The Official Crankcase Evacuation thread for Turbo Hondas / PCV / Catchcan /

[Tjabo]

Has anyone ACTUALLY RUN a slash cut to see how it works? I am planning to do that, but I'm not sure when I'll really get around to it, since my single 3/4" vinyl tube seems to be doing a very nice job of venting my crank case. I am thinking of running a spare MAP sensor to the crank case to get some vacuum/pressure data, and if I do the slash cut tube, I would also try to check it on that. Regarding Mr. Death's analogies to bottles above, from what I have always known of slash cut tube setups for at least 20 years now, his analogies are 100% INCORRECT. The fact of the matter is that the normal goal is not just to vent the crankcase of blowby gasses, but to actually produce a vacuum in the crankcase that helps to some tiny degree to actually increase the output of the engine. Obviously you can't create a vacuum in the crankcase if you have it vented. . . .

This ad is not displayed to registered or logged-in members. Register your free account today and become a member on Honda-Tech!

[Mr.Death]

Originally Posted by Tjabo

The fact of the matter is that the normal goal is not just to vent the crankcase of blowby gasses, but to actually produce a vacuum in the crankcase that helps to some tiny degree to actually increase the output of the engine. Obviously you can't create a vacuum in the crankcase if you have it vented. . . .

Vacume is produced by the slash cut or pre turbo intake if you want to go that route. Air sucked out through these openings, air enters through valve cover. Seems correct to me. Also I've been using the pre turbo for vacume for years and my motor is still running strong for years boosted. Works for me so I'm leaving it as is.

[Tjabo]

I'm not saying it will ruin your engine, just that it defeats one of the main purposes of the slash cut tubes in the exhaust stream, which is to create an actual negative pressure in your crank case via the Bernouli effect (IIRC). That simply can't happen if you have it vented to the atmosphere, as you correctly say, it will simply draw through fresh air.

The thing is, your crank case doesn't need fresh air, it NEEDS not to have positive pressure build up in it, and it WANTS to have a negative pressure in it. . . Hope that makes sense.

[kebroz]

Originally Posted by bdiz

http://www.ginger.cx/images/B20build...ase%20Evac.pdf


your welcome

GREAT!!! thanks.. ;-)

[gettin it]

did anyone ever get the honda part number for the fittings for the back of the block?

[cleansi]

It is important that you seal this opening with an Aluminum plug and not a rubber one

supid question but why wouldent you want a rubber plug?

[aasarsak]

Originally Posted by gettin it

did anyone ever get the honda part number for the fittings for the back of the block?

the answer to your question lies near the beginning of the thread. Go back and read it.

[aasarsak]

Originally Posted by cleansi

It is important that you seal this opening with an Aluminum plug and not a rubber one

supid question but why wouldent you want a rubber plug?

Hot aluminum melts rubber. Hot aluminum expands rubber. That is why it is used in gaskets. When it gets hot, it gets bigger and creates a tighter seal between mating surfaces.

If you plug it with rubber, the plug will get big and either pop out, or fall off. Aluminum will keep its size and shape, but a rubber gasket should be used between the plug and the hole.

[cleansi]

told you it was stupid. thanks common sense prevails !!!!!!!

[gettin it]

Originally Posted by aasarsak

the answer to your question lies near the beginning of the thread. Go back and read it.

Now i know that other company sales them, but i thought there was a honda part number for the plugs for the back of the block? Not the washers.

[aasarsak]

Originally Posted by gettin it

Now i know that other company sales them, but i thought there was a honda part number for the plugs for the back of the block? Not the washers.

There is a picture of the plugss still in the bag from Honda on one of the first pages.

Wait, which plugs/fittings are you talking about?

[aasarsak]

Originally Posted by cleansi

told you it was stupid. thanks common sense prevails !!!!!!!

It wasn't a stupid question.

You're welcome.

[ED9man]

disregard

[ED9man]

Should I have any issues if I remove the OEM black box and plug the hole, tap one of the threaded holes on the block with the OEM Honda fitting, and run two lines, one from the fitting on the block and one from the stock valve cover vent, into a T and then into an exhaust slashcut with a check valve on it? Is this going to pull enough vacuum consistently? I'm just worried about the exhaust not generating consistent negative pressure or if it was higher than atmospheric sometimes. Is it necessary to run two separate slashcuts? A redundant atmospheric vent with another check valve? The primary benefit I'm looking for is keeping my intake charge clean, but I would like to find some power by creating a partial vacuum in the block. Would it be beneficial to add another vent on the front of the valve cover? Looking for feedback on this set up, thanks. It's for an N/A B16 that will have a supercharger.

[aasarsak]

one of the threads talks about a guy who tested the slashcut and found that it generated minial vacuum at best and at times pressurized the tubes.

Another downside I see to doing a slashcut is potentially misdiagnosing engine problems. How do you know for sure you're having motor problems if you have blue smoke out of your tailpipe if you run this setup. Not worth it IMO.

Just my .02

[Tjabo]

ED9man, what does your exhaust consist of? That will probably make a big difference in your results with this method. If you try it, please let us know how it works out for you.

Originally Posted by aasarsak

one of the threads talks about a guy who tested the slashcut and found that it generated minial vacuum at best and at times pressurized the tubes.

Another downside I see to doing a slashcut is potentially misdiagnosing engine problems. How do you know for sure you're having motor problems if you have blue smoke out of your tailpipe if you run this setup. Not worth it IMO.

Just my .02

Have you tried it?

[aasarsak]

Originally Posted by Tjabo

Have you tried it?

Nope, that advice was based on the result of the guy who did do it and posted his results plus a little bit of my own common sense...

[b18ctrb]

Has anyone done this on a z6 block?

[oranginal]

i saw the options for the slash cut in the intake pipe and the wastegate/exhaust but can't you just run tubes from the breather and PCV opening to the ground and put a slash in them. this way when you are driving at a higher speed or on the highway you will get the benefits of the increased vacuum?

wouldn't this be better then just running both to an open breather catchcan?

[kjmagnum]

That's what I was thinking and I'm currently running that way. It's the easiest to hook up and hopefully gets some benefits.