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Hp and torque ratings of Mk IV Ls6 crate?

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Old 10-09-2006, 05:22 AM   #1
RDave
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Default Hp and torque ratings of Mk IV Ls6 crate?

I wondered if anyone had the specs for the above crate engine which had a compression ratio of 10.2:1 which was in between the 1970 Chevelle LS6's 11:1 and the 1971 Corvette LS6's 9:1.

I found this on the web:

"I'm looking at a 6th edition 1988 Chevolet Power Book right now with the following listed:

366250 Engine Asm, 454 CID (Typical of 1970 Corvette) Less Exh manifolds, distr & clutch. Open chamber CI heads with Closed chamber design piston. 10.2:1 CR, LS-6"

but there were no HP and torque ratings listed.

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Old 10-10-2006, 05:29 AM   #2
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Default The Specs were the same as the 1970 LS6 Chevelle..

A friend emailed me this:

Engine part # 366250
Stamped XAA above timing chain cover

Displacement 454
HP 450@ 5600rpms
CR 10.2:1
Bore and stroke 4.25 x 4.00
cam shaft solid lifter flat tappet 3904362 advertized lift intake/exhaust
0.500"/o.500"

I am asuming the torque was the same as the Chevelle LS6 also.

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Old 10-10-2006, 07:46 AM   #3
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I saw some dyno tests on them in Hot Rod a long time ago...they made beween 425-440 or so on engine dyno. The later versions of them actually went to a hyd flat tappet copy of the LS-6 cam with non adjustable valvetrain. In the dyno tests they were essentially a dead heat between the two cams. But they were only revving to 5200-5500 rpm or so.

JIM
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Old 10-10-2006, 09:30 AM   #4
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Quote:
Originally Posted by 427Hotrod
I saw some dyno tests on them in Hot Rod a long time ago...they made beween 425-440 or so on engine dyno. The later versions of them actually went to a hyd flat tappet copy of the LS-6 cam with non adjustable valvetrain. In the dyno tests they were essentially a dead heat between the two cams. But they were only revving to 5200-5500 rpm or so.

JIM
Hi Jim,

I saw an old Hot Rod test where they dyno'ed a Mark IV LS6 Crate engine and got 437 HP.

I was still curious at what GM rated the torque for this engine at, with the 1970 Chevelle LS6 coming in at 500ft lbs with an 11.25:1 compression ratio and the 1971 Corvette LS6 coming in at 475 ft lbs with a 9:1 compression ratio.

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