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454 H.O, 454cid /425HP Crate Engine = 1971 Corvette LS6?

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Old 09-03-2006, 04:27 PM   #1
RDave
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Default 454 H.O, 454cid /425HP Crate Engine = 1971 Corvette LS6?

This is my first post in the engine mods forum.

I wondered if this engine would be equal in performance to the
1971 Corvette LS6? :

http://www.paceperformance.com/index...D&ProdID=26941

Chevy High Performance did a baseline test on this engine using cast iron exhaust mainfolds (I'm not sure if they were the 1970 Chevelle LS6 or the 1971 Corvette LS6 type) and a generic stock exhaust:

http://www.chevyhiperformance.com/te...ne/index4.html

It looks like the cam is pretty conservative. I guess Chevy's HP and TQ ratings were done with headers, which explains the difference with the Chevy High Performance tests. Any thoughts?


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Old 09-09-2006, 08:04 AM   #2
VETTELESS IN PA
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I have the 454HO in my 69 Chevelle, and w/3.31 gears and 28" tall tires I was trapping at 107+. This was w/a leaky fuel line . Now that I have 26" tall drag radial, fixed fuel line, I hope to get 110 mph. I dont know what kind of #'s the Ls6 was turning, I'd be interested to know. There was a magazine test where both motors were tested against each other, and the 454HO won, but the backed alot of timing out of the LS6 motor b/c of fuel (lack of leaded fuel today). LS6 I would guess would of made more power if they put the timing in it I would imagine.
If anybody has the article I would love to see it.


Quote:
Originally Posted by RDave
This is my first post in the engine mods forum.

I wondered if this engine would be equal in performance to the
1971 Corvette LS6? :

http://www.paceperformance.com/index...D&ProdID=26941

Chevy High Performance did a baseline test on this engine using cast iron exhaust mainfolds (I'm not sure if they were the 1970 Chevelle LS6 or the 1971 Corvette LS6 type) and a generic stock exhaust:

http://www.chevyhiperformance.com/te...ne/index4.html

It looks like the cam is pretty conservative. I guess Chevy's HP and TQ ratings were done with headers, which explains the difference with the Chevy High Performance tests. Any thoughts?


RDave
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Old 10-08-2006, 10:09 PM   #3
Bill Dearborn
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Quote:
Originally Posted by RDave
This is my first post in the engine mods forum.

I wondered if this engine would be equal in performance to the
1971 Corvette LS6? :

http://www.paceperformance.com/index...D&ProdID=26941

Chevy High Performance did a baseline test on this engine using cast iron exhaust mainfolds (I'm not sure if they were the 1970 Chevelle LS6 or the 1971 Corvette LS6 type) and a generic stock exhaust:

http://www.chevyhiperformance.com/te...ne/index4.html

It looks like the cam is pretty conservative. I guess Chevy's HP and TQ ratings were done with headers, which explains the difference with the Chevy High Performance tests. Any thoughts?


RDave
I had one of the 71 LS6 cars as my daily driver for several years. The Corvette (not Chevelle) LS6 engine came with aluminum open chamber heads, a low profile manifold so the carb would fit under a normal BB hood, and it used Chevy's standard street mechanical cam which had been used in BBs from 1965 on. Its been 20 years since I sold the car so I can't remember all the carb details but I do know the carb was a Chevy part numbered 780 standard bore Holley. Since the pistons were the same as the ones used with the previous High Performance closed chamber heads going to the open chamber heads dropped the compression to 9 to 1. The car ran on regular gas and did not need to use leaded gas (no GM engine in a production car from 71 on required leaded gas since they knew they were going with cats in 75). The 425 HP readings for this engine were due to the reduced compression and the intake manifold which wasn't as good as the one on the Chevelle. The aluminum heads knocked about 70 lbs off the engine's weight which really helped take weight off the front end of the car.

The carb was the worst carb I have ever had in a car and convinced me fuel injection is the only way to go and I have never had anything but fuel injected high performance cars since and it feels great. It always blew power valves, leaked gasoline and was a general pain in the ***.

Bill
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