RE: Too much oil. (Full Version)

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Lille-bror -> RE: Too much oil. (4/14/2008 12:58:42 PM)





quote:


My own experiences indicate that lowering the oil ratio from 18% to 12% has actually resulted in cooler-running engines here. Perhaps that''s because we''ve also changed rom PAG-based synth/castor blend to an ester-based synth/castor blend I don''t know.


Hey Xjet.

Have you tried lowering the oil % in an engine to 12 %, which already have been broken in with 18% oil? Will the engine loose its compression?
I have a TT pro 46 that is broken in, and a Super Tigre GS45 that even after 1,5 liter fuel (5 % nitro, 3 % M and 12 % ML70) is not broken in. For the Super Tigre I have thought of mixing 0 nitro, 3 % M and 9 % Fuchs AeroSynth 2, but I am not sure what to mix for the TT.



Lille-bror -> RE: Too much oil. (4/15/2008 9:34:51 AM)

Both engines has been broken in with 5 % nitro and 15 % Aerosynth 3 oil - ½ liter (1/8 gallon) each, and then the Super Tigre has been further broken in with 1 liter (1/4 gallon) 5 % nitro, 3 % M and 12 % ML70.

Should you brake in your engine with the same fuel mix, you have planned to use after the break in?



XJet -> RE: Too much oil. (4/15/2008 9:46:03 AM)

Yes, I actually break my engines in using 18% oil and switch to 12% after a few tanks full.

The extra oil *is* helpful during the break-in process as it ensures that there''s a huge margin of additional protection available to allow for the tight-spots that will inevitably exist when an engine is brand-new.

I''ve noticed no loss of compression after changing to 12% from 18%.



Lille-bror -> RE: Too much oil. (4/18/2008 8:54:33 PM)


quote:

ORIGINAL: XJet

Yes, I actually break my engines in using 18% oil and switch to 12% after a few tanks full.

The extra oil *is* helpful during the break-in process as it ensures that there's a huge margin of additional protection available to allow for the tight-spots that will inevitably exist when an engine is brand-new.

I've noticed no loss of compression after changing to 12% from 18%.


Thanks for your tips, XJet :-)


quote:

ORIGINAL: rexracer

Interesting discussion. i felt the need to point out one thing that was said concerning motorcycle 2 strokes vs rc cars. When you get off the gas in an rc car (decell) the engine is NOT spinning at high rpm with less oil. As soon as you get off the gas, the centrifical clutch releases and the engine speed drops to somewhere near idle.


Hey rexracer.

That is also what I remembered, when I drove RC-cars. If the clutch were "on" after the gas was taken of, the car would brake, and it dosn't.



Lille-bror -> RE: Too much oil. (6/13/2008 10:33:09 PM)

Test results using different % of oil:

After all your good inputs in this topic, I have made some tests with my new Super Tigre GS 45 engine (has been running 5 liter / 1 1/3 gallon fuel). I thought a certain oil % was to keep the engine well lubricated. During the test I discovered, that the HP also increase/decrease when you chances the oil %, and the whole running attitude also chances.

I used 0 nitro, 3 % castor, Aerosynth2, APC 11/5 prop, stock muffler and Rossi 3 and 4 plugs. The engine was broken-in, and was in fine condition. I tested it on my test bench, where I could measure the kilograms it pulled + taco, and there bye calculate the horsepower.

Oil – Plug – RPM – HP – Comments

12 % (3/9) - Rossi 3 – 10500 - 1,40 - Unstable full-speed, rich middle range, and good idle. No flip-start.

15 % (3/12) – Rossi 3 – 10500 – 1,45 – Ok full-speed but tricky to adjust, ok middle range, and good idle. No flip-start.

18 % (3/15) – Rossi 4 – 10500 – 1,52 – Perfect running. Easy flip-start.

22 % (3/19) – Rossi 4 – 10500 – 1,50 – Perfect running. Easy flip-start.

25% (3/22) – Rossi 4 – 10500 – 1,49 – Perfect running. Easy flip-start.


The mixture was set to just increase a little when I pinched the tube. Damn, the mixture has to been set MUCH richer, when the oil % increases! No increase in RPM with less oil, as I thought, and awful running with 12 % oil. I haven’t tried chancing the compression, and it will to expensive to get Cooper-oil to Denmark (the oil XJet is using)

Pe Reivers: Congratulation with your football-team at the Euro2008 [8D]



pe reivers -> RE: Too much oil. (6/13/2008 11:02:56 PM)

Thanks! We just beat France 4 - 1!!

