Leaded vs Unleaded High Octane Fuel

Eric Villeneuve

Eric Villeneuve

Location
Timmins
Hi Guys,


Just looking to get some clarification between the difference that unleaded vs leaded fuel will have on your engine. I am currently running a 2013 superjet with aftermarket high compression head usually using anything from 93-96 octane by diluting leaded bases 100+ pro crate high octane race gas.

Looking to see what other people are running. Reason why I am asking is because I can get 102 octane fuel for cheap right now but it is unleaded so not sure if I can run this.
 
X

X2Kid

Location
Canberra, Australia.
Lead was only ever added to fuel to act as an upper cylinder lubricant in four-cycle engines (to prevent valve seat recession). It offers no benefit in a two-cycle engine and its absence will cause no ill effect.

The only thing you have to watch out for is fuel containing ethanol. That stuff is incompatible with most PWC fuel systems. If your high octane brew is ethanol-free you should go for it.
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Lead is also an anti-knock/octane adder, don't know where everyone got that its only for valve seats?
Your motor requires no lead to function. Lead is pretty much impossible to find besides avgas so I'm not sure how this is even a question. What PSI are you running? A mix of avgas and 91 octane pump is usually plenty for most people's setup.
 
Nsmith212

Nsmith212

Location
Concord ca
110 Sunoco and a lot of vp is leaded also. Where you really get the gains is oxegenated fuel it just doesn't play nice with carbs so after we run it we drain and run pump gas through.


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Eric Villeneuve

Eric Villeneuve

Location
Timmins
bored&stroked said:
Lead is also an anti-knock/octane adder, don't know where everyone got that its only for valve seats?
Your motor requires no lead to function. Lead is pretty much impossible to find besides avgas so I'm not sure how this is even a question. What PSI are you running? A mix of avgas and 91 octane pump is usually plenty for most people's setup.
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I will have to check my psi last time I believe it was in the 170-185 range. I was told that if you run 35cc domes you can get away with running 91 octane if you compression is below 185psi.

I wasn't sure if you were able to run av gas??? There is no issue with running this, like engine performance wise or just ware and tare on the engine. I've never dealt with this type of gasoline before.
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Yes avgas is fine. I'm not a fan of it by itself but mixed with pump or race gas its great, $4/Gal for 100 octane can't be bad right?!? lol. It just doesn't have the structure to burn at a high rate of speed [in other words high rpm]. Mixing it gives the missing link so to speak.
 
Eric Villeneuve

Eric Villeneuve

Location
Timmins
bored&stroked said:
Yes avgas is fine. I'm not a fan of it by itself but mixed with pump or race gas its great, $4/Gal for 100 octane can't be bad right?!? lol. It just doesn't have the structure to burn at a high rate of speed [in other words high rpm]. Mixing it gives the missing link so to speak.
Click to expand...


$4/gallon seems like a pretty decent price lol. I am not sure where I can get this but my buddy works at an aviation facility so hopefully he can hook me up.
 
lanmine657

lanmine657

Location
fortcollins
There are many factors that will determine your fuel selection, compression-pipe-ignition timing-porttiming-squish, usually 190psi is the pumpgas tipping point for most yami set ups
 
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Scribbleheli

Scribbleheli

Location
United States
I have a JS550 running 210-220 PSI.
I run a sunoco 110 mixed with 91 pump gas. In a 50/50 mix or there about. $9.75 a gallon :(:eek::oops:

I did run 91 octane all season since I didn't know where to get Race fuel at the time so I was running it pretty rich. With dual cooling, I didn't have any signs of detonation.
Its a rocket ship when Its mellowed out.
Cant wait to get the timing and tuning upped now that I have to good stuff :D
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Not sure what part of the world your in but its perfectly legal to buy gasoline. If it wasn't, the businesses wouldn't sell it to you. Aviation companys don't mess around, they are all about regulations since that's all aviation is.
 
Nsmith212

Nsmith212

Location
Concord ca
Aviation fuel is not legal to sell Exocet to airplanes in California which I'm guessing is a federal law because it is patrolled by tsa


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bored&stroked

bored&stroked

Urban redneck
Location
AZ
ahhh magic word there, California. Everything is illegal there. And its why I said bring a fuel can. Here in AZ, the pumps just say "for off road use only", nothing about aviation use only. Anyone can roll up, insert a credit card, and buy avgas. If they see you pump into a car/truck though, cops will be called.
 
Nsmith212

Nsmith212

Location
Concord ca
Exactly! Haha Yeah I took a gas can but it should be up to me to use it in it aircraft or off-road use it shouldn't matter for whoever is selling the fuel


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fast superjet chase

fast superjet chase

Location
Colorado
180-185 is the highest that I would run pump gas safely I ran 180psi in my old yamaha super stock for 10 years no problem on 91octane
 
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