Vacuum Pump Opinion

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tubbedamx

tubbedamx

Location Boise, Idaho
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Location
Boise, Idaho
Looking for your experience’s, opinions and pro’s/cons on running a vacuum pump on a street strip car. It’s winter, idle minds.

My experience with them is track only and wonder if the benefits would carry over to a street car. Like ring seal, oil leaks, pulls out condensation etc. They’re virtually no maintenance, considering. Only draw back I can see is cost. I get it, functioning pvc’s do a good job, but.

On my drag car, I used a moroso 3vane with the vacuum breaker set at 8 inches. The engine dynoed at 620hp (pump gas amc 390) without the pump. Later installed the pump and immediately picked up two tenths. Pulled the belt and slowed two tenths. Back to back runs.

The opinion of other racers at the track was, that’s what they do.
That said, there not talked about much here.

these guys sell a street duty set up for small and big blocks
GZ VP102 Racing Vacuum Pump Complete Kit
 
I run a Star Vacuum Pump on the Barracuda and all they had me change was switching the pulley from a plastic to an aluminum due to increased heat with the added time being run due to street driving. No issues aside from that.
 
Aspirator valves on the headers also work. Mounted like methanol jet valves on a two stroke. Your not using power to make power. Had a small block chevy here you could not lift the valve covers off with just a partial rpm increase.
 
I tried dual aspirators, on the street. The engine seemed a lil more potent, hard to tell. But as the rpm went up the baffles in the valve covers couldn't keep up, and the exhaust system started blowing large quantities of oil. To be fair, I am sending more oil to the top than most guys would. I tried a few things but since the lil 367 had a preponderance of power anyway, I just retired the valves.
I say preponderance of power, but I really mean that the 295s (BFGs or Coopers) suck for traction. But I learned to drive it and discovered that I liked sliding around, so never took it to the next step.
Don't underestimate the power of those aspirators, they really suck
 
I’ve used the aspirator valves in the past and they do work, as far as I know. Are the effective at low rpm cruising 1500-2500rpm?

Funny we had a green track manager for a while who was convinced cars were oiling the track, when they were just burning what little oil came through
 
This is just unproven thought, wouldn’t a vacuum pump suck oil off the cylinder walls promoting ring and cylinder wear? If this is indeed the case I would believe one would not be suitable for use on a street car unless all it does is street race.
 
ch1ll said:
This is just unproven thought, wouldn’t a vacuum pump suck oil off the cylinder walls promoting ring and cylinder wear? If this is indeed the case I would believe one would not be suitable for use on a street car unless all it does is street race.
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The vacuum pump reduces crankcase pressure. That promotes oil control and ring seal since both occur due to pressure differential.
 
tubbedamx said:
I’ve used the aspirator valves in the past and they do work, as far as I know. Are the effective at low rpm cruising 1500-2500rpm?

Funny we had a green track manager for a while who was convinced cars were oiling the track, when they were just burning what little oil came through
Click to expand...

I believe you can put a catch can between the aspirator valves to filter out excess oil before it goes to the headers. May be something to try first before the vacuum pump.
 
Rat Bastid said:
The vacuum pump reduces crankcase pressure. That promotes oil control and ring seal since both occur due to pressure differential.
Click to expand...
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there is already a vacuum created in the crankcase without a pump. The pump significantly increases vacuum and pulls the rings tight to the cylinder walls. I know the theory and how it works. If it is pulling oil off the crankshaft, it pulling it off the cylinder walls as well.
 
ch1ll said:
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there is already a vacuum created in the crankcase without a pump. The pump significantly increases vacuum and pulls the rings tight to the cylinder walls. I know the theory and how it works. If it is pulling oil off the crankshaft, it pulling it off the cylinder walls as well.
Click to expand...

How many inches of vacuum are we talking about, in your experience/opinion?
It would be difficult to pin wear on a vacuum pump with a race engine as I pulled mine apart every 3-4 years, it ran at 8 inches at peak. Crossing my fingers, 5 inches would be a benefit and keep the engine healthy
 
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ch1ll said:
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there is already a vacuum created in the crankcase without a pump. The pump significantly increases vacuum and pulls the rings tight to the cylinder walls. I know the theory and how it works. If it is pulling oil off the crankshaft, it pulling it off the cylinder walls as well.
Click to expand...
How is vacuum already created in the crank case?
 
ch1ll said:
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there is already a vacuum created in the crankcase without a pump. The pump significantly increases vacuum and pulls the rings tight to the cylinder walls. I know the theory and how it works. If it is pulling oil off the crankshaft, it pulling it off the cylinder walls as well.
Click to expand...


