Saito R3 Radial - recommended fuel??

[Phil Taylor]

Is anyone out there running their Saito R3 120 on anything less than the recommended 20% oil content?

 

I am using Optimax 20 Super SLV which works fine - but the amount of unburnt oil coming out the exhaust is incredible!

 

I run Laser engines (100's, 150 and 155's) which all run on the Laser 5 which is great with very little mess without any issues (I do like Lasers!).

 

I don't want to ruin my lovely new Christmas present - but I could do without the mess. I ran a whole gallon of fuel through and the Workmate stand I used looked like I had poured a litre of cooking oil over it!

 

Any comments/experiences would be appreciated.

 

Cheers Phil

[John Stainforth]

5 hours ago, Phil Taylor said:

Is anyone out there running their Saito R3 120 on anything less than the recommended 20% oil content?

 

I am using Optimax 20 Super SLV which works fine - but the amount of unburnt oil coming out the exhaust is incredible!

 

I run Laser engines (100's, 150 and 155's) which all run on the Laser 5 which is great with very little mess without any issues (I do like Lasers!).

 

I don't want to ruin my lovely new Christmas present - but I could do without the mess. I ran a whole gallon of fuel through and the Workmate stand I used looked like I had poured a litre of cooking oil over it!

 

Any comments/experiences would be appreciated.

 

Cheers Phil

Have you fully tuned the engine, i.e., both high speed and low speed needles? Generally, the low-speed settings have to be leaned out a very long way from the factory settings.

[Phil Taylor]

Hi John,

Yes tuned OK - transition is smooth and crisp (with 20% nitro not that hard), I am running with the Just Engines on board glow set up (recommended on other threads)with OS 'F' plugs.

 

The engine runs just fine - its the amount of unburnt (looks quite clean) residue coming out of the exhausts. Its a glow, so I know there is going to be smoke and residue (I have quite a bit of experience) its just the shear amount that is surprising....

 

If this is the way - then so be it. But running Lasers and going from 'std' to Jon's 'Laser mix' fuel which he told me had a little less oil made a massive difference to the amount of muck coming out of the exhaust and the amount of fuel the engine consumed. The re-tune when switching was dramatic - far leaner, but all my Lasers run brilliantly without any issues (no on-board glows and regardless of fuel tank position!)

[Nigel R]

Seem to recall there was an aftermarket manifold that improved oil flow to the crankcase? As well as evening out the low throttle running?

 

Maybe 20pc is needed for the stock motor?

 

I don't have one so the above should be taken with a very large pinch of salt. 

Edited February 13, 2022 by Nigel R

[Phil Taylor]

29 minutes ago, Nigel R said:

Seem to recall there was an aftermarket manifold that improved oil flow to the crankcase? As well as evening out the low throttle running?

 

Maybe 20pc is needed for the stock motor?

 

I don't have one so the above should be taken with a very large pinch of salt. 

Hi Nigel, the engine runs fine - its just the amount of exhaust waste (unburnt oil?) that is my issue. The instruction say to use 10-20% nitro and 20% oil. The Optimax 20 is only 18% oil but there is still a huge amount of exhaust waste. 

Just wondering if anyone out there was running the same engine but maybe on 15% oil (like Laser 5). Maybe I just need to live with it and get used to cleaning huge amounts of oil off the model again! ?

[Frank Skilbeck]

I'm running a Saito 40 (1/3rd a 120 R3 ?) on Weston Prosynth 2000 10%, inverted installation and it runs really well with no onboard glow with not much mess at all. It's had around 1 gall though it so far from new. I did try it on a 5% mix (Southern modelcrafts synthetic) and while it ran it didn't run as well as it did on 10%.

 

Note if you drop the Nitro down to 10% then you'll have to lean the mixture a bit and that would reduce the oil flow a bit too.

[Phil Taylor]

24 minutes ago, Frank Skilbeck said:

I'm running a Saito 40 (1/3rd a 120 R3 ?) on Weston Prosynth 2000 10%, inverted installation and it runs really well with no onboard glow with not much mess at all. It's had around 1 gall though it so far from new. I did try it on a 5% mix (Southern modelcrafts synthetic) and while it ran it didn't run as well as it did on 10%.

 

Note if you drop the Nitro down to 10% then you'll have to lean the mixture a bit and that would reduce the oil flow a bit too.

Hi Frank, do you know what the oil content is with the Prosynth? Its a good point you make regarding the nitro. Do you get a lot of unburnt residue in the exhaust? When I say a lot I mean you can see it pouring out of the exhaust! Even on full throttle its like someone is spraying cooking oil from a spray gun! Even the old 2 strokes didn't chuck out as much as this - its mad. On full throttle it goes through an 11oz tank in about four minutes flat.!

