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trooper Tdiesel · 09-24-2013, 03:10 AM

E10 with a 87 rating is with the ethanol

they blend 84~ octane gas with the ethanol making the 87 octane.

increasing comp from 8 to 9 will gain more mpg then going from 10 to 11 comp.
i found a chart on the net once and buy the time your up to 12 to 1 it was a lot less.
HAA found it SEE PHOTO.....

most heads can be shaved 0.040" but that's only going to get you about 0.5 compression or less.

the best way to know how much clearance there is, is to put a putty on top of the piston and put the head back on with the belt and crank over by hand, and pull head that will tell you how much space you really have to play with...

some times you can source flat top pistons from another engine that's in the same family that has a bigger chamber in the head and use the flat tops in combo with a head with a smaller chamber in the head to make for a comp boost.
or go the other way if you have flat top pistons all ready, and use a different head with smaller chambers.

or in some cases there are after market pistons that are extra tall to gane compression.

i don't know if the photo is right but it seems in line with my thinking at least.

09-24-2013, 03:10 AM	#3 (permalink)
trooper Tdiesel live, breath, Isuzu-Ds Join Date: Mar 2011 Location: oregon Posts: 231 puddle jumper - '93 Suzuki sidekick base model energizer bunny - '86 isuzu trooper base model Clifford the big red dog - '84 GM S-10 durango Thanks: 1 Thanked 20 Times in 17 Posts	E10 with a 87 rating is with the ethanol they blend 84~ octane gas with the ethanol making the 87 octane. increasing comp from 8 to 9 will gain more mpg then going from 10 to 11 comp. i found a chart on the net once and buy the time your up to 12 to 1 it was a lot less. HAA found it SEE PHOTO..... most heads can be shaved 0.040" but that's only going to get you about 0.5 compression or less. the best way to know how much clearance there is, is to put a putty on top of the piston and put the head back on with the belt and crank over by hand, and pull head that will tell you how much space you really have to play with... some times you can source flat top pistons from another engine that's in the same family that has a bigger chamber in the head and use the flat tops in combo with a head with a smaller chamber in the head to make for a comp boost. or go the other way if you have flat top pistons all ready, and use a different head with smaller chambers. or in some cases there are after market pistons that are extra tall to gane compression. i don't know if the photo is right but it seems in line with my thinking at least. Attached Thumbnails __________________ 1 86 T\D trooper with rare GEN 3 rods TRANS FIXED NOW DD 1 86 4WD 5sp pup is 2.3L gas, but plan on 2.2L diesel repower 1 91 trop, long term plan is a group buy of imported Isuzu 4JB1-T 2.8L I-4 engines, hoping to get price down to 2K not 3K plus 1993 sidekick my MPG toy, epa rating 26. i get 29/31 with stock drive train.