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Hi guys - quick question, is there a point in compression ratios where retarding the timing ceases to become an option to avoiding detonation?

Just wondering, doing a 11:1 duel fuel (propane) build and have the means to set duel spark tables (ecu).

thanks
 

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Hates: Liver. Loves: Diesel
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There is always an optimum point for ignition lead based on mechanical events like dome shape and size, head material, swirl, compression, etc. You can crutch detonation by retarding timing but its always just that; a crutch.

I would say (to answer your question) that for practical purposes, no. You would run out of tuning range before you ran into compression ignition. You could theoretically run a 14:1 engine on 87 octane with only about 20* ignition lead, but it would probably only rev to 3000 rpms and make very little power. No detonation, but so far out of tune that its undesirable.
 

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crossy said:
Hi guys - quick question, is there a point in compression ratios where retarding the timing ceases to become an option to avoiding detonation?

Just wondering, doing a 11:1 duel fuel (propane) build and have the means to set duel spark tables (ecu).

thanks

Yes. When compressive pressures spontaneously ignite the fuel without any spark. When your rig starts to "diesel".

In practical applications, 11/1 on pump grade gasoline takes judicious manipulation of advance curves and parts compatability to avoid damaging inaudable detonation.

I strongly suggest you look into the "head grooving" threads on this site.

http://www.hotrodders.com/forum/sin...ock-350-a-102958.html?highlight=head+grooving
 
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