Measuring crank case pressure

doublespaces

Administrator
Oct 18, 2016
8,356
AZ
I'm surprised how much talk there has been about PCV and crank case ventilation but I've never actually seen any logs with crank case pressure readings. There are a couple of things I think would be interesting to measure such as the amount of pressure at idle and WOT with various crank case ventilation setups.

Currently, my car has (as soon as I put it on the ground):

Plugged Head Ports
Flapper Delete to OCC to VTA
PCV Delete to OCC to VTA

By no means do I intend to keep this setup, I do not like the smell of an atmospheric vent.

First I'm going to start by measuring this with the Mishimoto catch cans I currently have. Keep in mind, one of them is missing the internal stone filter, I believe its the high side so the pressure restriction here is going to be less than someone else running the same can. I've found those things to be very restrictive and since the high side doesn't get a lot of gunk in there when the low side is sucked into the manifold during idle, I've been able to get away without having the oil separator stone filter thingie in there.

Next, I'm going to measure the actual vacuum being generated at my intake pipe, it is a K&N cone filter sitting in front of a 6266Gen2.

Once I have these readings, I'm going to block the Flapper and PCV ports with caps and connect my intake pipe to the front head port as I outlined in the service port thread and measure again to see how much if any vacuum or positive pressure I'm getting on the crank case at idle and WOT.

To accomplish this I bought a sensor off ebay:
1584769392104.png


This is the description:

-14.5-30psi

Description:

·Brand new vacuum pressure transducer. Stainless steel body.
·Input: -14.5 psi (-1.0 bars) to 30 psi (2.0 bars).
·Output: 0.5V -4.5V linear voltage output.
·Works for boost vacuum chamber, oil, fuel, water or air pressure. Can be used in oil tank, gas tank, etc.
·Accuracy: within 0.5% of reading (full scale).
·Thread: 1/8” 27 NPT.
·Wiring connector: water sealed quick disconnect. Mating connector is included.
·Wiring: Red: +5V; Black: ground; Green: signal output;
·It is an advance pressure sender than traditional mechanical pressure sender.
·Our material is using top of line 316 stainless steel and high temperature auto-graded plastic.
·Brand new pressure transducer. 316 Stainless steel body.
I'm going to disconnect my flex fuel wire and connect the 0-5v signal from this and I should be able to plot the pressure with an accurate timeline on my datalog.

Any thoughts or suggestions?
 
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Jeffman

Captain
Jan 7, 2017
1,352
Interesting idea. If you’re using a FlexFuel tune then your interpolation will be going up and down, like 0 to 100% ethanol, which could be bad. To avoid this problem you could have a special FlexFuel tune in which the 0% ethanol is the same as 100% ethanol, resulting in no effective change in tune parameters and engine control while you’re able to monitor crank case pressure.
 

Cruizinmax

Lurker
Jul 18, 2018
22
I agree with Jeffman's concern. For this to work successfully you will need a 0-5v input that doesn't effect an engine tuning parameter.

I would also suggest using a map sensor with a much smaller range. Using a 3 bar sensor will limit your resolution and we're dealing with very small amounts of vacuum /pressure in the crankcase. I feel a 1.5 bar sensor would be more than adequate. Perhaps a factory Honda map sensor.

I'm not really sure why people are so wrapped up with PCV on this platform. All other platforms I've dealt with have basically 3 general schematics. 1. OEM-Using engine vacuum to pull crankcase fumes in to the intake tract to burn them. 2. VTA-No longer using "positive" ventilation. Crankcase fumes are only pushed out from combustion blowby. 3. Use a mechanical vacuum pump to pull fumes from the crankcase and sending them to atmosphere.

There is so much more "low hanging fruit" than maximizing the PCV system. Installing a catch can to prevent oil from building up in the intake tract or dumping on the ground makes sense. Anything further really seems like a waste of money IMO. You guys have to pull the "vendor wool" away from your eyes and look at other platforms. Stop trying to reinvent the wheel. Hope this helps. Lol

Max
 
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doublespaces

Administrator
Oct 18, 2016
8,356
AZ
There is so much more "low hanging fruit" than maximizing the PCV system. Installing a catch can to prevent oil from building up in the intake tract or dumping on the ground makes sense. Anything further really seems like a waste of money IMO. You guys have to pull the "vendor wool" away from your eyes and look at other platforms. Stop trying to reinvent the wheel. Hope this helps. Lol
To be honest with you, the reason I'm doing these measurements is to do exactly this. I feel the crank case ventilation systems we use are unnecessarily complicated and I would like to take some measurements to validate what I'm changing.

The only reason I selected this sensor was because it comes in a convenient 1/8 NPT. If someone can point me toward a sensor that has something easy to connect to an also a better resolution that would be good. I know the sensor on the intake manifold is pretty good but I'd have to have something fabricated that I could connect to.
 
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The Convert

Captain
Jun 4, 2017
1,267
was that you on n54tech? pretty sure now that you mention it that it wasnt rob he just collected all the info from someone else who did it
I didn’t do a ton of testing and release the data, but was the person that found the oem tool and first started pushing for testing vacuum in the oil cap. At the time everyone was taking their vacuum at idle reading from their boost gauge and thinking that was the same as crankcase vacuum. Whomever put in the work to get a bunch of data points definitely deserves their credit, whomever it was.
 

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800HP Club (N54)
Platinum Vendor
Oct 24, 2016
1,057
Scottsdale, AZ
I'm surprised how much talk there has been about PCV and crank case ventilation but I've never actually seen any logs with crank case pressure readings. There are a couple of things I think would be interesting to measure such as the amount of pressure at idle and WOT with various crank case ventilation setups.

Currently, my car has (as soon as I put it on the ground):

Plugged Head Ports
Flapper Delete to OCC to VTA
PCV Delete to OCC to VTA

By no means do I intend to keep this setup, I do not like the smell of an atmospheric vent.

First I'm going to start by measuring this with the Mishimoto catch cans I currently have. Keep in mind, one of them is missing the internal stone filter, I believe its the high side so the pressure restriction here is going to be less than someone else running the same can. I've found those things to be very restrictive and since the high side doesn't get a lot of gunk in there when the low side is sucked into the manifold during idle, I've been able to get away without having the oil separator stone filter thingie in there.

Next, I'm going to measure the actual vacuum being generated at my intake pipe, it is a K&N cone filter sitting in front of a 6266Gen2.

Once I have these readings, I'm going to block the Flapper and PCV ports with caps and connect my intake pipe to the front head port as I outlined in the service port thread and measure again to see how much if any vacuum or positive pressure I'm getting on the crank case at idle and WOT.

To accomplish this I bought a sensor off ebay:
View attachment 36154

This is the description:



I'm going to disconnect my flex fuel wire and connect the 0-5v signal from this and I should be able to plot the pressure with an accurate timeline on my datalog.

Any thoughts or suggestions?
I'll take N54 selective memory for 200 Alex. Way back when Tony was testing shaft speed sensors and collecting a bunch of other data on Stage 2 turbos 7 years ago, he also had a crankcase sensor in place. The data was interesting, showing some pressure, but nothing extreme. I believe I remember no one really being interested at the time. I also agree with the others. Why try to work this into your FF tune. Just get any number of cheap data logging tools, and you can track any number of sensors. AEM AQ1 which we still use can take 8 inputs.
 
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