5Likes"the engine tuning bible"
07-19-2014, 06:12 AM
#466
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!
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!
If I missed something someone will chime in.
Forgot to mention the lean bog is coming from the Hsn being to lean to compensate for the Lsn being overly rich (the lsn is whats sucking your fuel and causing your runtimes to be low).
Hope this helps.
Last edited by lilchill; 07-19-2014 at 06:15 AM. Reason: forgot lean bog
08-12-2014, 10:35 AM
#467
Tech Adept
-
Last edited by Fatal1ty; 08-13-2014 at 11:47 AM.
08-13-2014, 03:18 AM
#468
Hi all,
I need some advice. The engine keeps on running for 1-2 seconds after wide open throttle. What could be the reason for this? I dont have the chance to go on the track at the moment. Starterbox only possible. Engine is Bullit 219, same as O.S
https://www.youtube.com/watch?v=fs9E-5u_zP0
thanks you!
I need some advice. The engine keeps on running for 1-2 seconds after wide open throttle. What could be the reason for this? I dont have the chance to go on the track at the moment. Starterbox only possible. Engine is Bullit 219, same as O.S
https://www.youtube.com/watch?v=fs9E-5u_zP0
thanks you!
Stop trying to tune on a starterbox...it doesn't work !!! put the car on the ground, warm it up for 10 minutes, then tune it while under load... Stop worrying what it does on the starter box as it means nothing........
09-17-2014, 02:36 PM
#469
Originally Posted by Fatal1ty View Post
Hi all,
I need some advice. The engine keeps on running for 1-2 seconds after wide open throttle. What could be the reason for this? I dont have the chance to go on the track at the moment. Starterbox only possible. Engine is Bullit 219, same as O.S
......
Hi all,
I need some advice. The engine keeps on running for 1-2 seconds after wide open throttle. What could be the reason for this? I dont have the chance to go on the track at the moment. Starterbox only possible. Engine is Bullit 219, same as O.S
......
09-17-2014, 02:53 PM
#470
I have the same issue and it sucks, but i've come to the conclusion that i need to bump up the idle before my mains even my qualifiers. Seems to me that the motors are leaning them selfs out (reaching a higher temp) and thus lowering the idle on its own.. Usually i'll heat up the motor then go out but once the motor reaches it's ambient temp the tune changes. Idk i have some figuring out myself im sick of flaming out do to a low idle.
An engines heat exchange ( cooling ) is done by 3 things , the head , the fuel ( the fuel is also the coolant in this example as its run on methanol ) and the chassis. Once an engine is at operating temp ( usually 6 hard laps ) it starts to saturate the chassis with heat as it absorbs heat from the engine through the engine mounts. This takes longer because the engine mounts do not dissipate as much heat energy as the heat sink its a bout a 2:1 ratio compared to the heat sink.
It will take about 15 minutes of hard running to saturate a chassis at which case you start to get problems if the engine is not tuned correctly. You will find people who experience the " lower idle " have tuned their HSN first instead of last.
The lower idle is caused the by the chassis saturation being full ie. the chassis cannot absorb any more heat so it starts to throw it back into the crank case causing it to over expand causing blow by ( reduction of compression ) and thats why you get a lower idle. The engine is over heated.
If you were to tune your Idle gap first , then your LSN then your HSN you will avoid this ( if its done properly ) #
Hope this helps
Cheers
M
09-21-2014, 03:48 AM
#471
Tech Rookie
expensive nitro engines
can someone help me with this? i have an lrp z32 and a nosram monster 30 similar engines.....why there are smaller engines much more expensive? is it ok to spend 400$ to buy a team orion engine? is the orion engine so much better than lrp? it costs almost the double money.
10-26-2014, 07:56 PM
#472
Two-stage idle
Just want to clarify some things about two stage idle:
- Basically it happens because idle gap too big and LSN too rich, right?
