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Hi, I'm converting my Jeep 4.0L 6 to lpg-only this April and want to complete a long-overdue 4.7L stroker project at the same time.
From my research it appears the ideal CR i'm after is 12:1 to 14:1 (stock is just under 9:1)
Has anyone done this (ie a high/er CR, naturally-aspirated lpg stroker either v8 or 6) or know of any good links for info ?
I mainly want to clear up whether the stock 4.0L bottom end (currently 140k on the motor) will like such a raise in CR or if big $$ are needed to prevent kaboom or spat head gaskets.
I'm building mild Cleveland with 224 @ .50 cam on straight gas... I asked around and general opinion was 10.0 to 1 compression, even Gas Research said that. Originally was hoping to go a bit higher than that the quality of LPG isn't so great anymore I've been told.
BTW if running alloy head(s) 11.0 to 1 would be acceptable.
I guess the 12-14:1 range I was looking at was more propane-based. Is there really that much extra non-propane in our lpg ? I guess so...
Have got a gas cam ready to go and was keen to up the cr a little as the pistons have to be custom made anyway so can order to suit.
Dismissed the idea of either super/turbo charging long ago for a million reasons - main one... I'm a tightarse
aint keen for the $$ alloy head. am just going to run a flowed stocker cast one with bigger valves.
as part of the stroker install an adjustable map sensor is going in for fine tuning but I'm keeping the factory computer. may have to address this later with an add-on chip.
