On Wed, 22 Aug 2007 21:05:57 +0700, wrote:

On Wed, 22 Aug 2007 12:27:55 GMT, "Pete C."
wrote:

Eisboch wrote:

"JohnM" wrote in message
m...


All two-stroke Detroits have a blower. It's necessary to the operation of
the engine, does the job that crankcase pressure does in a little
two-stroke. On the inline motors it mounts on the side of the block.

John

If a "blower" is defined by you as a turbo (i.e. .., device to increase air
flow into the cylinders), then you are in error. I know several people with
2 stroke DD 6-71's. Some are naturally aspirated, some have turbos
(blowers).

Eisboch

A "blower" generally refers to a direct driven super charger, not an
exhaust driven turbo charger.

The Detroit Diesel is a two stroke, diesel. The piston goes down on
the power stroke and comes up on the compression stroke. Without the
mechanical driven "blower" which simply blows air in through the
cylinder ports and through the exhaust ports at the beginning of the
compression stroke there would be no way to get a charge of air into
the engine.

If you wanted to increase the pressure and volume of this air flow you
could add a exhaust driven compressor before the "blower", But you
must have the "blower" for the engine to run.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

Neither being a two-stroke nor using diesel oil (nor indeed the
combination) requires a blower/turbo for such an engine to operate. It is
true that engines can be designed so that, were the blower/turbo with which
they are normally equipped to be removed they would not run, that would be
due to other design decisions, not to the choice of fuel, method of
ignition, and/or two/four-stroke operation.

Is anyone at rec.crafts.metalworking reading this thread??
If not, I suggest we (at rec.boats) stop further crossposting there.

On Wed, 22 Aug 07, jtay wrote:
Neither being a two-stroke nor using diesel oil (nor indeed the
combination) requires a blower/turbo for such an engine to operate.

Running a Detroit 4-53 without a blower (and maybe all Detroit 2
strokes -shrug- I dunno) would indeed take a complete and major league
re-design. Not just a few bolt on changes for sure.

Rick

On Wed, 22 Aug 2007 11:29:44 -0500, lid wrote:

On Wed, 22 Aug 07, jtay wrote:
Neither being a two-stroke nor using diesel oil (nor indeed the
combination) requires a blower/turbo for such an engine to operate.

Running a Detroit 4-53 without a blower (and maybe all Detroit 2
strokes -shrug- I dunno) would indeed take a complete and major league
re-design. Not just a few bolt on changes for sure.

Absolutely right. The Detroit 2 stroke design requires a blower to
move new air into the piston and purge the ehaust gases. It will not
run without it, and little or no increase in volumetric efficiency is
achieved. A turbo charger on the other hand is designed to increase
the air charge to the piston above atmospheric pressure, and therefore
horsepower is increased as the effective cylinder volume is increased.

The confusion arises from the fact that a Detroit blower can also be
used on a gasoline engine as a supercharger. Same basic device but a
different purpose and result.

In article ,
_ wrote:

[...]


The Detroit Diesel is a two stroke, diesel. The piston goes down on
the power stroke and comes up on the compression stroke. Without the
mechanical driven "blower" which simply blows air in through the
cylinder ports and through the exhaust ports at the beginning of the
compression stroke there would be no way to get a charge of air into
the engine.

If you wanted to increase the pressure and volume of this air flow you
could add a exhaust driven compressor before the "blower", But you
must have the "blower" for the engine to run.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

Neither being a two-stroke nor using diesel oil (nor indeed the
combination) requires a blower/turbo for such an engine to operate. It is
true that engines can be designed so that, were the blower/turbo with which
they are normally equipped to be removed they would not run, that would be
due to other design decisions, not to the choice of fuel, method of
ignition, and/or two/four-stroke operation.

Being a two-stroke, and a Detroit, it requires a blower to operate.
Come to think of it, I've never heard of any engines that are two
stroke and do not use forced induction of one form or another. Even
little chain saws use the crankcase volume as a blower.
Seems as if those two eliminated strokes--intake and exhaust--are
taken up by the blower.
How would you build an 2-stroke engine without forced induction?

