Hi Hugh,
My TR250 cam will be 274 seat duration, .426 value lift with 1.55:1 Roller
Rockers, and 110.5 Lobe
Separation. I already have the cam. I'm also using Group 44 Falcon Headers. How
can I get a feel for
the maximum CR with 93 Octane pump gas? Do you have any ideas?
Thanks,
Don Malling
Hugh Barber wrote:
> I use premium pump gas. The key is that I am not running a stock camshaft.
> You are correct that with a stock cam that about 9.5 to 1 is as high as you
> can go because with the stock cams, the cylinder pressures get too high. I
> first used a Triumph "S-2" cam and now use a grind by Elgin Cams, both with
> no problems. The longer duration of the more radical cams allow a higher
> compression ration - indeed in order to get the maximum effect from the
> cams, you have to raise the compression. Here is a link to a tech article
> about this subject. The particular article is about a Chevy V-8, but the
> principle remains the same.
> http://www.chevyhiperformance.com/techarticles/81679/
>
> This is one of the reasons why I believe its important to modify engines as
> a complete system (intake, engine, and exhaust), rather than doing it
> piecemeal. You end up with better results that last longer.
>
> Hugh Barber
> Hollister, CA
> '73 TR6
>
> -----Original Message-----
> From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
> Behalf Of Don Malling
> Sent: Wednesday, February 23, 2005 6:52 AM
> To: 6pack@autox.team.net
> Subject: Re: Are u kidding me???
>
> Hi Hugh,
>
> What sort of gas are you using at 10.5:1?
>
> I was under the impression that 9.5:1 was about max for 93 octane pump gas
> (R+M)/2
>
> Don Malling
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