Joined: 16 May 2007
|Posted: Wed Sep 10, 2008 11:41 am Post subject: Another good article from Tom Krause
Originally Posted by reneeangel
I suspect it's fuel...... we had 1/2 drum left over from the late model race we ran in June so I figured why not use it up.
Renee, Here's a piece I wrote several years ago on racing fuel........
I ran into problems a couple years ago with my 2-stroke kart engines, did a crash course in fuel engineering, storage and care. In the end I found that it is very difficult and expensive to buy useable fuel and keep it that way.
Common pump gasoline is brewed from "base" stocks and then additives are added to get it where it needs to be for common applications. It is specifically blended to be relatively stable and have a reasonable "shelf life" between the refinery and the end user while being handled with conventional methods, ie: bulk storage at the plant, truck transportation, and bulk storage again at the station.
While pump gas may not be the ultimate in absolute power, it is fairly consistant.
"Racing" fuel on the other hand is different. The "base" stock is essentially the same as any other common gasoline, it's the additives that are different and add the "whoopie" to the fuel. It is also these additives that can quickly cause some real problems if the fuel is not handled and stored correctly.
The additives are referred to as "light fractions" and are extremely volatile and unstable. Not volatile and unstable as in "BOOM", volatile and unstable as in the fact that they do not like to stay "in solution" with the base stocks, they very readily seperate from the base fuel and evaporate into the air.
The most common thing to compare "light fractions" with is the carbonation in a bottle of soda pop, and the storage and handling techniques are very much the same. Carbonation is the "light fractions" of the pop.
(yes, beer is the same, so for those of us that are more familiar with beer follow along, the conditions are the same.)
Take a bottle of pop(or beer), set it on a shelf and it will last a very long time before going bad. Take the same bottle and pour off 1/2 of it into a glass, re-cap the bottle as tightly as possible and set it aside for later. Right away you will start to see changes in the liquid you poured in the glass, the "fizz" will begin to rise to the top of the liquid and float away into the air. We all know that pouring pop (or beer) down the side of the glass will cause it to fiz(or foam) less, because we are eliminating or minimizing the "glug-glug" and mixing with air as we pour. Let that glass of pop(or beer) sit for a couple hours and it will go flat because all the light fractions have gone away.
That's OK, we still have some in that bottle we set aside earlier right?? Not, no matter how tightly we capped that bottle it will go flat as well. The fizz is still there, but it's not in solution with the liquid anymore, it's evaporated off into the air space in the top of the bottle. The pop(or beer) still goes flat at a slower rate, but it still does it. BTW, refrigeration helps, as do glass bottles.
So, what does that have to do with racing fuel???
Think about where you buy the fuel from. Do they store it properly in containers with a minimum of air space above the fuel?? Do they store it in a bulk tank underground or in a big barrel out in the sun?? Steel barrels or plastic barrels??
In my case, I had a motor on the dyno, I knew what kind of power it should make but it simply wouldn't make power, and it really didn't run all that well either, hard to start, misfired and slobbered, just generally lazy. I checked everything and found nothing until I got to the fuel in the tank. (the same fuel btw that I had been using for racing every week, and not running very well.) I had grabbed my race fuel because it was handy, not neccesarily because the motor on the dyno needed it.
Went to the corner convenience store and bought some plain old 88 octane, poured in the the dyno tank and the motor ran great, made all the power it was supposed to.
Obviously my fuel had gone bad, and may have been bad from the place that I bought it from, so I went to a different supplier. The local stock car supplier that sold gas at the local asphalt track should have good fuel, not?? NOT was right, the fuel I bought from them was actually WORSE than I already had!!! Also tried another supplier with the same results.
CRAP!!! Now what??? While many of the motors I was building(primarily Yamaha kart engines) would run on pump gas just fine, my Italian motors would not. What to do??
I ended up calling Phillips 66 and got hold of one of their racing fuels engineers. Had several long and informative converstions with him and learned ALOT. I later talked with some folks at VP fuels and learned the same things all over again.
What I learned was that I, most racers, and most fuel suppliers, were doing almost everything completely wrong when it comes to handling "racing" fuel. We were all essential destroying our expensive fuel before we ever used it.
Some rules for buying good fuel and keeping it good:
Buy fuel from unsealed "bulk" containers
Buy more than you need right now, unless you plan to store it correctly
Store fuel in bulk.
Store fuel in plastic containers.
Store fuel outside
Transfer fuel from one container to another an more than needed.
Do not store fuel in half empty containers
Buy fuel in SEALED oem containers
Keep the fuel in sealed containers as much as possible
Use metal containers with foil lined caps
Store fuel in the smallest possible quantities
Keep the fuel cool
In the end I went to buying fuel in 5 gallon cans, as soon as I cracked the seal I poured it off into 1 gallon metal cans.(NEW paint thinner cans from a paint supplier, with foil lined lids) and then kept it in a refrigerator. My karts ran ALOT better, everybody was convinced I was cheating. I was perfectly legal, I could prove it, and told anybody that asked what I was doing.
Still didn't mean I could drive worth a damn...............sigh!!!
A couple of simplified anology's:
"Pump" gas-- Is roughly the same as a pitcher of Kool-Aid. Consists of water(base stock) and coloring/sugar(additives to make it "good"). Mix it up and it will stay in solution and useable for a good long time as long as it's reasonably cared for. Eventually it'll probably ferment, but not likely before you get it drank.
"Racing" gas-- Is closely related to a bottle of Pepsi. Starts out roughly the same as the Kool-aid, a mixture of base stock and additives, but Pepsi has fizz, the "better" part. The problem is, the "better" part consists of what is know as "light fractions" or things that tend to seperate themselves from the solution and evaporate away.
Only difference is that the fizz or carbonation in Pepsi is added as a gas that when un-pressurized float to the top and fly away, the light fractions of racing gas are added as liquids which evaporate out of the solution, sometimes right through the sides of the container.(if kept in a plastic container).
So what happens??
A bottle of Pepsi will last a relatively long time if you do not open it. There is no place for the fizz to go so it stays in solution. As soon as you crack the seal some of that fizz goes away. If you pour off some of the bottle and re-cap it, no matter how tightly, the fizz will still go away. Doesn't leave the bottle, but it leaves the solution and ends up in the air space in the top of the bottle. The Pepsi has gone flat and there's nothing you can do about it.
The same thing is going to happen to your race gas. Once you crack the lid and leave an air space in that barrel, all the "better" stuff is gonna evaporate off into the air and you will end up with a liquid that will likely run worse than the pump gas. Will it ping,detonate or harm your motor?? No, because it has to be capable of burning to do that. The motor will run, but not as well as it would on pump gas, and you will very likely be seriously down on power.
(I have seen differences of 10-30% on the dyno between dead race gas and everyday pump gas)
Buy it used, buy it cheap and have fun!