LOM engines

"ChuckSlusarczyk" wrote in message
...
In article , Roger Halstead
says...
I wonder why they use such a low compression ratio? Even car engines
running regular usually run 8:1. This one is 6.3:1.
It would reduce the stress on the parts, allowing less expensive
materials than a reliable high compression engine.

I guess they can also use lower octane fuel as well.

Chuck


6.3 to 1 is the compression ratio for the Continental A-65, which loves 80
octane avgas when it can find it.

In article ,
Roger Halstead wrote:




I wonder why they use such a low compression ratio? Even car engines
running regular usually run 8:1. This one is 6.3:1.
It would reduce the stress on the parts, allowing less expensive
materials than a reliable high compression engine.


They use such a low compression ratio so they can use Russian gasoline!

On Thu, 30 Oct 2003 03:50:22 GMT, Orval Fairbairn
wrote:

In article ,
Roger Halstead wrote:




I wonder why they use such a low compression ratio? Even car engines
running regular usually run 8:1. This one is 6.3:1.
It would reduce the stress on the parts, allowing less expensive
materials than a reliable high compression engine.


They use such a low compression ratio so they can use Russian gasoline!
No. They use the low compression ratio because the Walther LOM engine
has a centrifugal engine driven supercharger. ANy higher CR would be
dangerous under boost.

Roger Halstead wrote in message I wonder why they use such a low
compression ratio? Even car engines
running regular usually run 8:1. This one is 6.3:1.
It would reduce the stress on the parts, allowing less expensive
materials than a reliable high compression engine.

Durability is one reason. Additionally, the typical bore and stroke in
aircraft engines is much larger than automotive engines. I forget exactly
why the larger bore and stroke is more susceptable to detonation, but I seem
to recall it has something to do the ratio of quench area to fuel/air charge
decreasing as the cylinder size increases.

D.

On Thu, 30 Oct 2003 03:59:54 GMT, clare @ snyder.on .ca wrote:

On Thu, 30 Oct 2003 03:50:22 GMT, Orval Fairbairn
wrote:

In article ,
Roger Halstead wrote:




I wonder why they use such a low compression ratio? Even car engines
running regular usually run 8:1. This one is 6.3:1.
It would reduce the stress on the parts, allowing less expensive
materials than a reliable high compression engine.


They use such a low compression ratio so they can use Russian gasoline!
No. They use the low compression ratio because the Walther LOM engine
has a centrifugal engine driven supercharger. ANy higher CR would be
dangerous under boost.

US turbo'd engines use either 8 or 8.5:1 and my 300 HP IO540 uses 10:1
I'd think it would have a lot to do with the gas they are designed to
use and well as durability and manufacturing cost.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2).