 

It sounds great runs well (top end is a bit inconsistent) but just drinks fuel like there no tomorrow...

[Frank Skilbeck]

No Weston don't quote the oil content of Prosynth, which is why I think some people won't use it. We have had a few members migrate over to it as when the shows were cancelled due to Covid it was about the only place you could get fuel delivered for a good price.

 

The engine runs very clean and an 8 oz tanks gives well over a 10 min flight with fuel to spare, so probably over 12 mins in flight quite easily, but obviously not at full throttle all the time. I've got the exhaust pointing down and so the exhaust gases exit below the wing (an old Tipsy Jr) with just a small amount of oil on the wing.

[Nigel R]

6 hours ago, Phil Taylor said:

engine runs fine - its just the amount of exhaust waste (unburnt oil?) that is my issue

I think the manifold helped there by distributing the mixture evenly to all cylinders, that means you can set it correctly for all three instead of having one or two cylinders running rich, so less unburnt being chucked it the back. Again, pinch of salt, just what I've read. 

 

Ps my experience of several os four strokes running pro synth matches Frank's.

Edited February 13, 2022 by Nigel R

[Phil Taylor]

19 minutes ago, Nigel R said:

I think the manifold helped there by distributing the mixture evenly to all cylinders, that means you can set it correctly for all three instead of having one or two cylinders running rich, so less unburnt being chucked it the back. Again, pinch of salt, just what I've read. 

 

Ps my experience of several os four strokes running pro synth matches Frank's.

Thanks Nigel. I think coming down to 10% nitro will help. I have also noticed the fuel nipple (main needle threaded section) was slightly loose - I could move the whole assembly back and forth (discovered this while taking off the fuel pipe!) so have tightened this up but haven't run it since (raining today) so maybe that wasn't helping!

 

I will try running it up again next week and run the higher nitro fuel through to bed it in and then maybe look at 10% fuel to try.

 

I would like to run it on the 5% Laser fuel (that way I only have to take one lot of fuel to the field!) but I worry that its not suitable. Perhaps I should ask Jon at Laser his thoughts...?

[Jon H]

I used to run a saito 450r3 on smc 5% nitro 15% ml70 and 2% castor fuel. It was clean enough i guess and ran fine but i got rid of it as it was no more powerful than a 360v laser but twice the weight and had a drinking problem. 

 

Your 120 has a master conrod with no bronze bush in it so you do need to be a little careful. Plenty of people run their single cylinder saito's on the laser 5 fuel and have had no issues. 

 

The problem is if the master rod fails, and they are known for it on the petrol versions, its a big repair bill and you would be in quite a fight with a warranty claim even if you were using the mfr spec fuel so using something else will be more of a headache. Not that its very easy to tell which oil is being used and how much after its detonated and i am told you will be better off sending it to japan than trying to deal with it in the uk. 

 

Currently i run everything non laser on 5 nitro 15% oil and that includes all my OS multi cylinders. I also have an ASP160 flat on 11% oil and it is perfectly happy. None have any glow support. 

 

If you want to play safe I would probably look for something like the optifuel 5 or 10% nitro and make sure the needles are as lean as they can be as has already been suggested. Turn off the glow for the tuning and only use it for starting as it should idle without it. Most certainly i would ditch 20% nitro, you will just be throwing money away. 

[Phil Taylor]

8 hours ago, Jon - Laser Engines said:

I used to run a saito 450r3 on smc 5% nitro 15% ml70 and 2% castor fuel. It was clean enough i guess and ran fine but i got rid of it as it was no more powerful than a 360v laser but twice the weight and had a drinking problem. 

 

Your 120 has a master conrod with no bronze bush in it so you do need to be a little careful. Plenty of people run their single cylinder saito's on the laser 5 fuel and have had no issues. 

 

The problem is if the master rod fails, and they are known for it on the petrol versions, its a big repair bill and you would be in quite a fight with a warranty claim even if you were using the mfr spec fuel so using something else will be more of a headache. Not that its very easy to tell which oil is being used and how much after its detonated and i am told you will be better off sending it to japan than trying to deal with it in the uk. 

 

Currently i run everything non laser on 5 nitro 15% oil and that includes all my OS multi cylinders. I also have an ASP160 flat on 11% oil and it is perfectly happy. None have any glow support. 

 

If you want to play safe I would probably look for something like the optifuel 5 or 10% nitro and make sure the needles are as lean as they can be as has already been suggested. Turn off the glow for the tuning and only use it for starting as it should idle without it. Most certainly i would ditch 20% nitro, you will just be throwing money away. 

Thanks Jon - I appreciate the advice ? If you did a radial 120 I would have bought one! I have to say that all (4) the Laser engines I have are so easy to set up and use.

