Vacume and diesel engines
- Thread starter Hooked_on_HP
- Start date
MikeD74T
Veteran Member
Redneck in training; you can stuff more air (oxygen molecules) in the combustion chamber said:
Ken
Veteran Member
In the army used to repair S/B Gen. Had one return with faulty gen and removed to repair.
The engine was in frame and govenor control rod removed air cleaner off and engine was started to check operation. no load on flywheel and govenor set for full rpm increase immediate to over speed. a boot was set on air intake to stall engine and sucked into the manifold. which had to be removed to clean out. Understand diesel has no vacuum but the
AP in this case was very impressive.
Don't place hand over intake to test.
ken
The engine was in frame and govenor control rod removed air cleaner off and engine was started to check operation. no load on flywheel and govenor set for full rpm increase immediate to over speed. a boot was set on air intake to stall engine and sucked into the manifold. which had to be removed to clean out. Understand diesel has no vacuum but the
AP in this case was very impressive.
Don't place hand over intake to test.
ken
firedog
Gold Member
Same thing with a lot of stationary diesels. Overspeed trips a S/D device on the intake. If there are any flexible boots in the intake piping between the shutdown valve and the manifold, the "less than atmospheric" condition will suck them in tight.
Soundguy
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Remember.. you changed the rules with the choke plate. No longer is it at AP in the manifold as you now have a restriction, and changing volume ( cyl on 'suck' stroke )... same amount of air, plus the changing volume, plus constant AP on the other sid eof the soft boot, and it's obvious what that happened.
soundguy
OP
Hooked_on_HP
Veteran Member
When I started this post I thought I was asking a fairly simple question expecting a fairly simple answer. Boy was I wrong. As far as I am concerned a diesel does produce vacuum but does not store it.
Bill
Bill
Soundguy
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I think the key is 'nominal manifold vacume' is ideally non existant on a NA diesel. Otherwise it entails filter or other airflow restriction.
soundguy
soundguy
Matt_Jr
Platinum Member
and communicate.
Egon
Epic Contributor
Maybe its all about fluid flow and differential pressures!
A better question for us nerdy tractor types that get all bound up in the details might have been "How much vacuum does a non-turbo diesel produce in the intake manifold compared to a gasoline engine?"
Gasoline engine at idle is 18-22" hg
Diesel engine at idle is much less than 1" hg
Gasoline engine working hard is 5-9" hg (3/4 throttle lets say going up a big hill pulling a trailer etc)
Diesel engine working hard is still under 1" hg (hopefully much less as it's a sign of a clogged air filter.)
Gasoline engine at wide open throttle full load is 1" hg
Diesel engine at full load is also about 1" hg.
jb