- After WOT and throwing throttle engine makes few pingpong sounds during setting into first idle stage. I'm pretty sure it's not Ok, but what exactly is wrong?
- Basically it happens because idle gap too big and LSN too rich, right?
- After WOT and throwing throttle engine makes few pingpong sounds during setting into first idle stage. I'm pretty sure it's not Ok, but what exactly is wrong?
01-04-2015, 05:37 PM
#474
hey dudes
Got a quick question for ya. Your cars warm and you believe you got it race tune, what should the engine rpm do? (Increase and getting louder or remain the same rpm and sound) When you pick the offroad buggy up by its rear wing?. Sort of like the buggy in vertical position.
03-20-2015, 03:40 AM
#475
Tuning a Nitro engine on a Savage X/XL: http://youtu.be/ma2_CghxiUk
On modern pro engines though, +\- 1/8 of turn is too much for fine tuning
On modern pro engines though, +\- 1/8 of turn is too much for fine tuning
05-14-2015, 11:10 AM
#476
I just wanted to post up and say this thread has helped me immensely. Thanks to all who have posted up information in this thread. 
I now understand what is meant by "carb balance"
Here was the situation I was having:
I was running my RB Kanai edition in my Losi 2.0, and after break in it always ran great, would idle for ever, even when the car was on its lid, and would not hang up and idle high after a run or coming in for fuel.
I just recently purchased a MBX7R and put the motor in with a Werks med clutch. All of a sudden I was having stalling issues after I would drive the car for a few minutes or come in for fuel. I tried everything it seems, differant fuel line diameters, lengths, richening the fuel, leaning it out, checking for leaks, even had the more experienced nitro guys look at it and they would say the same thing as me, must be running to fat and we would lean it out to the point it would lean bog and hang the idle up when I was breaking. After myself, and few other guys turning the needles in and out the tune was way off. So I started reading on this thread and began to understand how these little mills function.
The part that really stood out for me was the what I read about "heat saturation" This is what I believe that was happening to me. And because it was in a different chassis, it dissipates the heat differently. What do you guys think?
Any way, I set my needles back to stock and started over with the knowledge I gained here in this thread, and the tune has never been better. The needles are no where near where I had them, the LSN is in about 1/4 turn more, and the HSN is almost a full turn out from where I had it set when I thought it was running ok. I'm still a noob to nitro, I have lots of learning to do.
I now understand what is meant by "carb balance"Here was the situation I was having:
I was running my RB Kanai edition in my Losi 2.0, and after break in it always ran great, would idle for ever, even when the car was on its lid, and would not hang up and idle high after a run or coming in for fuel.
I just recently purchased a MBX7R and put the motor in with a Werks med clutch. All of a sudden I was having stalling issues after I would drive the car for a few minutes or come in for fuel. I tried everything it seems, differant fuel line diameters, lengths, richening the fuel, leaning it out, checking for leaks, even had the more experienced nitro guys look at it and they would say the same thing as me, must be running to fat and we would lean it out to the point it would lean bog and hang the idle up when I was breaking. After myself, and few other guys turning the needles in and out the tune was way off. So I started reading on this thread and began to understand how these little mills function.
The part that really stood out for me was the what I read about "heat saturation" This is what I believe that was happening to me. And because it was in a different chassis, it dissipates the heat differently. What do you guys think?
Any way, I set my needles back to stock and started over with the knowledge I gained here in this thread, and the tune has never been better. The needles are no where near where I had them, the LSN is in about 1/4 turn more, and the HSN is almost a full turn out from where I had it set when I thought it was running ok. I'm still a noob to nitro, I have lots of learning to do.
08-10-2015, 09:01 AM
#477
Tech Adept
Hi all,
I have some problems with my engine. On track is the tune really good, with awesome linear power and a nice dropdown to idle. It idles very stable and smooth. But after refueling, when I go WOT and suddently brake, the engine stalls directly. Any ideas why?
Cheers!
