How bout a 1.6 turbocharged 4cylford/merc.

[Steve Madsen]

Thinking about a buttercup with a DOHC 1.6L Merc XR2Capri motor.Plugs up,belt redrive tall up. 16 valve turbo charged, injected.. Light, torquey,powerful, heat,A/C, electric start, cheaper than a Conti.Any thoughts. All will be appreciated and considered.
Steve.

 

[Kupo Kupo]

Sounds cool. Biggest problem I can forsee is fitting the thing under the cowl as they are IIRC rather tall. DOHC doesn't help shorten the sucker either. Are you planning to use an intercooler or plumb it of the turbo into the intake mani? Using the intercooler (some would prefer to call it an AFTERcooler) would help lower intake temps significantly so you could use autogas otherwise you may be forced to run avgas to prevent detonation. Plumbing the radiator and making a shroud for it would be a pain, not that it's overly hard, I just hate working with fiberglass and finding -20AN fittings is difficult (and costly.) You'll most likely need an aftermarket ecu which could be expensive unless you go MegaSquirt. In all, cool project if you decide to go with it.

Side note: most auto conversion don't end up saving you ANY money. When you factor in the cost for all the custom parts, redrives, time to put it all together, etc., you could have gotten a used lyc or conti for the same price or less. That said, auto conversions are just way cooler.

 

[Dan Thomas]

I have to second that. I've been around homebuilts for 37 years and have seen this too many times. Myself, I put a Subaru in a Glastar for a friend at his insistence, even though I said that it would be better to just bolt a Lyc to it and get going. The costs and hassles with fiddling endlessly with various systems, besides the burned exhaust valves because they're so slender and temperature sensitive, made the thing much more expensive in the end. And when he sold it he took a huge hit on the resale value.

And that wasn't all. The auto engine isn't designed to run at near-redline RPM for extended periods. The Subaru redlined at 5600, but above 4700 or so the fuel consumption and engine wear got too high. The Lycoming, redlining at 2700, can be cruised at any RPM right up to redline and is very comfortable at 2500. So, with a fixed-pitch prop, cruise speed suffers with an auto conversion because the prop's RPM is so much less than its max RPM. The Glastar should cruise at 135 or so with 125 HP, but it would only do 110 with the Soob. Wide-open-throttle speed was the same for both engines, 143 MPH, indicating that the power is there at redline.

Nevertheless, there are a few successful conversions. Geschwender had several converted Ford V-8s running in cropdusters some years back. And the Thielert diesel worked well enough to get certified, buit they went broke for other reasons. If a guy wants to tinker, a conversion is a good way to spend lots of time and money. He should, if using a "modern" engine that was EFI controlled, stick with the full EFI system to avoid burning those skinny exhaust valves when the mix gets a little lean. But if he wants to fly, he should buy an aircraft engine.

Dan

 

[Kupo Kupo]

Given your talking about a buttercup, you would only need about 90-100hp. Try Firewall Forward or Raven Rotorcraft & Redrives : Geo Metro Suzuki Aircraft Engine Conversion : Ultralight & Rotocraft if you really want an auto conversion. To be honest, in your case, you may be best off with a used O-200. Just throwing ideas out there. Whatever you do, keep us updated as buttercups are such cool looking planes.

 

[DaveK]

Or a Corvair engine. Relatively inexpensive, pretty well proven and you can buy all the parts ready to go. www.FlyCorvair.com - Home of the Recognized Authority on Corvair Powered Flight has a bunch of info.