The Murphy Builders Site

If anyone likes to follow diesels for aircraft Thielert Aircraft of
Germany has several flying in certified aircraft. They claim their 125
is very close to the 320 in weight and ultimate HP. I have a pointer at
http://wrayt.tripod.com/diesel.html
Still looks a bit heavy to me ...but then I don't know the all up
weight of the 320.

--
Wray Thompson ...Rebel 306 ...home page http://wrayt.tripod.com/
My ICQ number is 29764664



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I looked up Wray Thompson's web site and was surprised to learn that the
Thielert engine is similar to one that I have tested on a dynamometer - the
Mercedes Benz OM-668 engine, which is used in Mercedes A170 vehicles. Same
bore (80 mm), same stroke (84 mm). Both engines lay on their sides in the
same way. Both engines have 4 valves per cylinder, aluminum blick and head,
and electronic fuel injection. The Mercedes engine produces 66 kW (88 hp) @
4200 rpm and has a nearly constant torque of 180 Nm (132 ft-lb) from 1600 to
3200 rpm. The Thielert data shows 135 hp at 2300 prop rpm (3887 engine
rpm). This translates to 178 ft-lb of torque at the engine. It is obvious
that Thielert has modified the turbo wategate opening profile. My tests
show that Mercedes gradually opens the wastegate as speed increases above
3200 rpm.

One difference is that the Thielert engine has a dry-sump lubrication
system, while the Mercedes has a wet sump with a different (and very
unusual) shape. I found that the oil temperature of the Mercedes engine
would exceed 275 F whenever it was operated at more than 70 hp for any
length of time. I hope Thielert has a more efficient oil cooler.

Overall, the Mercedes engine seems to be very rugged at the 88-hp level
(assuming that you have some additional oil cooling). However, the Mercedes
engine produces only 0.85 hp per cubic inch of displacement, while the
Thielert engine produces 1.3 hp per cubic inch. That is a lot for a diesel!

Does anyone know if the Thielert engine is based on the Mercedes OM-668
engine, or are they different designs? Mercedes has a similar 2.2-liter
engine that is used in the C-class vehicles. Does anyone know if Thielert
plans to modify that engine for aircraft use?
--
Roger Cole <rcole927@earthlink.net>
Elite 709



---------- Digest Message #4 ----------
Date: Mon, 24 Dec 2001 08:07:52 -0800
From: wrayt@sympatico.ca
To: murphy-rebel
Subject: Diesels

If anyone likes to follow diesels for aircraft Thielert Aircraft of
Germany has several flying in certified aircraft. They claim their 125
is very close to the 320 in weight and ultimate HP. I have a pointer at
http://wrayt.tripod.com/diesel.html
Still looks a bit heavy to me ...but then I don't know the all up
weight of the 320.

--
Wray Thompson ...Rebel 306 ...home page http://wrayt.tripod.com/
My ICQ number is 29764664



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These things are fairly useless unless they can burn jet fuel and the
big boys don't give a second thought to turbine fuel until it gets below
-40 degrees...

Ken

Keith Leitch wrote:

That Gemini sure looks promising. Just don't know if I would want a diesel engine where I'll be living. Northern MN get pretty cold. I know gelling isn't as big an issue as it once was but still have the fears of it.

Keith R661

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