I have some problems with my engine. On track is the tune really good, with awesome linear power and a nice dropdown to idle. It idles very stable and smooth. But after refueling, when I go WOT and suddently brake, the engine stalls directly. Any ideas why?
Cheers!
08-14-2015, 05:21 PM
#478
Tech Initiate
Hello,
I run a RB ONE RTR V2 with black RB engine, the car have more or less 4 liters.
The engine is properly tuning, if I drove at road, no track, the car works very fine, good throttle response and perfect high end. The problem are when I go to the track, with the same settings I drove for 4 minutes max and then the engine stalls and I have to re-tune the engine...more 4 minutes and happens the same!!!
The engine is not hot.
Also tried a new carburator.
The glow plug is new.
No leaks at fuel tank
The exhaust pipe was cleaned and had no leak
The air filter is clean
Any idea?
Thanks
Best Regards
I run a RB ONE RTR V2 with black RB engine, the car have more or less 4 liters.
The engine is properly tuning, if I drove at road, no track, the car works very fine, good throttle response and perfect high end. The problem are when I go to the track, with the same settings I drove for 4 minutes max and then the engine stalls and I have to re-tune the engine...more 4 minutes and happens the same!!!
The engine is not hot.
Also tried a new carburator.
The glow plug is new.
No leaks at fuel tank
The exhaust pipe was cleaned and had no leak
The air filter is clean
Any idea?
Thanks
Best Regards
08-20-2015, 01:08 PM
#479
I have 2 questions/scenarios for the nitro guru's...
Scenario 1: You've tuned the engine with a medium heat plug, and then changed the plug to a cold or hot plug. Will the tune be affected? If so, on which needle and by how much? +/- 1 hour or more?
Scenario 2: You've tuned the engine with a fully changed glow igniter. During staging for your next run, you've forgot the igniter in the pit area, so you borrow a buddy's igniter which is almost dead but has enough charge to get the engine started. Will the engine run out of tune due to poor glo heat?
Scenario 1: You've tuned the engine with a medium heat plug, and then changed the plug to a cold or hot plug. Will the tune be affected? If so, on which needle and by how much? +/- 1 hour or more?
Scenario 2: You've tuned the engine with a fully changed glow igniter. During staging for your next run, you've forgot the igniter in the pit area, so you borrow a buddy's igniter which is almost dead but has enough charge to get the engine started. Will the engine run out of tune due to poor glo heat?
08-20-2015, 05:39 PM
#480
I have 2 questions/scenarios for the nitro guru's...
Scenario 1: You've tuned the engine with a medium heat plug, and then changed the plug to a cold or hot plug. Will the tune be affected? If so, on which needle and by how much? +/- 1 hour or more?
Scenario 2: You've tuned the engine with a fully changed glow igniter. During staging for your next run, you've forgot the igniter in the pit area, so you borrow a buddy's igniter which is almost dead but has enough charge to get the engine started. Will the engine run out of tune due to poor glo heat?
Scenario 1: You've tuned the engine with a medium heat plug, and then changed the plug to a cold or hot plug. Will the tune be affected? If so, on which needle and by how much? +/- 1 hour or more?
Scenario 2: You've tuned the engine with a fully changed glow igniter. During staging for your next run, you've forgot the igniter in the pit area, so you borrow a buddy's igniter which is almost dead but has enough charge to get the engine started. Will the engine run out of tune due to poor glo heat?
but generally with colder plug and you'll want to lean out your mixture, and go a little richer with a hotter plug... how much depends. Try an hour or even half hour at a time until you hit the sweet spot. 2.The igniter shouldn't make any difference as long as it has enough juice to heat the filament and start the engine. Nitro engines run off catalysis... the methanol reacts with the plug filament and keeps it glowing hot and able to ignite the compressed fuel mixture. The igniter just sort of jump starts the reaction.
However, if you run the engine for a while with the igniter still attached and it dies as soon as you remove it, or starts running rough it can be a sign the plug is bad.