What should be done to the head of an EF or to make it better suited to LPG?
my car has done a headgasket.. so the head will have to come off soon!
the car is also copping a GRA Straight LPG conversion and so i'd like to get the head setup nicely so it can run LPG all the time, what else should be done to it to help in the way of LPG performance.
i don't want anything done to it that would impede if the engine copped a supercharger/turbo at some stage.
1995 EF II Falcon GLi: Heritage Green, 4spd Auto, AUII 17" Rims, Custom BA Front Bar, Lowered, Gas Research LPG, Clear Indicators, JVC MP3 Headunit, Phoenix Gold 6.5" Splits, Coustic 481QE Amp, Clarion 12" sub, Leather Seats, Power Window Conversion, 3.45 LSD, Pacemaker Comp Extractors, 2.5" Exhaust, Mandrel Bent Intake, High Flow Filter, Wade 1004 110 cam.
In Progress: BA XR Side Skirts, BA XR Rear bar, BA Shifter Handle.
well LPG has a higher octane than PULP so you can safely increase the compression and get a cam to suit LPG..
Im in the same boat .. running dedicated LPG and will be getting my head flashed up in the next fortnight after I get a 'stock' 1/4 mile time on Wed 3rd..Then i'll know and see the differnce hopefully
Gas actually has an Euivalent octane to premium unleaded, it has a ron of 98. its octane figure is actually between 118 to 124 depending which fuel site you check, but they always have a ron in equivalence to petrol which is always 98.
nocking the compression up will help it a little, but its no good if you are thinking of turbo or supercharging later on.
The standard heads arnt to bad for gas, but you could always look at porting etc. Depending on the condition of your head it might be worth getting the seats done or re cut. and guides replaced.
If your going to put a cam in then heavier valve springs, can help.
How can it have an octane rating (average?) of 118 to 124 and a RON of 98? There are three values given for octane, RON, MON and an average.. RON is research octane number, and is the highest number you will get, because it is done in optimum conditions. MON is sort've representative of a vehicle engine environment (higher temps, higher rpm engine), and the average is somewhere between the two.
Anyway, apart from that, the I6s dont respond very well to compression increases at all (like, you wont notice much power increase at all.. and after about 12:1, it'll decrease, obviously), so don't bother.. for the money, just get one of those GRA voodoo cams, and save up for the day lpg injection takes off.. if it ever does.
TQE, SWB, ATPS, Worst of the E-series.. and I wouldn't have it any other way
Not really sure how that octane works but i could send you the information on gas so you could see it for yourself. Or you could have a look at the impco website, on there you can find a download book of information called foxy factors which they go on about octane ratings of gas in there.
But basically it says what i said about the equivalent octane to petrol being 98.
Dont get your head decked to run a higher CR with gas
you'll need another head for when you blow it
Really, done that before have you?
10-10.5:1 is fine for LPG provided your timing is correctly setup, especially with an alloy head. My XE has been running LPG only for over 4 years at 10.5:1 and it has less pinging problems than my XF had running the same ratio on premium.
I run nearly 11:1 with the cast heads in my 351 and don't have any problems at all (but to be fair the cam in the 351 does have a larger amount of overlap than most I6 cams).
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