John Tee Posted September 20, 2020 Share Posted September 20, 2020 Just wondering. As I haven't spent too much on modelling this year, I have been looking at some bigger models. Am I right in saying ( think I read somewhere) that petrol engines are lower powered than our usual two strokes. I have several 20 and 25 cc Super Tigre 2 strokes and don't really want to spend out on a petrol engine and the accessories if I can help it. It may never come to pass but I like the thought of a bigger model. John Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 20, 2020 Share Posted September 20, 2020 I'd agree with that. As a rule of thumb, I'd say that a 2 stroke petrol is roughly the equivalent of a 4 stroke glow. Quote Link to comment Share on other sites More sharing options...
John Tee Posted September 20, 2020 Author Share Posted September 20, 2020 Thank you Martin. So if a 30 cc petrol is required I could use my Super Tigre 2000. john Quote Link to comment Share on other sites More sharing options...
Jesus Cardin Posted September 20, 2020 Share Posted September 20, 2020 It is most like Martin says, but petrol engines have evolved in recent times -as well as glow four stroke ones!- and if a gas 30cc is requird for the model, I should rather go with your Super Tigre 25cc. Quote Link to comment Share on other sites More sharing options...
John Tee Posted September 20, 2020 Author Share Posted September 20, 2020 Thanks Jesus John Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted September 20, 2020 Share Posted September 20, 2020 You could check online rpm reports for the different engines and then decide, e.g. a search using a DLE 30 suggests 7200 to 7300 rpm on a 19 x 8 prop, around 2.7 HP, a ST2000 gives around 9,400 rpm on a 16 x 8, around 2.9 HP. Friend had a Supetigre 25cc in a Wilga designed around a 30cc petrol, don't think we ever used full throttle, was off the ground on 60% throttle or so. Quote Link to comment Share on other sites More sharing options...
John Tee Posted September 20, 2020 Author Share Posted September 20, 2020 Thanks for your input Frank John Quote Link to comment Share on other sites More sharing options...
Robin Colbourne Posted September 20, 2020 Share Posted September 20, 2020 Many of the early generation petrol engines were derived from strimmer engines, so they were side port induction which limited power output. Others used chainsaw parts, e.g. Quadra, which were still sideport induction but often had reed valves to speed up port opening and closing. Modern two stroke petrol engines, purpose-made for model aircraft, use shaft or rear drum/disc induction which offer opportunities for greater control of induction timing. Methanol gives off less power than petrol by weight, but an engine can burn more of it, its higher octane rating allows higher compression ratios and it runs cooler, hence its popularity in some forms of motorsport. Why race car drivers love methanol Edited By Robin Colbourne on 20/09/2020 23:35:45 Quote Link to comment Share on other sites More sharing options...
John Tee Posted September 21, 2020 Author Share Posted September 21, 2020 Thanks everyone, given me some things to think about. I have collected the Super Tigres over the years and never fired them up all used motors John Edited By John Tee on 21/09/2020 16:03:22 Quote Link to comment Share on other sites More sharing options...
mal brewer Posted September 21, 2020 Share Posted September 21, 2020 Hi John, don't know if you have been informed, those big Supre Tigers don't require nitro in the fuel, and only 10% oil. I always used to buy 20% oil straight fuel, and dilute it with an equal quantity of neat methanol. Nowadays, of course, you can buy 10% oil fuel.............Mal Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted September 21, 2020 Share Posted September 21, 2020 Posted by Robin Colbourne on 20/09/2020 23:35:22: Modern two stroke petrol engines, purpose-made for model aircraft, use shaft or rear drum/disc induction which offer opportunities for greater control of induction timing. Edited By Robin Colbourne on 20/09/2020 23:35:45 Most of the rear carb models from the likes of DLE etc use reed valves, it's only the engines with a front carb that use shaft induction. The additional power mainly comes from them being tuned for model aircraft use (that and not worrying about noise) Quote Link to comment Share on other sites More sharing options...
Den Moran Posted March 25, 2021 Share Posted March 25, 2021 Hi! I have a Super Tigre 2000 25cc that I want to use in my Stearman. It was new when I bought it, but with no muffler/exhaust. Can anyone suggest a muffler type that will fit this model engine, please? I cannot find any on sale.Thanks, Den Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted March 25, 2021 Share Posted March 25, 2021 2 minutes ago, Den Moran said: Hi! I have a Super Tigre 2000 25cc that I want to use in my Stearman. It was new when I bought it, but with no muffler/exhaust. Can anyone suggest a muffler type that will fit this model engine, please? I cannot find any on sale.Thanks, Den Den Bisson Custom Mufflers in Canada can help. They make 3 types of muffler as standard: For upright engines, for inverted engines and Pitts style for side mounted engines. They only seem to list the ST2300 which was a later replacement for the ST2500 but you should be able to check exhaust flange size and mounting bolt centres using their website and your engine. Just Engines hold some sizes of Bisson products, depending on the style you need, so they could advise on fitting for your engine (and supply you if they have stock), but having ordered direct from Canada last year I can say that Janet Bisson was incredibly helpful and I wouldn't hesitate to use them again. In fact I am going to soon... Browse down this list to see the mufflers they do for the ST2300: https://www.justengines.co.uk/shop/exhaust-systems/two-stroke-exhausts/bisson-custom-mufflers-by-engine-manufacturer/super-tigre/bcmpst2023-bcm-2300/?v=79cba1185463 Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted March 25, 2021 Share Posted March 25, 2021 I belive just engines can fabricate one as well..... GG Quote Link to comment Share on other sites More sharing options...
