Pulling Forum - Octaine fuel ?

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Octaine fuel ?

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Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=163975
Printed Date: 27 Apr 2024 at 5:16pm
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Topic: Octaine fuel ?

Posted By: Macon Rounds
Subject: Octaine fuel ?
Date Posted: 29 Aug 2019 at 12:35pm

What Octane fuel is needed to support 175 PSI cylinder pressure ?

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The Allis "D" Series Tractors, Gravely Walk behind Tractors, Cowboy Action Shooting !!!!!!! And Checkmate

Replies:

Posted By: tbran
Date Posted: 29 Aug 2019 at 1:23pm

as a rule of thumb - excluding modified cams, a 10:1 CR would be approx. 150 PSI... so you have 12:1 CR ? IF so, assuming a tractor engine since posted here and a low RPM engine you are going to lug, about as high as you can find? E85 or aviation fuel.... most engines with high CR 's in automotive use have knock sensors to retard timing. Be careful.... IMHO

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When told "it's not the money,it's the principle", remember, it's always the money..

Posted By: DrAllis
Date Posted: 29 Aug 2019 at 1:39pm

That kind of compression is the exactly same as a 170/175 tractor and 87 octane is minimum and timing cannot exceed 25 degrees BTDC at full throttle. In fact 23 degrees BTDC is probably better. You'd do yourself a favor running 89 octane.

Posted By: Macon Rounds
Date Posted: 29 Aug 2019 at 5:01pm

Thanks for the info.....

I had been running 100 octane low lead Avgas but its not always convenient to get.

Thanks again.

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The Allis "D" Series Tractors, Gravely Walk behind Tractors, Cowboy Action Shooting !!!!!!! And Checkmate