hellracer

I know all about the debate on tuning to temp.. this is not one of those posts..

I had something partially plug the fuel line in my tank and it ran my werks .26V2 very very lean, to the tune of 320 degrees!! I had no idea for the first 3 minutes.. I shut it down and now it's sitting..

My question is: what do I look for in damamge that might have occured? (the crank still turns, the glow plug still burns)

Is there anything I need to check before I fire it up again?

Hellfire SS
werks .26V2
Odonnell 99 plug
Sidewinder 30%/12% oil

hpi apollo

you prolly just wore the sleeve/piston down a slight bit, just richen it up and run a good fuel with plenty of lube

GRANT ED

I ran one of my buggies to over 365 degrees. We had a rapid change in temp at the start of a 10 minute final. This caused my engine to run very lean. This was an important race and I did not want to pit unnecessarily so I stayed out. I knew it was lean and checked it after the race (which I won ). It showed 185 degrees C which is 365F. I let the engine cool and just kept using it. It probably did not help its life but it is still going strong.
I would suggest you do what HPI suggested and just keep using it.

Wide Open

yeah, just keep using it. if anything your sleeve may have expanded a little weirdly causing some abnormal wear, but considering you were not running it very long you should not have a problem with it being worn out.

125cchyperman

I agree with wide open, you didnt reallly run it all that long so not a whole lot of damag could have been done. Maybe a little less life for the engine, but thats not somehings that you can fix right now. I say just run it.

JayC1968

My Feedback: (3)

Anything above 300* is too hot...
Do some reading on tuning and you'll be ok.. Just do youself a favor and use plugs to adjust temps, plugs are designed for % of the fuel NOT for temps.

Fuelman

My Feedback: (6)

Above quote is bad advise and is Wrong!!!!!! 300 deg is not too hot.

Forget about the temps, they are nothing more than a curiosity factor and trying to tune an engine to a specific temp is an illogical approach.
The origonal post discussed a partialy pluged fuel supply issue, which caused an over lean condition which spiked his temps to be elevated over his normal ones. His question had to do with what to look for, for damage.

Heres what you look for if you think damage may have occured:
-Pull the head and look for fine scuffing on the cylinder walls or deepened blue areas of overheated chrome plating. If its scratched up or severly blued, it MAY have gotten too lean (notice I said too lean, rather than too hot).
-Check the piston pinch by running the piston through its stroke cycle and see if there is still an interference fit above the exhaust port, if there is and no scratches in the piston or sleeve exist, you are good in the piston and sleeve area.
-Pull the backplate off and look at the crankpin and con rod journal, if less than a tight fit or any egg shaping exist, it got too lean.

If all is good, the engine received little or no abnormal wear or abuse and go run it!!!!! (after you correct the plugged fuel feed issue)


You have to keep in mind that when an engine is run too lean, that causes an oil starvation which does the damage, the heat produced actually does not cause the damage. It is a double whammy on lean runs, if run too lean (not hot) the engine will rapidly have a temp rise because of the lean mixture AND lower lubrication quantities cause a friction heat increase.

The first place to receive damage will be the connecting rod and crank pin.

JayC1968

My Feedback: (3)

In my opinion 300* and up is to hot. I have had 2 mach 28's. One that I ran at a max of 265* which now has 10 gallons on it and still runs strong. The other one ran at 320-350 and it died after 4 gallons and had to be rebuilt. We are entitled to our opinions and this is mine.

I also meant to say DO NOT adjust temps with glow plugs.

axisrc

its ok just maybe cut some life out of engine dont worry not long enough to ruin the engine
mike

Wide Open

fuelman always comes to the rescue for these sort of things

GRANT ED

Listen to fuelman. He knows his stuff.

hellracer

thanks Fuelman, great advice.. everything turned out for the better..

ran it last night in a club night.. it ran good. Since I disassembled literally everything, it took a bit to get it back into a nice tune.. it ran great smoke and never topped 240 after a full tank run using Sidewinder 30/12

i didn't own a temp guage and had always been tuning to smoke and speed, but once it's tuned nicely, now I take a temp to see if I'm lean on the high side.

Fuelman

My Feedback: (6)

How is a temp gun going to tell you if you're lean on the high side?

hellracer

Again, as I mentioned in the inital post.. I don't wish to start a temp controversy.. I do not yet have enough track time to know what a temp 'really' means to my engine...