Den Moran Posted March 26, 2021 Share Posted March 26, 2021 Wow! There is a lot to go at there, Alan, with Bisson Mufflers. They are only 35km from my cousins' place in Humphrey, Ontario, as it happens. GG, I know I can get 'Just Engines' to make one, but I was thinking that another Super Tigre Engine muffler would have the same specs. I'll write to Bisson, and ask them. Thanks, both, Den 1 Quote Link to comment Share on other sites More sharing options...
David Davis Posted March 26, 2021 Share Posted March 26, 2021 Weston UK make Power Pipes for the big Super Tigres. https://www.westonuk.co.uk/Mini-Pipes-Plate-Fixing-Points--44mm/ I have one on a little SC 32. It's well made and it sounds beautiful to me, nice and quiet! I hate "Flying Chainsaws" as an old friend used to call them! Quote Link to comment Share on other sites More sharing options...
Den Moran Posted March 27, 2021 Share Posted March 27, 2021 Sorry , David, I'm not sure what a ' power pipe ' is. I'm looking for an exhaust box to fit this engine. Quote Link to comment Share on other sites More sharing options...
David Davis Posted March 27, 2021 Share Posted March 27, 2021 It's a sort of silenced expansion chamber which reduces noise and gives a slight boost in performance. Click on my link above and you'll see what they look like. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted March 27, 2021 Share Posted March 27, 2021 On 25/03/2021 at 10:55, Den Moran said: Hi! I have a Super Tigre 2000 25cc that I want to use in my Stearman. It was new when I bought it, but with no muffler/exhaust. Can anyone suggest a muffler type that will fit this model engine, please? I cannot find any on sale.Thanks, Den Hi Deb . I don't think you will find any off the shelf silencers for a ST 25cc as they are an old engine now. The power pipes or Throttle pipes made by Weston UK that Dave suggests would have to be very big / long for a 25cc engine and unlikely to be suitable for your Stedman unless you could run it through the fuz. It would be easier to phone Alan at Weston UK or Just Engines and askfor advice about a custom exhaust. There were some small cast aluminium mufflers available for ST engines but they weren't very efficient at silencing or with performance. Good luck with your search. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted March 27, 2021 Share Posted March 27, 2021 We got a Pitts style one from Just Engines last year, so give them a call too. Had a bit of a bark too it, but was quieter than a typical two stroke petrol. Quote Link to comment Share on other sites More sharing options...
J D 8 Posted March 27, 2021 Share Posted March 27, 2021 Jumping on to this band waggon,? where would a Laser 150 stand compared to say DLE 35 ? Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted March 27, 2021 Share Posted March 27, 2021 I have a Seagull Maxilift that original had a DLA 32cc in it, which was removed because it was too noisy and replaced with a Laser 150, the Laser 150 isn't quite as powerful, but sounds a lot better and meets the club noise limit, 82 Dba @ 7m. A Laser 180 would be a fairer comparison to a DLE 35. Based on my Laser 150 and DLE numbers on line the comparison is Laser 150, 16 x 8 prop - 8500 rpm roughly 2.3 HP DLE 35 18 x 10 Prop - 7,300 rpm roughly 2.9 HP 1 Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted March 27, 2021 Share Posted March 27, 2021 (edited) I have a Laser 150 on my 30cc Goldwing Yak55 and properly tuned it is more than adequate. I had to put the battery right up front to balance it because petrol engines are heavier than glow engines. I initially thought it wasn't quite enough but I discovered the throttle wasn't opening fully, once fixed, I got unlimited verticals. Edited March 27, 2021 by Andy Stephenson 1 Quote Link to comment Share on other sites More sharing options...
Den Moran Posted April 8, 2021 Share Posted April 8, 2021 I've bought one from Just Engines - I am now trying to find out what ignition battery to use - do I need two for the servo/receiver as well as ignition? Cheers, keep safe. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted April 9, 2021 Share Posted April 9, 2021 Den, you only legally require dual batteries/receivers etc if the model is over 25kg (without fuel) and these also have to be certified by the LMA over 25 kg scheme (details on the LMA website), below that it is up to you. Quote Link to comment Share on other sites More sharing options...
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