mrfred

iTrader: (50)

I finally got around to finishing up a series of crankcase pressure measurements with different valve cover ventilation setups with my 500 whp drop-in build. I obtained the pressure measurements by drilling and tapping a spare oil filler cap for 1/8" NPT and running that to a 75 psi absolute pressure sensor that I can log with EvoScan. I ran the pressure sensor through an 8-bit ADC converter in the ECU which produces a relatively large pressure measurement granularity of ~0.4 psi (i.e., the pressure read in EvoScan goes in steps of 0.4 psi). I will very likely remeasure some of the ventilation setups using the 10-bit ADC converter in the ECU because this will granularity in the measurement to 0.1 psi.

Results are described below. As can be seen, setups #3 and #4 got the pressure below 0.5 psi. And because of the relatively large granularity in the pressure measurement, its possible that both of those setups are significantly below 0.4 psi.

1) Completely stock valve cover ventilation setup: 2.3 psi at WOT peak power

2) Configuration shown in Figure 1: 0.8 psi at WOT peak power.
This setup provides additional ventilation under boost by replacing the PCV valve with a 3/8" barb that was hooked up to 7/16" hose that is VTA.

3) Configuration shown in Figure 2: 0.4 psi at WOT peak power.
For this setup, the stock PCV valve was reinstalled, and English Racing tapped the valve cover breather hole for 3/8" NPT (1/2" ID) and attached 7/16" hose that was VTA.

4) Configuration shown in Figure 3: 0.4 psi at WOT peak power.
For this configuration, English Racing also tapped the PCV port on the valve cover for 3/8" NPT, and this was VTA with a combo of 7/16" and 3/8" hose.


Figure 1. Modified configuration #1.



Figure 2. Modified configuration #2.



Figure 3. Modified configuration #3.

10isace

iTrader: (12)

Thanks mrfred!!! Great info.

So from what I understand is that the readings could be +/- 0.4 psi off? That's not a big deal.

Looks like anything bigger than stock ventilation on the DS is pretty good at 500 whp.

In config #3, you can eliminate the intake mani vacuum set up. Do you have any readings for vacuum at idle/cruise for all 3 of these setups?

TheBigD

iTrader: (10)

do you guys think the STM -12 fitting for the plugged balance shaft hole after removal would kick out to much oil? and or if i ran that -12 line all the way over to my catch can behind the driver headlight would that be to far to route a breather line

TheBigD

iTrader: (10)

for anyone wanting to remove baffles and worry about bolts backing out

https://www.evolutionm.net/forums/ev...n-new-way.html

CammedEvo

iTrader: (5)

What did the intake setup look like that was used for this test? I'm curious what role the ID of the intake/filter relative to the hose used to the valve cover would play in the amount of suction early. What i'm getting at is in theory if you could place enough suction on it early the rings would seal better and you'd get less gasses to deal with. If you have less gasses to vent you negate the need for increased diameter holes.

Also mrfred I think you made an error in reporting your data for the stock system pressure. 2.3 isn't divisible by .4

mrfred

iTrader: (50)

The valve cover vent hose was VTA and not hooked up to the intake pipe. In order to make good use of the intake pipe, I need to install a larger diameter barb on the intake pipe.

The suction created by the intake pipe during off-boost driving is miniscule (<0.05 psi), but with the addition of some checkvalves, it is possible to pull a vacuum on the crankcase using the factory PCV system (while still allowing it to crankcase to vent properly under boost). With the right setup, idling motor for a few minutes can produce 5 psi of vacuum on the crankcase.

Under boost, I've measured 1 psi of vacuum in my FP intake with a MAF and freshly cleaned Amsoil air filter. With a big enough hose (and fittings) between the valve cover and the intake, it might actually be possible to create almost 1 psi of vacuum in the crankcase. I think a -12 AN fitting and hose would be needed to do it though. People running a 4" SD intake will likely have less than 0.5 psi vacuum, so there not much of a sell for those people.

