Avgas

[artie on edge]

Don't believe all that you see or hear from "experts".Don't take what they or I say as the gospel.Do some research on their "facts" and then make an informed decision as to what you feel is right.Many,if not most, times you will find that the "experts" were full of BS.

Man aint that worth repeating....... 

[fabr]

Wow.... so much stuff to take in!

Ive run avgas here in Oz for years in our off-roaders BUT the engine was built to run on avgas. Also I dont know if our avgas is the same as yours (dont see why not but...). But for decades avgas was our sports std fuel. So much so that at larger events there was a tanker selling avgas direct to competitors.

Several years ago avgas was banned as competition fuel and we now use std pump gas AND the engines are built for this gas. The main reason for the banning was because of upper cylinder lubricant (read that as lead content). I am guess that that is what is diferent today, avgas has no lead content and the lubricant these guys are refering to is for valve seats etc. Thsi would be necessary for some aviation uses but not so for short life span competition engines (IMO.. of course).

When I say built for a certain fuel, this entails compression ratios (even engine gearing) and very importantly spark advance maps (particularly if using the entire rev range as a buggy does).

I come back to the fuel the engine was designed for, changing fules without consideration to other parts of teh engine can well lead to pretty quick destruction.

Good luck, if it aint broken ... dont fix it!

Lead is not necessary at all for valve life.All that is needed is hardened valve seats on the exhaust side. They can be integral induction hardened cast iron or steel inserts. Either one will allow the use of unleaded fuel of any kind. No upper cylinder lube is needed or necessary on any modern engine produced in the last approx. 25 years.   

[Punkur67]

Mate, the only real way to be certain is to measure your engine and these is a way of doing this assembled. Let me know if you need more. Basically you need to know what the compression ratio is. Simple as that. Then you need to to ensure that the spark advance is suitable. Again as simple as that. (do you own a burette?)

When I first started to read this thread and saw some of the responses I was "wooo... why NOT avgas..." Just needs certain parameters met. No big deal. But I wouldnt run the stuff unless I was certain it was set up for it (or an other fuel for that matter).

Good luck mate..
[/quote]

I know the stock motor needs a minimum of 91 octane and this one is running more boost and timing.

[Punkur67]

I think I am going to use the 100 unleaded fuel. I talked to a friend who is the distributor for race fuel down here and he said to just switch over to the 100 and there would be no problems.

[robndeb]

Lead is not necessary at all for valve life.All that is needed is hardened valve seats on the exhaust side. They can be integral induction hardened cast iron or steel inserts. Either one will allow the use of unleaded fuel of any kind. No upper cylinder lube is needed or necessary on any modern engine produced in the last approx. 25 years.   

I asked a buddy of mine who used to race offroad many years ago. He said that the VW engines they ran back then were made for leaded gasoline, more than likely the valve seats. He said that they all used Avgas with a few ounces of Marvel Mystery oil in it. He never had any problems at all.  I would like to try it in my buggy, because it is a lot cheaper than race gas. Only about 4.20 a gallon.

[Punkur67]

I talked to the shop that tuned my motor and they said I would only need to retune if I was looking to make more power cause I could run more timing. Im gunna make the switch when the car is done to VP.

[Yummi]

to VP.

?

[Admin]

Vp race gas...

[SPEC]

VP smells so sweet too
A guy could brain damage standing near ANYTHING running on VP

[Yummi]

My two stroke bikes run on race fuel, and I use a castor hybred based oil, so, it is the only two stroke mix I have sitting around the house - the leaf blower uses 2 stroke. 

I just love using my leaf blower for the smell alone.  It lingers in the garage and makes me think  about all the good times off riding the bikes / toys .... 

Only leaf blower on the block that is running $7.50 a gallon fuel  - I have no worries on detonation though 

[fabr]

Leave the fricken avgas in the av. Read up on it and how it is formulated. You will choose to use something other than av gas after you educate yourself and BTW DON"T take any one's  OPINION about it.There are FACTS about it that most don't know.I'm just not in the mood to waste my time pointing out the diff in avgas and race fuel again.A couple of bucks is not worth the possible issues.

[Admin]

IMO, a couple bucks a gallon more isnt worth the race gas period...Not for a weekend toy...set it up to run on premium and call it good... I see way to many guys shit setting in the garage because it cost 100.00 to run for 5 hrs...Hell i can burn 5 gallons an hour in my drak right now, cant imagine if it was 8.00 a gallon...

[Yummi]

Master is right on this one.  (He is lots of times, I just don't let him know) 

Run the race fuel and be done with it.  It is a small cost to pay to ensure that the motor, that has been built to run on race fuel, keeps running.  Pay a little now, a little bit at a time, or a lot later. 

Or: Pay a lot now to rework it, then try to recoup the cost in savings a little bit at a time later. 

The costs are already sunk, you just have to decide how you gonna pay for it....

[fabr]

Yep.

[fabr]

I run a turbo busa at a modest boost and it's fine tuned for prem pump gas. At a higher boost I'll lower compression and run VP.