NHRA Specs for 70 454 Where does the increased HP come from?

[Clem Z.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

go here and see for yourself what is being talked about. http://nhra.net/tech_specs/engine/

[William C.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

I'm with you Clem, as an old Jr Stock and SS racer I'm very familiar with the NHRA "Factoring" of identical engines.

[Steven B.]

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.

Joe

Dale's NHRA inspection jobs go back to the days of the Safety Safari.

Steve

[Pamela H.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

Clem, That site is where I got the information from in the first place. That is why I was curious, Thanks!

[Kenneth B.]

Re: 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...

This is the same for the 70 Camaro/Corvette LT-1 370 Corvette & 360 Camaro. Same block & parts. Marketing wanted you to get more for the price difference.

[Duke W.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

There was a power difference, but one could argue how much was from the dyno cell and how much was from marketing.

SAE gross ratings were derived with the OE exhaust manifolds, and the Corvette's "ram horn" manifolds flow better and, therefore, offers less parasitic power loss than the "log" manifolds used on the Camaro version of the LT-1.

The different exhaust manifolds was the reason for the different SAE gross power ratings although I suspect that the actual power difference was rounded up somewhat.

Duke

[Ray K.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

After a little research in some of my old parts catalogs it is my opinion that the horsepower difference is mostly directed to the camshafts and the RPM. The 454 rated at 345 HP @4400rpm used hydraulic camshaft #3963544. The 454 rated 360HP @4400rpmused hydraulic camshaft #3883986. The 454 rated 390HP @ 4800rpm also used camshaft #3883986.
Although some difference in the HP ratings from the 360HP to the 390HP can be attributed to exhaust systems or other tuning specs. it is mostly related to ( as others have said ) the marketing & advertising for the various car lines. Thus, the 360HP in a Chevelle was a 390HP in a Corvette.

Ray

[Duke W.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

Differences in SAE gross did not include the entire exhaust system - just the exhaust manifolds since SAE gross used large dyno cell pipes with an extraction fan and no mufflers.

There was considerably more difference in big block power ratings in different chassis than small blocks. Another example to add to the above is L-78. In the Corvette it was rated at 425 HP, but only 375 in the Chevelle. AFAIK the engines were identical interally.

I don't know if the Chevelle and Corvette used different manifolds, but if they did, it's hard to conceive that they made a 50 HP difference.

Duke

[Bruce B.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

Dale's NHRA inspection jobs go back to the days of the Safety Safari.

Steve

Dale Schafer is a long time NHRA official and ran fuel testing for a long time.
He was also one of the founders of The Albequerque (I can't spell) Dragstrip and he is writing the history of that drag strip, very interesting.
I met him a few times at the NHRA Nostaliga races at Bowling Green, KY.
Very nice and knowledgeable person.
Bruce B

[Joe L.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

Differences in SAE gross did not include the entire exhaust system - just the exhaust manifolds since SAE gross used large dyno cell pipes with an extraction fan and no mufflers.

There was considerably more difference in big block power ratings in different chassis than small blocks. Another example to add to the above is L-78. In the Corvette it was rated at 425 HP, but only 375 in the Chevelle. AFAIK the engines were identical interally.

I don't know if the Chevelle and Corvette used different manifolds, but if they did, it's hard to conceive that they made a 50 HP difference.

Duke

Duke-----


Chevelles with L-78 used different manifolds ("log" type) than L-78 Corvettes ("header" type).

Internally, the L-78 used in Chevelles was virtually identical to that used in Corvettes. However, the Chevelle L-78 was rated 375 HP @ 5600 RPM. The Corvette L-78 was rated 425 HP @ 6400 RPM.

[Patrick B.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

Duke-----


Chevelles with L-78 used different manifolds ("log" type) than L-78 Corvettes ("header" type).

Internally, the L-78 used in Chevelles was virtually identical to that used in Corvettes. However, the Chevelle L-78 was rated 375 HP @ 5600 RPM. The Corvette L-78 was rated 425 HP @ 6400 RPM.

200 of the 201 1965 Chevelles with 396-375 also used a hydraulic cam 3873844 which may have accounted for a lower rating RPM, but the 1966 Chevelles did use the same mechanical cam as Corvettes.

[Joe L.]

Re: NHRA Specs for 70 454 Where does the increased HP come from?

200 of the 201 1965 Chevelles with 396-375 also used a hydraulic cam 3873844 which may have accounted for a lower rating RPM, but the 1966 Chevelles did use the same mechanical cam as Corvettes.

Patrick-----


I was referring only to the 1966-69 Chevelles with L-78.