As you may already know, I am not a believer of lean oil mixes, and your observations confirm my findings.
Richer oil mixes are much less critical. The increased viscosity of the fuel "seemingly" needs richer fuel settings, because the needle is opened more to allow for the same fuel flow.



Jezmo -> RE: Too much oil. (6/13/2008 11:55:37 PM)

Many folks are mixing their gassers at 50:1 and even less on the oil. I have run tests on my G26 just exactly like Lille-bror did on his glows and found the same results. I have gone with 32:1 in it since doing the test although it made more power at 20:1. It just pukes too much oil at 20:1 and also is more costly at that ratio. Above 32:1 it starts losing power pretty fast and anything much over 50:1, I can hear the loss in rpm's. I am glad to see this happens with the glow fuels as well as I have been pondering switching to 12%. Think I'll stay where I'm at until I do some testing on my smaller glows. (40 thru 60's)

Edited to add: Congrats Pe.



XJet -> RE: Too much oil. (6/14/2008 5:00:35 AM)


quote:

ORIGINAL: pe reivers

Thanks! We just beat France 4 - 1!!

As you may already know, I am not a believer of lean oil mixes, and your observations confirm my findings.
Richer oil mixes are much less critical. The increased viscosity of the fuel "seemingly" needs richer fuel settings, because the needle is opened more to allow for the same fuel flow.

It's not the viscosity that is so much the issue... it's the amount combustible material in each unit of fuel.

With 20% oil you have 8% less available methanol per volume unit of liquid that passes through your carburetor so consequently you have to richen the mixture by a corresponding amount.

You are correct that the needles will be a little more sensitive with low-oil ratios but this should not be excessively so.

We run 5% nitro in our 2-strokes and 10% in our 4-strokes. With this small amount of nitro, perhaps our needles are a little less sensitive than when on a 0% nitro blend.

As for the power-gain/loss.

I picked up 600rpms in mid-winter when switching from 20% Morgans castor/synth blend (same stuff as in Omega) to 12% Coopers Plus-C.

I put this down to the improved lubrication qualities of Coopers and the lower viscosity (especially in winter).

The effect is not so pronounced in mid-summer but still measurable.




downunder -> RE: Too much oil. (6/14/2008 8:01:39 AM)

quote:

ORIGINAL: Lille-bror
Test results using different % of oil:

Well done, it's good to see actual test results and, like Pe, I'm not a believer in skimping on oil. I think your HP figures are way off though because you can't have varying HP at the same revs with the same prop but the running characteristics are the more important finding here. Like you, I've got a GS45 that I use as a bit of a test mule :). On 25% all castor (no nitro) it spins an APC 10x6 at 14,600 which I think isn't too bad.



pe reivers -> RE: Too much oil. (6/14/2008 10:43:30 AM)

I recently aqcuired the line of Putoline oils for glow and gas engines. Their gas engine 50-grade MHX racing oil is used by the side car MX multiple world champion. It struck me that he uses the oil in a water cooled two stroke mixed at 1:120!!! This is the only racer I know of that uses lean oil mixes. Most racing two strokes use mixes between 1:20 and 1:40
The oil is designed for 1:20 to 1:100 mixes. The manufacturer tech staff recommends to start with 1:40 though. I am running this oil in my test .15 diesel and 58cc MVVS, and in the latter now am down to 1:50. The engine inside still is very oily and slippery, like with the 1:35 I started out with. When I switched to this oil, I lost a few rpm due to the higher viscosity. Sustained power improved however very slightly.
I guess, the property of the oil to cling and stick to metal surfaces, combined with the ability to avoid metal contact between moving faces can determine how lean a mixture can be used, once sufficient oil film has been established.



Lille-bror -> RE: Too much oil. (6/14/2008 11:07:14 AM)

Cheers, Down. [;)]

[/quote]
Like you, I've got a GS45 that I use as a bit of a test mule :). On 25% all castor (no nitro) it spins an APC 10x6 at 14,600 which I think isn't too bad.
[/quote]

With an APC 9/8 prop (recommended by Super Tigre) it ran 12500, but was very unstable. I have read, like yours and what Bax has told, it should turn at least 12500… Last night I made some modification on the cylinder, and look forward to se the effect.