--
B.B. --I am not a goat! thegoat4 at airmail dot net

On Thu, 23 Aug 2007 11:08:52 -0500, "B.B."
u wrote:

In article ,
_ wrote:

[...]


The Detroit Diesel is a two stroke, diesel. The piston goes down on
the power stroke and comes up on the compression stroke. Without the
mechanical driven "blower" which simply blows air in through the
cylinder ports and through the exhaust ports at the beginning of the
compression stroke there would be no way to get a charge of air into
the engine.

If you wanted to increase the pressure and volume of this air flow you
could add a exhaust driven compressor before the "blower", But you
must have the "blower" for the engine to run.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

Neither being a two-stroke nor using diesel oil (nor indeed the
combination) requires a blower/turbo for such an engine to operate. It is
true that engines can be designed so that, were the blower/turbo with which
they are normally equipped to be removed they would not run, that would be
due to other design decisions, not to the choice of fuel, method of
ignition, and/or two/four-stroke operation.

O.K. Assuming that your statement is correct And starting from the
power stroke of a two stroke diesel engine.

(1) Diesel fuel is injected into the combustion chamber where air has
been compressed until it exceeds the ignition temperature of the duel.

(2) The rapidly expanding gases created by the burning fuel act to
push the only movable part of the combustion chamber, the piston
downward. At the bottom of the power stroke the gasses inside the
combustion chamber still are far hotter then ambient temperature and
thus exceed ambient pressure.

(3) the piston having reached the bottom of its power stroke begins to
be driven upward by the crankshaft and connecting rod. When it piston
reaches roughly the top of its compression stroke another injection
event occurs.

Now, as temperature of the gasses within the combustion chamber and
thus the pressure, is higher then ambient temperature and pressure at
the bottom of the power stroke the flow should be from the high
pressure area to a lower pressure area. In which case the engine would
not receive any air for the next stroke.

So, where does the two stroke diesel engine get the air necessary to
support combustion of the next injection of diesel fuel if not through
the use of a mechanical air pump, usually referred to as a "Blower" in
D.D. parlance


Being a two-stroke, and a Detroit, it requires a blower to operate.
Come to think of it, I've never heard of any engines that are two
stroke and do not use forced induction of one form or another. Even
little chain saws use the crankcase volume as a blower.
Seems as if those two eliminated strokes--intake and exhaust--are
taken up by the blower.
How would you build an 2-stroke engine without forced induction?



Bruce in Bangkok
(brucepaigeATgmailDOTcom)

wrote in message
news snip

Now, as temperature of the gasses within the combustion chamber and
thus the pressure, is higher then ambient temperature and pressure at
the bottom of the power stroke the flow should be from the high
pressure area to a lower pressure area. In which case the engine would
not receive any air for the next stroke.

So, where does the two stroke diesel engine get the air necessary to
support combustion of the next injection of diesel fuel if not through
the use of a mechanical air pump, usually referred to as a "Blower" in
D.D. parlance

Presumably it would get them by using the crankcase as a compressor like
a gas 2stroke does.

Whether it is possible to get the necessary compression for ignition,
especially while at cranking speed, while dealing with transfer ports
etc is left as an exercise for the student.

del

"Del Cecchi" wrote in message
...

wrote in message
news snip

Now, as temperature of the gasses within the combustion chamber and
thus the pressure, is higher then ambient temperature and pressure at
the bottom of the power stroke the flow should be from the high
pressure area to a lower pressure area. In which case the engine would
not receive any air for the next stroke.

So, where does the two stroke diesel engine get the air necessary to
support combustion of the next injection of diesel fuel if not through
the use of a mechanical air pump, usually referred to as a "Blower" in
D.D. parlance

Presumably it would get them by using the crankcase as a compressor like a
gas 2stroke does.

Whether it is possible to get the necessary compression for ignition,
especially while at cranking speed, while dealing with transfer ports etc
is left as an exercise for the student.

del


2 stroke diesels will run without a blower. I have a model airplane engine
diesel that jsut uses the crankcase like a gas rig. And there were a lot of
those 1 lunger diesels in Montereys, etc, that did not have a blower.

