LSN question.....

[chrisexv6]

I was wondering if the LSN being rich could cause engine temps to go up at idle, much like the LSN being too lean would be.

I have a Mach26 on my Savage that I have broken in, but it definitely lacks off-the-line power, if I let it sit for any amount of time. If I come off a half throttle pass, turn the truck and then gun it without letting it idle too long, it takes off like a bat out of hell. If I "line it up" for a pass and let it sit for 5 seconds or so, if I gun it it definitely doesn't go right away!!! Since it performs well if I dont let it idle, I'm guessing its too rich. However, if I watch the temps with the truck just sitting, they go UP instead of down. I could see how too rich of an LSN *might* cause temps to go up, but I figured Id ask the experts.

Thanks!!!
-Chris

 

[hb1111]

most trucks sitting the temp will go up because there is no air flow to cool it so i would lean you lsn needle just a hair at a time till it clears up make sure your truck is up to running temps before you make your adjustments take care of that then play with your hsn good luck....hb1111

 

[Rolex]

Being too lean will cause it to heat up, but it's true, they need the forward speed to maintain proper cooling.

 

[kingeightballz]

contrary to what these cats are saying, i believe that at idle the temps should go down a degree or two, and at the very least stay the same. Sure there isn't any air going thru the head, but the engine also isn't under a load, and if you have enough lubrication going on at idle the temps should naturally come down, not drastically mind you, but there is alot at play here. Say if we have our idle to high, especially if the low end is too rich then we have to cheat the idle up. Even if the idle sounds good, it is not the true idle. This can make the temps go up. What it sounds like to me is that you might have the lsn too rich, and the hsn too lean to compensate. What I do is start by puting my needles back to factory settings. This is super "break in" rich, but we know that the engine is at least designed to idle thru a whole tank, so adjust the idle screw so it will hold a idle at these settings. The temps will stick in the 170 or lower range. Then I blip the throttle and get the engine to clear out, I know they say it is bad to hold the model off the ground and rev the engine, but this is b.s. at these rich settings. Once it clears I take it to the street, and start adjusting the hsn. What i am looking for here is not acceleration but good high end rpm. I do a couple of high speed passes, if i don't like what i see, then i lean the hsn a hair, maybe a 1 hr turn. couple more passes, i do this until i got good top end. Now I check the temp after a couple more high speed passes and generally speaking i am in the low 200's maybe even lower, but my goal is to hit 200. Then what I do is let the engine idle for about 10 seconds and then floor it. It might take some leaning on the lsn to get her to rip off the line, I am watching now for acceleration and midrange. my topend should already be set so there shouldn't be any screwing around with that. Look for midrange bog, meaning if at half throttle and you floor it, is it acting like it was loaded up? or does she just open up and rip. If you got good low end, and top end but the engine is still boging in the midrange, you might need a hotter plug. Whatcha using now?? after all is said and done, you should have good smoke especailly out of a corner, temps about 215-240, awesome lowend power and even better topend. Remember this: The High Speed Needle also richens or leans the Low Speed Needle. It is like a ratio thing. The hsn adjust overall fuel flow, which is mostly noticed at high rpm. The lsn fine tunes the lowend and midrange for clean crisp performance. Plus the more patient you are the better off you are. It took me about 6 tanks back to back to fine tune my wasp but now she fires on the first or second pull and the only adj. i have to make is a slight adj. on the hsn depending on the weather. hope this helps
Zach

 

[hb1111]

contrary to what these cats are saying, i believe that at idle the temps should go down a degree or two, and at the very least stay the same. Sure there isn't any air going thru the head, but the engine also isn't under a load, and if you have enough lubrication going on at idle the temps should naturally come down,


take your radiator(real car) off your car and let it sit at idle and see what happens yep it will get hotter then a bastard, also the nitro engines are not oil cooled, they are AIR cooled

 

[kingeightballz]

I agree they are air cooled, but the lube in the fuel cools the engine also, check it out, fuel with say 10 % of lube makes an engine run way hotter then one with 16% lube. That would naturally tell me that the more lube the cooler the engine is going to run, therefore there some loss of heat at idle is not unheard of, and actually what you want to observe on a heat gun while the engine idles down. Now these engines weren't made to idle and look cool, they were made to use, so yeah your not gonna sit there and idle to just cool it off, but the temp should drop somewhat at idle with out a load.

 

[Rolex]

I just finished re-tuning my neighbor's 2.5, and at the beginning it hit 270 at idle. Richened up the LSN till idle temp was 205, then tweaked the HSN. It has a larger cooling head than the stock one, but it's ripping off the line and hitting good WOT, running at 240. No more stalling, and easy restarts.
The LSN DOES make a difference in temp. That's a difference of 65 degrees.

 

[G8RMaxx]

contrary to what these cats are saying, i believe that at idle the temps should go down a degree or two, and at the very least stay the same. Sure there isn't any air going thru the head, but the engine also isn't under a load, and if you have enough lubrication going on at idle the temps should naturally come down,


take your radiator(real car) off your car and let it sit at idle and see what happens yep it will get hotter then a bastard, also the nitro engines are not oil cooled, they are AIR cooled

An r/c engine is mostly cooled by the incoming fuel/air charge, which is why tuning is such a balancing act. The oil is a lubricant, but the more oil, the lower the combustion temp, because it makes a richer mixture. The atomization of the alcohol cools considerably, that's why it feels cold when it gets on your skin. It cools as it evaporates, as well as burns better. Air-cooling is less than half of the cooling. If you start a nitro engine cold, the temp will go up at idle too, with no air running over the fins, until it reaches the balance of internal temps, internal cooling, and radiant cooling. The leaner the mixture, the hotter the temps. Under normal running circumstances, the temp will go down when the engine comes back to idle, which is why I try to take my temps asap when coming off a run. Also when running a WOT, combustion temps are much,much higher, but that's when internal and radiant cooling is at it's peak too. Depending on where you check the temp, you could still get some residual heat from the engine as it comes to rest without air on the fins, then it should go down a little.
As for your prob, try leaning the lsn a little at a time, until it has the bottom and mid you're looking for, then just make sure your temps are in the acceptable range. Sometimes you have to tune for what type of running you're doing. If I'm at a large parking lot running WFO all over the place, I might be too rich on the hsn when I go to a park and fart around a little. That's one reason why you should tune for conditions, and not just temps.