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Tuning - Temp vs Performance

Old 03-29-2005, 08:29 AM
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ba_savage
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Default Tuning - Temp vs Performance

There has been several discussions around tuning to temp vs performance. Since I did not own a temp gun up until last week, I tuned to performace. I mainly tuned to top end performance due to the fact that idling was not a problem but WOT was. I was talking to the mech at the LHS and his advice was to tune to temp for protection since these trucks can go much faster than our ability to drive them. I took the advice. After tuning on a warm day in Houston I felt things were running fine. The next day it was about 20-25 degrees cooler and I wanted to try tuning to temp. I took the temp after several passes and it was around 230 (temp was taken while in my garage). I then took it out to a open area and ran it around. Checked the temp and it wouldnt get over 150-160. When I am checking the temp, I am holding the temp gun inside the head trying to shoot it in the head as far as possible. Am I doing something wrong.

What are your thoughts on tuning to Temp vs Performance since the air temp will obviously affect the engine temp.
Old 03-29-2005, 10:36 AM
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Nitronutt
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Default RE: Tuning - Temp vs Performance

My preference is to tune to performance (Within temperature limits). Once you get a good tune performance wise, then make sure that the temps are within range.

Performance tuning with 350 degree temps will make extremely short work of your engine (If it runs properly at 350, then you have another problem-probably an air leak).

The temp gun is a valuable asset to detect and diagnose air leaks. Also, some engines (Like my SH) don't perform well at colder operating temps. To increase my temps without changing my tuning, I simply raise the body to reduce airflow over the head. As long as temps are under 275, then I tune for performance. In extreme cold, some people even wrap their head with foil to get the temps up (I have run in weather as cold as 10 and never had to do this).

I like to see temps of at least 200. If your tuning is spot on, then I would leave it alone and somehow reduce air flow to get to 200+ degrees.

When you took it to an open area, chances are that you ran much more at high speed compared to at home (Me too!)...hence much more air flowing over your cooling head and keeping the temps down.
Old 03-29-2005, 01:37 PM
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cardriverx
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Default RE: Tuning - Temp vs Performance

I do the same thing, I tune it for preformance then check the temps to make shure it isent too hot. I run a motorsaver air filter, GH pipe, and 30% odonnell and when I have it tuned about pirfect preformance wise it is around 230 to 250 degrees. I just use the temp gun to make shure I am not killing the engine, I dont tune it using tempature.
Old 03-29-2005, 02:06 PM
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Super Corsair
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Default RE: Tuning - Temp vs Performance

I tune for preformance and temp. You don't want to burn up a motor just to go a little faster.
Old 03-29-2005, 03:29 PM
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Default RE: Tuning - Temp vs Performance


ORIGINAL: Super Corsair

I tune for preformance and temp. You don't want to burn up a motor just to go a little faster.
...but being hot doesn't hurt the engine, being lean does. If the engine is at peak tune (NOT LEAN) then there really isn't more speed to be had.
Old 03-29-2005, 03:33 PM
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joman2055
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Default RE: Tuning - Temp vs Performance

you should tune for both. unless you dont want your engine to last very long.
I put the top of a sock over my XTM Pro because it wont run over 180 or so. YOur engine should be between 210F and 280F. Too cold will not allow the parts to expand enough so tehy will wear out and too hot just destroys everything.
Old 03-29-2005, 04:25 PM
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Default RE: Tuning - Temp vs Performance


ORIGINAL: joman2055

too hot just destroys everything.

...so find the research that backs that up.... because it isn't out there. Being LEAN DOES DAMAGE NOT BEING HOT. 8 gallons out of a .25 that was run between 300F and 350F doesn't sound like everything was destroyed...