On Thu, 23 Aug 2007 21:15:47 -0700, "Calif Bill"
wrote:


"Del Cecchi" wrote in message
...

wrote in message
news snip

Now, as temperature of the gasses within the combustion chamber and
thus the pressure, is higher then ambient temperature and pressure at
the bottom of the power stroke the flow should be from the high
pressure area to a lower pressure area. In which case the engine would
not receive any air for the next stroke.

So, where does the two stroke diesel engine get the air necessary to
support combustion of the next injection of diesel fuel if not through
the use of a mechanical air pump, usually referred to as a "Blower" in
D.D. parlance

Presumably it would get them by using the crankcase as a compressor like a
gas 2stroke does.

Whether it is possible to get the necessary compression for ignition,
especially while at cranking speed, while dealing with transfer ports etc
is left as an exercise for the student.

del


2 stroke diesels will run without a blower. I have a model airplane engine
diesel that jsut uses the crankcase like a gas rig. And there were a lot of
those 1 lunger diesels in Montereys, etc, that did not have a blower.


Sure you do and it worked just like a glow plug engine. You mixed oil
for lubrication and some nitro-benzine, or something like that, and it
ran. Exactly as do sea scooters, 2-stroke motor cycles and chain saws.

And the reason is that you use the bottom of the piston coming down on
the power stroke to compress the fuel/oil mixture in the crank case to
force it into the combustion chamber.

But we were talking specifically about a Detroit Diesel 2-stroke and
the fact that it does need the mechanical driven "blower" to run.




Bruce in Bangkok
(brucepaigeATgmailDOTcom)

wrote in message
...
On Thu, 23 Aug 2007 21:15:47 -0700, "Calif Bill"
wrote:


"Del Cecchi" wrote in message
...

wrote in message
news snip

Now, as temperature of the gasses within the combustion chamber and
thus the pressure, is higher then ambient temperature and pressure at
the bottom of the power stroke the flow should be from the high
pressure area to a lower pressure area. In which case the engine would
not receive any air for the next stroke.

So, where does the two stroke diesel engine get the air necessary to
support combustion of the next injection of diesel fuel if not through
the use of a mechanical air pump, usually referred to as a "Blower" in
D.D. parlance

Presumably it would get them by using the crankcase as a compressor like
a
gas 2stroke does.

Whether it is possible to get the necessary compression for ignition,
especially while at cranking speed, while dealing with transfer ports
etc
is left as an exercise for the student.

del


2 stroke diesels will run without a blower. I have a model airplane
engine
diesel that jsut uses the crankcase like a gas rig. And there were a lot
of
those 1 lunger diesels in Montereys, etc, that did not have a blower.


Sure you do and it worked just like a glow plug engine. You mixed oil
for lubrication and some nitro-benzine, or something like that, and it
ran. Exactly as do sea scooters, 2-stroke motor cycles and chain saws.

And the reason is that you use the bottom of the piston coming down on
the power stroke to compress the fuel/oil mixture in the crank case to
force it into the combustion chamber.

But we were talking specifically about a Detroit Diesel 2-stroke and
the fact that it does need the mechanical driven "blower" to run.




Bruce in Bangkok
(brucepaigeATgmailDOTcom)

No, the statement was all diesels require a blower. There were lots of old
fishing boats with 1 and 2 piston diesels, that did not require a blower to
run. But they were designed like gas 2 stroke to use the crankcase as the
compressor.

"Calif Bill" wrote:
2 stroke diesels will run without a blower. I have a model airplane engine
diesel that jsut uses the crankcase like a gas rig

All 2 strokes are not designed alike. The term "2stroke" refers to how
often the piston goes up/down per power stroke. Not how air or fuel is
fed to the cylinder. The crankcase of you little diesel 2 stroke is
designed like an outboard. A DD crankcase is designed like your
automobile engine's (assuming it's a 4 stroke).
A DD 2 stroke can't run without a blower.

Rick