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From: William R. Bayne <[EMAIL PROTECTED]>
Date: Wed, 12 Feb 2003 21:13:01 -0600
To: Justine Fowler <[EMAIL PROTECTED]>
Subject: Re: [COUPERS-TECH] 0 200 engine part STC.
on 2/12/03 6:52 PM, Justine Fowler at [EMAIL PROTECTED] wrote:
I have an Ercoupe 415C with an 85hp engine overhauled using the 0 200 crank, pistons and rods under an existing STC. My question is what is the horsepower of this engine?Because horsepower varies with rpm, the easy response is that there is no single correct answer. But to be properly responsive, what you need to know is in the Continental Operator's Manual, Form X30012 (1980 Teledyne Industries, Inc.)
Your hardware has rotating parts identical to both C-90 and O-200 except for the cam (which is also the primary difference between the C-90 and O-200). If you go to page 8 you can see the C-85 cam is designed for peak output at the 2575 rpm that engine reaches rated horsepower. On page 28 that's where maximum horsepower and prop load cross, and if you look at the fuel consumption curve below, you'll see that maximum efficiency is nearer to 2475 rpm.
Your cam isn't going to be happy or efficient at 0-200 rpms, so consult the C-90 chart on page 29 and see that with a prop pitched to peak about 2575 rpm (which is what you should already have if it's not a climb prop) you should get 97-98hp
output from your engine at that rpm.
I have been told there is a difference in HP due to the difference in weight of the pistons and compression, and was told to use only 89 octane or 100LL. The holders of the STC say no horsepower was submitted to the FAA when it was approved and they did not require one.The difference in hp is due to the displacement increase from 188 cu. in. to 200.921 (see p. 4.) resulting from the longer stroke of the C-90/O-200 crank/rods combination and associated increase in compression ratio from 6.3:1 to 7.0:1. You can see there that 80/87 octane fuel is fine for all of these engines.
I have been told unofficially that if the engine is run as an 0200 it produces 103hp, if run as an 85 (which
is required) it develops 93 to 95 HP?
The FAA will argue forever (which you already know "...is required") you can't legally pull more than 85hp from this engine. So if you're flying the FAA somewhere, don't.
Otherwise...!
Has this combination ever been horsepower tested to show the real HP?
Fred C Fowler [EMAIL PROTECTED]
Probably not a good idea to spread around if and when...might cause an FAA "re-examination" of a really good STC that coupers and others benefit from.
Regards
William R. Bayne
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