+100000
quoted an older post here but that's so true, when a new clean engine is just broken in (on tarmac for instance), it will very rarely flame out even if the tune is not perfect.
Dust, hot weather and dirty air filter is likely be a engine killer if engine is not maintained properly after each session, as well as worn engine bearings or damaged plug, dirty fuel tank/filter/lines : ) ..... even with a good tune. Ultimately loss of compression


Sworkz/Mugen Super Sport/Go/Os engines/Futaba

A little tidbit....

Idle quality......I see some guys commenting here that idle quality doesn't matter.....I have to greatly disagree with this as I feel idle quality is extremely important......and feel that if your engine can't idle your chances of a flameout are dramatically increased......

Very important Test !!!!!! when you are done your qualifiers have your pitman leave your car idling so you can test how stable the engine will idle after it has been heat soaked.......... many times (especially a Nova ) the idle will drop substantially lower once the engine is fully heat soaked.....So often times guys will have no issues during the qualifiers, but in the main the engine starts flaming out after the first refuel........... So After a qualifier I demand that my engines are capable of sitting and idling for a few minutes without any trigger blipping or interference,..........And if a engine will not idle after a qualifier I will adjust it so it will...and if even after adjusting I can't get a stable idle I will not trust the engine in the main......If your engine wont idle after a qualifier, its likely going to cause you trouble in the mains if your not extremely careful

So in the end check and set your idle speed after the qualifiers, ignore how it sounds when you start it cold...as often many engines will sound lean and high idly when cold......but when fully heat soaked after a qualifier many engines experience a huge drop in idle RPM..which is where a big amount of flamouts come from.......Hundreds of times I have seen guys ace the qualifiers only to have all sorts of flameouts issues in the mains...........

this is something we have started doing more this season, and the results have been excellent.....On some engines the amount of RPM drop the idle goes thru when the engine is hot is quite big...A engine that runs perfectly for the first tank will barely want to run after the second tank........Its crazy, but when cold you would swear the engine is very lean with a exceptionally high idle..yet after 15 minutes on the track that every same engine will idle so low it will barely run.......Heat soak dramatically affects how these engines run and idle...

+1000000

Ho ho ho

Good info there Neil, i have noticed after a qualifier if your tune is not right it will show in how it idles when heat soaked. cheers.

Is this flow chart accurate in a way?

Totally agree the novarossi loves to drop its idle when heat soaked

First I want to thank everyone who contributed to make this a helpful thread, this helped me tremendously.
Second, I have tuned my two main engines to perfection, a Team Orion 3 Port with OS #8 plug and non-venturi carb and a Sirio Kanai Evo3 STI. The backup engine is giving me issues, it's a SH PT002 and it is ring a ping ringy whatever I do. HSN is 1 and 2/3 turns from closed and LSN is 2 turns from closed,deck height is .46mm if not mistaken and plug is OS #8. Right now the best I can do is very good bottom and rich top, doesn't goes smoothly mid to top. I'm 200m above sea level and temps are around 12ºC. Using a 2058 Orion pipe and power is lower than it was a couple years ago, this engine was treated well.
And just found fuel is Rapicon 25/9, does wonders on the other 2 engines...

*edit* Had a look at another engine like mine and the LSN was leaned 1 to 2 turns too much on my engine. Seems way better

Kinda new to nitro, I drove an OS last year and felt great but didnt know much about tuning and it kept shutting off when I landed a real big jump... My question is within the different brands of engines... OS - Novarossi - Werks - Reds - etc... is tuning them the same concept? Want the bottom and the top to clear out nicely and have steady idle?

Hi, and thanks for all the useful tips here.

I am looking for some advice on tuning my engine (Hobbyking SEG 21 $60 job).

To amuse myself i recently 'ported' the engine..
rctech.net/forum/nitro-road/257149-how-port-nitro-engine.html
NB: I haven't changed any timings, just smoothed the entrance to the ports ect.
Also did the 'singh grooves' in the quench area of the head

After these mods, the engine has picked up some power, but the tuning window has become very small.

If i lean it out enough to make it run really well, it gets too hot.
If i richen it enough to keep the temperature correct it is badly down on power.

What needs to be done to correct this?

Colder plug?
Lower compression?
Something else?

