quietnas1

It seems to me that alot of folks especially the newer folks tune only by using a temp gun or some temperature reading device. When I started back in 1994 there was no such thing. I asked at the hobby store hire can I tune my brand new OS .12 CV engine fire my RC10GT tub chassis kit. They gave me the basics and off I went. I tuned it by the smoke trail, how the engine sounded, and the performance of the engine. I beleive running in this way is becominga dying art.

To many times I have seen here in RCU the question � what temp should my engine be�. My answer is forget about temps and tune by smoke, sound, and performance, but people rarely listen.

I also have a friend that I run with that insists on using the temp reader. He is always running to lean trying to keep the temps just right and his trucks are always cutting off. I got tired of it one day, I tuned the engine on his T-Maxx my way and it ran flawless until he pulled out the temp reader and said it was running a bit to cool and started to lean it out. What happened was his truck cut out at wot and he was scratching his head. I told him several times stop tuning by temps but he will bit listen.

I think alot of these temp tuning guys need to go back to basics and just tune by smoke, sound, and performance. It would cute alot of tuning issues in my opinion.

sparky 25

IMO a temp gun should just be used for break in of a new motor.

suburban_hooligan

i feel ya.  i bought my first nitro in 2001 which was right about the time everybody started running around yelling temp gun, temp gun, you gotta have a temp gun.  you're going to destroy your engine if you don't have a temp gun.  <div>at that time i was the neighborhood mechanic and a few of my friends were already running nitro.  i had learned from them and the old school guys at the hobby shops how to tune without the crutch of a temp gun.  to this day i can tune an engine better without a temp gun than i can with one.</div><div>the whole temp gun thing drove me nuts.  "what should my temps be?"  whatever your engine likes to run at.  not all engines are exactly the same.  2 of my friends were running RC10GT  RTR's.  one ran 40 degrees cooler than the other.  identical characteristics and performance.</div><div>
</div><div>it's not just RC, its all of society.  we are becoming more and more dependent on technology and we are loosing the skills that got us to where we are.</div>

proanti1

My Feedback: (2)

I learned by using the spit method. Lick your finger and touch it to the head. If it slowly fizzles or dries up, you're perfect. If it instantly bubbles up or vaporizes, you're too hot. I've been doing this so long I can feel how hot it is just by holding the back of my hand about an inch over the head.

quietnas1

I agree 100%

The_Shark

ditto.

once the engine is fully broken i tune by throttle feel, smoke, sound, smelling the engine and by touching the head.

Its hard to explain but after many many year of running nitro you just "feel" when its in tune, i started out without the use of a temp guage, in my opinion they are NOT accurate for tuning, just because its a certain temp DOESNT mean its in tune.

all you need to remember is set your idle pin, set your high speed next, then set your low speed.

Argess

Tuning by eye and ear may be a skill, but it's not one that terribly difficult to acquire. In fact, with one-on-one instruction, it's very easy. However, many is the time that one new to engines has to figure things out on their own. A Temperature Gun can help them understand what is going on, and how needle changes affect their engine.

I have noticed there are basically 2 points of view. Those that use them for tuning, and those that don't. Both groups make valid points. I sort of see a gray area in between where a Temp Gun can be a useful tool if used as an aid in learning to tune, and as a double-check device, but not to be used to try to make the engine run at a specific temperature.

Here's how it can be handy:

1/ For someone learning to tune, measuring the temperature can yield a quick indication if the engine is very lean or very rich. It cannot indicate too rich or too lean to a fine degree.

For example, I once had my Savage running around 285degF after a few WOT runs over grass. I then tried the same driving over pavement and only achieved 225degF. Trying to sort this out with a temperature gun would be futile.

However, suppose you do a few WOT runs and measure 325 degF. You know it's too lean (everything else being normal), so you richen the mixture. If you pay attention, you'll know what the engine sounds like when running too lean, and if it stalls, you'll learn to recognize the sudden silence of a lean stall.

Or you could do a few WOT runs and only get up to 195 degF. Now you can be pretty certain the engine is running rich and you can lean the mixture a bit at a time. Again, if you are paying attention, you will now know what a rich engine sounds like (and looks like = lots of smoke) and if it stalls, you'll know what a rich stall is like.

So it can be a learning aid.

2/ Even once you are good at tuning, it can be an aid. Supppose you have your engine tuned really well at the top end, but are running in thicker grass than normal. If you use a Temp Gun and measure well up over 300degF, you are in the range where detonation could occur, and that can damage an engine. So it can give you peace of mind as sort of a double check device. In this case, tuning the HSN a bit richer than normal can help keep the temp down as well as provide increased lubrication for this tough driving over grass.

However you use a Temp Gun, don't try to tune for one temperature. Instead use it to try to understand what is going on and how your tuning attempts work or fail. As you can see below, there is a generality for desired temperatures, but even with a perfectly tuned engine, that temperature can change all over the place depending on driving style, weather, terrain and probably a number of other factors I can't seem to think of at the moment.



