Ian Jones Posted January 31, 2014 Share Posted January 31, 2014 I can't find a guide, there must be one somewhere, surely. It's not about engine size is it? As I understand it, it's power & torque and I've tried to make comparisons but power output is expressed in various forms and torque rarely mentioned. I'm particularly looking at some of the smaller petrol engines in the 15-25cc size. Quote Link to comment Share on other sites More sharing options...
cymaz Posted January 31, 2014 Share Posted January 31, 2014 Link here to gas engines from Evolution. This might be of help Quote Link to comment Share on other sites More sharing options...
Martyn K Posted January 31, 2014 Share Posted January 31, 2014 Hi Ian Good question - subscribed because I would like to know as well. Martyn Quote Link to comment Share on other sites More sharing options...
Allan Bowker Posted January 31, 2014 Share Posted January 31, 2014 A very timely question Ian and one I have been pondering for the past weeks. I have a H9 Katana 50 and by the Evolution engines chart Cymaz linked above plus advice direct from Horizon Hobby (US), I thought I was going to buy the Evolution 10cc See my thread here though. Despite the 10cc being a good match on paper, in reality it seems I need the 15cc. I will be watching this thread with interest. Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted February 2, 2014 Author Share Posted February 2, 2014 Thanks everyone, at the moment we have: Evolution 2st Glow 4st Glow 2st Petrol .60cu in 10cc .91cu in 15cc 1.20cu in 20cc Rc Universe Post 1.5cu in 25cc 2.7cu in 46cc 3.0cu In 50cc RC Groups Post 0.6cu in 0.91cu in 15cc* 0.75cu in 1.00cu in 17cc* 0.9cu in 1.2cu in 20cc* 1.2cu in 1.8cu in 30cc* * stroke not specified All the same 2strokes & 4strokes in both fuel types are often being quoted without actually specifying what comparison is being made, this to a petrol newbie is not very enlightening. What we really need is performance comparison for example a .60 2stroke can be expected to produce around xxhp so a suitable 2stroke petrol substitute would be an xxcc petrol because that size petrol typically produces a similar amount of power, anyone come across anything like that? Edited By Ian Jones on 02/02/2014 13:10:18 (thinks "I've sorted the overhanging text " Edited By Ian Jones on 02/02/2014 13:13:45 Quote Link to comment Share on other sites More sharing options...
cymaz Posted February 2, 2014 Share Posted February 2, 2014 This any good? Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 2, 2014 Share Posted February 2, 2014 Its an interesting question..... My take on it from fairly limited experience is that a 2 stroke petrol is about the same as a 4 stroke glow of the same size, thus a 10cc petrol 2 stroke equals a 60 glow 4 stroke or a 46 glow 2 stroke.... Of course as you get to the larger sizes (20cc plus) comparisons become a bit less meaningful as there aren't so many options... Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 2, 2014 Share Posted February 2, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
cymaz Posted February 2, 2014 Share Posted February 2, 2014 I can't find power output figures either for evolution. They are sometimes worthless as they are based on such unrealistic circumstances and rpm figures. I tend to go by what experience other rc users have with them and what planes they put them in and the weight of the aircraft. Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted February 4, 2014 Author Share Posted February 4, 2014 Actually Andrew it was looking at the NGH17GT at Just Engines that sparked this thread. If I get one of these it would be to match a specified .61-.75 2stroke/1.00-1.10 4 stroke. Thanks Cymaz, similar numbers as before, once again though the "gasser" they refer to is it 2stroke or four stroke? Appears possible that unless otherwise stated we are to presume 2stroke but it does leave things still a bit murky. Edited By Ian Jones on 04/02/2014 12:21:18 Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted February 4, 2014 Author Share Posted February 4, 2014 Sorry Cymaz, got your posts a bit mixed and I take your point. Not a lot of petrol users in my club though. Edited By Ian Jones on 04/02/2014 12:24:06 Quote Link to comment Share on other sites More sharing options...
Bandit Posted February 4, 2014 Share Posted February 4, 2014 I have a 20cc petrol from hobbyking in a P47 which was said to be a 1.20 kit. It's an older kit razorback with composite fuz. Think it was a CM pro kit. It has loads of character and tough as old boots. It goes like a rocket, most of the time the engine is burbling around half throttle. I liken it to a likable bumble bee that can be angered at any moment. I have a Phoenix Yak 54 with a 26cc petrol also from Hobbyking. This also seems like a rocket ship however it does seem a bit heavy for the model as I had a dead stick which turned the model into a dead brick but it was easily repairable just the undercarriage was damaged. I have a Great Planes 81" Yak 54 with a 45cc Petrol in it and it was said to be a 1.60 kit. It's power is adequate. Nothing overly spectacular but will hover. Bigger wings make it a lot more pleasurable to fly than the Phoenix yak54 but juuust fits in the car without any wheels which is why I got the smaller Phoenix Yak. So I think more than just power is an issue. I think the Petrols produce more power than they are given credit for but might be heavier, not sure as I have not compared weights. I suppose I should have, but I got grumpy with glow covering airframes in muck. Fuel consumption is a big plus but caution, if the engine runs a bit rich the consumption is a lot more hence my dead stick I pondered this size question for ages too and came-up with 20 is about 1:20 4 stroke glow. Take care with the set-up though. If it can rattle loose it will and buy a Rexel optical switch to cut the engine as a safety precaution because engines can come loose and pull the throttle open. Tape or clip every connection and run the engine for hours and hours to run it in. Hope that helps Quote Link to comment Share on other sites More sharing options...
cymaz Posted February 5, 2014 Share Posted February 5, 2014 Just phoned up Kings Lynn Models. The shop assistant couldn't be more helpful. After phoning Horizon he said there would be no engines in until March. This was because they were still being manufactured and none were available. So we wait........... Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted February 17, 2014 Author Share Posted February 17, 2014 It was the NGH 17GT that I was particularly interested in as a potential power unit for a Seagull 63" Sparrowhawk. In the end though it turned out that whatever exhaust I fitted I would have to make modifications to the air frame and/or cowl length to get it to fit. In short it's got to the point where .61 2 stroke will fit a treat at about 1/3 of the cost of a petrol engine that will need quite a bit of a workaround. I was looking for a quick finish on this one as there's years of other stuff already on my bench. So this time the 2 stroke wins. I haven't given up the idea for going down the petrol route at some point though. Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted February 17, 2014 Share Posted February 17, 2014 "Conventional" wisdom is a dangerous game Cynthia...................................... Can't directly compare Petrol/Glow, though I own both, but for a while I had two identical planes, one 52 2St Glow, the other 70 4St Glow. They were quality engines in good new run-in condition, both running the recommended nitro percentage and fuel type, also the recommended (and tested for) best prop and plug. The 2St ran rings round the 4St. Period. 2St Glows are simple, reliable, maintenance free, small for their power, easy to quieten, and while their fuel consumption is not as good, the extra cost of a 4St or Petrol installation can pay for quite a bit of fuel and I really don't need to fly for half an hour non-stop on a tank, I'm fun flying, not crossing the Channel!! Quote Link to comment Share on other sites More sharing options...
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