Empathy List Archives

RP

Richter-Pooh@rocketmail.com

Thu, Jan 11, 2001 7:51 PM

<<Without supercharging, how much air will a Ford
Lehman 120 running at 1800 RPM suck out of my engine
room? Is it displacement times RPM? (in cubic
inches per minute)
Jerry O'Neill>>

Yes, but don't forget to divide by two, since there is
an intake stroke only every other revolution. Let's
see, 6 liters displacement times 1800 rpm /2 is 5400
liters per min, about 1400gal/min, or about 190 cu
ft/min (all figures approximate, I don't have my
calculator here). Fuel consumption varies a lot
depending on load, but air consumption changes only
with rpm.

=====
Mark Richter, M.E., aboard M/V Winnie the Pooh,
custom Morgan 46 Pilothouse Efficiency Trawler.
"Mark's Mobile Marine" electrical systems repair & consulting. Homeport Stuart, FL

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<<Without supercharging, how much air will a Ford Lehman 120 running at 1800 RPM suck out of my engine room? Is it displacement times RPM? (in cubic inches per minute) Jerry O'Neill>> Yes, but don't forget to divide by two, since there is an intake stroke only every other revolution. Let's see, 6 liters displacement times 1800 rpm /2 is 5400 liters per min, about 1400gal/min, or about 190 cu ft/min (all figures approximate, I don't have my calculator here). Fuel consumption varies a lot depending on load, but air consumption changes only with rpm. ===== Mark Richter, M.E., aboard M/V Winnie the Pooh, custom Morgan 46 Pilothouse Efficiency Trawler. "Mark's Mobile Marine" electrical systems repair & consulting. Homeport Stuart, FL __________________________________________________ Do You Yahoo!? Yahoo! Photos - Share your holiday photos online! http://photos.yahoo.com/

D

david@kennett.net

Thu, Jan 11, 2001 10:07 PM

At 11:51 AM 01/11/2001 -0800, Mark Richter wrote:

Yes, but don't forget to divide by two, since there is
an intake stroke only every other revolution. Let's
see, 6 liters displacement times 1800 rpm /2 is 5400
liters per min, about 1400gal/min, or about 190 cu
ft/min

So then how about those Turbos? They will suck in a few more
Cu Feet and cram it into each cylinder.
Lets say increase the air pressure 3 times. Now from
my diving chart, that should be 9 times the volume
of air crammed into the Ford. Now does that mean we
have to allow for 9X190=1710 Cu Feet per minute. That's
quite a breeze. How much pressure does a Turbo Produce?
More questions than answer as usual. :)

Hatteras 42 LRC Skooch
St Croix USVI
David Stahl

Kennett Internet Services, 112 S. Union Street, Kennett Square, PA 19348
610-444-9008 Visit our web site at http://www.kennett.net

At 11:51 AM 01/11/2001 -0800, Mark Richter wrote: >Yes, but don't forget to divide by two, since there is >an intake stroke only every other revolution. Let's >see, 6 liters displacement times 1800 rpm /2 is 5400 >liters per min, about 1400gal/min, or about 190 cu >ft/min So then how about those Turbos? They will suck in a few more Cu Feet and cram it into each cylinder. Lets say increase the air pressure 3 times. Now from my diving chart, that should be 9 times the volume of air crammed into the Ford. Now does that mean we have to allow for 9X190=1710 Cu Feet per minute. That's quite a breeze. How much pressure does a Turbo Produce? More questions than answer as usual. :) Hatteras 42 LRC Skooch St Croix USVI David Stahl ************************************************************** Kennett Internet Services, 112 S. Union Street, Kennett Square, PA 19348 610-444-9008 Visit our web site at http://www.kennett.net

A

alexh@gte.net

Fri, Jan 12, 2001 6:25 AM

----- Original Message -----
From: "David A. Stahl" david@kennett.net

Hi David,

So then how about those Turbos? They will suck in a few more
Cu Feet and cram it into each cylinder.

You betcha! Shove in twice the air and it's pretty much like having twice as
big an engine. If I understand Boyle's Law, however, it is a simple
arithmetic relationship between pressure and volume. IOW: Doubling the
pressure from 14.7psi to 29.4psi will double the amount of air in a given
volume. BTW: I'm neither a physicist nor a diver, I got my information here:
http://www.mtsinai.org/pulmonary/books/scuba/sectiond.htm

How much pressure does a Turbo Produce?

