71 Corvette 454/425 Compression Ratio

[Bruce N.]

Is it 9 to 1 or 10 to 1? Is there any difinitive information on the 71 - 454 CR available on the Internet that I can print?
Thanks,

[Tom H.]

Re: 71 Corvette 454/425 Compression Ratio

Spec sheets I have show 9 to 1.

[Duke W.]

Re: 71 Corvette 454/425 Compression Ratio

Like all 1971 GM engines the LS6 was designed to operate on 91 RON unleaded gasolline, which is essentially the same as today's 87 PON.

The actual as-built CR was probably closer to 8.5:1 than the advertised 9:1.

If I was restoring one today I would assemble it with a true CR of 10.25:1, which would be fine with today's unleaded premium and the increased CR would improve torque/power across the range 5-10 percent and reduce fuel consumption by about the same amount.

Duke

[Bruce N.]

Re: 71 Corvette 454/425 Compression Ratio

Thanks Guys,
Where can I find a copy of the actual spec sheets?

[Clem Z.]

Re: 71 Corvette 454/425 Compression Ratio

try here. http://www.vettescape.com/

[Bruce N.]

Re: 71 Corvette 454/425 Compression Ratio

Thanks Clem