Avgas

[Punkur67]

I have no experience with avgas and have only heard rumors about how to use it properly. I just bought a 2.0 subaru motor that has been tuned running it and I dont want to pay the $750 to reprogram it especially with how great it runs on it now (269 rwhp). I have heard to put an oil cap full of marvel mystery oil or trans fluid in each 5 gallons for lubrication. Is this true? Anything else I should know about it?

[Yummi]

If it is 100 octane, just mix race fuel 110 and 91 - works for me.  Some places also sell 100 straight up.   

[fabr]

I have no experience with avgas and have only heard rumors about how to use it properly. I just bought a 2.0 subaru motor that has been tuned running it and I dont want to pay the $750 to reprogram it especially with how great it runs on it now (269 rwhp). I have heard to put an oil cap full of marvel mystery oil or trans fluid in each 5 gallons for lubrication. Is this true? Anything else I should know about it?

NO!NO!NO!NO!NO! Do not run av gas in it.I need to get to bed now but if no one replies tonight I'll go into why you DO NOT want to run avgas in an automobile or motorcycle motor.

[Punkur67]

Ive mixed fuel for a little octane boost when it did not matter but I don't want to blow up a motor that needs octane cause I mixed it too lean and ended up with 96 or something like that. I have heard that avgas is 100 octane 1000ft above sea level and around 125 octane at sea level. I wonder how much it will affect it if I run 110 sonoco. Any input???

[fabr]

If you need the octane run race gas.Again,good night and I'll put up some info as to the differences in 100 avgas and a 100 automotive blend.Just don't run avgas in anything other than a plane.

[Yummi]

[Punkur67]

I just want to make shure that I dont mess with the way it runs. I dont think too much octane will be a problem. If I have too much octane then I could retune for a little more power, but I just want to make shure that I am going to run a safe alternative. I am not looking to squeeze any more out of the motor. I dont mind paying extra for the fuel I just want to make shure that I choose a fuel that will be friendly with the tune that I have. I know I am being kind of a cheap a$$ cause I dont want to pay the local dyno shop the $750 but if there is a simple solution than I am all for it. Sonoco also sells 100 and 104 in unleaded. 110 is the lowest leaded that they sell, not that I am concerned about the lead (no 02 sensors).

[Yummi]

Hmmm, set to run on 100, you have access to 100 - why mess with it?   
Too much - not good - burns too slow.  Stick with 100 or the 91 110 mix.  My $0.02.
One of the smart guys will chime in soon and explain it much better.

[Yummi]

I dont want to pay the $750 to reprogram it

Is that an EMS Stinger from Outfront? They were very good to me when I sent my ECU off to them.   (We have the same setup EJ20 w/ 100 octane requirements) Just off the serial # they can tell you if it needs an update, and they are all done the same is my understanding, I don't think they would be $750.00 just for a flash / re-program.   

[Punkur67]

It was taken to the dyno shop and tuned in the car to optimise the setup. I was told that it cost the previous owner $750 to tune the current setup. I know that the shop is expensive, my buddy spent almost 2k on a tune and a boost controller but they went from 180 rwhp to 453 rwhp. They definately know what they are doing. 
The motor has a ball bearing turbo and a few other bolt ons. I dont remember the computer model it came with, I will have to look. I would assume if I ran the 100 or 104 I should be fine but I wanted some input from some of the guys here.

[Odyknuck]

Avgas has been a controversal subject for years. Use it, dont use it, mix it etc. I know it was designed for high altitude burning and have been told its no good for sea level engines. Heres what i do know. A) I dont run it, I use 110/high test 50/50 mix. B) Many guys I ride with that are running VW motors are using Avgas with no problem and they run great. VW motors are used in planes and Avgas is the fuel.

[borris]

In a nutshell avgas is formulated to vaporize easily at high altitudes. At sea level or any lower altitude it can cause misfiring and/or vapor lock. Its' antiknock qualities are not as good as many think. It IS high octane but with fewer antiknock properties.  Avgas is high octane but is intended for use in more steadystate engines that don't constantly go from near idle under load up to cruising rpm also under load. Octane really only controls burn rate. That is why av engines run fairly aggressive ignition timing BUT they don't have as much tendency to detonate as automotive engines since they are rarely "lugged". There's much more to the story but for now that's enough of my opinion.

[Yummi]

In a nutshell .... There's much more to the story but for now that's enough of my opinion.

Simple, succinct, cogent, easy to understand, not condescending. I am digging this Borris fella.

[Voodoochikin04]

im sure there is a million reasons not to use avgas.. but!!!   for years and years around my area everyone uses it in their atvs, dirt bikes, dirt track cars and drag cars. i have only heard bad stories about it when people dont mix oil with it. my friend ran it in his 91 eagle talon set at 20psi boost, used marvel mystery oil. never had a problem in the 5 years he ran it.  just my cents.

[borris]

Oil would make no difference since there is no oil needed or wanted in the combustion chamber of an engine.Especially a high perf. engine. Oil would only increase the likelihood of detonation.   Not doubting your friends word about not having a problem but I'll tell you this much ,it would have performed better with proper fuel.