Daytona955i

hi,

DIRECTION from Klotz :

>>R/C Model: 2-stroke glow engines mix at 15 -18%; 4-stroke glow engines mix at 5 -10%<<


I know that kl100 oil is Pure synthetic bases are blended with 20% BeNOL Racing Castor Oil ( BC-175 )...


... but what is the situations and in what type of engines can use mix at 5% ?!


thx

GhostRider32

I've never heard of glow 4 stroke fuel mixed at 5%. I personally wouldn't trust it. YMMV.

DSTIEBS

I think you may have that reversed? If not sure Check your four Stroke manual.

Daytona955i

hi,

sorry but I did not understand what you mean...

thx

DSTIEBS

I am sorry. You are correct. That is what Klotz says.

XJet

I noticed this on the Knotz bottle and questioned it a couple of years ago.

The reality is that 4-strokes can survive with much less oil than 2-strokes because, no matter how much (or little) oil I've ever used, they still end up with about half a teaspoon of oil in the crankcase. It seems that some kind of equilibrium is reached whereby the amount of oil blowing past the piston is matched by the amount going out the breather so as to leave a pretty constant pool of oil behind.

I currently run 12% of a (better) synthetic oil in my 4-strokes with no issues at all but I wouldn't be game/silly enough to do this with Klotz.

balsaeater

Model car engines 2 stroke can go as low ~5% as they tend to be under low loads and dont go full speed all the time.

Best I seen is small 40 OS LA run on 6% and 8% sythetic but at low RPM for sports use but really only for the pros

I now do 12% with my 180 Saito 4 stroke but I use EDL.If I went with Klotz I might opt to do 15%.Soon going to 10% EDL with the 180 saito so it the same mix as my MVVS 160 which uses less oil.However I alway do big props turning slowly

Balsaeater

XJet

I wonder if this might actually put *more* load on the key bearing points within your engine (and thus on the oil)?

When you break in an internal combustion engine you're warned not to use heavy loads.

I would suspect (but it's only a suspicion) that an engine turning larger props would actually be placing a larger demand on the film-strength of the oil it's using particularly in the conrod wrist-pin/crankpin areas.

You're still getting the same combustion pressures (therefore the same force applied to the piston) but it's maintained for *longer* when you're turning a big prop more slowly. When using a smaller prop at higher RPMs, the period of sustained pressure on the conrod bushes (when the oil is being forced out and the film thickness reduces) is shorter, allowing the film to be replenished during the intake stroke when the forces on the conrod are reversed and it actually changes from being under compression to being under tension (in a 4-stroke).

downunder

I've heard it said quite a few times that CL stunt engines operate under very heavy loads compared to RC engines which rather surprised me because I'd always considered they had a fairly easy life plodding along usually in a 4 stroke at rather conservative revs. But there may be some truth to this because combustion pressures on the firing stroke are much higher than when 2 stroking and they're driving quite large props generally (although usually a fairly fine pitch). The rods though seem to last extremely well but this could be because most CL flyers like to use a lot of oil and mostly castor.

The only engine I've ever had a rod problem with was my Rossi 45 that egged out the small end by 0.012". Imagine my surprise when I found it was unbushed! I's always treated it quite gently (or thought I was) because I only sport fly and had it tuned to run in a 4 stroke in level flight because it broke into a fast 2 stroke on uplines (it acted just like a stunt engine ) and was always fed 20% all castor driving an 11x6 prop. Maybe the rod would have lasted longer if I'd thrashed it with a smaller prop .

balsaeater

Me I am no expert.I look the net tosee what others do and try it.I run the engines in with 20% oil,After that I reduce the oil.

The less oil the more fuel the more power the less need or requirement t input any nitro to make up for power losses from High oil

Best I can figure it only the piston wrist arm and the type of bearing on the con rod that count and that requires the high oil content. The rest of the engine like ball race and piston liner could with glow fuel probably operate at 5% oil.Best I can figure its RPM that places the limit on the piston wrist arm.A OS 90 VRDF at 24,000 RPM needs 23% oil 50% castor 50% Syth

Other engines in the 10,000 RPM seem to recommend 17 to 18%. Lots of guys out there go with less than that.Seems in Europe with the Ester family of synthetic oils that figures of 10% to 12% are more popular.In the USA where PAQ synthetic oils are often used it seems that it less common to go below 15% oil and will nearly always seem to include 2% Castor in the mix.

