Genuinly stumped on this whole smoke issue.

[Vandriver007]

Hi everyone, bassically is my car fine or going to blow up on me! 

The basics first. 

Just bought a brand new HPI bullet MT 3.0 from Modelsport UK. 

Completed engine break in properly with factory carb settings, 2 tanks up on blocks, 1 tank round in slow circles up to half throttle, then another 3 tanks driving around flat car park up to full throttle in short bursts. So 6 tanks run through it now. 

Using 25% Fuel with an R4 medium glow plug. 

Outside temp around 6-9.c on all days if that helps. 

Car fires up after just a few pulls on the starter each time. 

After air filter oil/after engine run oil from HPI used after 3rd tank applied as per video guides. 

Idle gap set at between 1-1.5mm as instructed, car does not stall at full brake and idles at rest or brake fine. 

Tweaked the HSN first on tank 5 and pulls away fast without hesitation to great top speed, no cut out or stall on way to full throttle or at full throttle. 

HSN currently sat 1/2 turn to rich from a point of being so lean it did cut out at full throttle (so I know now it's at the fastest point it can be for me whilst keeping the engine lubricated just enough I believe?) 

No fuel leaking out of exhaust when tipping car on its side after shuting the car off. 

Have not touched the idle or LSN at all yet and car idles while running either stationary on occasion but most of the time with a small 1-2mph forward motion without brake on. 

All tweaking done once engine was warmed up properly after a few minutes. 

So all sounds pretty good so far I gather after watching/reading many hours of instruction material for new model owners........however now my smoke issue problem.

 

Why is it bearing in mind the car is not sluggish at all off the mark, getting to full throttle or at full throttle, with a nice and lean HSN setting (as said by the fact its about 1/2 turn toward rich from the stalling point when at full throttle) that I'm still getting what I think is far to much bluish/white smoke on acceleration? I know there is always ment to be some for lubrication which is fine. But mine spews out more in thickness quantity than I have seen on any video of someone driving there's on acceleration by about double I would say. Plus ticking over at idle there is practically no smoke at all, virtually no fuel being spat out the exhaust and also no fuel whatsoever leaking out the exhaust after the car is off and I hold it to the side to drain. 

How can I still be seeing so much smoke on acceleration with a nice and lean HSN setting, lean enough to not spit fuel out the exhaust at idle or drain out after running, and a car that feels great to drive with no real other issues I can tell of? 

Does this sound like a genuine problem with the engine, or just a case of the idle and LSN not being adjusted from factory settings yet? 

So sorry for the long post but hopefully someone who likes reading novels can help me! 

Daniel

 

[Stormbringer]

are you by any chance using Opti fuel ?

if you are it is a smokier fuel than some others and you need to be carefull you dont over lean it 

[locky]

Different fuel brands use different oils which have a different smoke level at the exhaust.  I wouldnt trust smoke levels. But you maybe too lean at the LSN.

 

If you lean the HSN then you have leaned the LSN, therefore weaker mixture and less oil at idle.  So try richening the LSN a little and see how it accelerates from stand still, keep reichening until it bogs, then leam it back a bit. The LSN adjustments are alot finer than the HSN so 1/12 increment is best. You need the idle mixture  rich enough to cool the engine.  After full throttle runs, the engine temp should come down at idle  by a degree of fahrenheit every few seconds.  If the LSN is too lean then the engine temps may not reduce but increase. A temp gun is useful in this case and then you start to know the tune by the sound and performance.

 

https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/

 

This is a good description, not my words...

IMO tuning by sound is the most accurate way to tune... a properly tuned engine will be crisp and on pipe when on throttle but quickly settle down when you let off the throttle.... If your engine has a steady high idle that sounds like a box of angry bees your too lean on the LSN...ideally you want your engine to idle low slow and relaxed and have a slight lope to it, almost like a Harley Davidson ...If your engine hangs RPM coming off the throttle your too lean,( of course assuming your idle gap isn't too large or your throttle linkage isn't hanging up ) ....coming off a high speed pass you want the engine to idle down quickly to a steady stable idle , then quickly step down again to an even lower idle with a lope , then as it it sits and idles you want it to slowly load up and get slower and slower, but at the same time the longer it can sit and idle the better, A healthy engine with a good tune will usually be able to sit and idle lopey like this for a couple of minutes, sounding like its going to stall but never actually stalling... Then with just a little burping of the trigger to clear its throat the engine should spring right back to life all crispy and and on pipe again .... Obviously at an indoor event or in confined spaces with other cars tuning by sound may be difficult or even impossible but in ideal conditions there is no better way to tune then by sound.....a lean engine will always sound lean and a rich engine will always sound rich and once you learn what ques to listen for its pretty much foolproof....