 

I will probably go to 10% (might try the Laser 5...) but to be honest to Saito instructions state 20% oil by volume - so I guess I'm not using spec levels anyway. Optifuel I think is 18% - so fairly close. Do you think they recommend such a high oil content just to be safe? I know methanol doesn't lubricate like petrol - but petrol engines run hotter and are using a 25/30/50:1 mix - it seems so unnecessary with modern lubricants to run our modern CNC machined engines on high oil levels. 

 

Would anyone run a modern car on a 20W/50 oil..?

 

Anyway - thanks again - I think I am a little happier now ?

[Martin Fraser]

Mine is still bolted to the workmate and has only had a few tanks of Optimix 4 stroke 12% through it. Its oil content is listed at 20% and I'm keeping it running a bit rich for now but it doesn't seem too messy. However, the unburnt oil only emits from the pipes and nothing from the crankcase breather? Also, it seems to take about 5 minutes to warm up and pull cleanly through the rev range.

 

Marty

[Jon H]

Just to clear up one small thing i see all the time. Petrol is a rubbish lubricant. Yes it is better than methanol, but both are utterly useless and the difference between petrol+ x% oil vs Methanol + x% oil is zero in practical terms. it is not a determining factor when it comes to the oil requirement of an engine, particularly a 4 stroke where the petrol/methanol is never anywhere near the crankcase anyway and you only have oil down there. In my own testing here i ran one of our engines on 40:1 methanol/oil without problems for about an hour. If it was going to die it would have died in under a minute. it was this that prompted my deeper dive into oil requirements. 

 

There is however a perception that petrol engines run with less oil so i suspect saito reduced the oil content for that reason, but pushed their materials too far in the process when they dropped to the 5% sort of area. This is why later revisions of their petrol engines have bronze bushed rods and a variety of other upgrades. IF we take 5% as the critical point, 15% should be fine by a wide margin. 

 

Ok so 20% by volume is how all our fuel is measured. the reason they specify volume is to prevent people measuring it out by weight as the 3 ingredients are all different densities. Methanol is the lightest, then the oil, and then the nitro is heaviest. I hand mixed some fuel here at work once and before i gave it a good shake all 3 were clearly floating in layers. 

 

Recommending 20% oil is probably saito playing safe to some degree. As with most things, quality is better than quantity so 30% goose fat will probably not lubricate as well as 2% proper oil. As they have no idea what oil people will use they play safe. They also probably do this to cover errors in mixing for those making their own fuel. As mentioned before my OS FF240 recommend 20% castor but it has been faultless on 15% synthetic. In all honesty, i could probably run it on 10% oil (like my ASP 160) judging by all the mess it makes but given the type of engine that it is and the fact that parts are either unavailable or very expensive, i will leave it alone.

 

Despite all this Saito make a recommendation on the fuel and really that should be the answer to the question. Shaving a few % here and there wont matter (18% oil) but deviating substantially from it means you are now the test pilot and head of RnD for your engine. IF anything happens, its more or less on you. 

 

One other thing i would recommend when it comes to complex engines like this is to treat it a little more gently. You have a very large number of parts flying around inside the engine and they are far less tolerant of abuse than a simple single cylinder engine. For example, dont just whazz it straight up to full power from cold. Start it, run it up to 3000ish revs and hold for a short time to warm up a bit. After 30 seconds or so slowly wind it up to about half throttle, and then slowly up to full power. Tune it up, and then off you go. Rapid rpm changes, full throttle dives etc should also be avoided to minimise thermal fluctuation and keep rpm under control. 

 

Saito seem to recommend very small props (13x8-14x6) for the engine and a peak rpm range of 8800-9500 on the ground. This seems really fast to me and i would expect a 120 to run at 8500rpm ish on a 15x8. I think some experimentation will be needed on props and personally i would stay as far below 9000rpm as you can and i would be looking at 8500 as a peak rpm if it were my engine. 

 

Hope all that helps, and as a curiosity which model is it fitted to?

 

 

 

 

[Phil Taylor]

1 hour ago, Jon - Laser Engines said:

Just to clear up one small thing i see all the time. Petrol is a rubbish lubricant. Yes it is better than methanol, but both are utterly useless and the difference between petrol+ x% oil vs Methanol + x% oil is zero in practical terms. it is not a determining factor when it comes to the oil requirement of an engine, particularly a 4 stroke where the petrol/methanol is never anywhere near the crankcase anyway and you only have oil down there. In my own testing here i ran one of our engines on 40:1 methanol/oil without problems for about an hour. If it was going to die it would have died in under a minute. it was this that prompted my deeper dive into oil requirements. 

