Debate: How important is vacuum in the crankcase?

[SWThomas]

I've been wondering about this and have heard several different opinions on the subject. How important is it to have some sort of vacuum device on the crankcase? Whether it be the PCV system or an electric/mechanical vacuum pump? I know quite a few people that run breathers but there's even more that still have the PCV system in place. I've read that evacuating the crankcase helps with sealing the piston rings which produces more power. Supposedly it also prevents blow-by and oil consumption. If this is so, what would be a draw-back in running breathers? Other than smelling oil periodically? Any long term issues with running breathers that you know of?

BTW, I'm currently running a breather filter on each cam cover and have completely deleted the PCV system.

Discuss...:cheers

[DolSVT00]

I think its BS................ JMHO Before all the emissions shit there was no such thing as a pcv egr blah blah bla. Law is that an internal combustion engine must consume all oil,gasses that would normaly vent to atmosphere from the crankcase,valve covers.......

If vaccuum was so effective..... what would be the use of an oil pump?




"I've read that evacuating the crankcase helps with sealing the piston rings which produces more power." Sales pitch by L&S to sell oil seperators that no worky but scares the shit out of NLOC:nutswinger: s

Among all the good and useful information I've read on NLOC,SVTP there's allwayse the bad and it's usually by the same group of weenie smoochers.

1. Line mod valve will ruin your transmission.... BS go spend your money on a greg evans signature valve body, while I run my 1/2 line mod for 2+ years with 0 issues and 80k miles.

2. you can run the stock MAF with a stock blower 4lb pulley....... BS It depends on the size of the intake tube, if you are running the stock rubber boot it will surely peg I have the datalogs to prove it.

3. A tune with an A/F of 11.8 @ WOT is perfect and safe. BS 11.8 at WOT is only 1/4 of a tune there is a ramp down and a ramp up that is extremely important when it comes to 60' times and good track numbers, someone with a 10.8 A/F could get better track times than you if his ramp's up and down are better. Do a test, punch half throttle and watch your A/F if it goes to 10 or lower its "because your fuel tables have been ass raped to obtain 11.8 at WOT and is a shitty tune that will net you 8mpg and slow ass track times" Quote from SAL@PSP LMAO

4.evacuating the crankcase helps with sealing the piston rings which produces more power and reduces engine wear. Again I call BS I have spent many worthless dollars on oil seperators and after 3+ intercooler cleanings I said screw this and put filters on, oil in the intake helps detonation and increses heat.......... But I guess crankcase vaccuum is more important.......Not

[1iron]

A vacuum pump will make more HP. They are pricey and worth a small gain. The PCV helps keep hyrdocarbons and other contaminantes out of your oil. They do not stop blow-by but they pull the blow-by out of the crankcase. I still run a PCV on my 66 Mustang but not on my 90.

Paul

[DolSVT00]

I think I missed that part about the mechanical vaccuum pump, I guess the oil sep crap i've been reading and have experienced drove me to insanity.

I do agree with the mechanical vacuum pump but your right it is pricey for the gain.

[SWThomas]

But how does an engine gain power from using a mechanical vacuum pump???

[DolSVT00]

But how does an engine gain power from using a mechanical vacuum pump???

Most racing engines are equipped with breathers in order to help reduce crankcase pressure which can cause oil leaks and adversely affect the way an engine accelerates. By further reducing this pressure with the help of a vacuum pump, a number of things occur. Free from crankcase pressure, theoretically a piston on the downward compression stroke has less resistance to impede its progress, thus allowing it to accelerate faster. Vacuum also aids in drawing oil from the rotating assembly quicker as well. Engine oil pressure tends to be reduced as a result of the vacuum inside the engine, and oil is drawn out from between the bearings and crank journal quicker than normal. As a result of this increased efficiency, we have redesigned a number of our racing oil pans as there are fewer scrappers and screens required when a good vacuum pump is used.

Straight out of a racing website I frequent.

[1iron]

My understanding is that hp gains form the mechanical vacuum pump are from better ring seal and reduced friction by using low tension rings.

Blower engines need a big ass vucuum pump to keep up with the blow-by.

Paul

[DolSVT00]

Don't get me wrong Im not against oil seperators that work although I have not found any.

I just get pissed off when they falsely make statements like L&S to sell a seperator that in fact does not work nor does it do what they claim.

[SWThomas]

So you don't think a breather on each cam cover provides enough pressure release for the crankcase?

[WWhittle]

So you don't think a breather on each cam cover provides enough pressure release for the crankcase?


it depends on the motor- depends on the setup- but generally speaking, a breather is a baby step to a vacuum pump.

and for the record- you will see a difference on your timeslip with a vacuum pump installed. not a big one- but there will be something there.

[SWThomas]

it depends on the motor- depends on the setup- but generally speaking, a breather is a baby step to a vacuum pump.

and for the record- you will see a difference on your timeslip with a vacuum pump installed. not a big one- but there will be something there.

I may have to do a comparison on this next time I go to the track. I'm just not buying that there would be a power increase with a vacuum pump. But I would love to be proven wrong.

[WWhittle]

I may have to do a comparison on this next time I go to the track. I'm just not buying that there would be a power increase with a vacuum pump. But I would love to be proven wrong.

i am speaking from experience. somewhere between .06 and .10 difference for me.

give it a try- like i said, it depends on the setup.