Another approach to the engine - prop - performance equation

[Bret S]

Haven't posted anything stupid in a while I guess what I mean to say is I haven't posted anything in a while

So to the point... I'm still a ways off from buying yet been dreaming due to all the IO-390-X postings and wanted to pose a question about engine power, prop and budget trade offs.

To keep the initial investment lower, but with an eye to the future when I want to buy an $11000 composite acro propeller to mate with the 210hp beast. I haven't seen anyone consider:

IO-390-X with a 3 blade Catto prop

$32000 eng
$1900 prop
--------------
$33900 total

- vs -

Lycoming IO-360-M1B with a Harzell BA and governer that I consider minimum performance level

$24400 eng
$1100 gov
$6100 prop
---------------
$31600 total

How much of the performance loss from a FP wooden prop with an additional 30 hp be vs. the 180 hp CS system?

I might assume I'd be doing 8000' crusing at %65 power with the IO-390-X to roughly equal the %75 power cruse of the IO-360 for fuel economy and yet want to do some deceint sport acro.

Any insights?

[rv8180]

That's my line of thought too.
Everything is set up for an easy conversion to a CS prop in case I want to change later.
[IMG]

[N941WR]

Here is another thought...

Why not ask Craig Catto to make you a four bladed prop? I'm sure he can give you the pro's and con's of such a set up.

I suspect you will have enough power to absorb the additonal power and wouldn't that look SO cool! Never mind it might cost you a few knots at Vcr.

[Bret S]

I know its a comparison that may be difficult to quantify given choice of propeller pitch and other factors, but...

IO-360-M1B (180hp) and Hartzell BA prop weighing est. 355 lbs
vs
IO-390-X (210hp) and Catto 3 bladed prop weighing est. 328 lbs

Weights taken from Lycoming spec sheets and this forum.

Does any one have a gut feeling about differences?

I'm an economy cruser so flat out top speed isn't the issue and I think I can get comperable MPG out of either system.

How might the two systems compare in climb rate?

[rv8180]

Originally Posted by Bret S

.........

I'm an economy cruser so flat out top speed isn't the issue and I think I can get comperable MPG out of either system.

How might the two systems compare in climb rate?

If that's the case, why not an 0-320 with a CS prop?

[Bret S]

Originally Posted by rv8180

If that's the case, why not an 0-320 with a CS prop?

High power + good CS aerobatic prop = vertical penetration in up lines as an ultimate goal, but costs $$$

If I buy the 180hp engine to start I'm probably not going to upgrade the 180hp engine to a 210hp later. For economy if I start with a FP prop on the 210hp then I'm spending about the same amount (budget wise) as the 180hp and WW200C aerobatic prop.

If I spend all my startup money on 180hp + CS prop then I have no upgrade path without buying and installing a new higher hp engine.

The question was posed: How close to a 180hp + CS prop will the 210hp and lightweight FP prop be since I'm still interested in performance. Maybe this approach makes no sense and that is what I'm trying to determine.

Bret

[burgundyja]

i am thinkining the same thing. one idea i had is to do the 180hp light engine and then put on a light composite prop. the question i have is what is the best place to get the engine. eci supieor mattick or lycomying. and what composite prop is the best for aerobatics?