EdwardN

iTrader: (1)

Again, if you go and see air moddeling control line team racing you will be ammazed how that diesels pick up the speed-instantly, less then a half second it is already on max RPM, they have if I am not wrong stop engine half lap before landing point, land the model, refuel it , start engine and goes to air arround 3 sec. Ammazing!!!!

Jonathan

iTrader: (2)

Hey Topgun

How's it going? I read that you have ran w/ no nitro and you like the results. My question then is this... if no nitro is better...would it be logical to assume that a low nitro say 10% is better than 30 or even 40% in what you're trying to achieve. BTW what are some of the steps you had to take to run with no nitro aside from just needle tuning... ie plugs and shimming?

Another question... I have a RB C5 .21 engine w/ a little more than a gallon thru it. It ran flawlessly until I switch glow plugs I was using a RB #6 but switched to Nova 6 (C6Tf) after I ran out of the RB's. After one tank... the nova plug popped... I richened the top slightly and subsquently popped 2 more plugs... Last nite I took it apart to check for wear... the rod pin on the crank's counter weight is out of round by .01mm and there is .02mm of play between the rod bushing and the crank pin. I am planning changing out the rod.... but I don't wont to change the crank unless I have to ... are these measurements within tolerances??Furthermore... the piston and the button looks slightly sandblasted... what effect would this have on the engine and should these be polished out.? Lesson for everyone else... not all # 6 plugs are the same...

Thanks in advance...

EVOLUTION

When you say the plugs popped,do you mean the filament has distorted?

If you were using a standard 6 and then went to a 6tf then they definitely aren't the same the 6tf is a colder plug assuming RB and nova plugs are the same which i think they are.Although colder wouldn't cause it,check the nova site which has a plug list and also what conditions they say to use them under.

As for the crank this is the measurements Rody gives;

If you have signs of sandbalsting also then you could be having pre detonation maybe you need to add an extra head shim but it depends on what % nitro you are running and your plug etc.

Jonathan

iTrader: (2)

EVO

Sorry...by popped...I meant distorted and no longer glows. BTW the c6tf is a "short body average filament" plug. If it was a cold plug, I have a feeling my motor would of been fine. I really don't know if the Novas are the same as RB... I can't seem to get to their site right now. The RB6 is the CP variety which is RB's competion line offered in 5,6,7 and 6 being the med. These are meant to resist higher temps...I know about pre-detonation... I was just asking of the ill effects (if any) of having a slightly sandblasted compression chamber. Thanks for the info on the crank though... I searched RB's site prior to coming here but couldn't find anything. So I appreciate the info.

EVOLUTION

Usually if the wire distorts like that it means that there is too much compression,so i was a bit confused as to why changing to "that" plug would cause it assuming nothing else was changed like head shims or nitro content.The c6tf according to the nova site is a cold plug,are you sure you didn't put in a c6tc?

http://www.novarossi.it/accessori_ing/candele.html

Jonathan

iTrader: (2)

Again... thanks for the link. A cold plug can withstand higher compression. However, the C6tf is a cold plug w/ "average" filament... possibly smaller than the RB 6 cp... thus the filament itself can't handle the same compression.. in other words it is a cold plug with an average filament. I am not sure why it's called a cold plug... I am guessing because it is of the short body variety... short body= less thermol mass= less heat retention.... I am guessing...

Corse-R

Hummm... all signs tells me you run a completely wrong setup on your engine.

An RB #6 isn't the same as Nova #6, on all mine .21's with a 25% of Nitro I run a #7Tf or a #8Tf depending heat and track condition and layout. A #6 is way too hot, get some Nova #7 and 8tf.

You suffered from pre-detonation and as a result, you got your piston pitted, again as result of: Too much nitro for a given chamber height, A too hot glow plug (probably those engine ran too hot compared to a .21). Check the chamber height (measure it with the tin wire method and tell us the measure and the Nitro % you will plan to use). If the filament on your plugs is distorted (pushed into the plug chamber), you have too much compression, add one or two 0.10mm shims as a starting point.

All mine .21's are very stable on temperature and rarely run hotter than 102 to 110ºC depending on how much I lean it and the engine, but with a Lola body, your engine temp should be there or slightly less (depending on your carb adjustment).

Probably you need to change that head and P/S, you can try to lap the piston dome (NOT the sides) with valvle grinding compound, change directly that chamber head, because the pits now is prone to have hot spots and have problems of detonation.

Jonathan

iTrader: (2)

First of all... you know I have a lot of respect for you. So please don't take offense to what I am about to say. Instead let's pretend this is like any other friendly but very loud bench racing... like I am sure you do back home.

Now... would you guys please tell me something I don't know... the 1st thing I've said was my motor was running tits (about what I would say in the pits ) prior to switching plugs and I meant it! With the platinum RB 6 plug w/.3mm of shims and 30% nitro, my motor was right at the limit especially for qualifying in which I give it the extra squeeze and come in at 249 F. This barely makes 5 mins... and yes I use the pressure chamber. So a "completely wrong setup...." Pleazzzze. Trust me when I say this motor was beautifully fast....

Secondly... I was the first to admit that the two plugs are diffferent. "lesson for everyone else...not all #6 plugs are the same..." I know cause I just experience the difference! As you know... the right plug is a key component along w/ nitro content and head clearance... everything else being equalled (pipe, clutch, gearing...) I simply made a mistake in the assumption... and I am doing the world.... all right... the 3 of you that are reading this a huge favor by sayign once again... not all #6 plugs are the same

Regarding salvaging a slightly pitted piston and sleeve... I think everyone here has read at one point that a pitted combustion chamber will create hot spots ... yada yada.... try telling Motorman or any of his disciples when they star the buttons. Personally... a slightly sandblasted button may be slightly more turblent and thus less efficient than one that's not. But then again... I had a modded MT 12 that developed a fuzzy button about half way thru its lifespan... which was an entire season... and it was fast till the very end. Now... I will be the first to admit that it got that way because I have ran it too lean... who hasn't at one point or another... With that said... I am going take your advice and replace it given the fact that this is a .21 whose combustion chamber has a greater surface area. But that comment about not lapping the side of the piston... I will get you back...

