Vac pumps???

Old 01-22-2009, 07:24 AM
  #1  
dparker
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Default Vac pumps???

This is kind of weird question. I went to a terminator this year and decided to go with a Moroso 4 vain vacuum pump. My reasoning was to get a little HP gain and keep the oil from milking as bad as it might without the pump. Yesterday a good friend that runs a blower and has been very successful in his racing career, was at my shop. His opinion was that the vacuum pump would only rob HP not increase and that a good Evac system with large enough ventilation would work just as well. I didnt really have an answer and Im not educated enough on the vac pump to argue. So hears my question to you:
Does the vac pump produce more HP over a good E vac system and Why? And does the vac pump keep the oil from milking as much on alcohol as a good E vc system and Why?
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Old 01-22-2009, 07:58 AM
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curtisreed
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We put a vacuum pump on our 468, alcohol Rupert on it. We did not pick up any et at all. The main reason we use them is to pull a little water out of the engine, although we have never milked the oil in this motor, our other sbc with a toilet, or my sbc with Rupert carb. We just have a small amount of water but not enough to milk the oil. To really see dividends with a pump usually the biggest gain is seen with low tension oil rings and getting the blowby out of the crankcase.

I bought one of the Mr. Gasket style pumps that were for sale just a while back and am going to install it on my motor this year. I doubt if I pick up any et at all. I would just like to get rid of the small oil leaks and get the small amount of water I see out. My 2 cents.

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Old 01-22-2009, 08:00 AM
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jmarksdragster
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A vacuum pump creates a vacuum in the crankcase to enhance ring seal, it also helps by allowing the piston to move down without pumping as much air in the crankcase. That in combination with low tension rings will free up HP, more than an evac system can ever do. There are gains even with standard rings. 10-12 inches is typical, more and you risk drying the components that rely on splash oil such as piston pins. Last, sealing the engine is a key to making gains. Dipstick tubes, leaking gaskets etc will allow air into the engine and diminish any gains.
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Old 01-22-2009, 09:57 AM
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signsbyesa
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door and jmark got it right, i was told to relieve pressure in the block,
that caused leaks and other gasket problems and yes the hp comes
from pressure free movement, i.e. crank, rods, some have gained
hp and some that have already have a good evac system did
not gain hp but i bet if the engine could talk it would be relieved
i have never ran one but w/a first bbc 496, EFI i am going to
try a vacum system from aerospace compnents, good luck bud :wink:
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Old 01-22-2009, 10:20 AM
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jmarksdragster
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While the Aerospace is OK, it doesn't make great vacuum (I have one). These guys make one of the best pumps out there and are not much more money.
http://www.starvacuumpumps.com/catalog.php
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Old 01-22-2009, 10:31 AM
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curtisreed
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Originally Posted by jmarksdragster
While the Aerospace is OK, it doesn't make great vacuum (I have one). These guys make one of the best pumps out there and are not much more money.
http://www.starvacuumpumps.com/catalog.php
Saw one of the star pumps for sale on RJ for $800.00 with the catch can, fittings and hoses.
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Old 01-22-2009, 10:50 AM
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hammertime
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These guys got it correct above. I've had motors on the dyno with proper evac setups and then swapped them over to the vacuum pumps. 1st motor 548 went from 959 to 971 this was no low tensions and a carb. 2nd motor was my current 582, made 960 without and 979 with it. 548 was a star pump with a built in regulator, second is a Moroso 3 vane without a regulator at all. I also run the terminator and have NO milk in my oil but you can do this with or without the pump. I think they are a great idea with injection just because the crankcase pressure is increased with the injection and it will elminate any issue there.
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Old 01-22-2009, 10:59 AM
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curtisreed
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Originally Posted by hammertime
These guys got it correct above. I've had motors on the dyno with proper evac setups and then swapped them over to the vacuum pumps. 1st motor 548 went from 959 to 971 this was no low tensions and a carb. 2nd motor was my current 582, made 960 without and 979 with it. 548 was a star pump with a built in regulator, second is a Moroso 3 vane without a regulator at all. I also run the terminator and have NO milk in my oil but you can do this with or without the pump. I think they are a great idea with injection just because the crankcase pressure is increased with the injection and it will elminate any issue there.
David,
Why do you say this and what do you think would cause it any different from a carb?

Curtis
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Old 01-22-2009, 12:33 PM
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dak697
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I use an electric pump.. I honestly do not think makes anymore horsepower but, I have it run whenever the car is running. I see the most benifit in geting moisture out of the motor. To get the pump to live you have to modify it but it is not a big deal. I have used the same pump for 5 years and it has not let me down. 505- alcohol injected
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Old 01-23-2009, 06:29 AM
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dparker
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Makes me wonder if the $1000.00 was well spent on the vac pump. But then again seems like I always get buyers remorse after I purchase something over $1000.00. At least it looks good on the engine.
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