2-stroke diesel is the (near) future?

On Tue, 24 May 2005 21:54:29 GMT, Thomas Tornblom
-to-reply wrote:

Steve writes:

Sport Pilot wrote:

Why the obvious apple and orange comparision?


To refute the statement that "more speed is more power."

You need to compare engines of equal size.


OK, Lets do it!

Dodge 5.9 Liter v8 gasoline engine: 230 horsepower at ~5000 RPM

Compared to:

Dodge/Cummins 5.9 Liter turbo-diesel engine: 325 horsepower at 2900 RPM


More speed is NOT more power any more than more torque at the same
speed is more power.


One BIG factor is being forgotten here. The diesel is turboed. This
makes it roughly equivalent to an 8 liter engine at about 6psi boost.
Any combustion engine produces power in proportion to the amount of
air consumed. On a diesel it does not necessarily "consume" all the
air that goes through it - but the maximum power output is definitely
limitted by how much air can be put through it. A turbo can eisily
double the amount of air an engine pumps through it at a given speed.

Running an engine at double the speed also increases the amount of air
going through the engine - not quite double due to reduced volumetric
efficiency at speed.

Double the CFM gives double the horsepower, before factoring in
frictional losses and / or pumping losses.

A naturally aspirated diesel engine generally produces less HP per
unit of displacement, but more torque at low RPMs due in part to less
pumping loss (no air throttle)
uh?

More torque at the same speed *is* more power.

power = torque * speed

Had the gas engine produced the same torque at 5000 rpms as the diesel
do at 2900, then it would have had about 560 hp at 5000.

Thomas

wrote:


One BIG factor is being forgotten here. The diesel is turboed. This
makes it roughly equivalent to an 8 liter engine at about 6psi boost.
Any combustion engine produces power in proportion to the amount of
air consumed. On a diesel it does not necessarily "consume" all the
air that goes through it - but the maximum power output is definitely
limitted by how much air can be put through it. A turbo can eisily
double the amount of air an engine pumps through it at a given speed.

Running an engine at double the speed also increases the amount of air
going through the engine - not quite double due to reduced volumetric
efficiency at speed.

Double the CFM gives double the horsepower, before factoring in
frictional losses and / or pumping losses.

A naturally aspirated diesel engine generally produces less HP per
unit of displacement, but more torque at low RPMs due in part to less
pumping loss (no air throttle)

SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.

Don Stauffer wrote:




SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.

You forgot supercharged plus turbocharged
http://www.wilksch.com/


--
Pub: http://www.slowfood.fr/france
Philippe Vessaire Ò¿Ó¬

Philippe wrote:
Don Stauffer wrote:





SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.


You forgot supercharged plus turbocharged
http://www.wilksch.com/


I know of some SI engines (aircraft engines) that have both geared and
turbochargers, but not any Diesels. Which Diesels are two-staged?

Don Stauffer wrote:

SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.

I believe that if you look at modern diesels currently being produced
and sold, you'll find virtually NONE rated at more than 50-60 horsepower
that are not turbo-supercharged. And equally few that are strictly
mechanically blown (the Detroit Diesel 2-strokes are no longer in
production). The VAST majority are, indeed, turbo-supercharged.

"Steve" wrote

I believe that if you look at modern diesels currently being produced
and sold, you'll find virtually NONE rated at more than 50-60 horsepower
that are not turbo-supercharged. And equally few that are strictly
mechanically blown (the Detroit Diesel 2-strokes are no longer in
production). The VAST majority are, indeed, turbo-supercharged.

Not true of some of our school busses that were produced in the past 5 or so
years. They make up for the lack of super or turbocharging with more cubic
inches.
--
Jim in NC

Morgans wrote:

"Steve" wrote


I believe that if you look at modern diesels currently being produced
and sold, you'll find virtually NONE rated at more than 50-60 horsepower
that are not turbo-supercharged. And equally few that are strictly
mechanically blown (the Detroit Diesel 2-strokes are no longer in
production). The VAST majority are, indeed, turbo-supercharged.


Not true of some of our school busses that were produced in the past 5 or so
years. They make up for the lack of super or turbocharging with more cubic
inches.

I say AGAIN... what percentage of the market is that? Tiny. And they
only TRY to make up with more cubic inches- a DT466E would run rings
around them.

"Steve" wrote

I say AGAIN... what percentage of the market is that? Tiny. And they
only TRY to make up with more cubic inches- a DT466E would run rings
around them.

I was not taking issue with the tiny percentage concept. I did take issue
with the following, and the NONE

I believe that if you look at modern diesels currently being produced
and sold, you'll find virtually NONE rated at more than 50-60 horsepower
that are not turbo-supercharged.

Not a big deal to me, one way or the other. I always found the non turbo
buses under powered, compared to their turbo brothers.
--
Jim in NC

On Wed, 25 May 2005 09:37:53 -0500, Don Stauffer
wrote:

wrote:


One BIG factor is being forgotten here. The diesel is turboed. This
makes it roughly equivalent to an 8 liter engine at about 6psi boost.
Any combustion engine produces power in proportion to the amount of
air consumed. On a diesel it does not necessarily "consume" all the
air that goes through it - but the maximum power output is definitely
limitted by how much air can be put through it. A turbo can eisily
double the amount of air an engine pumps through it at a given speed.

Running an engine at double the speed also increases the amount of air
going through the engine - not quite double due to reduced volumetric
efficiency at speed.

Double the CFM gives double the horsepower, before factoring in
frictional losses and / or pumping losses.

A naturally aspirated diesel engine generally produces less HP per
unit of displacement, but more torque at low RPMs due in part to less
pumping loss (no air throttle)

SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.


The post being replied to was comparing a turbo cummins to a gas
engine.

Nobody ever said all diesels are turboed.