I was rounding up when I wrote 0.4 psi per step. Its closer to 0.39 psi per step.

xXANCHORMONXx

iTrader: (15)

I had issues with my dipstick popping out at 30+ psi.

I had a completely custom catch can built. It's 1.1 gallon capacity and mounts where my ic sprayer was so it's out of the way. It had a 4 stage baffle system, 4th being removable ss wool. It has a 1 inch breather filter on it.

There are 4 inputs. 2 6an off of the vc, 1 off of the dipstick, and 1 off of the front of the block.

I designed it with a fumoto drain valve as wellso it's super easy to drain.

Overall I couldn't be happier and my intake stays nice and clean!

mitsubeastlee

iTrader: (3)

I just installed the STM tranny mounted 3 port catch can modified. It uses two -6an ports and one -10 an port.

-10an fitting off of the rear valve cover port
-6an off balance shaft inspection hole
-6an off side valve cover port

I will report back how much oil it traps after I am tuned.

CammedEvo

iTrader: (5)

I've been talking to one of my friends about this. I think were going to run a oil/water separator for a air compressor on the PCV side. Still un decided on how large ID wise I want to make the port on the valve cover. I suppose I could hook a map sensor to the PVC port and test the vacuum created relative to the size of the valve cover port.

I'm not sure what your ring setup is like on your motor but have you ever investigated how much HP gets free'd up when you place the crank case in vacuum?

desiromeo812

iTrader: (13)

As been noted by Tscomp in a few posts.. the side port on the VC is enough for most setups if enlarged, and that port is baffled very well, therefore you will not see much oil in your intake, if ANY.

With that said for people with under 500WHP it would be helpful to just use the stock system (as long as the PCV is not leaking). Alll they should need to do is enlarge the side hole and route it to intake.

If they want to keep the intake manifold clean, just use a catch can between intakemanifold and VC.

mrfred

iTrader: (50)

The only way I could pull a vacuum on the crankcase of my motor under boost would perhaps be with a smog pump or a real crankcase pump. I'd be tempted to try it, but I don't see how a 1-2 psi vacuum is going to make any difference in ring sealing when cylinder pressure should produce way more sealing force. Maybe I'm missing something in how the ring sealing works?

desiromeo812

iTrader: (13)

Hi! do you not suppose that maybe if you route the VC to intake it would cause it to sort of have a vacuum effect on the vc?

mrfred

iTrader: (50)

yes, it could. i mentioned that above. the degree of vacuum would depend on the amount of blowby, the restrictiveness of the intake (more restriction generates more vacuum as the turbo gasps for air), and how well the hose fitting on the intake is aligned to produce a venturi effect. for a non-restrictive high performance intake and a built motor, i'd be surprised to see more than 1 psi of vacuum generated in the crankcase.

mrfred

iTrader: (50)

I set up 10 bit ADC so that I can log crankcase pressure in 0.1 psi increments. Here is the latest info for WOT pulls:

- My custom crankcase evac setup creates a net crankcase suction under most daily driving conditions which means that its pulling in fresh air through the vent hose and helping to keep the crankcase free of moisture. I'm quite pleased to see this result.

- If I put -8 AN fittings and 7/16" VTA hose on both the valve cover vent and the PCV outlet, crankcase pressure remains at atmospheric pressure during a WOT pull.

- For configuration #1 in post 871, I have found that my crankcase evac cannot keep up with the amount of blowby generated during a WOT pull, and this setup results in about 0.2 psi crankcase pressure. Considering that the crankcase evac works reasonably well under daily driving, I'm quite pleased with this result.

My next test will be to hook the valve cover vent hose to the intake see how that affects crankcase pressure during a WOT pull.

99gst_racer

I think you'll find the intake pipe works better than the exhaust. After traveling through a turbine housing, the exhaust doesn't seem to be traveling fast enough (relative to it's diameter) to scavenge very efficiently.

With mine plumbed to the intake pipe, I logged roughly a .4 PSI crankcase pressure drop during high boost pulls (dropped from .4 to 0). And that was with a 4" intake pipe and no element on the end.