gkamysz

My Feedback: (19)

This is how my spark ignition conversion turned out. In addition to the ignition, I made internal oil passages like the OS Alpha series use to recirculate crankcase oil to the intake. I hope to run it soon. I'll be running methanol, E85, or gasoline. Some of the parts in the photos are dirty. They were shot after machining, before cleaning. I'll either buy the FSa-56 velocity stack or make one to improve fuel consumption.

Greg

[link=http://www.dieselrc.com/images/fs52ignition3.jpg][/link] [link=http://www.dieselrc.com/images/fs52ignition2.jpg][/link]

[link=http://www.dieselrc.com/images/fs52ignition4.jpg][/link]

buck1856

My Feedback: (49)

What did you machine in the head that connects to the crankcase to get oil?.A remote line from the pressure nipple on back case.

Patxipt

Greg opened some oil passages on the cam follower holes (3rd photo), made a small hole on the head (2nd photo) so oil can get into the intake before the valve and sealed it all tight!
(Greg saw your post on RCGroups -> good job! )

gkamysz

My Feedback: (19)

Oh yes, I forgot to mention that I also replaced the main bearing with an open type and the front bearing with a rubber sealed type. The crankcase vent is plugged, just visible behind the ignition pickup and the rocker cover has a gasket. The new vent is visible just in front of the intake valve and connected the crankcase to the intake port. A small hole is used to control flow.

captinjohn

gKamysz...sounds like a good plan. I think it was a O.S. Max 4 cycle that was used to set one of the longest RC flights. Take Care, Capt,n P.S. I wonder what fuel mix he used?

gkamysz

My Feedback: (19)

I guess Maynard Hill used Coleman fuel for his duration flights. He worked with the FS-61 for all his attempts as it was the largest he could use to obtain an FAI record with the 10cc limit.

http://www.modelaircraft.org/MAG/mhill/hillindex.htm

pe reivers

Chapeau.
Nice job, well engineered.

Jezmo

Greg, I am anxious to see how your conversion turns out. Since I converted my Saito 91 many, many folks have been asking me about converting an OS and how that would work out. My answer to them is "I don't see why it would be any different than the Saito" which truly impresses everyone that sees it run. You really can't tell that it is on gasoline except for the smell. If you had a tach you can see it's down 400 rpm's but that isn't too bad considering that I get to carry about half the fuel and that makes up for some of the power loss. If yours works well i have four guys that I work with that want me to help convert their OS's. Good luck man, I think it'll be a winner.

gkamysz

My Feedback: (19)

Thanks for the comments guys. It too expect it to run just fine. It's going to rain all weekend in Chicagoland, so I probably won't run it until Monday.

I have an Enya 46-4C that runs well with a CH ignition and methanol or E85. Even with all of the extra weight compared to glow it flew a Superstar 40 very well. The RCEXL seems to have a stronger spark on one LiPo cell. Spark ignition is fun in this size. The Enya was so easy to start. If you are familiar with their carbs, they have a choke where you pull the throttle barrel out. I'd pull the choke, give it a couple flips by hand and it would fire right up. Close the choke, and it was ready to go. This was as close to the gasser experience as you could get. I don't run gas. My biggest airplane is an Ultra Stik Lite, and it's electric....for now. I have an NIB FS-200 an another ignition.

gkamysz

My Feedback: (19)

I had a chance to run the engine today. It started up nicely and runs fine. The needles are sensitive on 0% nitro fuel. Idle transition is not great. I can't richen it enough slam the throttle open without it stumbling or quiting. If I do richen it, the idle is sloppy. It will idle very slowly but not at a mixture setting that allows any sort of transition. It seems the carb gets very rich at extremely low throttle settings. I pulled the rocker cover after about ten minutes of tuning the engine and it was nice and wet, much more oil than it ever has in it in stock form. The fuel had only 8% oil, balance methanol.

I have added a [link=http://www.dieselrc.com/projects.html]page on my site now[/link]. I'll add a photo tonight of the installation in the test airframe. I managed to get the ignition and fuel tank into the nose of an Avistar 40. I hope to fly it and get some performance figures tomorrow.

togatoga

My Feedback: (42)

Hi Greg, I am just getting around to converting my asp 180 four stroker to ignition. I'll be using an rcexl ignition with the magnet at 30deg. My question is , will the conversion make the engine able to run on methanol/nitro or if I want , on gasoline without any changes (except tubing) needed? Can I run gasoline and then decide on methanol the next day?
With the supplied carb, is there a fire risk as fuel comes out much more than a walbro.
Thanks

gkamysz

My Feedback: (19)

I have not tried gasoline yet. I did run E85 in the Enya. You definitely want to use compatible fuel lines. Even the 15% gasoline in E85 caused the silicone to swell and not hold onto fittings. I have run tanks of methanol and E85 back to back. I have found that some carbs will tune well running gasoline, but by design a two needle carb can only be ideal for one air/ fuel ratio. The needles will need to be adjusted substantially going from methanol to gasoline. If the carb is large for the displacement, you might find it to be unresponsive on gasoline. I can't comment on the fire risk as I have not run gasoline in these engines. I've read that you shouldn't use muffler pressure with gasoline. I'm not sure why it should be treated any different than alcohol. I did run muffler pressure with E85.

One concern is oil compatibility. Many oils for gasoline will not blend with oils for alcohol. I'm not sure what this would mean inside the crankcase of a four stroke.

togatoga

My Feedback: (42)

Thanks Greg for the info.Will be trying out my first ever conversion soon, an ASP180! I'd like to try gasoline first at a mix of 16:1 if what I've read in RCU is correct. This engine does have a big carb bore so as what you've mentioned , it might not throttle well so failing that I guess I'll fly on low nitro fuel.

