NHRA Specs for 70 454 Where does the increased HP come from?
When looking at the NHRA specs for the various 454's they all have the same components, Same cam, same pistons etc...where does the increased HP come from? Very confused...
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
If you are asking why the Corvette is usually a few HP higher, I suppose you could point to slightly more aggressive tuning in the distributor and carb or a less restrictive exhaust system. It could also be that the marketing department had a hand in advertised ratings. Remember the 430 HP L/88? Chip. -
Re: NHRA Specs for 70 454 Where does the increased HP come from?
Have you asked the NHRA where they obtain their figures?
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Pam,
What are the NHRA HP ratings by year that you refer to? You might ask Clem Z your question. I think he was a NHRA tech inspector in a former life. He is probably very familiar with their specs. He is a frequent poster on this board. I can dig up his contact info on here if you can't find it.
JoeComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Joe
I believe Clem was a Nascar inspector. I too am curious where these NHRA specs come from.
TerryComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
'Firstly, what specific combinations are you referring to? "70 454 was available with different compression ratios and also mechanical vs hydraulic camshafts. VERY diffferent configurations, totally unlike your '74.Bill Clupper #618Comment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
I believe what Pamela is refering to is the NHRA "factored horsepower" these ratings are what NHRA has come up
with to "level the playing field" so to speak, some ratings are raised and some remain the same or even lowered.
Stock and Super Stock classes are set my Power to weight ratios. Of course this is always a subject of great
contraversy over on the Class Racers website.
RichardComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Been there and done that, but even the factory had different ratings and configurations, 390 hp with hydraulic lifters and small port heads, and the Mechanical lifter Rectangular post engines, aluminum intakes and dual feed Holley carb.Bill Clupper #618Comment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Pamela-----
If you are referring ONLY to 1970 454's, all the LS-5's, Corvette or otherwise, have essentially the same components with the most notable exception being the exhaust manifolds. However, 1970 LS-6 (Chevelle only for 1970) has completely different components.In Appreciation of John HinckleyComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Let me clarify the question...In 1970 the 454 had a 345 HP, a 360 HP, and a 390 HP (also had a 450 HP but that configuation is irrelevant to my ? as th components were entirely different, different cam, intake, carb, lifters etc)....
The first three engines all had the same carb, the came cam, same heads, block, valves, springs, pistons and compression...yet they ranged from 345 to 390 HP...What accounted for the difference in HP when they had all the same elements????
I got the info off the NHRA Website for the Tech specs for the 1970 454...Comment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
No did not but i may follow up on that...thanksComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
If you have it handy that would be helpful. I'll have to go back into the NHRA website to pull up the information on the engines...Comment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Pam-----
The 360 HP 454 was used in 1970 SS454 Chevelles. It was essentially the same as the 390 HP 454 used in Corvettes and full size Chevrolets. The Chevelles and full size Chevrolets used different and more restrictive exhaust manifolds than Corvettes. That explains the lower rating for the Chevelle engine. However, it's inconsistent with the fact that the Corvette and full size Chevrolet LS-5's were rated the same horsepower. More likely, it's just a case of marketing folks having some control over advertised horsepower ratings. This probably explains why NHRA considered them all to be the same.
However, 345 horsepower 454 is NOT the same as LS-5. It used a different camshaft (GM #3963544 versus GM #3904359 for LS-5). The 3963544 camshaft was considerably milder than the 3904359.In Appreciation of John HinckleyComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
Pam,
Who are you replying to here? You might try using reply with quote...
JoeComment
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Re: NHRA Specs for 70 454 Where does the increased HP come from?
I suspect that what you are looking at is the "Factored" horsepower chart for different classes. This is not a true HP rating, but an arbitrary adjustment NHRA uses to equalize competition. In that case, A hypothetical would be the same engine in a Corvette (98 inch WB 50-50 weight dist) vs a Chevelle (108 inch WB 60-40 weight distribution) would perform with different results even at equal weights due to the inherent traction advantages of the Corvette's shorter wheelbase and better weight distribution. That oversimplifies the NHRA system, but is the easiest description I can make as to how the same engine is "adjusted" in horsepower for NHRA classification purposes. It has Nothing to do with any real differences in the engines.Bill Clupper #618Comment
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