I am currently using an OS P4 plug (turbo)

Any advice much appreciated.

dunno if this helps but a friend of mine bought a seg 21 and a 28 as well. he had the same type work done on the 21 and 28. the 21 runs very well but the 28 will not hold a tune right. im told its a carb problem from the factory. try sealing the carb and backplate first. or replace the carb maybe. it worked for him. i know buying a carb for this engine will cost more than the engine itself but if you have one already it might be worth it

Hope you guys don't mind me giving you the "story" of my engine so hopefully some people can make suggestions of what to try next!

It is an RB SLS5 that went into the car brand new during qualifying at Neo with just a quick box break in. Carb was setup by the rb factory guys and it ran the rest of Neo fine with a smooth steady idle, clearly rich but clean running, about 6 min tanks. Neo of course being a cool English low altitude spring.

Next to a club meeting in PA, didn't touch a thing, ran fine all day but still only 6 minutes runtime.

Through these meetings there was a slight tendency on track for the motor to stay on power a little as I came off the throttle, but nothing bad.

Next AMS, again even in the totally different atmosphere ran fine for MOST of the meeting...but as it had about a gallon through it by now was beginning to feel it may be time to chase performance, it was still definitely revving low and losing out on top end, smoke everywhere and in final qualifying sounded a bit unclean when flat on the straight. I leaned hsn an hour for the final and it felt a bit better but I lost a servo 4 laps in.

When I got back from AMS I decided to put a tank through on the box to check it all and then store how I normally would...and the idle would stay up high, 2 stage but even second stage being higher than before. (I live at sea level in VA).

I played around and richened lsn about 2 hours and slightly increased idle screw and got a nice clean low idle very quickly and an idle that could sit for a long time without stalling.

Have just done another meeting in a different car with a more compact manifold in the high heat of southern Virginia, engine now has over a gallon through it, and top end is not bad but still struggling for even 6 minutes run time. I also blew a plug. I tried reducing throttle EPA but it runs dirty at top as soon as I do (I set to just see the carb slider even at full throttle using a 7mm Venturi. I played with a slightly richer bottom too (1 hour) as I temped up at 245 after a qualifier (8 minute qualifier). In the final today I then kept getting lean full tank bog at pitstops, had one flame out coming off pitlane turning downhill right into turn 1 and another where it ran but at walking speed from the pitspot for about 15-20 seconds, then a bit dirty for a lap then back to good. Tends to be nice and smokey certainly on low to mid throttle...I don't naturally blip but at times was struggling a little to get a snappy corner exit and found mid corner blips helped this.

So, basically now what to do!?

Specifically:

1. I need more runtime, at least another couple of minutes, I am getting 5 - 6 minutes where my competition gets 8 - 9 (and the experts even more)..my brain says that it MUST have been set rich hsn to break in, and leaning hsn would be the best way of reducing fuel use age too... But I am weary about that high temp and risking the engine.

2. It's not particularly crisp off corners, would like a touch more zip.

3. Why would the full tank bog only occur today!? I was pitting in qualifying due to runtime issues and it didn't occur at all!?

4. If as I suspect I need to get brave with the hsn and keep leaning an hour a run whilst checking temp and chasing runtime, should I make counter adjustments to lsn (richen) to offset? I assume idle adjust comes last?

Any help much appreciated!

Dave, how much smoke the engine produces? Idle gap? Glow plug? Fuel? Does it sound crisp?
One thing I learned recently was that new gen fuels make little smoke, you have to go by sound and temperature.

It's a mistake to tune to temp. I also wouldn't trust fuel that doesn't smoke. What oil could they use that doesn't smoke? I have been making fuel with class 5 synthetic oil and it smokes more.

No specific temp was said, I meant whenever it doesn't go past the maximum temperature allowed by the manufacturer.
No idea what is a class 5 synthetic oil, but whatever is on Werks fuel smokes less than other fuels I had. Now I don't see that pronounced smoke puff other fuels made and performance is a bit higher, carb had a good tune with all tested fuels.

I agree that it's a mistake to tune to temp, as it depends on the age of the engine and the conditions, but it's good to get you in a ballpark tune. As for the oil, I have to disagree for the most part:
Who knows why it happens, but I've noticed something similar to what Zipty533 is describing. Watching older videos of well-tuned engines from a few years back show more smoke coming from the exhaust. Whereas now looking at other well-tuned engines, very little smoke comes from the engine, and temps are still within a safe range. I'd say it has something to do with cleaner-burning methanol, oil and nitromethane which doesn't create as much of a smoggy smoke, rather a cleaner, wispier smoke.