Here's where I am in my understanding of nitro motors. i understand that the high speed needle controls the wide open flow of fuel into the engine.. if it's run too lean, you get top end power, but no cooling from the fuel itself and the engine gets hotter.. and weakens the hardware, reduces power output, etc, etc

I've been told by a track goer who tq's the expert class that his engine (same as mine) can produce good power until it is leaned out to the point at which the engine runs into the 260 range. This is what I was referring to.. reaching a point in the adjustment of the HSN to the point at which maximum power is prodiuced while maintaining a sufficient flow to also cool the engine. (also a reason I re-routed the fuel line away from between the carb and head) Keep the fuel cold and flowing.

Fuelman, by all means help me if my reasoning is flawed.. I'm learning this stuff from these boards and the local track. You make a living with the stuff, I trust what you have to offer.

Cheers.

Fuelman

My Feedback: (6)

Hellracer,
I was not trying to be critical or make the post sound like a put down, it was just to make you think about exactly what you are being tought by the locals.

Temp is dependent upon so many variables that to try to dial in an engine based on head temp is like watching a big screen movie through a soda straw.
The first reason I can mention is that I have layed out 6 different temp guns, all new and all with new batteries gave me 6 different readings, none of them close to each other. And the funny part was that none of them were even close to a calibrated thermocouple attached at the base of the glow plug.
Atmospheric conditions like humidity, temp, barametric pressure and altitude all have significant roles in temp, so does plug, fuel, gear ratio, tire and track conditions as well as the weight of the car and how it is driven. Even identical engines in identical setups can have different sweet spots due to the tolerances manufactured into the engine or the amount of wear it has experienced.

The best way to tune an engine for a race is by running it around to get it nice and warmed up and when the tank gets about half empty, start making some racing laps. Listen and observe the engine/car. If it is picking up good top end but takes some time to clean out, it is probably a tad too rich. If it tops out and then sags or fades, the high speed needle is a touch too lean, richen it up until it can be held on the longest straight away without sagging. In the corners if it is hard to clean out coming off idle and spits a bit, the low speed needle is a bit too rich. If it initially spikes then wants to fade or catch its breth, the low end is too lean.

Fine tuning to a race by using your ears and eyes will always insure you have a properly tuned engine that will NEVER BE TOO LEAN.

As an example, at the 260 figure you mention, it might be running good but it could still be slightly too rich or too lean depending on all the other variables that race day. For instance if it was tuned and spot on earlier in the day and running 260 when the weather was at 80 degrees, now at night as the races go on the temp rapidly falls to 45 degrees, your engine might be retuned for 260 but it now may be way too lean.

hellracer

the third paragraph is the best I've ever seen it described.. thanks a million

Merry Christmas!

pfavale

I pitted the piston head on a XTM 24.7 when running above 300 degrees on the same Sidewinder fuel. Might be a good idea to check this out.

nautalis

I have a K4.6 engine which runs hot. I feel like the engine has plenty of cooling and I don't drive it too hard, but the temp reads above 300 F all the time. I get plenty of smoke coming out of the pipe across the entire rpm range. If I richen any of the needles the truck bogs, but if I lean it in, the engine races. There is a sweet spot. If I get lots of smoke I feel the engine is getting the lube it needs.

nautalis

I have a K4.6 engine which runs hot. I feel like the engine has plenty of cooling and I don't drive it too hard, but the temp reads above 300 F all the time. I get plenty of smoke coming out of the pipe across the entire rpm range. If I richen any of the needles the truck bogs, but if I lean it in, the engine races. There is a sweet spot. If I get lots of smoke I feel the engine is getting the lube it needs.

hpi apollo

sounds like you are either running too hot of a plug or you just dont have enough airflow, i added some klotz benol to my fuel and the temps dropped quite a bit

dbuggyracer

i use 2oz of klotz oil in a gallon of byrons 25% it takes the motor a little longer to warm up but its a little more lube just incase.

Dennis Powers
Cen Racing

rc_racer69

to check if anything broke/overheated
just take the cooling head off and the back plate to take off the piston and if the pistons discolored thats bad
but run it til it breaks is my motto
and when it breaks if possible keep runnin it lol