454 Big Block HP
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
No it won't make 390 hp. The rating was SAE gross which meant no accessories, headers, tweaked carb & ignition etc. It was also at the flywheel. In '71 the vette was rated both SAE gross and NET. NET means with accessories, production carb, exhaust (including mufflers) and still at the flywheel. 71 was 365 hp gross, 285 NET. I put my 71 on a chassis dyno when it was almost stock. Only non-stock item was a replacement cam with about 5 degrees more duration (maybe 10 hp). It made 255 hp at the wheels.
Thread Starter
Heel & Toe
Joined: Oct 2005
Posts: 23
Likes: 0
I kinda figured that, just stepping on the gas it never felt like 390, kinda dissapointing, so I guess to make it 390 you would have to do a lot like new cam, piston, full exhaust and carb. Mabe then do you think it could make the 390?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Zwede - Was there a higher HP 454 in 71 or 72? Many years ago I had a friend come over and we installed new brake lines in his 454. I can't be 100% sure, but I think that it was stock other than a doug Nash 5 speed. Compared to my L-82 350 ci it was a rocket ship.
It was probably the big block TQ that was impressing me.
It was probably the big block TQ that was impressing me.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
The LS-5 responds extrememly well to mods. Headers, small cam, single plane intake and 750 Holley got me about 400 flywheel hp (328 rwhp) vs the stock 285. Mild aluminum heads and a mild hydraulic roller cam bumped it to about 490 (392 rwhp). This is still a very mild combo setup for daily commuting. You can get 450 rwhp (over 550 at the flywheel) with good heads such as AFR 305 or Brodix race-rites and a bigger cam. It would still be very driveable. All without ever taking the short block out of the car.
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Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Originally Posted by scuba900
I kinda figured that, just stepping on the gas it never felt like 390, kinda dissapointing, so I guess to make it 390 you would have to do a lot like new cam, piston, full exhaust and carb. Mabe then do you think it could make the 390?
A stock LS-5 runs a 14-flat @100+ mph, 0-60 in 6 secs.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Originally Posted by zwede
No it won't make 390 hp. The rating was SAE gross which meant no accessories, headers, tweaked carb & ignition etc. It was also at the flywheel. In '71 the vette was rated both SAE gross and NET. NET means with accessories, production carb, exhaust (including mufflers) and still at the flywheel. 71 was 365 hp gross, 285 NET. I put my 71 on a chassis dyno when it was almost stock. Only non-stock item was a replacement cam with about 5 degrees more duration (maybe 10 hp). It made 255 hp at the wheels.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Originally Posted by scuba900
is that someones home page or a website, can you give me the whole address.
Burning Brakes
Joined: Aug 2005
Posts: 1,209
Likes: 87
From: Putnam county NY
2025 c3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
I'd love to see a basline test versus simple modifications like timing and carb tuning.
Maybe heads, intake and exhaust.
Maybe heads, intake and exhaust.
Melting Slicks
Joined: Nov 2004
Posts: 2,672
Likes: 6
From: Nevada City California
Originally Posted by scuba900
Has anyone ever put a stock 1970 vette with a 454 BB on the dyno and got the 390 HP out of it like it says it should?