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Old 08-10-2007, 08:35 AM   #1
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Default How to properly tune an engine for on-road racing,

hi all,

i am a newbie in nitro racing, i have been racing nitro for over 4 weeks now, but i have a few question than i can't seenm to find the answer, for your info, i am running a mtx4 with Os tz 3port+ nova 2630 pipe, my question are as below, so "Masters"out there please leave me a few hints, Thanks in advance

1) how do we run in a new nitro engine? does different brand or engine have different method of running in?

2) how do we know the engine its already run in? by liters of nitro used? or by listening to the sound of the engine, any guide?

3) do we need to always open the nitro engine to clean them like we do for electric motors?

4) also how about clutch setting? like the amount shim use on top of clutch spring, and shim use at the trust bearing end, also how tight do the thighten the clutch spring? do we change clutch spring ? currently ui have measure my clutch spring is 1.1mm, shim at 1.1mm, the trust bearing for free play of 3 on my eds flywheel tool(i don know what it means)

5) lastly, what is the optimum running tempreture? so that i am not too lean and not too rich, too lean i over heat, too rich i lose out on speed, so how do we tune it for best result.... so far i only run without the knowledge if i am too lean, i have overtaken some more expensive engine at straights during a race, so i was curious if i was too lean, but i did finish a 35minute race without the engine dying off...
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Old 08-10-2007, 09:32 AM   #2
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Well....
1. Lots of people prefer to just run the engine rich on the track for about 6 or 7 tanks (don't let it get into second gear, that's how rich it should be). One thing that I've discovered though is that most engine manufacturers tell you to run the engine wayyyyy richer than it should be....to the point where it won't even start....so sometimes it's not best to follow the instructions...but it depends on the engine.
2. Well, it'll probably take a while to completely break in, but like I said, after about 6 or 7 tanks you can start tuning it for racing. If it keeps getting stuck at the top and the you have to turn it over with a screwdriver to get the starterbox to turn it, just keep running it and it'll eventually loosen up. Only go easy with it at first, don't run it rich forever because with all that oil it'll never break in...
3. I take my engines apart after every race-day to clean and oil every little part. Some people never even take it apart, they just put oil in the glowplug hole, but I prefer to disassemble it often to check the rod and stuff. But whether you take it apart or not, put after run oil in it to prevent the internals from corroding (I think that's how you spell it....hmm..)
4. I wouldn't know....I run a serpent.
5. Stay between 210 and 270....some engines like to run hotter than others.
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Old 08-10-2007, 11:51 AM   #3
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1) there are so many ways to do it and all will create the same result. Most ways are based on the WOT which means wide open throttle with a rich setting. If it is on the bench, on the starterbox or in the car and if you let it cool down after each tank or run 1 liter in one run is your choice.

2) Difficult, in cool down situation without a glowplug you must feel a slight pinch when the pistion is at the top of the cylinder.

3) depending on which fuel, some fuels are agressive to the metal parts. An afterrun treatment would be wise at the end of the racingday.
When the engine is out of the car you kan open the backplate to tak a look at the crankshaft and bearings.
Cleaning pistons is not needed while some brands advise to do it.

4) Setting up a clutch is for every brand almost the same. The most impotant thing is to use a gap of 0.6-0.7 mm and shim the rest out under the clutchbel so you will have a very little axial play to give the thrustbearing a longer life. The thickness of the spring and the weight of the flyweights is only how you want to react and act your clutch, I like light shoes and a hard spring.
Adviseable is to use a bigger shoe-holder (wider in diameter) like Serpent has.