[/quote]
Well done, it's good to see actual test results and, like Pe, I'm not a believer in skimping on oil. I think your HP figures are way off though because you can't have varying HP at the same revs with the same prop but the running characteristics are the more important finding here.
[/quote]

HP figures way off??? I couldn’t image anything else! [:D]
I can clearly read the difference on the kitchen weight, when I tested the mixtures, and then calculate it into HP. Perhaps it’s the toque that changes. I wouldn’t now. [8|]



pe reivers -> RE: Too much oil. (6/14/2008 11:55:16 AM)

Same rpm on same prop would require the same torque to drive the prop.
However, our measuring equipment is not the most accurate, and atmospheric density and humidity influences these factors without one being aware of it. So slight changes in measured data cannot always be used for 100% reliablity predictions. Measurements within 5% therefore would be safe to consider as the same. (statistical Zero-option theorem)



Lille-bror -> RE: Too much oil. (6/14/2008 1:51:00 PM)


quote:

ORIGINAL: pe reivers

Same rpm on same prop would require the same torque to drive the prop.
However, our measuring equipment is not the most accurate, and atmospheric density and humidity influences these factors without one being aware of it. So slight changes in measured data cannot always be used for 100% reliablity predictions. Measurements within 5% therefore would be safe to consider as the same. (statistical Zero-option theorem)


Hey.

I made the test within 1,5 hour, no change in the weather, and the test with 12% oil vs. 18 % three times over 3 weeks, because of the rather big difference. If it wasn’t the HP or torque that changed, I don't not what it was, but I'm sure, that I can get the same results any day... Backyard science, you know! [:D]



pe reivers -> RE: Too much oil. (6/14/2008 2:09:51 PM)

Lille bror,

I do not question your test data, be assured of that. I may not have been too clear about the thrust differences, and how they come about. I will explain a bit more. I hope I am not being pedantic.
If air changes, so does engine performance, but typically, the propeller power demand changes almost equaly with the engine power output.
The propeller is an air brake, whose torque solely depends on air density and rpm.
So you may get same rpm, but different thrust figures (and hence power) as you have measured.
For tests like these, only rpm are of real importance because of the power/thrust.rpm correlation depicted above. When using prop rpm only on thesame test engine, most atmospheric variables are canceled out.



Lille-bror -> RE: Too much oil. (6/17/2008 9:40:52 AM)

Hey Pe.

Thanks for all your information’s. Always good to learn new things.

I forgot to write, that the more oil I put in the fuel, the more quit (less metallic) became the sound of the engine.
- With a more quit muffler, the engine would sound like the Danish 8 time winner of Le Mans, Tom Kristiansen’s Audi R10 TDI!!! [:D]



pe reivers -> RE: Too much oil. (6/17/2008 10:27:38 PM)

Oil has many functions in an engine. That's why I like a bit more, and it sure does not hurt performance.



XJet -> RE: Too much oil. (6/17/2008 10:49:02 PM)


quote:

ORIGINAL: pe reivers

Oil has many functions in an engine. That's why I like a bit more, and it sure does not hurt performance.

That may be true, but there's another aspect to consider...

Apart from nitromethane, oil is the most expensive component of our fuels.

If you (arguably) reduce the life of your engine by 10% by running (say) 5% less oil then in most cases, long before you get anywhere near wearing out your engine, you'll have saved enough money to buy a brand new one.

As I've found, there are very definite economic advantages to running a lower oil percentage.

If people want to run high-oil ratios for some reason that's fine, but I'd prefer to spend my money on something other than propping up the profits of the oil-vendors by using too much.



pe reivers -> RE: Too much oil. (6/17/2008 11:30:30 PM)

I spensd about 50 times the oil cost of the fuel I use up just by driving to the field.
savings would so be about 1% of my total cost of the day. In my book a no-brainer, though your opinion need not be mine.



XJet -> RE: Too much oil. (6/18/2008 12:13:56 AM)


quote:

ORIGINAL: pe reivers

I spensd about 50 times the oil cost of the fuel I use up just by driving to the field.


