REFLECTOR: Re: Props

[Chuck Harbert]

TEC, I knew somebody would catch that if I'm still turning 2,700, I'd still 
only be going 180 kts, but I didn't mention that I really have a HIO-360 
which is a 2,900 rpm rated engine (rated 180hp @26.5' MP @3,900'). It's 
actually an angle valve 200hp high compression IO-360, but it comes standard 
with high performance parts i.e. better rods, lighter valve train, etc. When 
I had it rebuilt, I had it upgraded with piston oil squirters, balanced, 
etc. I expect that I'll be able to turn 2,900 at 24-25" of MP (about 160-170 
hp) which will be close to 200kts at higher altitudes in cruise.  This is 
actually under rated hp (under turbo-normalized), so the engine won't feel 
overloaded/overstressed.

I've talked to Catto about this setup at length, and we designed the FP prop 
with this in mind. There are a number of people who turn their engines over 
rated rpm, preferably at higher altitudes, and thus at reduced hp which is 
an acceptable procedure (even the Lycoming factory guy confirmed this-off 
the record). I was also told that you should never run over 3,200-3,300 rpm 
even at reduced hp. The big issue with this is keeping your CHT's within 
spec, which is why I installed the IO-540 naca ducts. We'll see how it goes.

Chuck H





> Message: 2
> Date: Tue, 28 Jun 2005 15:20:59 EDT
> From: HYTEC45 at aol.com
> Subject: Re: REFLECTOR: Re: Props
> To: reflector at tvbf.org
> Message-ID: <67.47d0a71e.2ff2fd1b at aol.com>
> Content-Type: text/plain; charset="us-ascii"
>
>
> In a message dated 6/28/2005 11:48:51 A.M. Pacific Standard Time,
> c.harbert at comcast.net writes:
>
> I have a  turbo system ready to install which will bring up the static
> to 2,400 rpm  and I'm expecting higher speeds at higher altitudes at below
> normalized MP  which is what Catto designed my prop for.
>
>
> If your turning already turning 2700, turbo charging will gain you 
> nothing
> in cruise regardless of what flight level your at with a fixed  pitch 
> unless
> you want to turn over 2700.  You need a CS prop to  channel that extra HP 
> @ alt.
> Of course, takeoff and climb will greatly  increase even with the fixed
> pitch.
>
> TEC