Don't take my word for it... here's a guy (read the posts by fuelman in particular) with a vested intrest and some serious test setups and time, read this thread [How hot is too hot?] : http://www.rcuniverse.com/forum/fb.asp?m=2725842

Old 03-29-2005, 05:53 PM
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Default RE: Tuning - Temp vs Performance

that makes sense, but is that to say I could run my engine without the heat sink and it would not get hot enough to be damaged? heat can damage an engine- you could melt a piston. the point is, the engine would be damaged by lack of lubricant before it ever got that hot. tune for performance, and if its running right, dont worry about the temperature.
Old 03-29-2005, 06:22 PM
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Default RE: Tuning - Temp vs Performance

exesive heat is bad. heat can cause preignition and detonation killing preformance and hurting the cumbustion chamer. too much heat will seize CB and crank bearings the latter will wear down a crank. a mixture that is too lean will not allow enough fuel into the engine so most of it will boil off before reaching the combustion chamber. too much heat can make a hole in your piston or even melt it.

i have been told that the S-25 likes running around 300*F so im not saying that no engine should run over 300 just that 280*F is a good place to stay below for most engines.
Old 03-29-2005, 06:44 PM
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bibo
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Default RE: Tuning - Temp vs Performance

I think you should tune to both performance and temp because if you are running too hot ( even if not lean ) you are losing compression and the lower the compression the lower the performance and in most cases high temps is a result of lean settings so you have to keep an eye on temps anyway.

And each time the engine runs too hot the sleeve over expands and when the sleeve keeps on over expanding all the time gradually it will not return to it's original size and will lose it's tight fit around the piston and although I agree that it will not damage the engine ( if not lean ) , but it will affect the compression and the engine will become weaker overtime and will not give the same performance as a similar engine that has not been run on too high temps.

Old 03-29-2005, 10:55 PM
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Default RE: Tuning - Temp vs Performance

I am sure there are some variables but I am going to stay with the instructions that came with my 4.6 motor says to keep the temperatures 210 to 275. I will probably stay closer to the higher end as I think 210 is to cool. I will sacrifice some top performance to increases engine life.
Old 03-29-2005, 11:18 PM
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Default RE: Tuning - Temp vs Performance


ORIGINAL: Frost_
...but being hot doesn't hurt the engine, being lean does.
Thats why I keep outside temps in mind when I tune. If it's 45 outside I don't lean it out to get the temps up. I'll rap the head to get the temps up.

Hear's the things I keep in mind when I tune.

The temp of the motor. 220 to 300-f
outside temp.
my last needle settings.
The sound of the motor.
The smoke coming from the motor.
How the motor is performing.


Keeping all that in mind I can tell if its running to lean. I must be doing something right because I have 9 gallons on my motor right now and still going strong.
Old 03-29-2005, 11:31 PM
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Default RE: Tuning - Temp vs Performance

predetonation- that is a good point. i did not think of that because the fuel is detonated by the compression, but that would be possible at high temperatures. still, i think that is unlikely within any reasonable temperature. I have never heard of anyone having problems with detonation before top dead center with one of these engines. i think before you get the engine hot enough to cause predetonation or to soften the piston enough that damage could be done to it you would do damage as a result of being too lean. the metal will expand as it gets hot and its properties will change, as will its size to some degree, but this does not occurr continuously. the only significant change in the metal occurrs during the first few heat cycles, thus, break in. the other thing is, the sleeve is made out of aluminum, the same stuff as the piston, rod, and block, so the expansion will be the same on all of them, and at that, the piston gets hotter than anything in there, so it will see the most expansion. these engines are made with a lot of clearance between the piston and sleeve to alllow for expansion.
Old 03-29-2005, 11:53 PM
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Default RE: Tuning - Temp vs Performance

ORIGINAL: crankshaft

predetonation- that is a good point. i did not think of that because the fuel is detonated by the compression, but that would be possible at high temperatures. still, i think that is unlikely within any reasonable temperature. I have never heard of anyone having problems with detonation before top dead center with one of these engines. i think before you get the engine hot enough to cause predetonation or to soften the piston enough that damage could be done to it you would do damage as a result of being too lean. this guy bibo does not know what he is talking about. the metal will expand as it gets hot and its properties will change, as will its size to some degree, but this does not occurr continuously. the only significant change in the metal occurrs during the first few heat cycles, thus, break in. the other thing is, the sleeve is made out of aluminum, the same stuff as the piston, rod, and block, so the expansion will be the same on all of them, and at that, the piston gets hotter than anything in there, so it will see the most expansion. these engines are made with a lot of clearance between the piston and sleeve to alllow for expansion. if you don't know what you are talking about don't [email protected]#in talk.
The kind of heat needed to advance flash-timing WILL NOT OCCUR. Detonation however, WILL make heat (and the frying egg sound).