 

There is however a perception that petrol engines run with less oil so i suspect saito reduced the oil content for that reason, but pushed their materials too far in the process when they dropped to the 5% sort of area. This is why later revisions of their petrol engines have bronze bushed rods and a variety of other upgrades. IF we take 5% as the critical point, 15% should be fine by a wide margin. 

 

Ok so 20% by volume is how all our fuel is measured. the reason they specify volume is to prevent people measuring it out by weight as the 3 ingredients are all different densities. Methanol is the lightest, then the oil, and then the nitro is heaviest. I hand mixed some fuel here at work once and before i gave it a good shake all 3 were clearly floating in layers. 

 

Recommending 20% oil is probably saito playing safe to some degree. As with most things, quality is better than quantity so 30% goose fat will probably not lubricate as well as 2% proper oil. As they have no idea what oil people will use they play safe. They also probably do this to cover errors in mixing for those making their own fuel. As mentioned before my OS FF240 recommend 20% castor but it has been faultless on 15% synthetic. In all honesty, i could probably run it on 10% oil (like my ASP 160) judging by all the mess it makes but given the type of engine that it is and the fact that parts are either unavailable or very expensive, i will leave it alone.

 

Despite all this Saito make a recommendation on the fuel and really that should be the answer to the question. Shaving a few % here and there wont matter (18% oil) but deviating substantially from it means you are now the test pilot and head of RnD for your engine. IF anything happens, its more or less on you. 

 

One other thing i would recommend when it comes to complex engines like this is to treat it a little more gently. You have a very large number of parts flying around inside the engine and they are far less tolerant of abuse than a simple single cylinder engine. For example, dont just whazz it straight up to full power from cold. Start it, run it up to 3000ish revs and hold for a short time to warm up a bit. After 30 seconds or so slowly wind it up to about half throttle, and then slowly up to full power. Tune it up, and then off you go. Rapid rpm changes, full throttle dives etc should also be avoided to minimise thermal fluctuation and keep rpm under control. 

 

Saito seem to recommend very small props (13x8-14x6) for the engine and a peak rpm range of 8800-9500 on the ground. This seems really fast to me and i would expect a 120 to run at 8500rpm ish on a 15x8. I think some experimentation will be needed on props and personally i would stay as far below 9000rpm as you can and i would be looking at 8500 as a peak rpm if it were my engine. 

 

Hope all that helps, and as a curiosity which model is it fitted to?

 

 

 

 

Hi Jon, its in the Seagull 15cc size P47 kit. Did have a Laser 100 in it (flew lovely), but I fancied a radial for a long time and thought it would be ideal. The engine fits exactly (with cam covers just touching the cowl. Haven't flown it yet as I am not confident with the motor yet. Hopefully she will now sound as good as she looks in the air.

 

You are right of course - keep to the instructions, but I hate the mess. I will think about it and get it running on 10% and go from there. 

 

Thanks for your in put - really helpful ?

[Phil Taylor]

2 hours ago, Martin Fraser said:

Mine is still bolted to the workmate and has only had a few tanks of Optimix 4 stroke 12% through it. Its oil content is listed at 20% and I'm keeping it running a bit rich for now but it doesn't seem too messy. However, the unburnt oil only emits from the pipes and nothing from the crankcase breather? Also, it seems to take about 5 minutes to warm up and pull cleanly through the rev range.

 

Marty

Thanks Marty, always good to see what others are experiencing. I also dont seem to have much coming out of the breather - I have looked as its running and there is definitely the occasional drop coming through but nothing much - hopefully that's OK!  

[Jon H]

Nice P47, the RAF scheme makes a nice change ?

 

If you drop to 5 or 10% nitro you will see a big improvement in the cleanliness of the model as fuel consumption will drop significantly. Dont be shy about leaning the slow run as this governs at least 50% of the throttle range. 

 

Looking forward to a flight video ? 

[Phil Taylor]

18 hours ago, Jon - Laser Engines said:

Nice P47, the RAF scheme makes a nice change ?

 

If you drop to 5 or 10% nitro you will see a big improvement in the cleanliness of the model as fuel consumption will drop significantly. Dont be shy about leaning the slow run as this governs at least 50% of the throttle range. 

 

Looking forward to a flight video ? 

Thanks Jon. You can see it yourself down the ADMFC field ?

[Jon H]

1 hour ago, Phil Taylor said:

Thanks Jon. You can see it yourself down the ADMFC field ?

 

I dont fly there any more. 

[Phil Taylor]

4 hours ago, Jon - Laser Engines said:

 

I dont fly there any more. 

Sorry Jon - didn't know. Maybe I'll post a video ?

[Paul De Tourtoulon]

18 hours ago, Phil Taylor said:

Sorry Jon - didn't know. Maybe I'll post a video ?

You can always invite him there,,,,