5) the temperature of an engine is very difficult, a Novarossi or Picco based .21 engine runs at 100 - 115 degrees celcius whil the Sirio AAC engine does run at 85 - 100 degrees celcius. If you tune the engine to sound, visable smoke from the exhaust and visable performance then the temperature will be ok.
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Old 08-10-2007, 01:30 PM   #4
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Quote:
Originally Posted by Luke W View Post
Well....
1. Lots of people prefer to just run the engine rich on the track for about 6 or 7 tanks (don't let it get into second gear, that's how rich it should be). One thing that I've discovered though is that most engine manufacturers tell you to run the engine wayyyyy richer than it should be....to the point where it won't even start....so sometimes it's not best to follow the instructions...but it depends on the engine.
2. Well, it'll probably take a while to completely break in, but like I said, after about 6 or 7 tanks you can start tuning it for racing. If it keeps getting stuck at the top and the you have to turn it over with a screwdriver to get the starterbox to turn it, just keep running it and it'll eventually loosen up. Only go easy with it at first, don't run it rich forever because with all that oil it'll never break in...
3. I take my engines apart after every race-day to clean and oil every little part. Some people never even take it apart, they just put oil in the glowplug hole, but I prefer to disassemble it often to check the rod and stuff. But whether you take it apart or not, put after run oil in it to prevent the internals from corroding (I think that's how you spell it....hmm..)
4. I wouldn't know....I run a serpent.
5. Stay between 210 and 270....some engines like to run hotter than others.
run it rich for more then 6 to 7 tanks and i prefer using a break in bench for 6 to 7 tanks then leaving it rich run it on the track for 2 to 3 more and taking the engine apart after every race is not neccasary just turn the motor over on the starter box with the air filter off and hold it wide open while putting a few drops of after run oil in it with out the igniter so the motor cant start and never leave fuel in the carberator always dump the excess fuel out of it and the should run at about 210 to 250 270 is a little to hot
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Old 08-10-2007, 01:53 PM   #5
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4.)
A good starting point on the clutch top mut I feel is .9 or just turned in on one thread on the SG. There should be little to no play on the bell after assembly but it must be able to spin freely without binding.
3.)
After a good race, I do take the engine out to clean it and the airfilter. Check everything. Clean motor is a happy motor! Runs cooler also.
2.)
I've noticed that a good motor will show great power after a while of running. A while may be 1-2 gallons. I've had motors that broke in after 3 gallons. Always the .12's ???
1.)
Breaking in a motor... See above. These guys have it all right!
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Old 08-14-2007, 06:27 AM   #6
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hmm, i will try out al your suggestion..., hmm so far i think i fried my engine bearings, when cleaning engine, i find the bearing not that smooth anymore...? i wonder why...
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Old 08-14-2007, 11:07 AM   #7
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Well on the question of runnin in I use a different meathod. The purpose of runnin in an engine is to get the moving parts to expand and contact under close to normal operating temps. This meathod is known as heat cycling. Alot of people will tell you to just let your new motor sit and idle through 5 to 6 tanks. That does absolutely nothing but keep the engine cold enough to not really do any good. Click on this link...

http://www.johnnycoolguy.com/JCGR/ma..._break-in.html

Make sure when your done after every short "heat cycle" round to take and drop your piston down to Bottom Dead Center. These engines are 'ABC' or made of copper, brass, and aluminum. The piston and sleeve are made of two different types of metal which contract on cooling at two different rates. So you want to get that piston out of the way of the sleeve while they both contract.
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Old 08-14-2007, 12:36 PM   #8
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If you do not know where ABC stands for then you do know how to run in ????

ABC stands for:
- Aluminium piston
- Brass cylinder
- Chrome surface on the cylinder

Running a first tank idle does do a thing !
Let me show you this drawing a once made:


On the left side you see in a large way zoomed in the side of the piston (gray) and the cylinder (green) of a new engine. The side of the piston has a microscopic non smooth layer, if you start to rough the small tops can not stand the large heat and pressure (from the speed) and will burn and so break off.
The first tank idle will create a small flat top as shown on the right what will dispose the heat better and also can stand the pressure of the tight piston better.
When running WOT there is a lot of oil and cooling so the surface will slowly go to the shape of the cylinder, running at operation temperature is not needed in the first steps. By leaning out the main needle after every tank you automaticly bring the engine closer to operation temperature when the tops on the surface of the piston will be stronger.

But you can not compare running in processes because no engine is the same. Within those tolerances there are always differences which will result in a different time to run in and different treatments to finalise the fitting of the piston. And still not talking about tolerances in timings of the ports and crankshaft which makes the real noticeable differences (I do crankshaft tuning and know what small changes at the timing does).
All topdrivers have their ways to run in (some people like Picco sometimes only one tank) and all have fast engines to get into the final at the worlds or at least the half final.

I do not say the most written Cyrul methode is crap but I also will not say that his way is the only perfect way. Most methodes are based on WOT what only means wide open throttle with a huge rich settng so the rpm's are limited.

This knowledge is based on 3 years experiences in which I am involved with develloping a racing engine (and still is)
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Old 08-14-2007, 02:47 PM   #9
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Huh, good info Roelof. Learn somthing new every day.
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Old 08-14-2007, 11:32 PM   #10
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Quote:
Originally Posted by Roelof View Post
If you do not know where ABC stands for then you do know how to run in ????

ABC stands for:
- Aluminium piston
- Brass cylinder
- Chrome surface on the cylinder

Running a first tank idle does do a thing !
Let me show you this drawing a once made:


On the left side you see in a large way zoomed in the side of the piston (gray) and the cylinder (green) of a new engine. The side of the piston has a microscopic non smooth layer, if you start to rough the small tops can not stand the large heat and pressure (from the speed) and will burn and so break off.
The first tank idle will create a small flat top as shown on the right what will dispose the heat better and also can stand the pressure of the tight piston better.
When running WOT there is a lot of oil and cooling so the surface will slowly go to the shape of the cylinder, running at operation temperature is not needed in the first steps. By leaning out the main needle after every tank you automaticly bring the engine closer to operation temperature when the tops on the surface of the piston will be stronger.

