Today's Message Index:
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1. 02:30 PM - Re: 10:1 Compression / IO-360 200 HP (SCOTT SPENCER)
2. 05:29 PM - Re: RV6A Training ()
Message 1
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| Subject: | Re: 10:1 Compression / IO-360 200 HP |
Interesting to follow this thread...
Especially since I just upped my compression in the RV-4 from 8.5:1 to 9.0:1
on my O-320.
My personal experiences would make me tend to agree with jetpilotgeorge. I can
say that I detect no real differences in performance so far, and I have totally
given up the option to run on lower-octane fuels. I'm strictly 100LL now.
At 8.5 I found I could run most good-quality 87 octanes with no detonation. It
was right near the limit with stuff in that octane range. I've fooled around
with auto fuel for many years and while using an ANR headset I can hear (more
like feel) the onset of detonation. George is correct -it's very subtle and difficult
to detect unless it's really extreme detonation. Never hear it at all
without the ANR cutting out all the rumble.
I just ran the numbers using the formula from the article cited by Kevin Horton
earlier in this thread and found the efficiency increase gained by my doing
this to be a whopping one to 1.5 percent or 2.4 horsepower at best... and all
at the cost of longevity, reliability and the ability to run multiple (and less-expensive)
fuels.
A bad decision I feel... and if it wasn't so darn much work, I'd take those pistons
right back out today... and breathe easier. Big gains to be had going from
7.0:1 up to 8.5... just liabilities from 8.5 to 9.
All those people out there claiming they have such-and-such horsepower output
from their engines are mostly just blowing smoke. You hear it at every fly-in
or airport bull session. 99% have never run their engines on a dyno or otherwise
demonstrated what power they are really making. Some friends of mine just
had an O-320 built up with 9.0:1 pistons and cold-air induction and fuel injection
at a reputable shop. It was actually run in a dyno-equipped test cell at
Poplar Grove Airmotive. Made 168 horsepower. That's only 8 more than rated for
an 8.5:1 O-320 with a carb and Lycoming's own stock (hot-air) sump. I'd be willing
to bet serious money most of the gain is from the cold air alone and not
from the compression -and the math confirms it.
A stock O-360 would have been a cheaper and more reliable horsepower upgrade
-at the expense of some weight. Do your own math -lots of choices in this game...
but that's what makes it so interesting.
Your mileage may vary.
Scott
N4ZW
Message 2
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| Subject: | Re: RV6A Training |
Thanks. I will if a lead I now have doesn't pan out.
----- Original Message -----
From: "Carlos Hernandez" <carlosh@structuralaz.com>
Sent: Friday, July 18, 2008 11:10 AM
Subject: Re: RV-List: RV6A Training
>
> Try this yahoo RV group - http://groups.yahoo.com/group/OhioValleyRVators/
> These guys are active and I'm pretty sure they can answer that question
> quick.
>
> Carlos
>
> dwhite17@columbus.rr.com wrote:
>> Goodmorning all: My buidling partner and I need to get 3 hours each
>> traning by a CFI in a RV6A, RV7A or RV9A to satisfy our insurance
>> company. We live in the Columbus, Ohio area and were wondering if there
>> are any transition trainers in the area?
>> D. White
>>
>>
>> ------------------------------------------------------------------------
>>
>> Checked by AVG.
>
> --
> Carlos Hernandez <carlosh@sec-engr.com>
> Structural Engineers Company
> 2963 W. Elliot Rd. - Suite 3
> Chandler, AZ 85224
> Phone: 480.968.8600
> Fax: 480.968.8608
> www.sec-engr.com
>
>
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