Street/Strip Crankcase Vacuum using a PCV Valve

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weedburner

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Here's the evac system I had been using. These valve covers are a circle track design that originally used a crossover tube with a couple small breathers, I eliminated the crossover setup and made some adapters to plumb them into a separator can that I had also installed a pcv valve into. The hose out the bottom is connected to a standpipe inside the separator, other end of that hose connected to the inlet of the electric pump. Outlet of the electric pump had a large header evac style check valve to eliminate the vacuum leak when the pump was not turned on. Using the pcv valve as a crankcase vacuum source worked so well that I rarely turned on the electric pump, got to the point that I considered the electric pump system as dead weight.

evacpcv1.jpg


I ended up eliminating the hoses, separator, electric pump, and check valve. I replaced them with a modified version of the original crossover tube. Basically I made some Delrin check ball seats that fit inside the aluminum crossover tube's breather standpipes...


pcv2b.png

pcv2c.png


For the check balls, I bought some 1" dia nylon bearing balls, cost me around $5. I also installed my homemade adjustable pcv valve that had formerly been installed in the separator...

pcv2d.png


The plastic elbow on the pcv valve rotates, I pointed it off to the side and attached it to it's hose.

pcv2e.png


These check balls are pretty light-weight, launching the car does not cause them to become un-seated and leak crankcase vacuum.

Grant
 
Last edited:
weedburner said:
Here's the evac system I had been using. These valve covers are a circle track design that originally used a crossover tube with a couple small breathers, I eliminated the crossover setup and made some adapters to plumb them into a separator can that I had also installed a pcv valve into. The hose out the bottom is connected to a standpipe inside the separator, other end of that hose connected to the inlet of the electric pump. Outlet of the electric pump had a large header evac style check valve to eliminate the vacuum leak when the pump was not turned on. Using the pcv valve as a crankcase vacuum source worked so well that I rarely turned on the electric pump, got to the point that I considered the electric pump system as dead weight.

View attachment 1715749692

I ended up eliminating the hoses, separator, electric pump, and check valve. I replaced them with a modified version of the original crossover tube. Basically I made some Delrin check ball seats that fit inside the aluminum crossover tube's breather standpipes...


View attachment 1715749693
View attachment 1715749694

For the check balls, I bought some 1" dia nylon bearing balls, cost me around $5. I also installed my homemade adjustable pcv valve that had formerly been installed in the separator...

View attachment 1715749695

The plastic elbow on the pcv valve rotates, I pointed it off to the side and attached it to it's hose.

View attachment 1715749696

These check balls are pretty light-weight, launching the car does not cause them to become un-seated and leak crankcase vacuum.

Grant
Click to expand...
Nice!
That first set up looks like it could suck a golf ball thru a garden hose.
 
These check balls are pretty light-weight, launching the car does not cause them to become un-seated and leak crankcase vacuum.

"Crankcase vacuum"
Do you run a vacuum pump?
Most crankcases run at slight pressure even with a PCV
 
weedburner said:
Here's the evac system I had been using. These valve covers are a circle track design that originally used a crossover tube with a couple small breathers, I eliminated the crossover setup and made some adapters to plumb them into a separator can that I had also installed a pcv valve into. The hose out the bottom is connected to a standpipe inside the separator, other end of that hose connected to the inlet of the electric pump. Outlet of the electric pump had a large header evac style check valve to eliminate the vacuum leak when the pump was not turned on. Using the pcv valve as a crankcase vacuum source worked so well that I rarely turned on the electric pump, got to the point that I considered the electric pump system as dead weight.

View attachment 1715749692

I ended up eliminating the hoses, separator, electric pump, and check valve. I replaced them with a modified version of the original crossover tube. Basically I made some Delrin check ball seats that fit inside the aluminum crossover tube's breather standpipes...


View attachment 1715749693
View attachment 1715749694

For the check balls, I bought some 1" dia nylon bearing balls, cost me around $5. I also installed my homemade adjustable pcv valve that had formerly been installed in the separator...

View attachment 1715749695

The plastic elbow on the pcv valve rotates, I pointed it off to the side and attached it to it's hose.

View attachment 1715749696

These check balls are pretty light-weight, launching the car does not cause them to become un-seated and leak crankcase vacuum.

Grant
Click to expand...

Interesting. So at high vacuum the balls cover the breather holes and at low vacuum the balls get out of the way and let crankcase pressure out of the breathers. Am I getting that right???

So no vacuum pump either? I’d like to test all that on a dyno and see what happens.
 
512Stroker said:
"Crankcase vacuum"
Do you run a vacuum pump?
Most crankcases run at slight pressure even with a PCV
Click to expand...

No vacuum pump at all with the 2nd picture setup, just a pcv valve sucking against a sealed crankcase. Crankcase vacuum is essential for my low tension rings on the street, an earlier version of this engine only got around 250mi to the quart before I sealed it's crankcase and added the pcv valve.

