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Crank case pressure

Started by _LX355SLR_ , Nov 02 2015 09:20 AM

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49 replies to this topic

#26 TerrA LX

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Posted 05 November 2015 - 11:06 AM

^ Agree.

Yes but the pcv valve is not enough to vent a performance engine which needs to breath freely ..also pcv s suck in contaminated air which can cause detonation which is ok for stockers but not good for high performance engines

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#27 myss427

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Posted 05 November 2015 - 01:19 PM

Fix the rings and put a vacuum pump on it. On performance engines they stop oil leaks, free up some power and look pretty cool.

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#28 Shiney005

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Posted 05 November 2015 - 02:21 PM

I've never really thought about it until now, but would the high crank case pressures also restrict oil flow back down to the sump? I have seen a lot of work done with a die grinder to 308 blocks to help stop the top end from filling up at sustained high RPM.

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#29 TerrA LX

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Posted 05 November 2015 - 04:17 PM

^ yes, most definitely

That is why some vent straight from and return to (catch can oil) straight to the sump..

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#30 _STRAIGHTLINEMICK_

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Posted 05 November 2015 - 05:01 PM

^ yes, most definitely
That is why some vent straight from and return to (catch can oil) straight to the sump..

Yeep thats right, i said a couple of posts ago to vent from the sump and one of the main benefits is to allow oil drainback to the sump where u need it.
If u are running an electric fuel pump then u can vent from the pump block off plate

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#31 jd lj

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Posted 05 November 2015 - 06:12 PM

If you run a vent from the sump I'd assume that it'll work better above the oil level. Otherwise would it possibly have a kind of hydraulic lock.

My 202 high volume sump has a port quite low on one side for an oil temperature sender which is no longer being used. I'd wondered if plumbing into this would be advantageous.

I know that I have some sump pressure that needs to be dealt with, but I'm not in a position currently to do a rebuild. I've seen a lot of track cars run a hose from a side plate to the catch can, how effective is that method?

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#32 _STRAIGHTLINEMICK_

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Posted 05 November 2015 - 09:03 PM

If you run a vent from the sump I'd assume that it'll work better above the oil level. Otherwise would it possibly have a kind of hydraulic lock.

My 202 high volume sump has a port quite low on one side for an oil temperature sender which is no longer being used. I'd wondered if plumbing into this would be advantageous.

I know that I have some sump pressure that needs to be dealt with, but I'm not in a position currently to do a rebuild. I've seen a lot of track cars run a hose from a side plate to the catch can, how effective is that method?

The vent needs to be above the oil level.
directly out of the sump is best . then fuel pump flange , then siďeplate.anything is better than nothing.

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#33 _Bomber Watson_

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Posted 05 November 2015 - 09:05 PM

I run mine from the sideplates.

A lot better than the rocker cover.

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#34 WhiteA9XS

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Posted 05 November 2015 - 09:39 PM

The problem is the bad ring seal, not the lack of a vacuum pump. If your house kept filling up with water the smart thing to do would be to fix the roof rather than put a bilge pump in the loungeroom...

On the money Oldjohno , i have just experienced this , was a fresh engine had slight fuming and blew rear main seal ... rings stuck inside piston groove .

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#35 _Bomber Watson_

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Posted 05 November 2015 - 10:20 PM

If your house kept filling up with water the smart thing to do would be to fix the roof rather than put a bilge pump in the loungeroom...

*hides bilge pump in loungeroom*

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#36 _oldjohnno_

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Posted 06 November 2015 - 05:05 AM

The vent needs to be above the oil level.
directly out of the sump is best . then fuel pump flange , then siďeplate.anything is better than nothing.

Exactly. The manifold side of the sump in line with a main web is the best spot. The sideplates aren't really ideal because they are still above the drainback holes in the block, though it's what I use and it seems to be OK. The front plate has one more drain hole than the rear so would probably be the better choice.

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#37 _STRAIGHTLINEMICK_

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Posted 07 November 2015 - 12:57 PM

*hides bilge pump in loungeroom*

If the pump cant keep up its time to get into the dinghy.

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#38 _Agent 34_

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Posted 07 November 2015 - 04:45 PM

a dingy in the lounge room ?

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#39 _oldjohnno_

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Posted 07 November 2015 - 06:18 PM

a dingy in the lounge room ?

Well you can't leave it in the kitchen. The crocs would chew it to bits...

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#40 _STRAIGHTLINEMICK_

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Posted 08 November 2015 - 04:55 PM

I hate fu##n crocs .how did they get that far south

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#41 _oldjohnno_

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Posted 08 November 2015 - 05:02 PM

I hate fu##n crocs .how did they get that far south

Straight down the hallway I guess...

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#42 _STRAIGHTLINEMICK_

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Posted 08 November 2015 - 06:28 PM

Straight down the hallway I guess...

Were you on that swamp people show johnno.

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#43 _oldjohnno_

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Posted 08 November 2015 - 07:27 PM

Yep that was me with the banjo. I was smiling cos I like to show off my teeth - both of em...

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#44 _STRAIGHTLINEMICK_

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Posted 08 November 2015 - 09:18 PM

Ha , Thought the photo looked familiar. Good onya Johnno

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#45 _LX355SLR_

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Posted 18 November 2015 - 07:16 PM

i have installed a PCV valve and it has made no noticeable difference. leaks the same amount but could just be because the seal is gone already. I have out a plastic bag over the rocker cover filler hole and at idle is slightly sucking the bag inward but would obviously be a different story at high revs. Vac pump sound interesting. Where are these being installed...of the maniofld?

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#46 _Mint_

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Posted 18 November 2015 - 08:20 PM

I recently tried a bottle of this stuff http://rislone.com.a...in-seal-repair/ on my weepy neo rear main seal after another guy used it and said it worked great so far its doing the job

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#47 TerrA LX

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Posted 19 November 2015 - 04:40 AM

i have installed a PCV valve and it has made no noticeable difference. leaks the same amount but could just be because the seal is gone already. I have out a plastic bag over the rocker cover filler hole and at idle is slightly sucking the bag inward but would obviously be a different story at high revs. Vac pump sound interesting. Where are these being installed...of the maniofld?

There should be no manifold vacuum at hi rpm coming thru the PCV, the valve should close and all engine pressure and blow by at hi rpm should flow into the air filter.

Edited by TerrA LX, 19 November 2015 - 04:42 AM.

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#48 _oldjohnno_

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Posted 19 November 2015 - 05:02 AM

There should be no manifold vacuum at hi rpm coming thru the PCV, the valve should close and all engine pressure and blow by at hi rpm should flow into the air filter.

At lower vacuum levels like at WOT the PCV is actually at it's most open position, to give the most flow despite the low vacuum. If the engine is in good shape there shouldn't be much backflow at all into the air filter.