... when you tune try to consider the LSN to be only your idle mixture control and your HSN is for everything else... meaning only use the LSN to tune the mixture while the engine is at idle with the throttle at full close....do all other tuning by the HSN....separating the idle mixture like this will simplify the tuning process and end up giving a good consistent tune every time..basically once you set the gap use the LSN to set the ideal idle quality and mixture.. then as you dial in the HSN you will go back and slightly readjust the LSN, always aiming for that calm and relaxed idle ...I usually start rich on the HSN and get a baseline LSN and gap to start from, then I do wide open blasts in short grass and slowly dial in the HSN till I find peak performance, as I go along continually readjusting the LSN to maintain that low and slow idle .... If the engine has a lean bog off the line fatten the HSN, and if it has a rich bog lean the HSN............if your coming off a high speed pass and the idle hangs then your too lean on the HSN...... non matter what you do to the HSN always maintain that perfect idle mixture using the LSN.... You want a engine that can idle well, but gradually loads up and idles slower and slower the longer it idles...

[m4inbrain]

My personal thought on that, after experiencing something somewhat similar?

 

Weather. If it runs well, it's tuned well. If you have concerns, get a glow plug thermometer (technically not necessary, any IR thermometer will do, but i found the one that you plug the "glow plug hole" with more accurate), check engine temp. 

 

Tuning by sound works, but i find combining sound, smoke and temperature is by far the most accurate, at least from all the things i tried. Temp gives you a great indication whether or not your engine is happy, if i were you, i'd check the temperature and if it's nice and toasty/happy (the correct kind of toasty), just send it. The problem in particular with smoke alone is that the smoke can change based on outside conditions. If you don't move anything now, just wait until the outside temperature picks up, it'll smoke less. Much like 1:1 cars.

[Stormbringer]

best to err on the rich rather than lean side sometimes you sacrafice performance but your engine will live longer 

[Nitroholic]

Your fuel will have a stated oil percentage.....should be on the bottle somewhere, or just google it.

 

Basically your nitro fuel is made up of 3 things....

 

Nitromethane ... ( 25% in your case )

Methanol ( the bulk of the fuel )

Oil ...for lubrication. This also gets burnt, and makes the smoke.

 

Now...the fuel I use has around 11% oil, but some...like hte old Opti RTR blend ( sold branded as HPI too ) had 15% oil. Safe to say, you can guess there will be a different level of smoke from those at an identical tune.

 

You have broken your engine in as per the book, and that is fine. You have tuned your motor to a level you were happy with...past that level...then back a bit. It is most likely absolutely fine! What you are doing though, is experiencing hte perfectly natural concern that you might be about to ruin an expensive new toy, but my advice is...relax a bit!

 

Buy a cheap IR thermometer, and check your temperatures. That will confirm that the tuning you have done has not resulted in over heating. I ignore smoke as a tuning ref in the main, as with a bit of practice you can hear if hte motor is happy, or if it is 'screaming' and running lean. That wil let you marry up what you see, what you hear, and what the engine temperature shows. Also...as mentioned above...find the spot on tune...then richen it up a fraction. Gives a margin for error, and as you are not racing...well...if it's not giving max power...you won't really notice.

 

Just make sure the thermometer you get covers the range you need, and don;t just look at ones stated for RC use. This...for example...is the sort of money an 'RC' one goes for :

https://wheelspinmodels.co.uk/i/279822/

 

It reads -50C to 380C ( more than you are gonna need.... if you have temps over 250F .... 120C...then you are getting too hot... )

 

move away to generaic IR thermometers.,..

 

https://www.ebay.co.uk/itm/Digital-Thermometer-Infrared-Handheld-Temperature-Gun-Un-Contact-IR-Laser-Point/402710404635?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D231203%26meid%3D375604bbf48144cf9de0038c3ae95ec5%26pid%3D100010%26rk%3D3%26rkt%3D12%26sd%3D353392876408%26itm%3D402710404635%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganicWithV5Tree20Ranker%26brand%3DUnbranded&_trksid=p2047675.c100010.m2109

 

and the price difference is obvious.

 

The unit I have cost me £7 and was identical ( apart from branding and colour ) to one that used to be sold badged with HPI for 3 times the price.

[Vandriver007]

Thanks so much for all the great advise guys and I will take it all on board and change a few things based on what you all said tomorrow when I'm next out with it. 

I didn't know about the oil content in the fuel (I'm using Optimax 25% RTR with the higher oil content I now see) but now I do the smoke makes perfect sense and makes me happier knowing it is lubricating the engine really nicely due to the smoke even though I'm running it pretty lean at the moment. Once this litre runs out I got with the car I've got 2.5lts of Opti 25% Race formula waiting to be used I also bought. Now I know about the oil content though and see this Race mix has less in than the RTR I will make sure to turn it back another quarter or so more to rich just to be sure I'm still lubricating the engine nicely. That will cut the smoke down a bit too. 

Thanks again.

 

[babylon]

As others have said, Tune by sound and not smoke, I use THIS that is mixed on site at a shop near me, First thing he said was that you can't tune by smoke as it doesn't produce any, And he was right, Brilliant stuff, And they do a whole Range.

They even make there own Engines  and Pipes.

Still remember when I went in once and the owner asked what car I had, Said it was a Thunder Tiger S3 with the Tunnel chassis(Best chassis ever), Just so happened he had the same car and bought it out to show me, Difference was he's engine leaned to the centre like the old old Hyper 9, And the chassis was exactly the same as the one below and like mine, Difference was he's was totally made out of Carbon Fibre, Where in gods name he got a 3D chassis like made from Carbon Fibre God only knows, I never asked, But I will when I go back, Must have cost a fortune.