piston failure

[Tuner]

the term we've always heard around here is that avgas is " dry " , a small amount of 2 stroke oil or marvels helps this ,, if you know of something better , by all means

Avgas is not "dry". A better description is "clean". You think it is "dry" because it does not leave an oily residue when it evaporates, like pump gas and many race fuels. Avgas is intentionally designed, refined and blended, to not leave deposits of a harmful nature in the engine. Other fuels leave an oily residue which eventually oxidizes and forms gum that burns to form carbon deposits and causes sticky rings and valve stems. For obvious reasons, such as walking home from 15,000 feet up in the clouds is no fun, aircraft engines must avoid problems which would only be a minor inconvenience in an engine on the ground, or even in a boat.

Again, Avgas is not "dry" ....... it is "clean".

Do not add anything to Avgas except an octane booster which contains MMT if you need higher octane than 112.

Do not add oil, 2-stroke or otherwise, unless you are using it in a 2-stroke engine which requires oil in the fuel.

[jet1]

Ok boys. The world marathon rqce is over!!! I am now the A class world jetboat marathon champion. We got a set of pistons design for us from mahle and had no issues with them for the 600 miles that we put on them at WOT. Alot of the information that i was able to gather from the talented people on this forum helped us make the proper decision for our pistons.

Kevin, I guess it really was just a piston issue after all.

Mark

[Kevin Johnson]

You had Mahle design a set of pistons for a Jetboat and they did not fail and from that you deduce that vibrations had nothing whatsoever to do with the original failures.

[jet1]

Well that or it really just doesn't matter as long as it works. Sometimes good enough is exactly that!!! My fellow competitor running the same engine different mounting, different boat manufacturer, differnet pump manufacturer, 200 rpm higher also changed to a set of billet pistons and rods, he also had zero issues with his pistons on this 600 mile race. I do not see the need to over complicate things. I will probably take them out this winter and send them to mahle to be checked over for more information.

We were told by Diamond, Mahle, and CP that the stock piston design was horrible for an endurance application and that what they could supply without the need to rebalance would be 7-10 times stronger.

Mark

[MadBill]

Ok boys. The world marathon rqce is over!!! I am now the A class world jetboat marathon champion. We got a set of pistons design for us from mahle and had no issues with them for the 600 miles that we put on them at WOT. Alot of the information that i was able to gather from the talented people on this forum helped us make the proper decision for our pistons.

Kevin, I guess it really was just a piston issue after all.

Mark

Great that we all could be part of your winning team!
("Success has a thousand fathers; failure is an orphan.")

[af2]

the term we've always heard around here is that avgas is " dry " , a small amount of 2 stroke oil or marvels helps this ,, if you know of something better , by all means

Avgas is not "dry". A better description is "clean". You think it is "dry" because it does not leave an oily residue when it evaporates, like pump gas and many race fuels. Avgas is intentionally designed, refined and blended, to not leave deposits of a harmful nature in the engine. Other fuels leave an oily residue which eventually oxidizes and forms gum that burns to form carbon deposits and causes sticky rings and valve stems. For obvious reasons, such as walking home from 15,000 feet up in the clouds is no fun, aircraft engines must avoid problems which would only be a minor inconvenience in an engine on the ground, or even in a boat.

Again, Avgas is not "dry" ....... it is "clean".

Do not add anything to Avgas except an octane booster which contains MMT if you need higher octane than 112.

Do not add oil, 2-stroke or otherwise, unless you are using it in a 2-stroke engine which requires oil in the fuel.

That is the best explanation of AV Gas I have seen. I ran it for years mixing 50:1 in two strokes with minimal build up compared to others running Trick fuel at the time with major gunk ( for a better word) at the time in the early 90's