scottyfusion

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hi all! i got a ?? I JUST FIRED UP MY LST FOR THE FIRST TIME THIS YEAR AND I CANT GET IT TUNED SO THAT IT RUNS GOOD UNDER 230. I MEAN IT DONT EVEN SHOW PERFORMENCE UNTIL LIKE 250. SO HERES THE QUESTION IM USING FUEL THATS PROBLY 5 MONTHS OLD. IT HASNT SEEN ANY HEAT IT WAS REFRIGERATED AND NO SUNLIGHT AND WAS WRAPPED IN ONE OF THOSE INSULATED BAGS FOR 1 GALLON BOTTLES FROM TRINITY. IS IT POSSIBLE THAT THE OIL IN MY FUEL HAS GONE BAD OR GONE AWAY EVEN. AND THATS WHY MY LST IS RUNNING HOT??

JUST A LITTLE BACKGROUND ON THE MOTOR. BLEW UP THE FIRST ONE (WASHER FAILED) SO THEY SENT ME A BRAND NEW ONE AND I BROKE IT IN SWEET TOOK MORE TIME THEN I USULY DO. SINCE THE BREAK IN ITS ONLY HAD MAYBE 6 TANKS THRU IT AT MAYBE 220. IT GETS AFTERRUN OIL AFTER EVERY RUN AND HAD IT OVER THE WINTER AS IT SAT ON MY SHELF LOOKING PRETTY. AND IM NOT NEW TO THIS BY ANY MEANS.

ANYONE HAVE ANY IDEAS??

jefx

Well, fuel does go bad over time. If you've had the fuel for 5 months, then it's pretty old. Plus there's no telling how old it was when you bought it.

I've ran old fuel before and experienced the same thing you are. Old fuel just won't provide good performance, it'll run sputtery at normal operating temps, and trying to find a good tune with acceptable temps is almost impossible.

I don't think it has to do with the oil going bad, but more along the lines of the nitro evaporating or just losing it's potency, even if it's been sealed.

It's hard to just scrap a gallon of expensive nitro fuel, so try buying a quart of fresh fuel and save the old stuff. Run the fresh fuel and see if it helps the situation. If it runs better on the new stuff, then you know where the problem is.

scottyfusion

My Feedback: (1)

thanx jefx i already scraped that gallon................ it sucked... but buying a knew gallon sounded better then a new motor!!
i ran a tank threw it and got great crap your pants performence at about 220.

if you talk to my neihbors tell them im sorry about there fresh spring garden[X(]....i just couldnt resist!!

ZondaC12

screw that!!! dont waste that stuff! put it in a two stroke weed eater or something that needs a 5:1 gasolineil mixture. itll run cooler and with extra power! oh wait they dont make two stroke gasoline engines that run on 5:1 the lowest ive seen is 24:1. ROFL one day i was like i wonder what the spec is for my traxxas top fuel and i did the calcs and 18% oil is friggin FIVE to ONE. hehehehe.

no but seriously outdoor power equipment (lawnmowers, snowblowers, tractors, chainsaws) engines are unbelievable. theyll seem to run on just about anything that is burnable. take it from me, ive run a little nitro through my go kart engine (tecumseh 5 horsepower off a snowblower from 1978) and it ran just like normal.

ya know what else i ran through it? i keep a plastic gallon bottle that i put old oil from oil changes in my lawnmower, snoblower, gokart and gasoline (and small quantities of old nitro fuel) that goes bad, so this thing, last summer, had like maybe 20% gasoline, 5% nitro fuel, and 75% sae 30 MOTOR OIL!!!! so the mixture wasnt nearly as thick as motor oil, very thinned out, close to consistency of gasoline or water. i burned that whole gallon in my go kart. it was HILARIOUS!!! the thing smelled like crap, you could constantly see puffs of black smoke from the muffler, especially when you floored it, the thing idled too low it would stall if you didnt feather the gas, and it sounded just a little funny, and the piston and inside of the cylinder head had lots of carbon build up and that spark plug was BURIED in carbon dust and moisture from the oil. towards the end of the gallon the engine no longer started LOL and i spent half a day by putting fresh gas in the system, cleaning the plug and pulling MANY times to get it cleared out and started again. i felt SO stupid but it was fun.