That's a question that is getting harder and harder to generalize about,
what with all of the different control systems that are in use. It's
probably fair to say that boost levels for the engines we are concerned with
here are fairly modest; Certainly below 1 bar (14.7psi).

OTOH: In the context of engine room ventilation it would seem prudent to
have as much extra capacity as possible.

Breathily yours,

Alex

----- Original Message ----- From: "David A. Stahl" <david@kennett.net> Hi David, > So then how about those Turbos? They will suck in a few more > Cu Feet and cram it into each cylinder. You betcha! Shove in twice the air and it's pretty much like having twice as big an engine. If I understand Boyle's Law, however, it is a simple arithmetic relationship between pressure and volume. IOW: Doubling the pressure from 14.7psi to 29.4psi will double the amount of air in a given volume. BTW: I'm neither a physicist nor a diver, I got my information here: http://www.mtsinai.org/pulmonary/books/scuba/sectiond.htm > How much pressure does a Turbo Produce? That's a question that is getting harder and harder to generalize about, what with all of the different control systems that are in use. It's probably fair to say that boost levels for the engines we are concerned with here are fairly modest; Certainly below 1 bar (14.7psi). OTOH: In the context of engine room ventilation it would seem prudent to have as much extra capacity as possible. Breathily yours, Alex

Y

yourcaptain@earthlink.net

Fri, Jan 12, 2001 3:34 PM

Go into the engine room with a barometer and have some one close you in and
run the boat wide open. If you see a drop in pressure you need more
ventilation. Of course you can live with a very slight movement of the dial.
.
Captain Al Pilvinis

"M/V Driftwood"--Prairie 47
2630 N.E. 41st Street
Lighthouse Point, Fl 33064-8064
Voice 954-941-2556 Fax 954 788-2666
Email yourcaptain@earthlink.net
Website http://home.earthlink.net/~yourcaptain

Go into the engine room with a barometer and have some one close you in and run the boat wide open. If you see a drop in pressure you need more ventilation. Of course you can live with a very slight movement of the dial. . Captain Al Pilvinis "M/V Driftwood"--Prairie 47 2630 N.E. 41st Street Lighthouse Point, Fl 33064-8064 Voice 954-941-2556 Fax 954 788-2666 Email yourcaptain@earthlink.net Website http://home.earthlink.net/~yourcaptain

R

rbryett@ibm.net

Sat, Jan 13, 2001 3:32 AM

Go into the engine room with a barometer and have some one close you in

and run the boat wide open. If you see a drop in pressure you need more
ventilation. Of course you can live with a very slight movement of the
dial.<<<

There's an even simpler and cheaper way to do it. Find some transparent
plastic hose, and form it into a U-tube with one open end in the
engine-room and one outside. Then fill the hose with water until the level
rises to some suitable level for convenient viewing, and mark the level.
Run your engines at full chat and mark the new level in the tube (if
different). If the engine's demand for air is greater than the vent
capacity, one should see the water rise at the "engine" end of the tube or
fall at the "atmosphere" end.

I'd have to admit that I've never actually tried using a U-tube in quite
this application, but I once worked in a group that used the same technique
to measure the pressure drop across a ducted radiator in a racing car.

Regards, Robert Bryett
Sydney, Australia.
mailto:rbryett@ibm.net

>>>Go into the engine room with a barometer and have some one close you in and run the boat wide open. If you see a drop in pressure you need more ventilation. Of course you can live with a very slight movement of the dial.<<< There's an even simpler and cheaper way to do it. Find some transparent plastic hose, and form it into a U-tube with one open end in the engine-room and one outside. Then fill the hose with water until the level rises to some suitable level for convenient viewing, and mark the level. Run your engines at full chat and mark the new level in the tube (if different). If the engine's demand for air is greater than the vent capacity, one should see the water rise at the "engine" end of the tube or fall at the "atmosphere" end. I'd have to admit that I've never actually tried using a U-tube in quite this application, but I once worked in a group that used the same technique to measure the pressure drop across a ducted radiator in a racing car. Regards, Robert Bryett Sydney, Australia. mailto:rbryett@ibm.net

trawlers@lists.trawlering.com

Re: TWL: RE: Engine room ventilation