Intake tract vacuum

[Deleted member 32467]

I'm torn down so can not check with my gauge..

How much vacuum (if any) is available if you tapped into the intake of these Duramax engines? I have an LBZ.

If we weld a bung into our intake horn right near the turbo will there be consistent vacuum there? Will the vacuum increase with throttle?

What about where the stock "Air filter service gauge" is in that grommet near the air filter box, would vacuum from that point be consistent with vacuum up closer to the turbo in the air horn?

Thanks for any input,

 

[PureHybrid]

Yes there will be vacuum, more when the boost comes on. It would hardly be measurable at idle speeds. I think the max inlet restriction most turbos like to see is 17in? Don't quote me on that.

What are you trying to accomplish?

 

[jlawles2]

Its a diesel, any vacuum you see will be from the air filter. I would not rely on getting any vacuum from the intake.

Vacuum in a gas engine is generated by the closing of the throttle body. At low RPM you get high vacuum since the throttle is the least open (more restriction) and the engine is trying to pull air in. At WOT you get the least vacuum since there is less restriction.

 

[Chevy1925]

Yes there will be vacuum, more when the boost comes on. It would hardly be measurable at idle speeds. I think the max inlet restriction most turbos like to see is 17in? Don't quote me on that.

What are you trying to accomplish?

what?

 

[oscyjack]

Curious as to why you're wondering about vacuum

Opposite of a gas basically on these. More vacuum at wot and zip at idle or close to

 

[JoshH]

what?

He's talking about between the air filter and the turbo. The restriction from the filter will create a small amount of vacuum that will increase as the volume of air being moved by the turbo increases. A more restrictive filter will increase the vacuum, but I don't think you could ever get enough vacuum from the engine to use for anything that requires vacuum to operate. That is why GM put a vacuum pump on LB7s that had an EGR system.

 

[Chevy1925]

He's talking about between the air filter and the turbo. The restriction from the filter will create a small amount of vacuum that will increase as the volume of air being moved by the turbo increases. A more restrictive filter will increase the vacuum, but I don't think you could ever get enough vacuum from the engine to use for anything that requires vacuum to operate. That is why GM put a vacuum pump on LB7s that had an EGR system.

i was even re-reading the OP post and Pure's post but kept thinking they were talking about the intake manifolds/post turbo. it was racking my brain cause i know Pure aint no newb to diesels. i just wasnt putting things together right

not on my game this morning lol

 

[Mike L.]

:wheelchair: You're getting old James.

 

[Chevy1925]

:wheelchair: You're getting old James.

my hair line agrees :roflmao:

 

[Vmyrhaug]

I installed banks air filter kit with ram air scoop. My filter indikator was moving on New stock filter. After installing banks no movment on indicator, no black/gray smoke, and i'm sure some power increase...

 

[Deleted member 32467]

Thanks fellas!

Without kicking the PCV reroute hornets nest.. My opinion is the crankcase should be scavenged. I bought an oils separator to mount on the firewall from Mishimoto and plan to tie back into the intake tract to pull some crankcase pressure and condensation from the motor.

I have read everything on the internet it seems, most guys talk about a Racor, or Parker separator, but not how they plumbed it.

When I ordered my intake horn, I did not request a bung in it and it is powder coated. Now need to decide if I need to screw it up and tig weld a bung on there, or try my current idea and plumb my return where the air filter service gauge is right after the factory air box.

 

[PureHybrid]

i was even re-reading the OP post and Pure's post but kept thinking they were talking about the intake manifolds/post turbo. it was racking my brain cause i know Pure aint no newb to diesels. i just wasnt putting things together right

not on my game this morning lol

It's ok, we all have those days :hug:

Yes, there isn't very much vacuum, especially with a good filter. But there is enough to operate a vacuum regulator when installing a CNG / propane kit.

 

[PureHybrid]

Thanks fellas!

Without kicking the PCV reroute hornets nest.. My opinion is the crankcase should be scavenged. I bought an oils separator to mount on the firewall from Mishimoto and plan to tie back into the intake tract to pull some crankcase pressure and condensation from the motor.

I have read everything on the internet it seems, most guys talk about a Racor, or Parker separator, but not how they plumbed it.

When I ordered my intake horn, I did not request a bung in it and it is powder coated. Now need to decide if I need to screw it up and tig weld a bung on there, or try my current idea and plumb my return where the air filter service gauge is right after the factory air box.

Sounds like it should work.

BUT if the separator doesn't do its job for some reason, you'll have oil dripping from the airbox, and possibly gum the MAF sensor up (if you plumb to the filter minder port). $.02