The pcv valve has been modified to make it work similar to adjustable orifice, currently set to draw around 12-15"Hg in the crankcase while cruising down the highway. Here's a RacePak graph showing crankcase vacuum during a 6.25sec long WOT 3rd gear pull with the pcv valve as the only vacuum source. Nitrous system was NOT turned on, this pull was NA.
...Red line- engine rpm
...Blue line- WOT switch
...Yellow line- crankcase vacuum

shopmulepcvonly.jpg


The pull started out with 12.6"Hg @ 2600rpm. When the pull ended at 6250rpm, even without the electric pump running the crankcase still had 3.9"Hg of vacuum left. I should add that the 355" engine is well sealed, no dipstick (oil level sight glass), Total Seal gapless top rings, and a 114 LSA nitrous cam.

When blowby exceeds the volume of the pcv, the check valves un-seat and any pressure is vented thru the breathers.

Grant
 
yellow rose said:
Interesting. So at high vacuum the balls cover the breather holes and at low vacuum the balls get out of the way and let crankcase pressure out of the breathers. Am I getting that right???

So no vacuum pump either? I’d like to test all that on a dyno and see what happens.
Click to expand...

You got it right. The version before this had an electric vacuum pump as backup, but I rarely needed it. Decided to cut the extra weight and let the breathers be the relief.

Grant
 
weedburner said:
No vacuum pump at all with the 2nd picture setup, just a pcv valve sucking against a sealed crankcase. Crankcase vacuum is essential for my low tension rings on the street, an earlier version of this engine only got around 250mi to the quart before I sealed it's crankcase and added the pcv valve.

The pcv valve has been modified to make it work similar to adjustable orifice, currently set to draw around 12-15"Hg in the crankcase while cruising down the highway. Here's a RacePak graph showing crankcase vacuum during a 6.25sec long WOT 3rd gear pull with the pcv valve as the only vacuum source. Nitrous system was NOT turned on, this pull was NA.
...Red line- engine rpm
...Blue line- WOT switch
...Yellow line- crankcase vacuum

View attachment 1715749711

The pull started out with 12.6"Hg @ 2600rpm. When the pull ended at 6250rpm, even without the electric pump running the crankcase still had 3.9"Hg of vacuum left. I should add that the 355" engine is well sealed, no dipstick (oil level sight glass), Total Seal gapless top rings, and a 114 LSA nitrous cam.

When blowby exceeds the volume of the pcv, the check valves un-seat and any pressure is vented thru the breathers.

Grant
Click to expand...
Dam Boy
We need to change your handle to - Professor Vacuum
Nice job
 
yellow rose said:
So no vacuum pump either? I’d like to test all that on a dyno and see what happens.
Click to expand...

It would be a lot of work to verify the benefits on a dyno, as the main benefit to me is being able to run lighter tension ring packs on the street. It's part of what helps me net 20mpg on the highway without an overdrive, not to mention less wear/tear on the cylinder walls. Easier to cool the engine too. I'm 3100rpm @ 70mph.

Grant
 
weedburner said:
It would be a lot of work to verify the benefits on a dyno, as the main benefit to me is being able to run lighter tension ring packs on the street. It's part of what helps me net 20mpg on the highway without an overdrive, not to mention less wear/tear on the cylinder walls. Easier to cool the engine too. I'm 3100rpm @ 70mph.

Grant
Click to expand...
20 mpg - nice
But I am from MO you offer up a statement like that and you are going to have to show me some proof.
 
512Stroker said:
20 mpg - nice
But I am from MO you offer up a statement like that and you are going to have to show me some proof.
Click to expand...

Mileage was calculated using a gps tracking app on my phone, never bothered to hook up the speedo. Car is currently 2300lbs, 4spd manual, on radials with fairly good aero. TruTrac diff allows it to roll pretty free thru the corners. Low compression pump gas engine with nitrous, it'll also do 70mph in 1st gear :) Here's a link to the car's build page- http://grannys.tripod.com/20102.html

Grant
 
weedburner said:
Mileage was calculated using a gps tracking app on my phone, never bothered to hook up the speedo. Car is currently 2300lbs, 4spd manual, on radials with fairly good aero. TruTrac diff allows it to roll pretty free thru the corners. Low compression pump gas engine with nitrous, it'll also do 70mph in 1st gear :) Here's a link to the car's build page- http://grannys.tripod.com/20102.html

Grant
Click to expand...
What the hell kinda A body is that!
Cant say that I am familiar with that one.
 
weedburner said:
It would be a lot of work to verify the benefits on a dyno, as the main benefit to me is being able to run lighter tension ring packs on the street. It's part of what helps me net 20mpg on the highway without an overdrive, not to mention less wear/tear on the cylinder walls. Easier to cool the engine too. I'm 3100rpm @ 70mph.

Grant
Click to expand...


I was talking about monitoring crank case vacuum, but I forgot you are data logging.
 
512Stroker said:
What the hell kinda A body is that!
Cant say that I am familiar with that one.
Click to expand...