On the subject of where to aim it, aim it at the glow-plug. Hold the gun against the cylinder head. This is the only way to get consistently reliable results. As mentioned above, the Temp Gun sensor is conical. Below is a picture of the typical coverage one can expect. As you can see, the further away you aim the gun, the more area the sensor sees, and the average temperature will drop and the gun will read low.



Keep in mind engines are mostly metal and won't melt from these low temperatures. Detonation is the enemy and that comes from running too hot. However the odd over-heating while trying to obtain a good tune probably won't hurt anything. I once brought a buggy in and measured around 400degF at the glow-plug. I richened it a bit, and it was fine. No damage.

Bascially, tune by sound, performance and smoke, but I still use my trusty temp gun when I am running on grass to make sure I don't go over 300degF with my typical driving. On hard packed dirt or pavement, I probably wouldn't need to do that check.

And of course, where I think everyone will agree, a Temp Gun is a great tool for break-in as you know when to shut it off and let it cool.

SLAYERDUDE

I started in nitro with the same as the OP, O.S. .12 in an RC10GT...
Followed the manual and that engine still runs strong today, never had a temp gun until a few years ago.
Sound and smoke, more sound than smoke on the BB engines, my K5.9 can be engine damaging lean with an air leak but still puff clouds of smoke so that can be decieving.
Temp guns can be helpful at times, but are WAAAY over relied upon by waay too many people these days.

JohnP2

Argess, I feel you are spot on.

I agree wholeheartedly that you "learn by experience", and at the same time, having something that augments that learning process (i.e. knowing the temparture of your engine) does not hurt, as long as you take everything else into consideration. i.e. analyze thingsit inclusters.</p>

378

My Feedback: (4)

It may also help to grow up with a wrench in your hand. I learned on full scale stuff and had absolutely no trouble translating that to RC.

The_Shark

ditto to 378.

sometimes its EASIER to work on a 1/1 car than some repair jobs on a r/c. Tuning a Quadrajet Rochester carb is easier than some cheap ass RTR engines out there.

i learned a great deal of 1/1 cars suspension geometry and mechanics from reading and playing gran-turismo before i actually worked on cars.

378

My Feedback: (4)

Now now, I wouldn't say tuning a Quadrajet is easier than one of the knockoff RTR engines. You've got four barrels, four jets, four idle screws, and some complicated linkages to tinker with if you want to get it to behave itself, and any one of them out of whack will make things run funny. Matter of fact, Quadrajets can be enough of a pain in the ass that many gearheads won't even bother with them, opting instead for a Holley 750.

I'm not sure, to be perfectly honest, if there's an analog to those junky clone engines in 1:1 engines. It's not like there's any V8s floating around muscle car circles that absolutely refuse to cooperate regardless of the carb simply because they're poorly designed. All the V8s will behave nicely if you know what you're doing and don't buy a junkyard carb and expect it to bolt on and function.*

I will say it's easier to tune one of the domestic I6s you find in older pickup trucks though. They only have 1 barrel carbs








*I actually did buy one once. Nearly new 300cfm 1bbl for 69 bucks. Put it on my engine, reset the screws to defaults, and it worked! Spent about two days tinkering with it and I got it purring like a kitten. Had I just slapped it on and been done, however, I'd have been running it lean as hell and the idle would have been way too high.

quietnas1

Yup learned to tinker on my real cars wich helped with rc. My favorite set up was my Mikuni carb (similar to a webber) on my bridge ported 13B Rotary on an 85 Mazda RX7.. Man I miss that car.

Neways back on topic. Here is an example of someone who was asking about temps in the ST forum. A member have the person some old school advise, I agreed with the advise given and the next post after that was pure ridicule. Here it is......... � needs to be like vvvvvvvvbbbvvvvvbvbvv at idle then weeeeeeeeeeeeeeeeeeeeeeeiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiii! when you hit the gas this is perfect

if its like viiiiiiviiiiiiiiiiiiiiiiviiiiiiiiiiiii then wiiiiiiiiiiiiuuuuuuuuuuuruurrrrrrrr thats too lean

if its like bbbububvvvvbub then vvvvvvvvvvweeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeiii ii then its too rich�.........

Also its not the first time. So I stop giving advise. Yes agree the temp gun can be a good reference tool but far to many try to tune with only the temp gun and just don't listen to anyone that tries to help with some old school advise. I feel that if you tune by temperature alone you will do your engine more harm than good.

378

My Feedback: (4)

That's odd that they'd try to translate into text the sound of the engine when there's so many good videos out on the subject.


When asked, I usually juts drop this one: [youtube]http://www.youtube.com/watch?v=ma2_CghxiUk[/youtube]


I believe that an excellent guide because A: it's the old school 'tune by smoke, sound and performance' method that doesn't even mention a specific temp number at all, let alone say to tune to one, and B: Because they recorded an actual engine running lean, rich and perfect, the sounds you hear in that video are accurate.

The_Shark

darn you! you stole my bubvvvbubviiiiiiiiiieieeeeeeeeeeeeeeeeeeeeeeeeeeee nonsense!