Old Perkins Diesel questions:
I have questions for diesel experts on this forum about "detuning" my
Perkins 6 cylinder Turbo diesels. I would also welcome suggestions for
other forums where this might be posted.

Background: I have a 34' Silverton hull that I have rebuilt as a pilot
house trawler. The boat is powered by twin 354" 180HP Perkins 6 cylinder
turbo diesels. This is WAY more power than I ever need for this boat. I
run it like a trawler even though it is a planing style deep V hull design.
These motors have given me more than 1200 hours of reliable operation
loafing along at 1200 to 1300 RPM.

I wish to simplify the plumbing on the motors to have fewer maintenance
items and gain space in the engine room. My first choice would be to find
someone with a similar pair of normally aspirated Perkins and do an even
swap. But that is likely to be hard to find.

Second choice is to get rid of some of the turbo related plumbing on my
motors. I am well aware of all the differences in injection pump specs
between normally aspirated and turbo diesels.

A good place to begin would be removing the large, bulky intercoolers and
running the turbo outlet directly to the intake manifold. There would be a
huge gain in engine room space and accessibility, and I would not have to
maintain the intercoolers. MY OPINION is that the importance of the
intercooler increases as the diesel gets closer to full throttle operation.
My guess is that at half throttle or less as I use these motors, I would not
notice much difference without the intercoolers. The fuel /air mix at
cumbustion would be a little less dense, but not greatly so. Opinions?

A third choice is to remove the turbo's all together. At idle, a turbo does
very little. But I suspect that you would get quite a rich mixture and a
smokey exhaust at even moderate loads. Does anyone have experience (perhaps
through losing a turbo while on a long cruise) with how well a turbo diesel
works at low to mid power without a turbo?

Thanks for any input (or even speculation) - Tom
respond here or: removing percent signs:

On Fri, 12 Mar 2004 21:04:52 GMT, "tkranz"
wrote:

Old Perkins Diesel questions:
I have questions for diesel experts on this forum about "detuning" my
Perkins 6 cylinder Turbo diesels. I would also welcome suggestions for
other forums where this might be posted.

Background: I have a 34' Silverton hull that I have rebuilt as a pilot
house trawler. The boat is powered by twin 354" 180HP Perkins 6 cylinder
turbo diesels. This is WAY more power than I ever need for this boat. I
run it like a trawler even though it is a planing style deep V hull design.
These motors have given me more than 1200 hours of reliable operation
loafing along at 1200 to 1300 RPM.

I wish to simplify the plumbing on the motors to have fewer maintenance
items and gain space in the engine room. My first choice would be to find
someone with a similar pair of normally aspirated Perkins and do an even
swap. But that is likely to be hard to find.

Second choice is to get rid of some of the turbo related plumbing on my
motors. I am well aware of all the differences in injection pump specs
between normally aspirated and turbo diesels.

A good place to begin would be removing the large, bulky intercoolers and
running the turbo outlet directly to the intake manifold. There would be a
huge gain in engine room space and accessibility, and I would not have to
maintain the intercoolers. MY OPINION is that the importance of the
intercooler increases as the diesel gets closer to full throttle operation.
My guess is that at half throttle or less as I use these motors, I would not
notice much difference without the intercoolers. The fuel /air mix at
cumbustion would be a little less dense, but not greatly so. Opinions?

A third choice is to remove the turbo's all together. At idle, a turbo does
very little. But I suspect that you would get quite a rich mixture and a
smokey exhaust at even moderate loads. Does anyone have experience (perhaps
through losing a turbo while on a long cruise) with how well a turbo diesel
works at low to mid power without a turbo?

Thanks for any input (or even speculation) - Tom
respond here or: removing percent signs:


Tom,

The P6354T can be downrated by removing all of the Turbo equipment,
BUT, you will need to get the injection pumps recalibrated as the
governor spring rates are different on some models.

The engines will be slightly lower on output than a standard non-turbo
engine as the compression ratio is less, but you will still get about
100 HP but torque will be compromised.
Just for interest http://www.woods-group.co.uk/index.html have a
couple of ex-admiralty non-turbos fully marinised from £1500 each,
straight swop to fit, and you could sell off your old uns complete.

HTH

John