Vacuum pumps
Registered User
Joined: Nov 1999
Posts: 2,801
From: Nashville, TN
Originally posted by Pro Stock John
First guy... I'm not sure 385rwhp level that I would bother. You have to seal off your pcv system too (I think).
Email Madman.
First guy... I'm not sure 385rwhp level that I would bother. You have to seal off your pcv system too (I think).
Email Madman.
Registered User
Joined: Oct 2002
Posts: 1,639
From: Toledo, OH
Hey, this is kinda delayed, but there was a link to this post in LT1 tech and I started reading it then realized it was really smart people talking. But anyway, I saw that Stephen87iroc was looking for an LT1 air pump, I still have mine if you still want one.
Registered User
Joined: Feb 2000
Posts: 1,248
From: Bountiful, Utah
I've put this pump on two cars this summer on "SEALED" crankcases with good results. The pump makes sick vac 18" with ease... STAINLESS STEEL BRAKES ELECTRIC VACCUME PUMP # 28146
Its just like the gm pump but you can buy one
Its just like the gm pump but you can buy one
Registered User
Joined: Mar 1999
Posts: 659
From: Chicago, IL
Jeff, it's JUST like the caddy pump or does it do more?
I have heard of folks with the caddy pump getting less than 10 inches of vacuum but honestly I'd like to see more data.
I have the caddy pump and am tempted to slap it on.
I have heard of folks with the caddy pump getting less than 10 inches of vacuum but honestly I'd like to see more data.
I have the caddy pump and am tempted to slap it on.
Registered User
Joined: Feb 2000
Posts: 1,248
From: Bountiful, Utah
John...
my gm pump was "new" when I tested it back years ago, it made 16~18" at 13 volts.
We tested the stainlees brakes pump in Aug this year in the same mannor as the gm unit was tested { deadheaded}
and it pulled 18" @ 13 volts!
Very nice unit and very QUITE!
They fit nice up under the the fascia under the drivers headlight assembly.
I would not hunt junk yards with this being available
my gm pump was "new" when I tested it back years ago, it made 16~18" at 13 volts.
We tested the stainlees brakes pump in Aug this year in the same mannor as the gm unit was tested { deadheaded}
and it pulled 18" @ 13 volts!
Very nice unit and very QUITE!
They fit nice up under the the fascia under the drivers headlight assembly.
I would not hunt junk yards with this being available
Registered User
Joined: Feb 2000
Posts: 1,248
From: Bountiful, Utah
Ya the two look just alike other than the mounts. The ssb pump has a better mount and "is" quiter than the gm pump for some reason???
If your gm pump is new and not from a junkyard I'D BE PUTTING THAT THING ON
Just be sure to seal up the crank case with no external sorce for a vaccum leak.
Power up your Gm pump with just a vaac guage on it and see what it makes for vac, then when you plumb the system together you'll know if your crankcase is sealed or not. If its sealed it will make within pound or two of the deadheaded vac reading.
If your gm pump is new and not from a junkyard I'D BE PUTTING THAT THING ON
Just be sure to seal up the crank case with no external sorce for a vaccum leak.
Power up your Gm pump with just a vaac guage on it and see what it makes for vac, then when you plumb the system together you'll know if your crankcase is sealed or not. If its sealed it will make within pound or two of the deadheaded vac reading.
Last edited by Hot Rod Hawk; Oct 30, 2003 at 07:21 PM.
Registered User
Joined: Feb 2000
Posts: 1,248
From: Bountiful, Utah
Yes you could run both at the same time. But if you run a trans-go vaccum modulator like John and me run on our 4l60e's you know they splice into the vac line for the brakebooster for the supply line to the Modulator.
Just reroute the Trans-go line directly into the Intake for tha vaccum signal.
You would not want the trans modulator to see High vaccume all the time or you will cook the trans!
At wot a trans go modulator eqpt'd 4l60e MUST see "zero" vaccume at wide open throttle to apply full line apply pressure to the clutches!!!!!!!!!!
....Keep the electric vaccum pump off of the modulator line!!!
ok did I say keep the electric vac pump off of a trans-go modded 4l60e trans modulators vacuum supply line "ENOUGH"
Just reroute the Trans-go line directly into the Intake for tha vaccum signal.
You would not want the trans modulator to see High vaccume all the time or you will cook the trans!
At wot a trans go modulator eqpt'd 4l60e MUST see "zero" vaccume at wide open throttle to apply full line apply pressure to the clutches!!!!!!!!!!
