Simon Chambers Posted October 15, 2012 Share Posted October 15, 2012 Just reading in this months RCM&E (WOO's article) that this its possible on a standard glow engine to run it on straight petrol with no other mods apart from needle settings, petrol safe tank+tubing and keeping the glow plug always lit. Has anyone tried this on here? Even though he say's that its possible to run on it, would the compression not need to be lowered? Tempted to buy an old engine off eBay and give it a go on a test stand. With very cheap glow plugs, on-board glow starters and small light LiPo/LiFe packs for power available now, it does seem a very reasonable, relistic proposition. Cheers, Si. Edited By Simon Chambers on 15/10/2012 20:51:46 Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted October 15, 2012 Share Posted October 15, 2012 I've just read that article with considerable interest too Simon. I think your idea of risking an ebay special is a good one... unless the feedback here says otherwise. What's the effect on silencing/noise I wonder? Edited By Ian Jones on 15/10/2012 20:58:19 Quote Link to comment Share on other sites More sharing options...
Rusty C Posted October 15, 2012 Share Posted October 15, 2012 mmmm Very interesting, However I cant see it being to reliable, Surely pre ignition would be a major issue. not to mention the lack of lubrication Pre detonation ( edit) rusty Edited By Rusty C on 15/10/2012 21:01:45 Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 The WOO reckons that petrol has better lubricating properties than methanol, and thus can have lower oil content (10%). I don't really have a clue (chemistry isn't my speciality) but I suppose it must be better, otherwise Spark Igntion engines would seize up from the less oil put into them. As the petrol would be ignited by the compression, rather than a spark, maybe pre ignition wouldn't be as bad? Noise wise, they can't be any worse than a Chinese spark ignition engine with a sound deflector type muffler on them! Someone at my club has converted a Satio glow into petrol (with spark ignition) and he uses the same stock silencer. Certainly isn't noticeably loud. Plus there are quite a few different muffler solutions for glow based engines, so finding and fitting a bigger silencer should be a bit easier than for some standard petrol engines. Cheers, Si. Edited By Simon Chambers on 15/10/2012 21:09:43 Quote Link to comment Share on other sites More sharing options...
Rusty C Posted October 15, 2012 Share Posted October 15, 2012 Sounds like it could be worth a shot, Maybe a wee winter shed project. Lets us know if you try it yourself. I find it hard to see how it would work though, And if it does why is it not more well known ? rusty Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 I wonder why too. Maybe its just because no-ones really thought about it? Brian Winch did mention that some old Italian engine manual stated that it could happily run on glow and petrol too. The only problem I have with experimenting with it, is that I don't have any petrol models (yet). So I'll have to invest in a fuel container, petrol fuel pump, tank, pipes, etc, etc. Which is hard to justify for just playing around! Si. Quote Link to comment Share on other sites More sharing options...
GONZO Posted October 15, 2012 Share Posted October 15, 2012 Just a few threads to prove there is nothing new under the sun: **LINK** **LINK** **LINK** Enjoy the read HTH Quote Link to comment Share on other sites More sharing options...
Andy Green Posted October 15, 2012 Share Posted October 15, 2012 You can run a glow motor with glow fuel but spark ignition. Andy Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 Posted by GONZO on 15/10/2012 22:48:11: Just a few threads to prove there is nothing new under the sun: **LINK** **LINK** **LINK** Enjoy the read HTH Ah excellent. Plenty of reading to keep me up late tonight. Si. Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 Posted by Andy Green on 15/10/2012 22:51:36: You can run a glow motor with glow fuel but spark ignition. Andy But running a glow motor on petrol with glow ignition is simpler and lighter than spark. If it runs well on it that is. The two big benefits I see is that you can use less oil - so less mess and an easy to find, cheap source of fuel - my LMS is now a 20-30 minute drive away the other side of the city. Si. Edited By Simon Chambers on 15/10/2012 22:59:55 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 15, 2012 Share Posted October 15, 2012 As the links describe running a glow on petrol (gas) is not that simple. The fuel/air ratio is very different. The carb is unlikely to work well at the very weak mixtures required and will be extremely sensitive.to adjustment. Petrol and methanol react at a different rates to the platinum in the glow plug so the combustion timing is out. The engine will produce less power. At slow speeds the ignition is likely to fail completely unless the glow is kept on and even then low speed running will be inconsistent. If it was easy to do I sure it would be much more common that it is. Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 So having a read through the first 10 pages or so of those threads, two things I've noticed: Mostly they're using standard 'gas'/petrol engines on petrol with a glow plug to eliminate the need for the spark ignition unit, etc. Those that are using a standard glow, recommend: Use more oil than you would with an equivalent petrol-oil mix, as the conrods bushings will knacker out quickly. Use a run-in engine, not a brand new engine. As the extra heat from the petrol may cause a new, tight engine to seize. Maybe other points, not read them through yet. Si. Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 15, 2012 Author Share Posted October 15, 2012 Posted by Simon Chaddock on 15/10/2012 23:31:00: As the links describe running a glow on petrol (gas) is not that simple. The fuel/air ratio is very different. The carb is unlikely to work well at the very weak mixtures required and will be extremely sensitive.to adjustment. Petrol and methanol react at a different rates to the platinum in the glow plug so the combustion timing is out. The engine will produce less power. At slow speeds the ignition is likely to fail completely unless the glow is kept on and even then low speed running will be inconsistent. If it was easy to do I sure it would be much more common that it is. Some suggestions on there in using a heli carb as its a smaller carb. I did wonder if using a rear mounted needle, you could swap the rear mount needle assembly with one from a smaller engine. Do the smaller engine needles let less fuel through? I.e. use a 25 sized needle on a 46/52 sized engine on petrol. However there are a lot of people running glow engines on petrol with spark ignition ok. Is this likely to be less critical than a glow plugged, running on petrol engine? Glow driver doesn't bother me, as they're cheap. Battery wise, either LiFe, or even a Li-ion cells with inbuilt low voltage cut off - then you don't have to worry about flattening them. A glow plug @ 1.5v, 4A = 6W + 15% loss in efficiencies = 6.9W. A 2.5Ah 6.6v LiFe Pack = 16.5Wh. So 2 1/4 hrs run time on the safe side. With that sort of life, it would be possible to run the receiver off the same pack too if necessary to save weight. Also as the fuel consumption is lower, a smaller tank can be fitted - thus leaving room+weight free for another pack if necessary. I might try it on an old Irvine 40 some time soon. With glow engines going cheap (especially the big'uns), if it does work well, then it could be a neat trick. A gallon of petrol with some cheap 2T oil is going to be cheaper and easier to get hold of than glow fuel - especially as the fuel consumption will be less. Cheers, Si. Quote Link to comment Share on other sites More sharing options...
