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#21
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Corvair conversion engines
"Bret Ludwig" wrote in message oups.com... I just think hanging a prop on a crank directly is a non-starter in the first place...especially on a crank and case not specifically designed for this in the first palce. Maybe a good redrive and flywheel would be a better way to go? That is my opinion, also. -- Jim in NC |
#22
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Corvair conversion engines
When it really gets down to facts, most often aircraft engines really
don't cost any more than auto conversions and the aircraft engine appears to be more reliable. No redrives needed, redundant ignition and lots of other things that makes them better. I was a firm believer in auto engine conversions but i haven't seen many last a long time except for the Subaru and Rotax engines. Morgans wrote: "Bret Ludwig" wrote in message oups.com... I just think hanging a prop on a crank directly is a non-starter in the first place...especially on a crank and case not specifically designed for this in the first palce. Maybe a good redrive and flywheel would be a better way to go? That is my opinion, also. |
#23
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Corvair conversion engines
wrote in message ... When it really gets down to facts, most often aircraft engines really don't cost any more than auto conversions and the aircraft engine appears to be more reliable. No redrives needed, redundant ignition and lots of other things that makes them better. I was a firm believer in auto engine conversions but i haven't seen many last a long time except for the Subaru and Rotax engines. There are many V-6's running, some significant numbers, time wise. VW's flying all over the place. Mercedes diesels in what, Thielert brand name? Oh, by the way, Rotax is NOT an auto conversion. -- Jim in NC |
#24
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Corvair conversion engines
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#26
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Corvair conversion engines
I just think hanging a prop on a crank directly is a non-starter in
the first place...especially on a crank and case not specifically designed for this in the first palce. Maybe a good redrive and flywheel would be a better way to go? That is my opinion, also. -- I partially agree. I agree that hanging a prop directly on the end of an automotive crank, even if you put it on the flywheel end, is a recipe for a short tbo even at low power and for a high failure rate at high power. (If you only use it to push an airboat around the local swamp, you can keep a couple of bottles of skin-so-soft in your tackle box.) However, switching to a traditional aircraft powerplant may not solve the problem. You really only have the full value of testing, experience, and service history when you mate an unmodified engine to an airworthy propeller with which that engine was certified--and preferrably in a combination used by a large number of aircraft in regular service for a reasonably long time. Remember the crankshaft problems in some of the Cessna 172's soon after the change from the Continental O-300 to the Lycoming O-320. (I think it was an early 160HP version, but have long forgotter the dash number--and the problem was promptly solved.) There have been other "teething" problems as well on various engines... In the special case of a KR-2, which was the subject of at lease two of the Corvair engines torn down and inspected, the plane sits too low to swing a 70+ inch diameter propeller; and IIRC was originally designed for VW engines swnging 52 inch diameter propellers. I have heard that the KR-2S sits enough higher to accept a larger prop, possibly 60 inch diameter. That seems to negate the reduction drives, although a shaft drive, similar to the one Steve Whittman developed for his V8 powered Tailwind, could be interesting. BTW, the plans are still available--I think Aircraft Spruce still sells them. Also, Revmaster (and possibly others) offers an aircraft engine based loosly on the VW dimensions and a Jabiru could work--especially with a 3 blade prop... |
#27
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Corvair conversion engines
On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize
wrote: I don't think there's any dispute over the relative cost of engines. This issue is longevity and whether one wants to fly an airplane with an engine that might not make it to the next airport. Cal, the statement I was responding to was from the guy who said that auto engines end up essentially costing as much as an aircraft engine. I was posting my actual costs to suggest that the costs are, or can be, very much lower for the auto engine conversion than for a rebuilt aircraft engine. But I chose to do all the work, except for the machining of the engine parts, myself. If you do not wish to put in that kind of time, or do not have the knowledge to do so, then the options tend to be a lot more expensive. Buying a firewall forward package and simply bolting it in place and connecting the wires and fuel lines will of course cost a bunch more than doing everything yourself. Perhaps this is what that gentleman was talking about. Corky Scott |
#28
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Corvair conversion engines
wrote)
I bought two 3.8L Ford V6's for $150 each, bought new pistons from Roush racing, new rings, had the best block shot peened bored and honed, had the best crank turned and nitrided, bought new bearings, new cam, new distributer with two sensors installed for dual ignition, new pistons, new timing gears and chain, planed the heads, had four new intake valves installed and new guides installed as well, new valve springs, roller rockers, new lifters, new carburetor, old style NWAero psru, ARP studs for the crank bearings and cylinderheads, fabricated my own headers, and STILL spent only about $6,000. Why not fuel injected? Also, is that two for $3K each? What does that setup weigh? Was matching a prop to your engine a problem? 3 bladed prop? Curious... Montblack |
#29
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Corvair conversion engines - cracked crank link
"Morgans" wrote in
: "Cal Vanize" wrote Good points all. The point that stood out most for me was the part about the crank from the engine that William built for his own demo 601. From the article: "This engine represents a standard installation, albeit one that was flown at its limits by Gus"... "showed stress fractures on both sides of the area in question." at 200 hours. "no nitride" \ Yes, that paragraph does seem to run contrary to the rest of the _long_ website's information. So what gives, others in the know? His recomendation of nitriding every corvair crank is NEW based on this data and the several KR crank issues in the recent past. In other words, nitriding was considered optional until the last week or so.... -- -- ET :-) "A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."---- Douglas Adams |
#30
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Corvair conversion engines
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