Me I use 15cc 90 sized planes with 26cc 160 or 30cc 180 engines in the plane using biggest props with fine pitch. This means that engine is often only at 1/3 regime and only WOT for punch out from hover or for vertical climbs from takeoff.Basically plane follows the prop a lot more like a electric engine with gearing with larger props .
I suspect on that type of use the strain for the piston wrist arm and con rod bearing is low

Best I can figure if you look a non needle bearing for the con rod on the Saito gasoline and the same in glow we see that you can go as low as ~5% in gasoline version and recommends ~18% with glow versions.In other gasoline engine with needle bearing for the con rod they can go as low as ~2% for oil.

It seems that gasoline fuel acts as lubricant so lubrication demands are less.Also seems that Methanol fuels need a different type of lube and more of it to lubricate glow engines and to some extent methanol or etahanol are not a lubrication friendly fuel types.


If others know more shoot as i always want the lowwest oil content possible without to change to ~20% lowwer power often heavier gasoline engine versions

Balasaeater

downunder

That's not really correct if you think about it. Take a fuel that's 85% methanol and 15% oil then run the engine and tune it to peak. Then add enough oil to bring it up to 20% oil which leaves 80% methanol. Run the engine again and you'll find the needle has to be opened just a little more to be tuned correctly. In both cases you're tuning the engine to get exactly the same rate of flow of just the methanol into it. Same flow of methanol gives the same power. The only thing that extra oil will do is give slightly less methanol in the tank so the flight time will be slightly shorter.

XJet

But DownUnder, remember also that (unlike the methanol) the oil will not vaporize so you'll actually have more incompressible material in the cylinder/chamber so upping the oil percentage will also effectively raise the CR by a small amount.

I must work out the *actual* amount that it's raised one day. I suspect it's too small to make much difference but it could go part way to explaining why the big SuperTigres run *really* bad on hi-oil fuel blends. They knock, rattle and kick when you try to use 20% oil in them and the manufacturer recommends 12%. Maybe going to 20% effectively raises the CR so much that they become overcompressed?

I can't think of any other reason why these (big Supertigre, ie: > 23cc) engines run so badly on hi-oil fuels.

downunder

I did a "back of the envelope" calculation some years ago by using a 10cc (.60) engine and assuming it ran for 10 minutes at 10,000 rpm on a 300cc (10 ounce) tank using 80/20 fuel. That meant there was 60cc of oil that had to go through the engine in that 10 minutes. At those revs the engine turned 100,000 times. So each time it drew in a fresh mixture then it also drew in 60/100,000 cc of oil or .0006cc per rev. Of course, these are all guesstimate figures but they won't be far off what an engine would do in practise.

Now a 10cc engine will have a combustion chamber volume of around 1cc which would give a compression of 11:1 so if you reduced that head volume by .0006cc with oil you'd have a compression of 11.006:1 and I don't think we need worry about that .

All of this of course is starting with 20% oil so if you increased the oil content by a few percent then the difference becomes even less.

balsaeater

If I recall there is another issue to do with advancing retarding of ignition which is more powerfull effect than the minor compression issues

Best I can figure adding oil to methanol will retard the ignition and reducing the oil content will advance the igniton.Retarding will only cause a power loss .Too advanced an ignition will make the engine predetonate and make the the piston crown hot and make a hole in Piston or other undesirable effects.

Adding some Nitro will increase compression effects but best I can see will retard ignition

The glow plugs are not so good or have the precission as spark ignition for setting the timing so the abilty to start to get pre ignition effects can more easily happen with glow engines

Balsaeater

Sport_Pilot

Actually there is a slight gain in power from low oil percentages, though somewhat small. The gain is because the oil displaces air, thus even though the needle has to be backed off there is more fuel air mixture. But for small changes from say 20% to 15% I doubt you would notice it on the tach.

Sport_Pilot

I have always thought the extra oil was mostly to help the 4-2-4 break. I know some engines will not do this well with reduced percentages. Though the Fox Stunt .35 need the oil for cooling, as that engine lacks sufficient cooling area for lower oil percentages.

Daytona955i

hi,

can you explained me what is EDL ?

many thanks.

balsaeater

http://www.modeltechnics.com/materials.htm

E.D.L.2 - A synthetic oil developed by Model Technics in 1980 and is still under continuous development. Considered to be at the front of synthetic oil technology.

Balsaeater

Daytona955i

Again now also for KL-189 thant is 100% synthetic

klotz says:
Pure synthetic base materials ... For use in all R/C helicopters, planes, boats, cars and trucks with glow engines.

R/C 4-Stroke glow engines: Mix at 7-10%. Can be used with any nitromethane mixture !!!!! [X(]



klotz can not write a second mistake or coincidence...


...I already did my fuel at 12% of only synthetic for all my 4-stroke without problems of breakage or temperatures ...


now i pass serenely to 10%