John Olsen 1 Posted October 16, 2012 Share Posted October 16, 2012 If you are going to carry a battery to run a glow driver, why not just put in a spark plug and a CDI unit? I have done this to a Saito 62, it started first try. Actually I ran it first on glow fuel with spark ignition while I sorted out a local source of suitable oil for the petroil mix. Now it has run on petrol and it is lovely, with a very slow steady idle. The mixture settings are a little bit more critical than with methanol based fuel, because of course the needle is closed down more. I haven't managed to put a tachometer on it yet, but you can hear the individual beats when it is idling slowly. John Quote Link to comment Share on other sites More sharing options...
Andy Green Posted October 16, 2012 Share Posted October 16, 2012 John, How did you mount the sensor? Andy Quote Link to comment Share on other sites More sharing options...
SA Allan Posted October 16, 2012 Share Posted October 16, 2012 Just Engines sell conversion kits , might be worth a look they do have instructions that can be downloaded. Quote Link to comment Share on other sites More sharing options...
Andy Green Posted October 16, 2012 Share Posted October 16, 2012 I have the kit, just looking for ideas on how to mount the pickup on a Saito. Andy Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted October 16, 2012 Author Share Posted October 16, 2012 If glow plug with petrol works well, then the lack of crank sensor and heavy/bulky CDI unit would be a big benefit - especially on the smaller glow engines. The faffing around with mounting the crank sensor and making shims to change the compression has always put me off the conversion kits. Can you buy ready made shim kits to lower the compression on engines? Such as for the ASP's that JE sell. Si. Quote Link to comment Share on other sites More sharing options...
Alwyn Gee Posted October 16, 2012 Share Posted October 16, 2012 I thought all you IC deciples loved all the noise and mess and here you are trying all sorts of wierd and wonderful ideas to get rid of some of it. Just take the bull by the horns and admit to the benefits you really want and rip out that noisy, smelly, oily thing and fit a beautifully clean, quiet, reliable electric motor. You know you want to!!!!!!!!!!! Alwyn Quote Link to comment Share on other sites More sharing options...
GONZO Posted October 16, 2012 Share Posted October 16, 2012 You may find these two 4st conversions of interest **LINK** **LINK** HTH Quote Link to comment Share on other sites More sharing options...
Andy Green Posted October 16, 2012 Share Posted October 16, 2012 Thanks, Interesting reads, the problem with the Saito is that there isn't a boss housing the front bearing that you can get to. The only way I can see to do it is to come off the cam cover. If you have a Saito you will know what I mean. Andy Quote Link to comment Share on other sites More sharing options...
GONZO Posted October 16, 2012 Share Posted October 16, 2012 Ah! See what you mean. Have a look at this Saito site, bottom but one on the menue list **LINK** HTH Quote Link to comment Share on other sites More sharing options...
Solly Posted October 16, 2012 Share Posted October 16, 2012 I'm surprised at the comments aimed at lack of lubrication using petrol/oil. One of my clubmates and myself both ran Merco 61's on sparks for 6 years using the same mix as my strimmer (40 to 1 synthetic oil) without any adverse effects to the compression or bearings. In fact I've yet to actually meet anyone who has experienced engine wear using petrol/oil, just a lot of people who warn against it! Quote Link to comment Share on other sites More sharing options...
GONZO Posted October 16, 2012 Share Posted October 16, 2012 Solly, Was it one of the 'genuine' Merco produced engines or a conversion? Got a NIB Merco sparker but thought about changing the spark electrics for a newer system before use. Quote Link to comment Share on other sites More sharing options...
Solly Posted October 16, 2012 Share Posted October 16, 2012 Gonzo, - they were the genuine Merco engines, though my spark system packed up after about a year and was replaced by a new system. My clubmate's example ran OK until he sold it after over 6 years use. Please note that while these engines run fine on the test stand, the carbs are very sensitive to fuel levels ie. climbing and diving, which is why we used ours just for steady vintage flying. Quote Link to comment Share on other sites More sharing options...
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