Snorbitz Posted July 2, 2010 Share Posted July 2, 2010 So i've finally made up my mind to put a CRRC 26R petrol engine in my CMP 120 size Japanese Zero. I've ordered new fuel bung,opto kill switch and tygon fuel line and heavy duty on/off switches (for ign+rx) and other than that i can't think of anything else unless somebody can tell me otherwise?. I'm still undecided about weather i should fit it onto anti vibration mounts. Maybe i'll wait and see how it feels on the test bench first. Its a fairly new version of the engine with the rear mounted carb so maybe i'll do a bit of a running report on here as so many people seem to be going over to petrol engines now and i know i found some but not all of the info i needed in a few weeks of internet searches. You can never have too much info i reckon. Would anyone be interested i wonder?. Quote Link to comment Share on other sites More sharing options...
Lee Smalley Posted July 2, 2010 Share Posted July 2, 2010 i recently bought a MVVS 40 cc petrol and whilst its a great engine the instructions regards starting priming etc were rubbish, (for a top end engine) but as long as you have a kill switch then i think your fine, just remember petrol has far more vibration and as a result MG servos are a must really Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 2, 2010 Share Posted July 2, 2010 Just adding a post so I can follow your thread Shuglu......petrol appeals to me too!!! Have you seen the Rx controlled switches from Just Engines....here Lee, why do petrol engines vibrate more? With their lower compression ratios I would have expected less vibration than a glow motor.....Or is it that they are simply physically bigger hence the vibes are bigger too?? Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 2, 2010 Share Posted July 2, 2010 I suspect a frequency problem don't you ,they're lower reving aren't they.If the airframe is man enough then I think it would dampen down the engine vibration best on a fairly rigid mount (glass reinforced nylon?),Advantageous to the electronics on board & that's what matters ,Isn't it ?.Pure guess work but based on my 52 sized glows -4st ..Edited By Myron Beaumont on 02/07/2010 18:16:29 Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted July 2, 2010 Share Posted July 2, 2010 I've never used petrol, but like many I have been considering it recently. So like Steve I'll be watching your experience with interest. BEB Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted July 2, 2010 Share Posted July 2, 2010 Oooerr! That's 1000 posts!!! BEB Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 3, 2010 Author Share Posted July 3, 2010 OK so i've now ordered the engine from one source, manual kill switches from another and the opto kill from Just Engines (you must have read my mind Steve). I have my fuel bung and Tygon fuel tubing and today i went out and on the advice of others i went to a "garden machines" type shop and got my generic felt petrol filter for just over £3 so there was a couple of quid saved straight away. It is nicely weighted too which will be handy. I also asked if they had 1/8 bore petrol fuel tube and the guy said he did but the outer diameter is larger than the silicone tubing i showed him as a guide. He didn't have any to show me but i don't need any more just yet but will remember that for future ref. I've decided to get everything together before i start to build mainly as i don't have the engine in my hand yet i don't know where the throttle will cable will lie and everything else revolves around that really. Some photos would be useful about now to see what the "before build" and bits and pieces look like so thats my job for the morning. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 4, 2010 Author Share Posted July 4, 2010 So here is the bare fuz with only the cowl mount installed. The cowl and nose on the Zero is huge so fingers crossed not much cutting of the original form will be required, The engine dimensions suggest maybe a little around the spark plug but as the carb is rear mounted nothing for that. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 4, 2010 Author Share Posted July 4, 2010 And from the inside you can see it has a 3/4mm ply backing plate bonded to the inside of the fibreglass mould. There is a 30mm square engine mount to go on the outside so that should be ample strength i hope.Just checked the DHL Tracking number i have from the supplier and i should have the engine in the next day or so fingers crossed. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 4, 2010 Author Share Posted July 4, 2010 Tygon fuel tube, Dubro petrol tank bung and felt filter along with my chosen throttle cable. Using this one to avoid the dreaded mtal to metal issues i read so much about.My intention is to have the ignition box in the engine bay for what i think are obvious reasons. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 4, 2010 Author Share Posted July 4, 2010 I decided to crack on with the fuel tank plumbing today. My initial thoughts are for a 2 pipe system and "T"-ing into the carb line for fill/drain(still not decided 100% on this idea yet...in fact the more i think about it the less i like the idea of back flushing the filter during filling!!). I've always used the solid pipe in the clunk pick up tube ever since a firm lading in a trainer flicked the pipe to the front...That caused some head scratching for a while...never again. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 5, 2010 Author Share Posted July 5, 2010 I've slept on the idea of a 3 pipe system and i think its the way to go. Now as far as the breather goes i read its a good idea to make a couple of coils in the line to prevent syphoning and stick them to the top of the tank before it exits in the engine bay in a neutral air area. Do they mean flat on the tank or upright. Any thoughts on that chaps? Quote Link to comment Share on other sites More sharing options...
