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From: William R. Bayne [mailto:[EMAIL PROTECTED]
Sent: Friday, November 18, 2005 6:07 PM
To: Ed Burkhead
Subject: WRB Re: [COUPERS-TECH] Costs involved inconverting 65hp engine to 75hp or 85hp
RLYTECH
Al,
The 65hp Ercoupes (prewar) have the A-65 Continental. This engine has no provision for a generator or starter, and most did not originally have the necessary electricals (wiring, battery) for night flight. They also had only one wing tank! The A-65 engine cannot be "upgraded" to anything else.
The postwar Ercoupes up through the CD Model were fitted with the C-75 engine, starter, generator, battery, etc. The E and G Models had the C-85. There is very little difference between the C-75 and the C-85. Many 75 hp have been converted to 85 hp. I'm not entirely convinced that this conversion makes a meaningful improvement in actual performance. A full explanation as to why is rather involved and more than I will attempt herein.
Because C-75/C-85 cranks are increasingly hard to find, several STCs have been approved allowing use of C-90/0-200 cranks, rods and pistons in overhauling C-75/85 engines. This conversion is quite worthwhile. Knowledgeable "fine tuning" of such can yield climb and/or cruise performance equal or exceeding a C-90 or 0-200 (depending on propeller and pitch selected). If the overhauled engine has a good crank, it might sell on eBay for something near the cost of the STC and necessary parts! If the crank is bad, you need a crank anyway.
Forneys, Alons and M10s originally fitted with the C-90 tend to weigh 100 lbs + more than an Ercoupe due to metal wings, additional equipment and upholstery. This seems to usually cancel out any performance advantage the "extra" 5 hp might otherwise offer the original airframe.
Any facility run by an A&P or IA is "qualified" according to the FAA to do this, but you would best search for one that has successfully done the operation once (or more, as you would a doctor). You should not volunteer yourself, your plane and your wallet as a guinea pig for anyone to learn on at your expense.
Best of luck,
William R. Bayne
<____|-(o)-|____>
(Copyright 2004)
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On Nov 18, 2005, at 5:21 PM, Al Ebbers wrote:
Hi: Right now I'm a Coupeless member. As I shop around for an aircraft I was wondering what it would cost to convert a 65 hp engine to a 75 or 85 hp engine. And if such an engine was converted to the higher horsepower, would the work performed qualify that as a major overhaul for engine time. And, along the same line does anyone know of a facility or AP that is qualified in Texas or adjacent States to do such work? Thanks.
Al Ebbers
Austin, TX
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