What fuel are you high compression guys running?

[IBMFD3S]

as i see it: the problem is detonation and probably exhaust valve is a hot spot so the fuel ignites on it's own because of the high pressure and/or a hot spot.
if LPG or CNG is not available I think there are 2 options IMO:
either start injecting water or a mix of water and methanol as it lowers the grade of self-igniting surcomstances. in that case you can put pump gas in it.

here some figures:
gasoline, including racegas, auto-ignites at 660 F.
alcohol, (methanol, ethanol and isopropyl) auto-ignites at 858 degrees F.

'of course we know' that the primary deal with lower intake temps is more oxygen molecules per volume. and when you are talking oxygen nothing beats alcohol, or methanol specifically.

meth is 49% oxygen by weight
ethanol is 34% oxygen by weight.
gasoline is zero% oxygen.

as to cooling:

meth is 1.154 MJ/Kg
eth is .913
gasoline is .297

methanol is the winner.... lots of oxygen and lots of cooling. so i would think about injecting methanol or a mix of methanol with water.

/edit: with the above i mean (of course) injecting pump fuel with xx% of a mixture.