GONZO Posted July 5, 2010 Share Posted July 5, 2010 Have look at this site . Page 107 bottom right talks about placement of tank vents etc. Its a big down load - 18.4MB. http://www.toni-clark.com/ftp/e-Kat_11_2008.pdf Quote Link to comment Share on other sites More sharing options...
Lee Smalley Posted July 5, 2010 Share Posted July 5, 2010 i have never put coils in my breather pipe and i dont suffer from syphoning, the tank is under constant vacuum thanks to the carb and so fuel never comes out of the breather, as for metal gears on servos i suppose its down to the lower fequency but i can tell you from experience petrol engines vibrate far more dont forget the kill switches from SM services are less than 20 quid Quote Link to comment Share on other sites More sharing options...
Lee Smalley Posted July 5, 2010 Share Posted July 5, 2010 sm services have alook here for good stuff that works and is cheap!! Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted July 5, 2010 Share Posted July 5, 2010 I'd second the vote for SM Services stuff - I use their servo slowers. They do just what it says on the tin and a darn good price! BEB Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 I've now recieved my engine and this is what you get in the box. All nicely packed and comes complete with engine mounts. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 Heavy duty on/off Switches and opto isolator switch from Just Engines also arrived. I like the fact that this opto switch comes with an "ON" LED to tell you when the ignition is live. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 I've spotted my first potential problem in that the choke butterfly which needs to be close for priming of the engine sticks out beyond the engine mount...ie into the firewall area. I think you'll see what i mean from the photo. I've also noticed that the choke and carb levers are very close together. That's going to be a little challege connecting them all up. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 The block of wood in the previous post is the spacer that you get with CMP Zero to adjust the final prop position and i've worked out that the block plus engine brings me to where i need to be to clear the cowl with the prop. It comes with a hole already in it and luckily its just where the choke flap sticks out. It means that i'll have to route the fuel lines somewhere else though.Initial impressions of the engine are its nicely built with no nasty rough edges and all the parts look like quality items. I like the addition of a spark plug spanner and correct size allen key for fitting the exhaust/mounting bolts. So far so good. The test bench is all ready now to fit it to so i can start the "running in" procedure. Quote Link to comment Share on other sites More sharing options...
GONZO Posted July 12, 2010 Share Posted July 12, 2010 Do not have the prop too close to the cowl like in a normal slim cowl installation. The prop will be more efficient if the rear of the prop is up to 1'' away from the radial cowl face. It may look odd on the ground but the further away from the cowl the more efficient up to a point, its all a compromise. It's your call. Quote Link to comment Share on other sites More sharing options...
GONZO Posted July 12, 2010 Share Posted July 12, 2010 The new engine looks like one of the new CRRC 26R units. Be very interested to hear how it goes. Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 The prop is one thing i have to change actually as i bought a 16x8 to go with the V2 crrc engine but i think it'll be ok to start running it in on, then swap to an 18" as is required. The rear mounted carb version of this engine has nearly a 1/3 more horses than the side carb version and hence requires a bigger prop. I'll bare your comments in mind though Gonzo when i come to finally mount it in the plane. Cheers. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 12, 2010 Share Posted July 12, 2010 If it were mine Shuglu I might be tempted to open that hole in the plywood spacer up a bit......the engine will need clear space around the carb to breath effectively..... Looks a very nice motor too!!! Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted July 12, 2010 Author Share Posted July 12, 2010 Yes its the latest version of the 26cc engine CRRC make. Max power has gone up from 2.4 to 3.15ps and hence the prop size required has increased too. (I've got a 16x10 for sale if anyone is interested!). I think i'll go for an 18x8 to start with but i'd like to go to 3 blades eventually once i'm happy everything is well bedded in. I've got my 2 stroke mineral oil for the running in from a local autoparts shop but will be going over to a fully synthetic once the first few gentle flights are out the way. Probably BelRay H1R. Quote Link to comment Share on other sites More sharing options...
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