bmod ehaust evac system

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
phantomfab
Member
Member
Posts: 116
Joined: Sun Dec 25, 2016 4:12 am

bmod ehaust evac system

Post by phantomfab » Mon Apr 16, 2018 2:50 am

Hey everyone. I have a question concerning USRA Bmods. The question is being we are only allowed to run the evac system using a one way valve on the header and we can only use it on one side is there any advantage to running one. Also, if i do install one do i use the style that slips into a gromet and uses a breather such as the picture supplied or is it better/worse to weld in a fitting to the valve cover. Also wonder if a hose from the oil pan to the valve cover would make any difference as well. Thank you all.

phantomfab
Member
Member
Posts: 116
Joined: Sun Dec 25, 2016 4:12 am

Re: bmod ehaust evac system

Post by phantomfab » Mon Apr 16, 2018 2:51 am

since the picture wouldnt load I though I would just upload a link to a set like i was talking about.

http://www.jegs.com/i/JEGS-Performance- ... 0/10002/-1

rebelrouser
Member
Member
Posts: 117
Joined: Tue Sep 15, 2015 2:25 pm

Re: bmod ehaust evac system

Post by rebelrouser » Mon Apr 16, 2018 12:53 pm

I have run this system for years in drag engines, Yes it will improve performance, how much? Maybe a couple HP, depends a lot on ring package, how good the oil pan is, etc. Best thing I like about the system is it reduces oil leaks. I use clear plastic hoses, and I can see real fast if blow by is getting excessive just by watching the amount of oil and water vapor in the hoses when engine is idling.

User avatar
MadBill
Guru
Guru
Posts: 13156
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: bmod ehaust evac system

Post by MadBill » Mon Apr 16, 2018 1:43 pm

There were some posts a while back re evac systems. I believe a SpeedTalker came up with an ultra-effective design that's in one of David Vizard's books, wherein the discharge tube is pointed straight downstream in the throat of the merge section. I want to say it pulled ~ 10" Hg...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

englertracing
Guru
Guru
Posts: 1041
Joined: Thu Sep 29, 2011 8:55 am

Re: bmod ehaust evac system

Post by englertracing » Mon Apr 16, 2018 5:52 pm

http://speedtalk.com/forum/viewtopic.ph ... 8&start=30
I think this is what Mad Bill is talking about.

I think it will be as good as it gets,
use a 1" hose to connect it to the valley. I would try to use it without a check valve,
or if your not into that use two check valves in parallel as to not restrict it.

Scavenging from the valve cover is not ideal as the air will be flowing counter the oil drainback
I think connecting it to the valley would be ideal, (not sure how that would work with whatever manifold you are using)
Connecting a hose from the pan to valve cover would have a similar effect

also don't expect earth shattering gains.

User avatar
MadBill
Guru
Guru
Posts: 13156
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: bmod ehaust evac system

Post by MadBill » Mon Apr 16, 2018 6:07 pm

englertracing wrote:
Mon Apr 16, 2018 5:52 pm
http://speedtalk.com/forum/viewtopic.ph ... 8&start=30
I think this is what Mad Bill is talking about.
That's the one!
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

geraldtson
Member
Member
Posts: 78
Joined: Tue Feb 10, 2015 9:50 pm

Re: bmod ehaust evac system

Post by geraldtson » Tue Apr 17, 2018 10:52 pm

I don't care for them but if they help or fix something by all means. Someone used to make a bolt up (2 bolt) breather system designed more for the tall cast aluminum erson and such valve covers which could be converted to the evap breathers with a little hose and a couple clamps. Speedway-Allstar Performance- Erson may still carry them. The grommet style you referred to should work fine without all the welding.Depending on your valve covers. Wish i could do the picture thing on here,got a set of the bolt up on latemodel in shop. I need to tighten up!

Post Reply