Just sharing the breather/checkvalve thing, might work on an A-body too. For some Mopar content in this thread, here's a pic of a naked dirt latemodel I built back in the late '80's...

latemodel3a.jpg


Won a few features, at the time it was the only Mopar at the track. The engine was a 440 BBM that was mounted backwards in the car. The homemade transmission's input shaft plugged into a hub that bolted onto the engine's damper. Backwards engine meant that the drivetrain spun backwards. Quickchange was modified to flip the spool, putting the ring gear on the other side of the pinion.

The car after that one was powered by a homemade 4 rotor rotary engine, it's what originally got me into the Mazda. Here's a link to that car's page and info, you will find the Mopar car at the bottom- https://grannys.tripod.com/4rotor.html

Grant
 
weedburner said:
Here's the evac system I had been using. These valve covers are a circle track design that originally used a crossover tube with a couple small breathers, I eliminated the crossover setup and made some adapters to plumb them into a separator can that I had also installed a pcv valve into. The hose out the bottom is connected to a standpipe inside the separator, other end of that hose connected to the inlet of the electric pump. Outlet of the electric pump had a large header evac style check valve to eliminate the vacuum leak when the pump was not turned on. Using the pcv valve as a crankcase vacuum source worked so well that I rarely turned on the electric pump, got to the point that I considered the electric pump system as dead weight.

View attachment 1715749692

I ended up eliminating the hoses, separator, electric pump, and check valve. I replaced them with a modified version of the original crossover tube. Basically I made some Delrin check ball seats that fit inside the aluminum crossover tube's breather standpipes...


View attachment 1715749693
View attachment 1715749694

For the check balls, I bought some 1" dia nylon bearing balls, cost me around $5. I also installed my homemade adjustable pcv valve that had formerly been installed in the separator...

View attachment 1715749718

The plastic elbow on the pcv valve rotates, I pointed it off to the side and attached it to it's hose.

View attachment 1715749719

These check balls are pretty light-weight, launching the car does not cause them to become un-seated and leak crankcase vacuum.

Grant
Click to expand...
Sorry to drag up a really old thread. This is a very creative solution. I have been considering doing something like this but with a vacuum/ catch can and pluming it to both the pvc/intake manifold and the exhaust-powered E-vacs so in theory when manifold vac goes down, the evacs kick in. Just need to figure out a crossover for the two vacuum sources but it seems like it would work well. How did you do the crossover from your vacuum pump? or did you just run it as the only option?
 
bjkadron said:
Sorry to drag up a really old thread. This is a very creative solution. I have been considering doing something like this but with a vacuum/ catch can and pluming it to both the pvc/intake manifold and the exhaust-powered E-vacs so in theory when manifold vac goes down, the evacs kick in. Just need to figure out a crossover for the two vacuum sources but it seems like it would work well. How did you do the crossover from your vacuum pump? or did you just run it as the only option?
Click to expand...

I use the 2 , 3/8'' vacuum nipples sticking out the back of my 1200 cfm throttle body , have a separator , then a rigged 1/4'' plastic ball valve , "was originally for a kidney dialysis system", to adjust the vacuum , then to the pass. side cover .
haven't got any oil in the separator , and controlling the vacuum to about 11 inches ...sure helps with oil leaks . reg.pan evac set up on the drivers side cover...
 
bjkadron said:
Sorry to drag up a really old thread. This is a very creative solution. I have been considering doing something like this but with a vacuum/ catch can and pluming it to both the pvc/intake manifold and the exhaust-powered E-vacs so in theory when manifold vac goes down, the evacs kick in. Just need to figure out a crossover for the two vacuum sources but it seems like it would work well. How did you do the crossover from your vacuum pump? or did you just run it as the only option?
Click to expand...

I put a check valve on the exhaust of the electric pump. If a situation arose where the pcv could not keep up, the idea was that the check valve would open to relieve any pressure buildup. That single check valve was the same valve as used on the exhaust powered evac systems.

In my application the pcv valve draws way more vacuum than the electric pump during casual driving, which allowed me to activate the electric pump only when I was going to make a WOT pass. I was turning the pump on manually at the time, although I could have turned it on automatically with my WOT switch. Lucky for me I eventually forgot to turn the electric pump on, to my surprise data logger told me the pcv valve was enough and I didn't actually need the electric pump. From that point I eliminated the electric pump and moved the check valve to inside the breathers. To this day when I remove a breather to add oil to the engine, the top half of the check balls as well as the inside of the breathers are clean and dry.

I should add that it's important to keep the engine sealed, that way the pcv only has to deal with actual blow-by rather than external air leaks. In my case the pcv valve draws 15"-18"Hg in the crankcase during casual driving, making it hard to maintain a seal over time at the top of the china wall. Initially I made spacers to fill most of the gap (raised port heads), but still eventually Ultra Black would get pulled thru. I almost started using Right Stuff instead, but didn't want to have to pry the intake off when the time came. Now I back up the Ultra Black with a thin band of Right stuff applied over the outside after installing the intake, fixed the problem.

Grant
 
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