I hate to be the bearer of bad news, but the part towards the end... AAC? I think not. The big-block engines in question use brass sleeves, which expand further, faster than aluminum. This is a physical upper limit since at some point, the sleeve will expand enough that proper compression will not be possible. If no lean-damage occured (which is generally just lost life, not instantaneous physical destruction) the sleeve will cool down with the engine and all will be well.

Honestly guys, Airplane engines are ABC and are beaten up much more, but for some reason last MUCH MUCH LONGER. 20 gallons on a Thunder Tiger .25 ABC is not uncommon. These engines are tuned as follows: Once broken in, set the transmitter to WOT. Hold the tach in front of the prop. Lean/richen (depends on where ya start) until the tach is reading the highest RPM at WOT. These engines are abused in planes, being held at high throttle for extended amounts of time and running MUCH MUCH hotter than what we are talking about here. So let's see, they are made with the same materials, run tuned for max RPM, and temperature is ignored. 20 gallons... or could it all be in the drastically different breakin?
Old 03-29-2005, 11:54 PM
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Default RE: Tuning - Temp vs Performance


ORIGINAL: Frost_
[How hot is too hot?] : http://www.rcuniverse.com/forum/fb.asp?m=2725842

Ok, I read it! I agree with some of it but not all of it. I still say that over 300-f is to hot and should be avoied. "With that said" any thing under 220-f is to cold and could do damage to the motor.
Old 03-30-2005, 12:02 AM
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Default RE: Tuning - Temp vs Performance


ORIGINAL: Frost_

Honestly guys, Airplane engines are ABC and are beaten up much more, but for some reason last MUCH MUCH LONGER.
Air plane motors turn 8000 to 12000 RPMs Car motors turn 25000 to 30000 RPMs.
The lower the RPMs the less wear. Car motor also have more abuse.
Old 03-30-2005, 12:16 AM
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Default RE: Tuning - Temp vs Performance

I would think there would be more of a load on a truck or car motor comparison to an airplane engine. Seems there would be less stress on turning a prop then wheel contact to the ground. All so as said above an airplane turns MUCH less RPM and would defiantly make the engine last much longer. Most car and truck engines turn over 3 times what an airplane engine turns.
Old 03-30-2005, 12:19 AM
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Default RE: Tuning - Temp vs Performance

All so airplane engines have air going over them all the time from the prop.
Old 03-30-2005, 11:28 AM
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Default RE: Tuning - Temp vs Performance

ORIGINAL: crankshaft

predetonation- that is a good point. i did not think of that because the fuel is detonated by the compression, but that would be possible at high temperatures. still, i think that is unlikely within any reasonable temperature. I have never heard of anyone having problems with detonation before top dead center with one of these engines. i think before you get the engine hot enough to cause predetonation or to soften the piston enough that damage could be done to it you would do damage as a result of being too lean. this guy bibo does not know what he is talking about. the metal will expand as it gets hot and its properties will change, as will its size to some degree, but this does not occurr continuously. the only significant change in the metal occurrs during the first few heat cycles, thus, break in. the other thing is, the sleeve is made out of aluminum, the same stuff as the piston, rod, and block, so the expansion will be the same on all of them, and at that, the piston gets hotter than anything in there, so it will see the most expansion. these engines are made with a lot of clearance between the piston and sleeve to alllow for expansion. if you don't know what you are talking about don't [email protected]#in talk.
crankshaft , you telling me I don't know what I am talking about ? Actually it's you who don't know what you are talking about.
From the middle of your post downwards you did not say a single correct information.
First you said "the sleeve is made of aluminum" which is way wrong and then you said "these engines are made with a lot of clearance between the piston and sleeve to alllow for expansion" which is also way wrong as the engines we are talking about features non-ringed pistons and it's actually the main design of those engine that they rely on a very tight fit between the piston and sleeve with almost no clearance at all and the sleeve expands outwards and not towards the piston.