Now the real reason why I am still up typing is I may have figured out what the real culprit was... Although the 2 brands of plugs are different in temp ratings, I believe that the body length is the real difference... I am assuming that the short body plugs (C6Tf) has a shorter hole for the filament and thus less volume. If this is true... then this difference will undoubtably alter what was an optimum squish band and raise compression...

Bring it on Rough-R

Corse-R

The main difference on a Tf and a Tc plug is their body who is exposed to the air. A Tc plug has more metal on their body and dissipates more heat, thus robbing heat on the combustion chamber, developing less power.

A Tf plugs has a smaller body, so it absorbs less heat from the combustion chamber, letting more heat into it to make power. This is what I undertanded ever about plug bodies (could be wrong, but never told me this).

In all two types of plugs, the cavity for the filament is the same, so the unique difference would be the type of body and how much heat robs from the combustion chamber.

3 shims of 0.10mm is what I use on mine engines using 25% of Nitro, probably your engine will be happier with an additional shim, specially if you run on very humid and near the sea level. Worths a try to check if it improves with the additional shim and a colder plug.

Your mileage problems can be caused by a too hot plug too. It heats too much the engine and you need to open the needles a little more, thus draining more fuel and getting less runtime. Try to use a Nova #7 (blue pack - the normal ones, or check the same in gold model, probably a little shinier at high rpms) as I advised and change accordingly the carburation, probably your problems come from a wrong selection of the plug.

Jonathan

iTrader: (2)

Corse-R

My friend... you are way too civil...

Later!

Corse-R

Hehehe..... I prefeer the things very slick (so a lot of KY for me). The one that prefeers roughness is Eddie. There are others, but are a mix 50-50% of KY and WD40.

EdwardN

iTrader: (1)

Hi Jonathan. I am OK.
I am running some engines with no nitro. Deefenetly less nitro is better then more of it. It is the best way to use 5 % nitro-it will give more stability for engine tunning, plain methanol with oil is little bit different way to tune engine. It is required more precise tune head clearance and change it according to weather condition. With lower nitro content or no nitro at all you have to go less head clearance ( at some point you will required to have different head with lesser volume). No nitro has less abbility to go to preignition and hoter plug can be use. The needle tunning procedure will be more or less similar as a regular nitro content. But again, engine will be more sensative to weather condition (tramendouse change only). For me it is not problem to tune head clearance, but may be for some people it will, just needs to play with that for a while.
About your problem with glow plug, I don't know them by number, but for sure if you have sand blasting-it is pre ignition condition, detonation. The way to fight with that is put colder plug and depend of your head clearance may be add some .15 mm shim there, but don't put too much, if you do, you will make it worse.
About your cranck, 0.01 mm is ok, but check for non roundness and play 0.02 mm is very good play, I wouldn't spend money to change conrod yet, In my opinion 0.06mm-0.095mm it is time to change it, but make sure if pin on cranck is round, if it is not you will ruin next rod in couple runs. If you have acces to chrome plating, chrome the pin and lap it to size-it will work forever.
If you decide to polish top of the piston, make sure after your polishing it is still totaly flat ( read somewhere it was recomended to sanding top surface of sleeve to make less head clearance-was totaly wrong). any kind of interaption on the top of piston is not good for performance, but more then sand blasting is worse warnish-it makes Navas work like OS This I am doing periodically. Again, you have to be very carefull when you deside to clean top of the piston, don't make it as a dome ( unless you have point to do it in purpose).

Jonathan

iTrader: (2)

Thanks Topgun.... Just to be certain... so having a pin that is out of round by .01mm is OK ? Btw... I haven't read anything this interesting in a while... regarding the chrome plating the rod pin... my friend and I were just talking that last nite! We are aslo looking into coating the entire crank w/ some kind of coating as the Rody tunes.... Titanium nitrite??? I think.... Keep up the good work...

Corse-R... I staying away from the lubes dude... Except for castor oil... My Oakie inlaws used it for everything from upset stomachs and stuff.... back in the day of coures

EdwardN

iTrader: (1)

You are very welcome. 0.01 mm non round isn't warning to buy new shaft ( unless you have dollar tree). I will not bother to change it yet. In my opinion to plate whole shaft doesn't worthe it, just the pin is enough. I don't know why JP or Rody doing it, probably to raise the price. What you got to do with pin- first of all, before plating lap it to make sure it is round with tollerance 0.005 and after that plated with hard ( "blue" if you can find). After that you have to lap it again, because the chrome doesn't plate evenly, you need to make even and round again. If you do this-this cranck will last for years We try to plated with titinum nitrite, aluminum nitrite, tungsten corbide and other types, galvanizing plating , plasma coating-the only old method was woking right-hard chrome by galvanizing plating. The rest was just come out easy, not that dependable as chrome. We also tryed and was succesofull-dril out the pin from the web and use high spped cutting steel for pin, but this is very difficult process, no need to try, not too much benefit to compare with chrome plating. Right now, we are working to make conrods with roller needle bearing on the cranckshaft pin side. There is no problem for .21 size, but little bit problem with .12, but I hope we will resolve it too. I will put pics, as soon as I get.

Slammed

Hi,

Please leave me some of your experiences with the new STS RS5 .12 engine. This would be the 2003 version. I know there were some problems with the older versions. I want to know if it has improved.

Thanks in advance,
...Slammed