 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion Groups General ModelsRailroadsRocketsRadio Controlled Air ModelsHelicoptersLand ModelsWater ModelsModelGeeks.com Contact UsLink To UsSearch & Site Map |
Model Forum / Radio Controlled / Land Models / September 2006Very Lean Engine?
Hello, As I understand it - the closer you get to closing the HSN, the leaner the engine is? is it safe for me to run my TT MTA4 as close it will go before the engine cuts out? What are the effects of doing this? As say compared to 2.5 turns out? Gary. > As I understand it - the closer you get to closing the HSN, the leaner the > engine is? is it safe for me to run my TT MTA4 as close it will go before > the engine cuts out? You are correct in that closing the high-speed needle leans the mixture(less fuel per same amount of air). Now, while the manuals will tell you to do the "lean to peak and then barely back it off" routine, 10 years of experience have taught me that a slightly richer mixture than what the manufacturers recommend will give you a dramatically longer engine life. Running it at or too close to stoich will cause the engine to run hotter and you'll burn out your piston/sleeve assembly much more quickly. I think most manufacturers call for 1/16th of a turn out from the leanest point. I'd go closer to 1/8th of a turn or very slightly more for safety and longevity reasons. Bear in mind, I'm in Arizona and things tend to get very hot here in the summer. If you are in a cooler climate you might get away with running leaner. You'll have to put some hours on the engine to see what works best for you. Just as an FYI, the first sign of excessive wear in the piston/sleeve assy is the loss of idle. If you can't get your engine to idle but it runs okay if you keep the throttle open, all other things checked and verified, you are probably looking at a worn out piston/sleeve. Chris > Bear in mind, I'm in Arizona and things tend to get very hot here in > the summer. If you are in a cooler climate you might get away with [quoted text clipped - 4 lines] > other things checked and verified, you are probably looking at a worn > out piston/sleeve. Thanks for the tips.... Gary. PS - Scotland, cooler climate? You better believe it - I was FROZEN today, and the sun was shining. >> As I understand it - the closer you get to closing the HSN, the leaner >> the [quoted text clipped - 24 lines] > > Chris Sound advice! I always run mine as rich as I can while still getting decent performance out of them. Sure, I could lean and have more power, but I'd rather have an engine live for 16 gallons (The S-25 will not die!!!!) then 2. Doc >>> As I understand it - the closer you get to closing the HSN, the leaner >>> the [quoted text clipped - 31 lines] > > Doc Yea that's usually how I run too. But be careful, too rich can apparently be worse than too lean... (i don't know if I beleive that though...). Of course, I'd never see 16 gallons on an engine because I get bored and want to change them :-)  SignatureDan - on his PC > Yea that's usually how I run too. But be careful, too rich can apparently > be worse than too lean... (i don't know if I beleive that though...). I don't see how. With 4-stroke gassers such is true d/t cylinder washdown, but with 2-stroke nitros more fuel = more lube = longer life. > Of course, I'd never see 16 gallons on an engine because I get bored and > want to change them :-) Ya know, I've been trying to hurt the S-25 for 2 gallons or so. I have it leaned to the max, am running consistent temps between 290*-310* and it refuses to die. Hell, it refuses to slow down even. Not the most powerful mill out there, but it's lasting power is to be commended! Other than when I fist got started and blew a few mills d/t not knowing what the hell I was doing with a screwdriver and HSN, I've only killed one, and that was a few weeks back at the track when I cooked the .26 in my buggy d/t an air filter leak and super fine dust on the track. Hmmmmmm, Tower has a $25 off $199 or more right now.................that brings the .30 VG down to $224.99..............he he he he! Doc >> Yea that's usually how I run too. But be careful, too rich can >> apparently be worse than too lean... (i don't know if I beleive that [quoted text clipped - 18 lines] > Hmmmmmm, Tower has a $25 off $199 or more right now.................that > brings the .30 VG down to $224.99..............he he he he! I remember the first engine I saw properly let go - my mates Force .21 - the first engine any of us had ever used - we didn't touch the HSN at all, it just, worked :-) One day it seized, so we took it apart, there was a few shards of metal in it (we later found out these came from where the conrod attachs to the piston...). Then it ran perfectly again after we took those out, then a couple of runs later it was flat out across a car park, then started to sound a bit rough, then my mate said "She's not happy" then pooof. It seized. Conrod had parted company with the top of the piston in a very destructive way... Force engines. Don't you just want one :-) SignatureDan - on his PC >>> Yea that's usually how I run too. But be careful, too rich can >>> apparently be worse than too lean... (i don't know if I beleive that [quoted text clipped - 30 lines] > > Force engines. Don't you just want one :-) Those old Force .21's have a reputation for being some of the WORST engines ever made! (especially the F21P4) Doc > > Sound advice! I always run mine as rich as I can while still getting > > decent performance out of them. Sure, I could lean and have more power, [quoted text clipped - 3 lines] > Yea that's usually how I run too. But be careful, too rich can apparently > be worse than too lean... (i don't know if I beleive that though...). I can see how too much fuel could potentially be bad in the sense that the fuel has two functions - it carries the lubricating oil for the bottom end, bearings, and piston, and it also has the fuel for the combustion chamber. I've always been under the impression that under optimal conditions the heat of the engine is enough to vaporize the fuel component and leave the oil mostly behind, thus providing lubrication while the fuel is drafted up into the combustion chamber. Excess fuel due to a slightly over-rich mixture could dilute the oil and prevent proper vaporization, thus preventing an adequate oil film from protecting the critical crankshaft pin/conrod connecting point. During the break-in process the engine temperatures and loads are so low that the excess fuel does no harm, it simply cushions the piston/sleeve as they form a perfect fit to each other. I had an OS max .12CZ-Z engine years ago in my RC10GT..I broke it in and ran it every weekend and a couple times during the week for about 5 -years- before it finally refused to idle. I never touched the carburetor or anything else aside from an occassional air filter cleaning..it was the most maintenance-free powerplant I've ever owned. Proper break-in and a slighly rich mixture..and I got a -lot- of service out of that engine. As always, your mileage may vary... ;) Chris |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.