i found out for the first time the other day that engines only usually last for about 6 gallons of feul does this mean that the engine will be completly brocken or can i simply replace the piston and what ever else is worn out or would the engine be beond repair


mj

you can replace the piston and sleeve.

as long as no damage other than wear cause the need for your your fine. i read an article with a guy running the say engine for ever. he did change the piston and sleeve twice from wear.

when it does wear down, a new engine ona rtr isnt that expensive and you might want to upgrade to a faster one anyway.
ill see if i can find that article on the super long life

IT literally means that the piston and the sleeve have rubbed against each other for too long and that there is way too much gap between them at this point. this lets the expanding gases LEAK through this gap and this means loss of power!

you can replace it or get it "pinched".

The philospphy is that since its just a tad loose, who not just crush it back in?!
I dont know how it works but I think otheres can give you some info on that.
Also search a few previous posts I think there are some numbers to call too on some of the older posts
-ram

What exactly does pinching do to the engine? I have heard the term used alot and I know what it does...but what does it actually physically do to the piston and sleeve?

If you have 6 gallons of fuel through that engine, then I would say you got your money out of it and then some.

The most I have ever seen out of an engine was 4 gallons, that was an MT-12 and I was very happy about reaching that point with it.

From my experience the connecting rod, crank, and bearing all get significant wear after several gallons of fuel.
A piston and sleeve replacement is a gamble in my opinion. The connecting rod is certainly prone to snap and the front bearing can give out.
To do it the right way you would have to replace the crank and the connecting rod as well. The cost associated with that would of course buy you a new engine.

With some engines the cost of the piston and sleeve alone will almost buy you a new engine.

With 6 gallons of fuel through it I would say grab a new engine...Of the same kind of course.
Just my opinion.

Dbow

I expect to reach well over 6 with my street force

I have over 6 on a second hand mach.15. She still screams and idles like a charm! Got to love high oil content fuel!

damn i cant find that article about that super use glow engine.
i think the guy said he had almost 20 gallons through the same case.
he did a couple pistin/sleeves, and i dont know but im guessing he did crank/rod too. it was one of the whacky hobbiest (like me)who like to do these kind of tests.
ill try and find it again...its very interesting .....i found it on yahoo search engine while looking for a piston/sleeve if you want to help look.

i have a picco i use for onroad and it lasted for 10 gallons on the first piston and sleave and the second piston and sleave lasted another 6 gallons before the end bearing and rod went. dont expect to get that kind of usage from a tiawan engine!

I agree with dbow on that one. Engines do see a very high amount of stress at high RPMS like that.

IF you calculate the momentum of the reciprocating parts at 35K RPM..its mind boggling!!
35000RPM= 70,000 UP/DOWN strokes per minute
That means that the engine 's con rod changes direction by 180* 1150 times PER SECOND!! (70000/60) Correct?

Thats an insane amount of momentum generated by that little piece of metal and what it lacks in weight is made up in speed!
I can definitely see a conrod shattering due to stress!!
Piston/Sleeve replacement is only part of the story.

If you can hook me up with some technical whitepapers about this please PM me! I'm wondering what real world numbers look like!

Thanks,
-ram