When you don't have enough knowledge about something just stay quiet and watch instead of giving wrong information to other people and embarrassing yourself.

And by the way why did you edit your post , found you were wrong and wanted to save yourself ? What a cheap move!
Old 03-30-2005, 08:43 PM
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Default RE: Tuning - Temp vs Performance

Frost is right about airplane engines, temps are hardly ever taken. And Yes they do get more air moving over them, but not until about 1/2 throttle and higher and the reason is the prop wash is very turbulent at low speeds usually when taxing out/in and ground break-in (not break-in as in crashing). I have a .91 two stroke that has over 5 gallons so far turning about 12,500 rpms and when I'm in the air, I have it a WOT the whole time. Even if it is turning less rpm than what my savage is turning, that is still a lot of stress on the parts. BTY, it's not allways smooth sailing up there, if your doing aerobatics, then you're constatly playing with the throttle from idle to WOT to idle to WOT .... you get the idea. Anyhow, Frost is right about how we tune the motors. First break - in the engine, then go to WOT and read the TACH keep leaning it out until the rpms stop climbing and then back off so that you are about 500 rpms on the rich side. Fact: When your plane is in the air, it leans out due to the fact that prop is moving through the air instead of trying to act like a stationary fan on the ground so it gets "unloaded" up there. Anyhow, I had my motor apart the other day and the internals look like new still with over 5 gals.
Old 03-30-2005, 09:56 PM
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gasoline hpi
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Default RE: Tuning - Temp vs Performance

airplane engine are detuned compared to a car engines. wot on an airplane engine is not like wot on a car engine. most airplane engines do not have the breathing capabilities to turn enough rpm to do damage to itself. a car engine turns a lot more rpm, enough that the stresses generated are at the limit of the strength of the components of the engine. still, a plane engine is equally saceptable to being damage by heat or a lean condition, so in theory car engines should be able to last nearly as long under similar conditions, at least in terms of temperature.
Old 03-30-2005, 10:09 PM
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Default RE: Tuning - Temp vs Performance

When it comes to the airplane and car engines it is all most like comparing apples to oranges. When something is turning 3 times the RPM there is 3 times the stress. Yes the cylinders are NOT made of aluminum and there is not much clearance at TDC as the cylinders are tapered to get the compression, as there are no rings. That is why an engine is harder to turn at TDC. Old motorcycles back in the twenties and earlier ran taper bores even thaw they had rings. Back then they where running cast iron pistons.
Old 03-30-2005, 10:23 PM
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Default RE: Tuning - Temp vs Performance

yeah, thats why pistons and sleeves wear out as fast as they do. at that, I am not sure you could run rings with this much compression, 20:1 or whatever it is. I would think its close to that. the rings would have to have a lot of tension, and would create a lot of drag all the way up and down the cylinder. guess thats why we run a tapered cylinder and not rings, its only a lot of drag near tdc. btw, cast iron pistons would be really heavy, wouldn't they?
Old 03-30-2005, 10:36 PM
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Default RE: Tuning - Temp vs Performance

Yes the old cast iron pistons where very heavy but back in the twenties if you cursed at 20 t0 30 miles and hour you where flying. Back then just about all the roads where dirt. Harley did not start running aluminum pistons till the early 30’s. Matter of fact Harleys where total lost oil systems till 1936. Yes the oil went throw the motor and out on the ground. They got any where from 750 to 1000 miles to a gallon of oil.

Motor cross 2-cycle race bikes only run one piston ring to cut down on drag. It will not be long you will not see 2 cycle race bikes any more do the pollution laws. That is why 2 cycle street bikes where outlawed in the seventies. Just hope they do not do that to the engines we run in our nitro cars and trucks!!!!!!!!!!!!!!!!!
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