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Avgas


Guest vhpacer73

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Guest vhpacer73

What adjustments would need to made to the engine (toyota 4k) when using avgas?(off-road use) I just put a head on it with an 11:1 comp ratio. So yeh I spose timing?? And what else???

Thanks

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Guest vhpacer73

Yeh thanks.Yep its just a standard head been planed a couple of mm. I know it has an 11:1 comp ratio. The motor has a jetted 32/36 webber and a lumpy cam. It used to have a heavily ported head but I found out that it was actually robbing the motor of power, because it was ported for a much more powerful engine. Will running it on av (or mostly av) just lead to engine troubles in the future?

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only if ya get pulled by the cops :lol: on an older engine av is prolly better cause it has lead in it which lubes the valve stems and guides and stops valve seat recession which is the wearing out of the valve seat cause unleaded is dry and the valves rotate when the engine is running. 4ks have an alloy head anyway so you wont have that prob cause they have hardened valve seats.

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You'll also want to fit twin sidedraughts or you will just be wasting your time, the only way to get any real power out of these engines is with twin sidedraughts

or a big fuckin hairdryer :lol: the only prob with av is that ya cant roll up to the place that sells it and fill ya beast up, UNLESS.. make some plywood wings up and try and convince the seller its an areoplane :lol: . ive been experimenting with 98 with nulon octane boost for the corty as it also has too much comp 4 pump gas . this combo works well and feels pretty much the same as av can even keep my 17deg timing the same. have to go to 10deg on 96 then it wont start or idle properly. can go 12-15 on 98 better but still feels a bit flat.

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or a big fuckin hairdryer the only prob with av is that ya cant roll up to the place that sells it and fill ya beast up, UNLESS.. make some plywood wings up and try and convince the seller its an areoplane . ive been experimenting with 98 with nulon octane boost for the corty as it also has too much comp 4 pump gas . this combo works well and feels pretty much the same as av can even keep my 17deg timing the same. have to go to 10deg on 96 then it wont start or idle properly. can go 12-15 on 98 better but still feels a bit flat.

Dam thats alot of advance.. how high is your comp ratio again?

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its about 10.7-1 but i have a 310dur cam so the engine bleeds comp until about 2500rpm because the inlet and exhaust valves overlap so much. theres less chance of detonation after 3-4000 because the engine is free reving and not loaded right up. because my engine is basically a race item i am more concerned about total advance not static advance. i set it up at 2500rpm to 38deg total which is heaps for a chevy. which works out at about 17deg static

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ya cant roll up to the place that sells it and fill ya beast up

yes you can

anyways. i take it you have an aftermarket exhaust...? without a catalyc converter (i know i cant spell) i hope.... because those things dont like av gas.

if you want av gas, just go to BP kumeu, talk to jeff AND ONLY JEFF!!! and tell him Neil that used to work there send you and ask if you can get some av gas. he might ask you to come back on a different day, but i'm pretty sure he'll let you get some.

but then again, i take it you are getting it at mates rates... because if you have to pay full price (~$1.90) then its NOT worth it. as you get ALOT LESS mileage out of avvy then 98

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hey thanx for the heads up bro , but im not about to drive 500kms just to buy avgas. ill just drive the 8 kms to the aerodrome and fill up a couple of 20s for $1.60 lt. hey and my cars pure oldschool bra there are no mod cons and certinly no cats in my exhaust cept for the occasional one i might run over :lol: haha

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