I just yanked the 165HP Perkins out of my boat. (Hydrolocked- due to a weird
failure in the intercooler- and with 4000 hours on a 20 year old engine it
seemed the right thing to do).

I replaced it with a naturally aspirated Perkins, somewhat the same engine but
with a better injection sytem and an exhaust manifold cooled with the engine
coolant rather than salt water. The NA version of the engine is 135HP.

I thought I'd probably lose a little speed, but I've picked up at least a half
knot.
(I do cruise the NA 100 RPM higher than
I did the turbo)

One of our local Perkins mechanics has told me, in the past, that he has been
able to convert the 165's to naturals.
I'm not sure what the process involves, but he led me to believe the engine
will still run
OK with the turbo removed. (It would make sense that the injectors and/or pump
might need to be changed.) At the lower end of the RPM range you report, you're
only getting "some" benefit from the turbo in any case.

I wouldn't worry much about overheating the engine due to lack of an
intercooler if you switch to NA- the air charge cooler is really only required
because the air gets
superheated when it is pressurized by the turbo. I'm not sure the air on the
output side of the air charge cooler could ever be considered refrigerated. :-)

If you have spoken with a mechanic who says he has done one of these
conversions, I would love to get in touch with him. I am looking for a
first hand experience.


"Gould 0738" wrote in message
...
I just yanked the 165HP Perkins out of my boat. (Hydrolocked- due to a
weird
failure in the intercooler- and with 4000 hours on a 20 year old engine it
seemed the right thing to do).

I replaced it with a naturally aspirated Perkins, somewhat the same engine
but
with a better injection sytem and an exhaust manifold cooled with the
engine
coolant rather than salt water. The NA version of the engine is 135HP.

I thought I'd probably lose a little speed, but I've picked up at least a
half
knot.
(I do cruise the NA 100 RPM higher than
I did the turbo)

One of our local Perkins mechanics has told me, in the past, that he has
been
able to convert the 165's to naturals.
I'm not sure what the process involves, but he led me to believe the
engine
will still run
OK with the turbo removed. (It would make sense that the injectors and/or
pump
might need to be changed.) At the lower end of the RPM range you report,
you're
only getting "some" benefit from the turbo in any case.

I wouldn't worry much about overheating the engine due to lack of an
intercooler if you switch to NA- the air charge cooler is really only
required
because the air gets
superheated when it is pressurized by the turbo. I'm not sure the air on
the
output side of the air charge cooler could ever be considered
refrigerated. :-)

If you have spoken with a mechanic who says he has done one of these
conversions, I would love to get in touch with him. I am looking for a
first hand experience.


"Gould 0738" wrote in message
...
I just yanked the 165HP Perkins out of my boat. (Hydrolocked- due to a
weird
failure in the intercooler- and with 4000 hours on a 20 year old engine it
seemed the right thing to do).

I replaced it with a naturally aspirated Perkins, somewhat the same engine
but
with a better injection sytem and an exhaust manifold cooled with the
engine
coolant rather than salt water. The NA version of the engine is 135HP.

I thought I'd probably lose a little speed, but I've picked up at least a
half
knot.
(I do cruise the NA 100 RPM higher than
I did the turbo)

One of our local Perkins mechanics has told me, in the past, that he has
been
able to convert the 165's to naturals.
I'm not sure what the process involves, but he led me to believe the
engine
will still run
OK with the turbo removed. (It would make sense that the injectors and/or
pump
might need to be changed.) At the lower end of the RPM range you report,
you're
only getting "some" benefit from the turbo in any case.

I wouldn't worry much about overheating the engine due to lack of an
intercooler if you switch to NA- the air charge cooler is really only
required
because the air gets
superheated when it is pressurized by the turbo. I'm not sure the air on
the
output side of the air charge cooler could ever be considered
refrigerated. :-)

Clyde Mehaffey, of Seattle, has told me
he has done this conversion.

The utlimate Seattle source for Perkins is Larry Stewart, of Stewart's Marine.
206-789-4600. I've done business with Larry for a long time, and bought my new
135 from him. Larry originally predicted that my boat might be faster with the
135- and he turned out to be right. Larry is known as the Perkins guru up this
way. You might ask Larry his opinion about pulling the turbo off a 165. Even
though Clyde has done it, I'd run the concept by Larry before going ahead with
it.

Sort of like getting the opinion of more than a single physician.

I don't have a phone number for Clyde, (I frequently run into him around
various docks in the area, he's a busy and respected diesel technician).... but
Larry will.

(I haven't regretted replacing my old 165 rather than attempting a rebuild. The
new engine is a thing of beauty. But the price of a new engine is into five
figures, you've got two, and still have relatively low hours. My 165 would have
gone 6000 hours, I'll bet, if the air charge cooler hadn't gone way weird on
me.)

Clyde Mehaffey, of Seattle, has told me
he has done this conversion.

The utlimate Seattle source for Perkins is Larry Stewart, of Stewart's Marine.
206-789-4600. I've done business with Larry for a long time, and bought my new
135 from him. Larry originally predicted that my boat might be faster with the
135- and he turned out to be right. Larry is known as the Perkins guru up this
way. You might ask Larry his opinion about pulling the turbo off a 165. Even
though Clyde has done it, I'd run the concept by Larry before going ahead with
it.

Sort of like getting the opinion of more than a single physician.

I don't have a phone number for Clyde, (I frequently run into him around
various docks in the area, he's a busy and respected diesel technician).... but
Larry will.

(I haven't regretted replacing my old 165 rather than attempting a rebuild. The
new engine is a thing of beauty. But the price of a new engine is into five
figures, you've got two, and still have relatively low hours. My 165 would have
gone 6000 hours, I'll bet, if the air charge cooler hadn't gone way weird on
me.)