Andy J Posted April 22, 2022 Share Posted April 22, 2022 Not particularly happy with some 10% fuel I recently purhased so I want to increase the nitro content by 1 or 2%. So can niromethane be purchased at all as a fuel addative? Quote Link to comment Share on other sites More sharing options...
David Davis 2 Posted April 22, 2022 Share Posted April 22, 2022 It can in France but that may not be much help to you! I'm sure that there must be places in the UK which sell it. Have you tried googling nitro suppliers Andy? My club stocks methanol, oil and nitro and mixes its own fuel. I recently ran out of 10% and tried my OS four-strokes on 5% but they didn't seem too happy. We added 65cc to a gallon (4.55 litres) of straight which by my maths produces a 12% nitro content and the engines love it! Quote Link to comment Share on other sites More sharing options...
Don Fry Posted April 22, 2022 Share Posted April 22, 2022 Yes you can, but you need a license to purchase it. If you really think you need more nitromethane why not mix 10 and 15 % mixes. Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 22, 2022 Share Posted April 22, 2022 7 hours ago, Andy Joyce said: Not particularly happy with some 10% fuel I recently purhased Why? What is wrong with it? Its very doubtful another % or so of nitro will make any meaningful difference to anything. Quote Link to comment Share on other sites More sharing options...
Andy J Posted April 22, 2022 Author Share Posted April 22, 2022 Was using 12% for my RCV 58CD which was suffering from over heating and having marginal power for the model it is installed in. Now find that the recommended 10% for this engine has reduced its performance such that the model is now under powered and is certainly flying a few kts slower. Could purchase some higher obtain fuel but now left with 2gals of the 10%, hence the desire to tweak its nitro content. Engine was also running better on the 12% as find the needle setting quite critical on the 10% fuel. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted April 22, 2022 Share Posted April 22, 2022 (edited) 13 minutes ago, Andy Joyce said: Engine was also running better on the 12% as find the needle setting quite critical on the 10% fuel. Critical, oversensitive needle Andy Is more likely plumbing/ pressure leak, cracked fuel tube/ tank pressure leak Or dirty needle/ carb gunge / partial mechanical breathing blockage Edited April 22, 2022 by Denis Watkins Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted April 22, 2022 Share Posted April 22, 2022 My .58 was running on 10% marginal power and over heating, sold on,,,, Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 22, 2022 Share Posted April 22, 2022 (edited) i have an rcv 120 and have run it on the standard laser 5 fuel i use in everything. Its been fine in all my ground testing to date. IF it was overheating before then its likely you have a cooling issue not a fuel issue as i know folk who have used those 58's on 5% nitro without issue. It is extremely unlikely that 2% nitro is enough to completely break the performance of the engine and i suspect there is another issue. RCV engines by their design suffer badly from mechanical wear as sealing of the sleeve valve is lost. What prop are you running and what are the peak revs? I just had another thought. i guess you were using optifuel 12 before? if so what are you using now? Edited April 22, 2022 by Jon - Laser Engines Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted April 22, 2022 Share Posted April 22, 2022 I sold my ..58 to a club member who stripped it and changed the bearings, now it just won't work, can anyone out there tell me how to time it please ?. thanks Paul Quote Link to comment Share on other sites More sharing options...
Caveman Posted April 22, 2022 Share Posted April 22, 2022 Paul, timing the engine is explained in the RCV manual attached. GDBRCV 58CD manual.pdf 1 Quote Link to comment Share on other sites More sharing options...
Andy J Posted April 23, 2022 Author Share Posted April 23, 2022 22 hours ago, Jon - Laser Engines said: What prop are you running and what are the peak revs? I just had another thought. i guess you were using optifuel 12 before? if so what are you using now? Prop is a hard plastic 12X6 of unknown manufacture. Afraid I have no means of measuring the revs. Have run my other RCV58CD which is in a Flair pup on a wooden 13x4 so may try that prop on this model. 12% fuel was from Model Technics although unclear now to me from the label if this was also 10% or 15% as both numbers feature on the label. 10% fuel I just purchased is Prosynth 2000. Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 23, 2022 Share Posted April 23, 2022 12x6 should be good for a 50-60fs. You might get better performance from 13x6 or 12x7 depending on the model type. As for the rest, i am not aware of a 12% nitro from from MT so its likely to be 10 or 15. As for the prosynth, i thought you might say that and it could very well be your problem. Its well known i am not a fan of that fuel, and the symptoms you report are consistent with things i have seen during my own testing using a variety of 4 strokes. I recommend you try something like the optifuel 12, MT contest 10 if they still make it, laser 5 works fine in my SP although i have only bench tested it so far.. In fairness, almost anything else would be better than what you have. 1 Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted April 23, 2022 Share Posted April 23, 2022 I'm running Prosynth 2000 10% in a Saito 40 and it runs really well, the only "problem" I've got after running almost a gallon through the engine is that the throttle cut doesn't always work now. Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 23, 2022 Share Posted April 23, 2022 1 hour ago, Frank Skilbeck said: I'm running Prosynth 2000 10% in a Saito 40 and it runs really well, the only "problem" I've got after running almost a gallon through the engine is that the throttle cut doesn't always work now. Thats fair enough Frank, but i wouldnt make such a fuss if i didnt think it was justified. Ultimately as this is not a laser engine being discussed i am just another modeller giving an opinion and its no skin off my nose either way. Even so, i would strongly recommend an alternative is used. When i get back into testing my rcv 120 i will try some weston fuel. I still have some in hand from my earlier experiments. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted April 23, 2022 Share Posted April 23, 2022 No skin in this game, I've numerous clubmates using Pro Synth, not a one suffering issues, all long time modellers mostly running O.S, Saito engines. These lads wouldn't be buying fuel that damages their engines, as I expect other users wouldn't, anyone know how long this fuel has been on the market ? 1 Quote Link to comment Share on other sites More sharing options...
