1974 SD 455 new and still has it...HP ( net )rating of 290. The 73 was 310. Car is Quick! AS I recall on radials at E town he went mid 13's

[Xplantdad]

Thanks to Wikipedia...

[ QUOTE ]
In 1973 and 1974, a special version of the 455, called the SD-455, was offered.

The SD-455 used the left over components from Pontiac's 366 NASCAR engine and was built as a full bore racing engine producing over 540 horsepower and was then toned down to appease the EPA and to meet GM's strict horsepower policy which required all GM vehicles to hold the HP to under 300. As a result, the PMD engineers listed the SD-455 at 290 HP but in reality, was producing in final form, 371 HP SAE NET (Approx 440 gross horsepower).

What made this engine unique was the ease with which it could be returned to its 500+ horsepower form. The SD-455 is often considered the last of the true musclecar motors and by many, considered to be the most powerful factory Pontiac engine ever produced.

[/ QUOTE ]

All this with an 8.4:1 compression ratio...

[akcamaro]

That makes me all warm and fuzzy inside. Now I want one even more.