2nd Gen Non-Engine/Transmission Does a turbo always have boost?

[RSchwarzli]

Hey guys, does a turbo always have possitive boost? For example, on turbo gas motors while driving down the road or highway, the boost gauge will read on the vacuum side of zero. Once the throttle is mashed though, there is possitive boost. Is that the same for a diesel? Is it possible for a waste gated diesel to run on the vacuum side of a boost gauge, or do diesels always run possitive? Thanks,



Robert

 

[DMcPherson]

with no throttle plate there is no vacuum. so it will usually be 0 and under driving conditions usually be making some boost when on the throttle.

when I put a boost gauge in my truck it was kind of like a novelty because its allways 10-20 psi, if my car was like that I would allways be doing 100 mph.

 

[Vaughn MacKenzie]

I have a '82 Blazer 6. 2L turbo diesel that the previous owner put a boost/vacuum gauge in. It does bear very slightly to the vacuum side when decellerating and at idle, otherwise it is always above 0.



Vaughn

 

[DGerth]

Vaughn,

My Dodge usually reads about 0-16 lbs. ogf boost usually on the low side even when in a good pull such as comming over the horse haven hills from Unatilla to "the cities". What gives ? is my turbo or waste gate going west ?

Any ideas pard?

dg

 

[2broke2smoke]

way back before tdr was invented i bought an autometer boost gauge that showed vacuum as well ...



my '91 intercooled first gen NEVER showed vacuum ...



boy was i glad this site showed up

 

[wtfd6]

like DMcpherson said, on most diesels there will never be vaccuum. i only say most because I dont know about every kind. because there isnt a throttle plate and throttle body like there is on a gasser. gas engines need the correct amount of air so there is a plate to regulate it. since our diesels fuel is injected directly into the cylinder after the compression stroke, we dont need one. our fuel isnt compressed with the air like in a gasser.

mark

 

[NoSeeUm]

Mostly True

To make the air flow into the cylinders there must be a difference of pressure.



So unless you are raising atmospheric pressure on every intake stroke... .



It would seem that there has to be vacuum at some point in the manifold. I would guess vacuum is greatest in the cylinder and decrease as you move outward in the intake piping. This would be more true for non-turbo charged engines or turbo charged engines at low power.



I have no clue what it would be, but it exists.



Jim