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This message was automatically forwarded on behalf of Bill Bayne. Please address any responses to the mail list or directly to Bill at: [EMAIL PROTECTED] -----Original Message----- From: William R. Bayne [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 21, 2006 10:22 PM To: Ed Burkhead Subject: Re: [COUPERS-TECH] Going for the overhaul rlytech Hi John, There was an extended discussion on this subject almost exactly two years ago (see Tech archives). This STC engine/prop combination is much more like a C-90 than a 0-200 in terms of operating rpm. The longer stroke of the C-90 translates to increased displacement. The higher compression ratio gets greater efficiency from modern fuels. The C-90 cam is designed to "peak out" at lower rpm than the C-85, so the C-85 cam is the "better" of the two. Look at the power curve of the C-90 operating at the 2575 rpm of the C-85, and you get about 94 hp. With the standard Stromberg carb, fuel flow might limit this to 93 hp, which is within 10% of allowable rated hp. For a "real" C-90, Continental approves 2625 rpm (95 hp) for take-off (1 minute only), so it would not appear prudent to cruise this unit above 2475 rpm (because of its longer stroke). Tweak the prop to optimum for your personal "mission requirements", and you should have a better, more efficient engine than any stock C-90 or (derated) 0-200. Regards, William R. Bayne <____|-(o)-|____> (Copyright 2004) -- On Feb 22, 2006, at 01:39, Anne and John wrote: > So, how much extra horsepower can really be expected from this STC, or > how much bang for the buck ??? > > The C85, C90, and 0-200 all have the same bore size, the C90 and 0-200 > have the same specs for piston stroke and compression ratio, so > pressumable have the same crank, the C90 has a higher lift cam, with > slightly more duration, the 0-200 similar lift, much more duration, > and possibly a larger carb. It would seem that adding the crank would > turn the 85 into a 90 without the better cam profile, which would kind > of make it a C-87, or a C-88. > Thats a lot of work and money for 3 or 4 extra horsepower. > My Continental Engine overhaul manual says that cranks can be ground > 10 thou under, would that not be the cheaper route to go, especially > with the extra machining that is necessary on the case. > > Just a thought. > > John H. CF-TSS ============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm
