I am planning on building a 71" GSP Spitfire and am opting for the more ecomical 2str conversion engines. I have a couple of chainsaws I don't really use. Husq 335 xpt, Sachs/Dolmar/Makita ps401, Stihl 034, and Husqvarna 272XP. I may also be able to recover a Stihl 044 for its engine. Stored it away when it fell off the truck and broke the mount. Engine is still fine. I think these would be too big for this plane though.

Anyway, I want to put a conversion in the Spit, and guess the size of required engine to be around 25-30 cc. Does anyone sell a conversion kit for the most common engines? I read that a Stihl or Husqvarna Weedeater engine in this range would be a good choice. Are there mounts and things I need to make?? Which Stihl/Husqvarna engine would be the most powerful?? Where would I buy a kit? Where can buy the best electronic ignition?? Does someone provide 'plans' on how to do this?? I am interested in doing one, yet ignorant.

Meanwhile I will go through the forums and see what I can find. These forums are great!

Thanks,

This sounds like a nice project, but I looked at the GSP Spitfire and the spec’s say it has 945 sq in of wing area on a 71” wingspan.

I’ve got a 25cc homelite done by Carr Engineering – and it weighs 64 ounces – 4 lbs – I would think that would be way too much weight for this airplane. Now there is a real good discussion going on about converting these engines to a CD ignition – and that may save you some weight, but I don't think you'll get enough weight savings from just an ignition conversion.

The weight of a Magnum 1.20 4-stroke is 31 ounces – just under 2 lbs – and I don’t see anyway of shedding that much weight from any of these Weedeater/Chainsaw engines. Somebody else may have a better idea – and probably will have – but I think you might want to consider a larger model if you want to go with a gas engine conversion. Maybe someone out there knows of an engine that can get you back into the 30-35 ounce range and would fit that airplane.

Now one thing you could do – and I have been looking at this a little bit – is taking a regular 2 cycle glow engine – and converting it to ignition. I’ve got an article from a RCM magazine where they converted a Supertiger 90 over to gas. You could put a CH ignition, or the unit that RCIGN1 (on this forum) sells – send me an email with your address and I’ll copy the article and mail it to you – if your interested. They ran about a 15:1 ratio of oil - just to make sure the rod bearings got enough lubrication. Now maybe if you could get a 90 - 120 2 cycle and convert it - you might have something really going for you.

By the way – would you be interested in parting with that 044 Stihl engine – I’ve been looking for one for a Mustang for next year’s project. Maybe even that 96" wingspan Mustang that GSP has -

Hope some of this helps
Ramrod25

Hmmm... sounds discouraging. This is the plane I like and I really want a gas powerplant. Glow fuel just gets expensive and the engines worth having in this class are just too expensive.

Let me make sure I still have that Stihl. I left it in a friend's garage. You can email me that article at [email protected] or
4633 Blue Run Road
Somerset Va 22972

Much appreciated!

well you could probably get a 21 cc echo to do the job. they are about 1lb lighter than the poulans and homelite with greater power.

I'll get that article and copy it tomorrow and get it in the mail -

By the way - go look in the "marketplace" section - there is a SuperTiger 2300 for about $139.00. There appears to be two good ways to go on the ignition. RCIGN1 sells his ignition system for (I think) about $35.00 + you'll need the proper coil from CH - about $21.00 - so for about another $50 you can convert it to gas - or you can buy the CH ignition kit for $89.00 plus the magnet - so let's say for $100 you can get the CH system which retards and advances the timing. So for around $250 (round numbers) you can get a gas engine in this airplane that ought to have plenty of thrust and not weigh too much. At the cost differential in fuel, it doesn't take long to justify the conversion.

Maybe some other guys will comment on this approach - but I think that's not too bad a deal. By the way, CH sometimes has used ignition sytems - apparently some people upgrade their systems, and trade in a good ignition. I bought one and he guarenteed it for 90 days - it's going on an 45cc Stihl (when I can get to it).

Regards
Rodney Wren

Hi:
I have 4 ryobis,later I get a 25 cc gasser and found it heavier than the ryobi.i worked in my own conversion kit ( prop hub, new muffler and very lightaluminum mount and it weight 1.200 grms. included the plastic 18x10 prop),so may be the sst 2300 and the ignition would be around that.
The ryobi with standar magneto and flying wheel was at 1.380 grms, already converted.
But for 71" WS, I think the best would be a 2 or 4 stroke 120, if te airplane is light it would need few rpms to fly and do some aerobats so there would be no such fuel consumption.

But gassers are so cool!!!

It´s up to the customer.