All the more reason to save money where you can? [8|]

But as you say intelligent people can agree to disagree.



downunder -> RE: Too much oil. (6/18/2008 5:28:36 AM)

I'll be honest, I know that 20% (or 25%) all castor has been great for the last 50 years for me so I'm not about to try dropping to 15% on the off chance my engines will survive. And with castor only costing me $8 a litre it's not worth the risk.



XJet -> RE: Too much oil. (6/18/2008 5:52:50 AM)

You're lucky then... around here (where you can no longer get Castrol M), castor costs the same as synth about $17-$20 a litre!

If you use a traditional synthetic or synth/castor blend such as Klotz SuperTechniplate at 20% then each litre of fuel contains about $3.33 worth of oil.

Now I usually burn at least 2-3 litres of fuel a weekend (say $10 worth of oil) which means my annual oil-bill (at 20%) is around $500 when using a low-tech oil at old-fashioned ratios.

Now if I use a hi-tech oil like Cooper's Plus C, I can get better protection and performance with just 12% oil. Surprisingly, I end up paying about the same price for Coopers as I do for Klotz, Morgan's or straight castor so...

Do the numbers again and you find that a litre of fuel with 12% oil has only $2 worth of oil. That's $6 a weekend or $300 a year.

The savings over a year amounts therefore to an astonishing $200 more than enough to buy a brand spanking new engine every year.

Now since my oldest engine (a TT46Pro) has been thriving on a diet of 12% for almost two years now and shows no sign of wearing out, I think I'll have banked at least $600 in oil savings before I have to even think about replacing it.

So running 20% or 25% oil is (from my perspective) something like flushing your money down the toilet.



Lille-bror -> RE: Too much oil. (6/18/2008 7:10:05 AM)


quote:

ORIGINAL: XJet
You are correct that the needles will be a little more sensitive with low-oil ratios but this should not be excessively so.

We run 5% nitro in our 2-strokes and 10% in our 4-strokes. With this small amount of nitro, perhaps our needles are a little less sensitive than when on a 0% nitro blend.


Hey XJet.

Have you tried skipping the nitro, and using a total of 18 % oil instead? Then your fuel costs perhaps will be lower and your engines easier to adjust.




XJet -> RE: Too much oil. (6/18/2008 8:18:40 AM)

We use 5% nitro in our 2-strokes and 10% in our 4-strokes because it makes them nice and easy to tune.

With the lower oil content, it gives us the equivalent of 10% and 15% respectively.

With the nitro-shortage really starting to bite (I managed to score 4ltrs today the very last that I could find) we may go back to 0% for the 2-strokes but the 4-strokes really like that bit extra.

In winter (I'm in the southern hemisphere) our engines seem to run just a little too cold with 0% nitro, regardless of the oil content.

I know that because right now we're out of Cooper's oil (with little prospect of getting any more) so we've gone back to using Morgans castor/synth blend at 18% (nitro at 5%) and the loss performance is *really* noticeable. People are moaning at me that their engines just aren't performing like they did before. Going to 0% nitro with 18% oil will really knock the power-back on most of the engines we're running (TT46Pro, ST90, ASP 52, etc).



Lille-bror -> RE: Too much oil. (6/18/2008 10:01:31 AM)

I’m sad to hear about the shortages.

The Cooper oil really must be something unique. Danm, I would like to test it.



balsaeater -> RE: Too much oil. (6/18/2008 10:06:25 AM)

A lot of the guys I know on the circuit with the bigger 2 and 4 stroke larger engines from 20cc to 50cc glow best I can tell are like me mostly using synthetic oil ester type like EDL @10% to 12% and no castor with zero nitro or maybe 10% for the 4 strokes and lots of them even use that brew on well run in smaller 40 sized or even smaller motors
I have heard of some guys even going to 6% synthetic oil Ester Family oil type like EDL with no Castor and I will try to copy this trend as at local import prices of 65 Euros a UK gallon for EDL (~ $110 a USA gallon ) 6% oil can save me a lot over 12% oil
(best I can tell the USA oil is PAG family oil type which cant go so low in oil content as the Ester family oil types )
Really the less oil the more power in the fuel and lower cost and with tweaking of jets or similar I am sure the rougher running and lower RPM from lower oil content issues can be sorted out and engine costs are dropping so I figure I can handle a small extra increase in wear rates if necessary from engines if the oil content can be halfed to 6%

Balsaeater



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