The biggest problem with auto engine conversion to marine use is the
transmission. Marine transmissions absorb the thrust from the propeller and
have large thrust bearings designed for that kind of load. Other types of
transmissions quickly wear out due to that thrust which they were never designed
for. There are solutions but they all tend to be pricey.

JJ

On Fri, 5 Mar 2004 23:12:43 -0500, Terry King wrote:

Hi Brian,

I've done conversions on automobile V-8's and run them for years..

I have a 350 GM in the same boat I built in 1978 (25th anniversary last
Summer on Lake Champlain).

The 'conventional' conversion adds exhaust manifolds, water
pump/plumbing, flame arrester, drive train solution, and motor mounts.

Since it's been so long since I've done one, and I'm interested in 1 or 2
small diesels for a slower bigger boat, I wonder what people here have
done.

In article ,
says...
I've done an engine aero conversion, and there is more to it than
meets the eye, so I am leery.
But thinking on your suggestion, we are talking cooling and we are
talking forward/reverse. Think you could handle those?
If you can, VW would be very, very promising.
Or howz about a Mercedes?

James Johnson
remove the "dot" from after sail in email address to reply

Good thought, about thrust bearings....
To get a feeling for the size of the force, I'll explore the curious
fact that a given HP gives more thust at lower operating speed.

Ignore losses (!)
Take 20 HP as the example
20 HP = 20 X 746 watts, say 15 kW

And let's take speeds of 2 mph, 4 mph, 6 mph
Roughly, thats 1 meters/second, 2 m/s, 3 m/s
so the maximal thrust is 15,000 newtons, 7,500 newtons
and 5,000 newtons at each speed.

Converting to US customary, that's
3300 lbs (Really?) at 1 mph, 1600 lbs at 2, and 800 lbs
at 3 mph respectively.

I guess that's why an aero conversion can get by with the little
thrust bearings fitted to the VW bug engine (for instance)
but a boat engine needs tougher stuff.....

Brian W

On Wed, 17 Mar 2004 00:47:06 GMT, James Johnson
wrote:

The biggest problem with auto engine conversion to marine use is the
transmission. Marine transmissions absorb the thrust from the propeller and
have large thrust bearings designed for that kind of load. Other types of
transmissions quickly wear out due to that thrust which they were never designed
for. There are solutions but they all tend to be pricey.

JJ

On Fri, 5 Mar 2004 23:12:43 -0500, Terry King wrote:

Hi Brian,

I've done conversions on automobile V-8's and run them for years..

I have a 350 GM in the same boat I built in 1978 (25th anniversary last
Summer on Lake Champlain).

The 'conventional' conversion adds exhaust manifolds, water
pump/plumbing, flame arrester, drive train solution, and motor mounts.

Since it's been so long since I've done one, and I'm interested in 1 or 2
small diesels for a slower bigger boat, I wonder what people here have
done.

In article ,
says...
I've done an engine aero conversion, and there is more to it than
meets the eye, so I am leery.
But thinking on your suggestion, we are talking cooling and we are
talking forward/reverse. Think you could handle those?
If you can, VW would be very, very promising.
Or howz about a Mercedes?

James Johnson
remove the "dot" from after sail in email address to reply