cymaz Posted April 24, 2022 Share Posted April 24, 2022 (edited) Is it the tank/ fuel feed, cooling, prop selection, plug age and needle settings that are more critical than fuel? We've had an issue with an old Leo engine on one of our club trainers. It was slow to pick up and would idle well. After checking all the plumbing, glow ,etc a 1/4 turn richer on the low end needle was all that was needed. Runs beautifully Edited April 24, 2022 by cymaz Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 24, 2022 Share Posted April 24, 2022 Not sure exactly how old but i am sure it was the new hotness in the late 90's at my old club. As for buying something that causes damage...well you dont know if it will until it does. You trust the claims the manufacturer makes and this has always been my problem with it. Things can seem fine for ages and then boom. A bearing explodes. The performance also seems to vary between engines and some just dont like it. A friends TT91 fs just collapsed completely and ran extremely hot. The laser 70 and 120 i tested didnt seem to mind, the 100, 155 and 180 were not at all impressed. I was going to do a full comparison test over the long term on my twin. I was going to run the left engine on pro synth and the right on laser 5 and see what happened over a long period of time. I gave up almost immediately as the engines refused to run together. While the 70 seemed ok on the bench, vs another in the same model the performance was poor so i gave up. Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 24, 2022 Share Posted April 24, 2022 11 minutes ago, cymaz said: Is it the tank/ fuel feed, cooling, prop selection, plug age and needle settings that are more critical than fuel? We've had an issue with an old Leo engine on one of our club trainers. It was slow to pick up and would idle well. After checking all the plumbing, glow ,etc a 1/4 turn richer on the low end needle was all that was needed. Runs beautifully The slow run meters fuel from 0-60% throttle so yep, the slow run makes a big difference. changing to the new optifuel the other week required nearly a turn leaner on the slow runners on my la7 to make it run properly. Ran like a dog at anything below full power until i did that. Quote Link to comment Share on other sites More sharing options...
cymaz Posted April 24, 2022 Share Posted April 24, 2022 (edited) I fear this thread could go down the, “my fuel is better than your fuel” route, but is there an art to manufacturing glow fuel? I assume ( perhaps quite wrongly) that all the nitro and methanol is bulked in on chemical tankers from main refineries. The chemical composition doesn’t change, so it must be the oil % that the manufacturers can only control. Therefore how could the oil make a difference to the combustion properties? Edited April 24, 2022 by cymaz Quote Link to comment Share on other sites More sharing options...
cymaz Posted April 24, 2022 Share Posted April 24, 2022 (edited) An interesting read, it’s from the US though. https://coxengines.ca/public/files/Gibeault.pdf Edited April 24, 2022 by cymaz Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 24, 2022 Share Posted April 24, 2022 1 hour ago, cymaz said: I fear this thread could go down the, “my fuel is better than your fuel” route, but is there an art to manufacturing glow fuel? I assume ( perhaps quite wrongly) that all the nitro and methanol is bulked in on chemical tankers from main refineries. The chemical composition doesn’t change, so it must be the oil % that the manufacturers can only control. Therefore how could the oil make a difference to the combustion properties? I dont have anything more to say really. I made my recommendation and cant do more than that. I dont make fuel so its not like its my fuel i am promoting. I just have confidence in it so i am happy to say so. Equally i do not have confidence in others so will say that too as the problems experienced here are the same as those i have seen myself testing that particular brew. The biggest factor in fuel quality is the quality of the ingredients. Methanol is available in a variety of purities and at different costs and this would make a difference in fuel performance. However, as i have no data on the methanol used by the various manufacturers i cannot say if this is a factor or not. To bring it all back to the OP and ignore the brand argument, given the problem started when the fuel changed from type A to type B i would recommend inspecting the tuning first to make sure it is correct for the new fuel, and if you still get no joy then it is only logical to change the fuel back to type A or trying a new one all together . If the problem then disappears then you have your answer and fuel B was the problem. 3 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted April 24, 2022 Share Posted April 24, 2022 When I was living 'Up North' in the 70's I bought 20 litres ( not gallons ) from a chemist, I mixed it with castor and they ran perfectly as good as the 20% nitro special Cox fuel. Quote Link to comment Share on other sites More sharing options...
J D 8 Posted April 24, 2022 Share Posted April 24, 2022 My SP60 in Seagull SNJ has run fine on 5% model technics for many years. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 25, 2022 Share Posted April 25, 2022 On 22/04/2022 at 18:38, Paul De Tourtoulon said: I sold my ..58 to a club member who stripped it and changed the bearings, now it just won't work, can anyone out there tell me how to time it please ?. thanks Paul Mesh the gears so that at TDC the inlet is just closing and ex is just opening. On poppet valve engines it's described as " on the rock" Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted April 25, 2022 Share Posted April 25, 2022 Turning the engine over tdc in the correct direction of rotation, exhaust just closing, inlet just opening, valve "over lap" dependant. " On the rock".... Do you know the valve timing and have a timing disc, knowing the clearances used ? For a poppet valve 4t engine... Quote Link to comment Share on other sites More sharing options...
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