Building a good crankcase ventilation system?

Indy · Post by **Indy** » Thu May 05, 2005 2:30 pm

I've been reading some various tech articles on some different crankcase evac systems. Most are focused on naturally aspirated drag V8's, though, and I need a bit more perspective.

I was wondering what a good vacuum system could look like for a high-boost, street driven 4cyl. The thought of a vacuum pump has been running in the back of my mind for quite a while, but I'm not sure that it's worth it.

Nate

donk_316 · Post by **donk_316** » Thu May 05, 2005 2:49 pm

I bought a Moroso crankcase evac kit. I know GN guys use them with good results so ill run one and see how it goes.

Post by **eHoward** » Thu May 05, 2005 8:01 pm

Endyn's modified Moroso is very popular:

http://www.theoldone.com/components/breather

Shaun41178(2) · Post by **Shaun41178(2)** » Thu May 05, 2005 9:03 pm

yea I was going to say something what howard posted.

Of course SUmmit sells all the stuff too. Can prob find a deal there or hell check ebay.

quit worrying about all the accesories that your engine will need and just get the darn thing in. You can buy all that other stuff later. Right now you are looking at spending money that brings the install and running of you engine no closer to reality. Get the major stuff first and get it installed. Then worry about those toys.

just my opinion

donk_316 · Post by **donk_316** » Thu May 05, 2005 9:09 pm

That fancy breather unit is nice.

But thats not the same idea as the Moroso crankcase Evac kit which uses weld in bungs into the Exhaust to "suck" out the fumes from the crankcase through their valve cover air/oil baffle / seperator...

...Ill post a link

http://store.summitracing.com/default.a ... search.asp

Thats what i have but the two breathers are piped to a T then down to the downpipe.

AkursedX · Post by **AkursedX** » Thu May 05, 2005 9:23 pm

This is one of those areas that I am kinda "dumb" on. Can someone explain to me the advantages of having one of these upgraded systems?

Post by **eHoward** » Thu May 05, 2005 9:33 pm

CLick on the link I posted.

God wrote:This is one of those areas that I am kinda "dumb" on. Can someone explain to me the advantages of having one of these upgraded systems?

AkursedX · Post by **AkursedX** » Thu May 05, 2005 9:39 pm

Ahh ok, that makes sense now. I never really though of that being an issue since I thought that pressure created by one cylinder moving down would be counterracted by another moving up, but I guess at high rpm's, air just doesn't move fast enough....

whipped · Post by **whipped** » Thu May 05, 2005 11:59 pm

God wrote:I never really though of that being an issue since I thought that pressure created by one cylinder moving down would be counterracted by another moving up

That's what I think. Is it more because of blowby? Or just slow air?

The Dark Side of Will · Fri May 06, 2005 6:13 am

God wrote:I never really though of that being an issue since I thought that pressure created by one cylinder moving down would be counterracted by another moving up, but I guess at high rpm's, air just doesn't move fast enough....

Bay to bay breathing is a big issue.
The LS1 originally had bay to bay breathing windows machined into the block. The LS6 block had those windows cast in place.
The Northstar has bay-to-bay breathing windows machined in place (block is die cast rather than sand cast).
The new supercharged Northstar has a closed deck sand cast block with the breathing windows cast in place with radiused edges. Supposedly just going to radiused edges gained them a few ponies.
Of course these engines have very robust bottom end structures that come down almost to the level of the oil in the crank case and almost seal one bay off from the next.

With high crank case pressure, the engine is fighting pressure inside the crank case to pull the piston down on the intake stroke. The pressure is also obviously a parasitic loss on the power stroke.

Despite the extra parasitic loss of running the pumps, engines ALWAYS pick up horsepower from going to a dry sump system.

Kohburn · Post by **Kohburn** » Fri May 06, 2005 7:35 am

donk_316 wrote:That fancy breather unit is nice.

But thats not the same idea as the Moroso crankcase Evac kit which uses weld in bungs into the Exhaust to "suck" out the fumes from the crankcase through their valve cover air/oil baffle / seperator...

...Ill post a link

http://store.summitracing.com/default.a ... search.asp

Thats what i have but the two breathers are piped to a T then down to the downpipe.

I would imagine putting a catch can between the breathers and the exhaust would be a good idea to avoid blowing a lot of smoke

donk_316 · Post by **donk_316** » Fri May 06, 2005 9:21 am

Kohburn wrote: I would imagine putting a catch can between the breathers and the exhaust would be a good idea to avoid blowing a lot of smoke

lol!

Dude,
They dont suck oil out past the valve covers... its like any other valve cover /pcv system with baffles either built into the valve itself or on the inside of the valve cover.

Kohburn · Post by **Kohburn** » Fri May 06, 2005 9:55 am

LOL ass :la:

you know how many times i've seen oil get past the shitty baffles? if baffles worked there would be no need for a catchcan

edit to add: funny the fiero valve covers have internal baffles and they had a recall to move the breather pipe past the filter so it would stop soaking the filter in oil.. hmm whats that you say? the baffles don't allow oil past? hmm odd. :fart:

donk_316 · Post by **donk_316** » Fri May 06, 2005 12:43 pm

IF you knew ANYTHING....

The little bit of oil that does get sucked in is to lubricate the muffler bearings.

Dummy.

Kohburn · Post by **Kohburn** » Fri May 06, 2005 12:59 pm

donk_316 wrote:IF you knew ANYTHING....

The little bit of oil that does get sucked in is to lubricate the muffler bearings.

Dummy.

shit I forgot about the muffler bearing - if those go out they'll blow up and the shards will go through the firewall and kill you.. someone should make scatter sheilds for those muffler bearings.

Indy · Post by **Indy** » Fri May 06, 2005 2:03 pm

Kohburn wrote:.. someone should make scatter sheilds for those muffler bearings.

Already thought of that. I finally get to put all those old Pepsi cans to good use. :thumbleft: