Vacuum Pump

Pittman

Pittman

New member
Anyone ever try one? Ive talked to more than a few around here with the 14:1 + compression big blocks and they are all running the vac pumps. These guys are seeing a difference when using them. Ive had some tell me we dont have that much head pressure but hell 25lbs or so going into the chamber I bet way exceeds 14:1.

Anyway on a big block engine dyno has shown at least 30hp and some times more way more. Even using total seal gapless.
 
Maxtor

Maxtor

New member
Hoover uses one, I can't remember what HP gains Jim said they got from it but I remember it seemed substantial. You may try contacting Jim or Matt to get details.
 
L

little black psycho

New member
I wanted to try this but couldn't figure out what pump I am going to use. I know a couple Buick guys using smog pumps from newer cobras and say they work great. I really can't justify $300-700 for the pumps out of jegs and summit. I found alot of really good info on pumps when I did a search and every pump that I thought was perfect turned out to be crap and some pumps only lasted a day. So if you come up with one please share some info.
Thanks
 
ghettosled

ghettosled

SYTY SUPERSTORE
I may be wrong here, but I believe the only vacuum pump the Hoovers run is hooked up to the brake booster.
 
MotorMouth

MotorMouth

Member
How much vacum do you need to make a differance? The reason I ask is I have the old air pump off of my 1997 Camaro LT1 and it seems to pull on hell of a vacum when you plug it in. I am not that confident that it will work but I figured I would bring it up. I might give it a shot, if it dose not work it did not cost me anything except my time..

Brian
 
B

Boosted

New member
I think the problem with using smog pumps is that they wear out quickly in comparison to the purpose built pumps.
Plus doesn't logic say that the smog pumps pump air instead of suctioning? I guess they find some way for the smog pump to suck the air from within the engine, as opposed to atmospheric air? Not sure on that part of the equation

Z
 
Maxtor

Maxtor

New member
ghettosled said:
I may be wrong here, but I believe the only vacuum pump the Hoovers run is hooked up to the brake booster.
Click to expand...

Mike - You are right, they have a simple electric air pump hooked up to the brake booster to hold the brakes at the line, but I'm nearly positive they also have some type of smog pump that is belt driven for the engine. I saw it this October in Bristol, it's all plumbed up with SS braided line. I'll try to see if I have any pics of it.
 
Pittman

Pittman

New member
ghettosled :
Im in the rough stages of drawing a mount out now. My plan is to mount the vacuum pump of the side of the alternator. I will yank the alternator pulley off and jig it up on a lath to weld the vacuum pump drive pully on the front (with acces to alt nut). The mount will be adj for belt tension. I plan on using the aerospace setup but as mentioned they're not cheap.

Ya know I dont know what they will do on our motors but the poeple I talk to say 30hp+ on big blocks. I bet with our head pressure we could see some gains.
 
L

Lynn D. Brown

New member
So why would U get that much HP Gain from just lowering the crankcase pressure ? Because U R lowering the pressure on the other side of the pistons ?

Say U had a cylinder pressure of 300 Psi (max) w a 600 HP engine. What Press could U have in the crankcase - 5 Psig ? Reduce it to 0 psig, and what would U have - 10 HP Gain Max ?

O the other hand, maybe it isn't that simple.
 
jwaller

jwaller

Evil Genius/SyTy Guru
Lynn D. Brown said:
So why would U get that much HP Gain from just lowering the crankcase pressure ? Because U R lowering the pressure on the other side of the pistons ?

Say U had a cylinder pressure of 300 Psi (max) w a 600 HP engine. What Press could U have in the crankcase - 5 Psig ? Reduce it to 0 psig, and what would U have - 10 HP Gain Max ?

O the other hand, maybe it isn't that simple.
Click to expand...

the idea is that u can eliminate ring flutter, blow-by, and pcv issues all making for more power and a cleaner eng compartment.
 
Falco

Falco

Donating Member
Could someone post pictures of an installed vacuum pum in a SyTy? I guess it could be put in the place of the AC compressor if the AC has been deleted...

Later,
 
jwaller

jwaller

Evil Genius/SyTy Guru
to my knowledge no one has yet done it.

it is more difficult bc the purpose built pumps all use v belts and our trucks dont.

so thats why I was looking for an electric vac pump that would do the job.
 
jwaller

jwaller

Evil Genius/SyTy Guru
ya ed thats the link I posted way back when. but I've never been able to get them on the phone. everything on their site sounds good and all. but I just havent been able to get one from them. maybe you'll have better luck.
 
P

panic

Guest
I'll bet one of the reasons the belt-driven smog pumps fail in service is that they're under load too frequently (100% duty cycle).
Has anyone tried the obvious: use the smog pump, but vent the inlet from the case with a solenoid valve attached to a Hobbs (boost sensitive) switch?
Vent line should be big, and end in a small filter (or T into the inlet duct?). Motor operating NA mode: pump has no restrictions free flow and outlet.
Motor in boost mode: switch sees boost (or low vacuum, your choice), bypass closes, pump draws vacuum from case.
The deluxe method would be an A/C electric clutch, so the pump free-wheels when not needed, but more weight, wires, etc.
 
Pittman

Pittman

New member
Mounting

Mounting

Im working on a mount that puts the pump next to the alternator. I would have liked to have done a billet mount but it will be powrder coated instead. The alt drives the pump.

They do run a V belt no doubt about that. You have to pull your alt pulley off and jig it up on a lathe to weld the V belt pulley to the outside. Its about $950-1000 to do this. The pump kits are $600 with resevior and hose. The rest is chewed up in the machine shop. Im just trying to make my truck a little different (plus I hate leaks)
 
MotorMouth

MotorMouth

Member
OK, I just thought of soemthing else. Thoese reed style vacum things that you see on race car headers for pulling crank case vacum, would one of thoese work?? I aske because I am just finishing up my new down pipe and exhaust and was wondering if this would work. Just thinking out loud..

Brian
 
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