Jezmo

FWIW I have been running muffler pressure on my SuperTigre 51, Saito 91, and Saito 180 all using stock carbs and running gasoline/spark. I have over 75 hrs. on the SuperTigre and more than 50 on the Saito 91 set up this way with no troubles at all.

bogbeagle

I've just bought one of these rcexl units with the intention of converting a 4-stroke glow to spark ignition. The unit hasn't arrived yet.

So, what compression ratio have you chaps found to work OK? I intend to run the engine on methanol, if possible; it's about the same price as petrol, over here....cheaper, if you buy in bulk. Gonna use Aerosave as lubricant, I think...around 5%. Just Engines seem to think that 5% will be OK. What do you think?

Haven't decided which of my engines to convert yet...probably a cheap one!

All pointers gratefully received.

David Turner
UK

gkamysz

My Feedback: (19)

I think 5% of Aerosave will be perfect. I think with a high quality lube like Aerosave, Aerosynth, or Motul Micro, even less would be acceptable.

I'm currently running stock compression ratio. I had 10,000RPM on a Graupner Super Nylon 12x6 today. Fuel was 8% Klotz Techniplate and balance methanol. I haven't optimized timing. I just eyeballed it during assembly. I would convert a good engine. There is no sense in converting an engine with a second rate carb as it will be more sensitive. The FS-52 carb has only 1-2 clicks before it's well off peak.

Surprisingly, my FS-48 diesel conversion turns the same prop at 10,500 so there might be a little more in the FS-52 ignition.

I have photos and video to upload tonight.

togatoga

My Feedback: (42)

I am confused, please help me out. You mean you can use just 5% oil if using methanol? We're talking straight methanol right? Isn't it a bit low as methanol has no lubricant property unlike gasoline.

tkg

My Feedback: (1)

Tagatoga has made a VERY GOOD point. You are just changing the ingition source from glow to spark. You are not mechincally changing the engine to run on less oil. You are still running the same methanol fuel. SO be VERY careful about 5% oil

gkamysz

My Feedback: (19)

Correct. However the lubrication situation in four strokes is very different than two strokes. A four stroke collects a certain amount of oil in the crankcase, then, the excess is pushed out the breather vent. This only means that if you started with an empty crankcase it would takes longer to accumulate that amount of oil with less oil content in the fuel. This is very different than a two stoke where oil is continuously and actively pumped through the engine and out the exhaust. I ran 10% oil in my FS-48 diesel. In the end this amounts to less than 10% oil in methanol. The volume of oil per stroke was less. If anyone has a copy of Peter Chinn's Model Four Stroke Engines, you will find comments about running 5% oil in glow four strokes on page 82. It also says that many manufacturers have started to recommend more oil 10-15%. The book was written in 1986.

Please note that the oils I mentioned are routinely run at 10-12% in two stroke engines in Europe. I will likely not use less than 8% Klotz, because it is not of the same caliber as those oils.

Methanol does have a lower lubricating qualities than gasoline, but one must consider boiling point. Methanol boils at 148°F. While gasoline has a range of 100-400°F. About 35% of gasoline's components boil above 148°F. Most engines will reach this temperature, so methanol quickly boils off. Not all of the gasoline will evaporate so this will dilute the lubricant and reduce it's viscosity. However, in my FS-48 diesel kerosene boils at even higher temperatures and this didn't seem to cause problems, but I was using castor oil. I'm going to try the diesel again next week running synthetic oil.

Read everything you can, decide what will work for you. If it works or fails you've learned something.

gkamysz

My Feedback: (19)

I just added [link=http://www.dieselrc.com/project1.html]some photos and video to the page[/link].

bogbeagle

Thanks for the input. Will scan the video later today, when I have a bit more time.

I was thinking about lubrication, though.

My little .30-sized four-stroke uses fuel with a 20% oil content. The engine runs for about 15 minutes on 5 ounces of fuel. So, in 15 minutes, that engine consumes one ounce of lube oil.

Of that one ounce, how much is just passed to atmosphere via the exhaust? Let's speculate that 50% is lost to the exhaust. Ergo, my little .30-sized engine gets only 1/2 ounce of lube oil per 15-minute run. This is a tiny amount and I think that it gives the lie to oil being an important medium in the cooling of our engines. Even the full one ounce of oil, eked out over that 15-minute run, couldn't possibly carry away much heat energy.

Am gonna try stock compression and decent engine. I don't want to run petrol, because some of my engines have pumps which contain silicon components. I hope that I'm correct in thinking that Aerosave won't harm those components.

togatoga

My Feedback: (42)

Greg, thats a mighty fine plug socket you made.The one supplied by rcexl is kinda c**ppy. Its just a silicon sheath with no lock, keeps slipping out all the time. Are there any commercially available plug sockets or do we have to fabricate it ourselves like what you did out of a mcdaniels.

gkamysz

My Feedback: (19)

CH Ignitions offers this type of spark boot. They don't list it on their website. I called and inquired about it. They cost 13USD. I had the parts and I like making things, so that's what I did.

captinjohn

Greg, I sure understand about crappy ignition boots. Can you show a few photos how to make a good one? thanks Capt,n

gkamysz

My Feedback: (19)

Unfortunately, I did not take photos while building it. I have another to make soon, but I need to get another McDaniel head lock.

I just want to clarify that the CH boot is just like the one I made, not a crappy one.