How is there a vacuum in the crankcase without a pump or similar? There isn’t. And it has to do with pressure differential. Nothing gets “sucked” off of anything. To make it simple, the second ring is a scraper. It scrapes the oil off the cylinder wall. The oil ring catches the oil and sends it through the holes or slots in the piston back to the crankcase. What causes that is a pressure differential. The difference in pressure between the high pressure (combustion pressure) and the relative pressure in the crankcase. The higher the pressure differential, the more effective the rings are. The more effective the rings are, the thinner they can be. The thinner they are, the more power you make. There isn’t a vacuum in the crankcase unless you make a vacuum in the crankcase.
 
wish4hemi said:
An article on the subject, one which I’ve contemplated many times myself.
Gallery: Pick Up Power, Longevity & Seal Leaks With An External Vacuum Pump - Mopar Connection Magazine | A comprehensive daily resource for Mopar enthusiast news, features and the latest Mopar tech
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I don’t have time to read all of that article right now, they make a mistake pretty early. They say the 440 used a “closed” PCV system and I don’t believe that to be correct. Every OE PCV system I’ve seen is an open system that brings in fresh air to the valve cover and pulls it through the crankcase and back into the engine to be burned. In that case, there is no way for that system to develop any vacuum in the crankcase.
 
tubbedamx said:
How many inches of vacuum are we talking about, in your experience/opinion?
It would be difficult to pin wear on a vacuum pump with a race engine as I pulled mine apart every 3-4 years, it ran at 8 inches at peak. Crossing my fingers, 5 inches would be a benefit and keep the engine healthy
Click to expand...
15 pretty easy
 
tubbedamx said:
None of my engines have 15 inches of vacuum in the crankcase….or any as far as that goes. Are we measuring in the same spot? I usually tap the fuel pump block off plate or the valve covers.
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I run a jesel belt drive and front mount distributor so a friend modified a factory distributor so that we could pick up vacuum there.
 
'68cuda416 said:
I run a jesel belt drive and front mount distributor so a friend modified a factory distributor so that we could pick up vacuum there.
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That’s got to be a sweet setup….I’ve seen a couple pics of your hotrod.
Here’s what I was working with. Pump gas survivor car.

8D3562EE-BAE3-4B1E-A28F-C6B527B6C757.jpeg


4140AC57-6425-4D98-BE1A-280B4AA9E5D4.jpeg
 
Built around a street car class our local track had. It was pretty fun, had 30-40 cars in it. Pump gas, mufflers, full functional interior, stock bodied including wheel wells (severely limited tire size compared to GM cars), wipers…etc. Many times I wanted to pull it apart and restore it and chassis. AMC 390, Indy -1 heads (BB dodge exhaust ports) and intake, 727, 5500 stall and a 9inch.

2C927594-9F00-4CFA-86DB-009C702CF384.jpeg


4698993B-D33C-4745-85F3-77C05E4F9034.jpeg


857836D1-821A-48F0-A5BD-A285671FBA38.jpeg
 
tubbedamx said:
Built around a street car class our local track had. It was pretty fun, had 30-40 cars in it. Pump gas, mufflers, full functional interior, stock bodied including wheel wells (severely limited tire size compared to GM cars), wipers…etc. Many times I wanted to pull it apart and restore it and chassis. AMC 390, Indy -1 heads (BB dodge exhaust ports) and intake, 727, 5500 stall and a 9inch.

View attachment 1715841816

View attachment 1715841817

View attachment 1715841818
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Very cool, I love the AMX's actually and if the right one came along someday I would probably add it to my stable
 
There’s several nice examples out there like you said coming across one that scratches the itch. A big bad color car, with a 401-4spd, rally pack interior…. Gotta love the early’70’s and there ambition.
 
tubbedamx said:
None of my engines have 15 inches of vacuum in the crankcase….or any as far as that goes. Are we measuring in the same spot? I usually tap the fuel pump block off plate or the valve covers.
Click to expand...

most people think around 8, maybe 10 is ideal.
Get up around 15-20 you can be looking at premature piston pin wear.
Couple things to consider…. Pump is more help with a thinner ring pack, less help with a Jurassic era ring pack.
A non “ racy” oil pan deal is more likely to benefit from a vacuum pump. Fancy, well designed pan, less gain relatively speaking
Make sure the motor is sealed up good to maximize gains..
Most typical weekend racers can probably find other ways to make power, and often do. To me this is a race only deal and requires lots of attention to detail …
 
tubbedamx said:
How many inches of vacuum are we talking about, in your experience/opinion?
It would be difficult to pin wear on a vacuum pump with a race engine as I pulled mine apart every 3-4 years, it ran at 8 inches at peak. Crossing my fingers, 5 inches would be a benefit and keep the engine healthy
Click to expand...

not sure on how much vacuum with or without a pump.
you only pull your motor apart every 3-4 years? no rering between seasons or valve jobs during the season?
 
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