**SORRY TO RAMBLE** but i just had to share that

BACK ON TOPIC............NOW!

Frost_

My Feedback: (1)

LOTS AND LOTS of engines run like CRAP at below 230F... There is no reson to tune for 230... every engine is different. Many of the Sirio line aren't making peak power until 290F or so... As long as you aren't running lean, the upper range of the 200s is NO threat to your engine. My buddy runs his Mach in his LST from 250-270 depending on lots of factors. The temps are just observed and are in NO WAY used to make a tuning decision. Tune the engine for power, not temperature. An engine being run lean is not gonna give anywhere near optimum performance, nor is being run rich. Don't be scared of 250, especially if the engine is pulling here.

jefx

My Mach .26's (I have 2 of them in two different trucks) run really well between 230 and 250. I usually shoot for around 210 with the body off (which is a bit rich and sluggish), but warm up to around 240+ with the body on.

I accidently got one of my Machs up to 270+ when I switched to White Lightning fuel and was re-tuning. Once it reached that temp, it suddenly lost a considerable amount of power and responsiveness. I immediately brought it in and shut it down. So from my experience, 270 is definately too hot for the Mach .26. It will pull wheelies all day long in a 13 pound LST at temps between 230-250.

Frost is right though. Temp measurements are only a guide to help in tuning, not the definitive answer in what's right or wrong. Also temp guns can vary in accuracy, and will also vary depending on the cooling head's finish and emmisivity setting of the temp gun.

cardriverx

Im with frost, if anything under 220 is too cold, I run my savage 25 at about 240 to 270, and it has no problems. Nitro engines can handle alot of heat as long as they are not lean. what fuel are you running?

scottyfusion

My Feedback: (1)

im running monster horse 20%.
i agree that temp should be used as a refrence but everyone says "as long as u dont run it to lean!!" my question is how do u know its to lean other then temp?? and please dont tell me loss of performence!
i mean an motor can still give good performence even though it is "burn up your cylinder lean" dont u think?

thanks for all the help

cardriverx

well acaually being lean IS a loss of preformance, when the motor bogs down is a symptom of being lean. these motors can handle temps. over 300 degrees, running it hot wont hurt it aslong as it isent bogging down when you give it gas or bogging down when it gets to its top end, also knowen as being lean.

jefx

Overheating goes hand in hand with being too lean. So by saying "Don't worry about temps as long as it's not too lean", is not a very helpfull statement. An engine that is too lean will overheat. That's why a temp gun is a handy tool in tuning.

An overlean engine will lose power and responsiveness when it gets hot. It may even cut out at high speeds, stall, or have a hard time idling. Often times it'll be hard to restart after it stalls from overheating. All of these conditions are caused from being too lean.

These engines will continue to perform better as you lean them out all the way to the point where it starts overheating. If you tune for optimal power, chances are that you are right on the ragged edge of being too lean, and you're probably decreasing the engine's life span. This is an acceptable comprimise for some, who want every last bit of power out of an engine, and don't mind replacing or rebuilding it every few gallons of fuel. But others would rather be on the safe side of the tuning range for increased life out of their engine.

Most engines won't perform well under 220 degrees, but the Mach performs very well in the 230-250 range, while still maintaining a long life span.

Another problem with not temping an engine is that you won't know that it's too lean until it's already there. By then, the damage is already done. An overlean engine won't act like it's too lean until the temps become high enough for it to overheat, which may take over a half of a tank of fuel. Bu that time, you have already driven the engine at an overlean setting for a half tank of fuel.

RC Prodigy

Well I'm confused now because I don't let my engine (Duratrax Torq .16) get above 205°F and I use Byron's 20% Nitro and 12% Lubricant. It performs well at around 180-195°F, although, the other day I may have overheated it because I stopped it to check the temp and it was at 240°F, and when I tried to restart it, the fuel backed up out of the line, as though it was boiling out of the carb, however, It didn't stall, I stopped it. Even at high speeds, there is still a significant amount of smoke.