But you can not compare running in processes because no engine is the same. Within those tolerances there are always differences which will result in a different time to run in and different treatments to finalise the fitting of the piston. And still not talking about tolerances in timings of the ports and crankshaft which makes the real noticeable differences (I do crankshaft tuning and know what small changes at the timing does).
All topdrivers have their ways to run in (some people like Picco sometimes only one tank) and all have fast engines to get into the final at the worlds or at least the half final.

I do not say the most written Cyrul methode is crap but I also will not say that his way is the only perfect way. Most methodes are based on WOT what only means wide open throttle with a huge rich settng so the rpm's are limited.

This knowledge is based on 3 years experiences in which I am involved with develloping a racing engine (and still is)
Once I use WOT technique : Open throttle, ultra rich setting, and the engine temperature was Cold ( maybe 55-60 celcius ), and here was the result : .... after two races, the engine sleeve tightness is already gone.

I was breaking with WOT method three times ( 2 NSR12S5 and 1 RB WS7S3 ) and they were short live
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Old 08-15-2007, 01:16 AM   #11
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Once I use WOT technique : Open throttle, ultra rich setting, and the engine temperature was Cold ( maybe 55-60 celcius ), and here was the result : .... after two races, the engine sleeve tightness is already gone.

I was breaking with WOT method three times ( 2 NSR12S5 and 1 RB WS7S3 ) and they were short live
Anyother method othe then WOT?
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Old 08-15-2007, 02:13 AM   #12
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I was breaking with WOT method three times ( 2 NSR12S5 and 1 RB WS7S3 ) and they were short live
Then in my opinion you did do something wrong or used the wrong fuel....
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Old 08-15-2007, 02:39 AM   #13
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Here is my method : I don't say this is the best..... you are free not to follow.

Step 1 : Buy engine gasket to lessen the pressure from brand new p/s/r, for eg. add .10mm + .10mm + .10mm . I also give couple of drops after run oil to bearing, sleeve, conrod, before the break in begin.

Step 2 : Break in close to operating temp for 6 tanks :
2 tanks on the bench, stop for 20 minutes,
2 tanks on the track, stop for 20 minutes,
2 tanks on the track while you lean out during the last 2 tank process.

Step 3 : clean engine internals and lubricate everything with high quaility after run oil ( clear type )

As engine grow older ( become less and less compression ) ...... take out the gasket one by one ( every two races ).
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Last edited by asw7576; 08-15-2007 at 04:32 AM.
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Old 08-15-2007, 02:45 AM   #14
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Then in my opinion you did do something wrong or used the wrong fuel....
o-donnel 25% is wrong ?

original glow plug ( c7tf ) from the engine is wrong ?

even my friend quit using WOT because the p/s/r were short live.
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Old 08-15-2007, 03:10 AM   #15
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WOT method is great IF you keep the temps above at least 160F. Wrap foil, use a hairdryer, mill some fins off a spare head..... whatever it takes.

The first time I tried WOT method I checked temps on the first tank and the engine was 100F I immediately wrapped the head with foil. After that I used a spare head milled in half with only 4 fins left and I still wrap the head.

Now I use a Hudy bench and wrap the head using incrementally increasing RPM's..... example:

35PLUS21 Break-in:

60F ambient temps and head wrapped halfway w/ foil tape. The last three passes I removed about 1" of foil from the top fins- about three fins. I used 25% Byron's and the #7 plug that came with it.

8K RPM

1). 160F start- 192F end (8K- 9.5K end)
2). 160F start- 200F end (8K- 10.2K end)
3). 160F start- 192F end (8K- 9.7K end)

10.5K

4). 170F start- 192F end (10.8K- 11.3K end)
5). 165F start- 192F end (10.8K- 11.4K end)- leaned botton 1/8 turn as temp started lower than tank #4. Using this method you want to start each tank at least as hot as the previous- not less.

16K RPM

6). 170F start- 195F end (16K- 16.4K end)- lean top 1/8 turn.
7). 196F start- 205F end (15.8K- 16.6K end).... see this baby loosening up. Started at a lower RPM, finished higher than tank #6!!

16K RPM w/ 4- 5 second full throttle bursts

8). 170F start- 225F end (16K- 28.2K ending)- leaned top about 1/4 turn after I saw it would not overheat on a few WOT bursts.

I hit 30K RPM just as she was almost dry...... I didn't have enough fuel left in the tank to chance a verification back up pull, but 28.2K was re-producable a few times at about 1/4 tank left.


Run two more tanks in the car sneaking up on race tune. The top will be about 1/2 turn rich from the end of break in from my experience with this method.

This method works great! I got it from a member here and modified it slightly for myself. It really easily loosens the engine up with increasing RPM's and temps with each series of passes. Complete cooldown between each tank. You'll need a handheld tach that you can get on ebay for $30.

There's many ways to skin a cat... use what works for yourself and you are comfortable with. I always clean and inspect before break-in and perform an inspection about halfway through and at the end..... plus after every race day
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