....Keep the electric vaccum pump off of the modulator line!!!
ok did I say keep the electric vac pump off of a trans-go modded 4l60e trans modulators vacuum supply line "ENOUGH"
Last edited by Hot Rod Hawk; Nov 2, 2003 at 12:54 PM.
Registered User
Joined: Jun 2001
Posts: 239
From: WhiteSalmon, Wa. USA
Could this be the answer to my ?
Originally posted by Stephen 87 IROC
I'm assuming you mean as crankcase ventilation?
For every cubic inch above a piston, there's an equal amount below it. Your basic crankcase ventilation system is a simple PCV valve which sucks that air back into the engine to be reburnt. The downside is that you're sucking oil and water vapour back into the cylinders.
Racers have used other ways of keeping the crankcase clean and reducing pressure inside it. Exhaust evac systems have been around for years. They use a check valve similar to the AIR valve on your exhaust manifolds. When hooked into the exhaust system down at the end of the headers, the exhaust gasses can create enough vacuum to keep the crankcase pressure low. They pull very little from the crankcase at high rpms though.
In the last 30 years or so when the car manufacturers started using air pumps (smog pump) to inject air into the exhaust to reduce emissions, racers found that these pumps can also suck a lot of air out of the crankcase with a few modifications. Smog pumps are still used today but there are now better vacuum pumps available to do the job. Moroso makes a very good but expensive belt driven pump. GM produces an electric AIR pump for the exhaust on late model F-bodies that's supposed to work just as good for pulling the crankcase down into a vacuum.
The theory is that when the crankcase is in a vacuum, the pistons are not trying to compress air below them. This means some HP is free'd up. Having lower crankcase pressure also allows the rings to seat tighter against the cylinder walls. You'll also eliminate any oil leaks from the engine.
There are some drawbacks from running a crankcase in a vacuum. The rear main seal is designed to keep oil from going out. If the crankcase is in a vacuum, it can easily draw dirty air into the crankcase through the rear main seal. The common way to correct it is to install the seal backwards.
Too much vacuum can be hazardous. No more that 14-15" of vacuum should be used. A vacuum pump of any kind in a well sealed engine can pull 28" of vacuum. This is enough to pull the oil out of the wrist pins and bearings. The best way to limit the amount of vacuum is with a vacuum relief valve. It's preset to open if the vacuum become too great. Think of it as a controlled vacuum leak.
Dyno results vary but a 2-5% increase in HP can be expected.
I'm assuming you mean as crankcase ventilation?
For every cubic inch above a piston, there's an equal amount below it. Your basic crankcase ventilation system is a simple PCV valve which sucks that air back into the engine to be reburnt. The downside is that you're sucking oil and water vapour back into the cylinders.
Racers have used other ways of keeping the crankcase clean and reducing pressure inside it. Exhaust evac systems have been around for years. They use a check valve similar to the AIR valve on your exhaust manifolds. When hooked into the exhaust system down at the end of the headers, the exhaust gasses can create enough vacuum to keep the crankcase pressure low. They pull very little from the crankcase at high rpms though.
In the last 30 years or so when the car manufacturers started using air pumps (smog pump) to inject air into the exhaust to reduce emissions, racers found that these pumps can also suck a lot of air out of the crankcase with a few modifications. Smog pumps are still used today but there are now better vacuum pumps available to do the job. Moroso makes a very good but expensive belt driven pump. GM produces an electric AIR pump for the exhaust on late model F-bodies that's supposed to work just as good for pulling the crankcase down into a vacuum.
The theory is that when the crankcase is in a vacuum, the pistons are not trying to compress air below them. This means some HP is free'd up. Having lower crankcase pressure also allows the rings to seat tighter against the cylinder walls. You'll also eliminate any oil leaks from the engine.
There are some drawbacks from running a crankcase in a vacuum. The rear main seal is designed to keep oil from going out. If the crankcase is in a vacuum, it can easily draw dirty air into the crankcase through the rear main seal. The common way to correct it is to install the seal backwards.
Too much vacuum can be hazardous. No more that 14-15" of vacuum should be used. A vacuum pump of any kind in a well sealed engine can pull 28" of vacuum. This is enough to pull the oil out of the wrist pins and bearings. The best way to limit the amount of vacuum is with a vacuum relief valve. It's preset to open if the vacuum become too great. Think of it as a controlled vacuum leak.
Dyno results vary but a 2-5% increase in HP can be expected.
Ken
Registered User
Joined: Sep 2000
Posts: 550
From: KC; Where grandma drives in the left lane
I need a vacuum pump for our 620hp 8000rpm GT-1 motor. Would this Caddy pump work sufficiently? I'd run a belt drive model if that worked better, but it sounds like the electric may be a better part for us?