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 Post subject: bbc vacuum pump
 Post Posted: Sat Jan 09, 2010 9:19 pm 
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im getting ready to put together my 13.5 to 1 498 for my drag car. consistency reliabilityand simplicity are my main objectives. i was thinking about a vacuum pump for this engine. im leaning against it. i know it will make more power and seal up better but for what im doing i dont think its worth it. in my experience vacuum over 8 in hg causes oil pressure fluctuation on wet sump engines. i figure it might make another 15 hp with it at this vacuum. what do you guys think?


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 Post subject: Re: bbc vacuum pump
 Post Posted: Sat Jan 09, 2010 10:38 pm 
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EVAC systems will pull upwards of 5 inches or more on a well sealed engine. They don't cost much and don't take any power to run'em.

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 Post subject: Re: bbc vacuum pump
 Post Posted: Sun Jan 10, 2010 9:20 am 
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gnicholson wrote:
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im getting ready to put together my 13.5 to 1 498 for my drag car. consistency reliabilityand simplicity are my main objectives. i was thinking about a vacuum pump for this engine. im leaning against it. i know it will make more power and seal up better but for what im doing i dont think its worth it. in my experience vacuum over 8 in hg causes oil pressure fluctuation on wet sump engines. i figure it might make another 15 hp with it at this vacuum. what do you guys think?



Simplicity by all means stick with the breathers.

Vacuum pumps been worth 15-25hp on my setups, @ 8in @ idle ... never a oil pressure issues with wet sump.

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 Post subject: Re: bbc vacuum pump
 Post Posted: Tue Jan 12, 2010 9:41 pm 
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im using an evac setup now. ive never tested it to see how much vacuum it will pull. might be a good thing to check on the dyno. maybe 1st find out how much each header will pull then check total crankcase pressure. in any case im getting ready to orfer the rings so i need to make up my mind


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 Post subject: Re: bbc vacuum pump
 Post Posted: Tue Jan 12, 2010 11:51 pm 
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I've had an Evac system suck a valve cover gasket in a couple of times so they do suck. Like you, I've never measured it before but I do know mine works.

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 Post subject: Re: bbc vacuum pump
 Post Posted: Wed Jan 13, 2010 8:22 am 
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Ken0069 wrote:
I've had an Evac system suck a valve cover gasket in a couple of times so they do suck. Like you, I've never measured it before but I do know mine works.


On one of Randy's engines that was on the dyno we hooked the vacuum sensor to the crankcase to test the evac system. If my memory serves me correctly it was 2-3"hg. With the evac unhooked it made no measurable change in HP.

My vacuum pump showed 10-15hp at peak hp and 20-25hp at higher rpm, closer to shift rpm.

Rick


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 Post subject: Re: bbc vacuum pump
 Post Posted: Wed Jan 13, 2010 8:57 am 
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What was your vacuum psi Rick with the pump???

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 Post subject: Re: bbc vacuum pump
 Post Posted: Wed Jan 13, 2010 1:57 pm 
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Beretta wrote:
What was your vacuum psi Rick with the pump???


Crankcase vacuum peaked a little over 15"hg. (no regulator) The comparison dyno pull was with no belt on the pump and crankcase vented.

Rick


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