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I am having some difficulty sourcing automotive 100 octane fuel for my incoming Radical SR3 1500. I understand that the radical doesn't have a knock sensor so I have to worry a bit about denonation. Anyone ran 100 octane Low Lead avgas in their radical or SR? Any issues? Should I just buy track gas at their ridiculous markup? Thanks!
Aviation fuel is not the fuel recommended for your SR3 1500. "Low lead" designation for avgas is only low lead by avgas standards and is nowhere near low lead by street standards. It's not the right stuff to put in your car.Quote:
Originally Posted by Philip944
I use Sunoco SS100 in my SR3-1500 (apparently the same fuel used at Spring Mountain for their cars and what they recommend) and it's one of the common fuels provided track-side at my local facility. Your SR3 only consumes about 10 gals per hour of on-track time, so that might not be the right place to economize.
Knut
Av gas works fine in most race engines, since it has a fair amount of lead you might not want to use it in some of the electric FI systems because of oxygen sensors fouling but anything else is fine. Cosworth recommends adding a small percentage of oil to the gas as it is very dry and my guess is that this is to protect the Lucas mech units which have very tight clearances. It is a hell of a lot cheaper than the "racing gas" and works just fine.
As a follow up, just bought 100 LL Av gas yesterday. $3.99/gal sure as hell beats race gas!
Two weekends ago I was at the track and spent some time talking to the Sunoco rep. I have been using LL avgas since I bought my sport racer 5 years ago with no fuel related issues; a WSR with a 4age engine ,12:1 compression, and 8k rpm.
His take, which has been the most comprehensive I have heard to date, is the avgas uses kerosene in it which benefits aviation engines as they are working at high altitude. At low altitudes the kerosene will burn hotter effecting power output. Also he mentioned LL has some additional detergents which may have negative effects on power also. He seems to think I might free up 5-10 hp by switching to race gas.
In class 10 hp isn't needed to win and in group 10 hp wont help reach the front runners who are 5 sec a lap faster.
A draw back to race gas is all that cool stuff that makes it better also likes to evaporate. Use it or loose it. I will some times come back from the track with 10 gals left over. With LL I just store it in a cool dark place and save on my expenses next time out. If the race gas goes bad well there is 100$ down the drain.
Until I am within 2 secs of the leaders I am going to keep using LL and put the cost saving to track time.
Miguel
I worried about the shellac left by most pump gas when it evaporates, and justified AvGas for that reason because our cars spend a lot of time sitting. It turns out Sunoco race gas is also formulated to leave no residue.
The $6 plus per gallon difference between av gas and race gas as far as I am concerned more than makes up for any marginal difference in performance if it's real or imaginary!
I grew up in the 1950's living two miles from Phillips 66 research center and engine lab. Their engine lab was a delight to a young budding motorhead. At any time they had up to 32 engines, of all types, on dyno's running sometimes at full throttle to failure. What no one remembers is that Phillips had their own nuclear reactor, I think in Idaho, but I don't remember the location for sure. If the researchers wanted to investigate, for example, ring wear on the third ring of an engine, they would pull down the engine and send those rings to Idaho to be irradiated. They would put a radiation sensor in the oil pan and graph the increase in radiation in the oil to understand the wear. As a young kid I thought that was cool. I received lectures on the differences between oils, gas formulations, why we shouldn't put drip gas we tapped off he local oil field pipes in the car, etc.
I was told that Phillips aviation fuel was designed with lower flame front speeds for lower rpm aviation engines as well as high altitudes. I use 100LL in my Ivey FF and FC engines except when a series requires pump gas. I also use it in my generators for the reasons Tim says above.
I don't use it in my non-catalytic motorcycles because I suspect at higher rpms there would be incomplete burn. I don't know that and have no data to support the decision.
Everything above is here say as I didn't work in the labs, although my Dad spent 30 years there and was awarded 74 US Patents. (I am really proud of him) If we wanted to make up a rule, we might say 100LL in engines that turn 9000 RPM or less, and race gas in those that turn higher. Don't take my word for it. Decide for yourself, Ha.
YMMV. Have fun today, Jim
I think this is BS. I can't find any reference to avgas containing kerosene. As for detergents, I believe it has FEWER than pump or race gas.. Avgas is the probably the purest form of gas available to us.Quote:
Originally Posted by Seabrid
10 HP? Mybe if you use some of that toxic VP stuff....
AVGAS is pretty light and does evaporate but doesn't leave nearly as much deposits to gum things up like auto fuel. It's designed to sit for months in an unused airplane.
It also doesn't destroy your fuel cell like a lot of hi-perf street gas.
The potential drawback is that it's designed for steady throttle applications. Sometimes a rapid drop in pressure (like when blasting the throttle open) can cause the fuel to condense on the cylinder walls and cause a stumble. I don't think I've ever run into that condition though.
That happens to me several times per session. I just figured that's what happens with carburetors. Huh.Quote:
Originally Posted by Rick Kirchner
Probably jetting more likelyQuote:
Originally Posted by TimH
I run avgas in my Honda 2k generator because it won't go stale between uses - however it will foul the plug if run for some time. LL is not very low lead. I buy it locally for about $4/gal.
I figure maybe I should be squeezing the throttle open a little sooner rather than slamming it open after the apex. The hiccup just tells me I'm late to the party.Quote:
Originally Posted by BeerBudgetRacing