Tony @ MPH

I ordered a set of those Krank Vents from ET Performance -- you know, the chrome-looking, $100 check valves. At first I was skeptical and wondered what would make a check valve worth $100, but after fiddling with them for a minute or two it's obvious.

These valves provide positive, 100% closure when you blow against the check mechanism. The website says they will hold over 100psi but I didn't try hooking them up to the compressor since I have nothing on my car that will even come close to that. But when you flip them around and blow "with" the check mechanism they open right up and flow like there's nothing there at all.

That's a stark difference to other check valves -- these things clearly open under 1psi (it's hard for any of us to blow over 1psi) and I would speculate that they open closer to 0psi than they do to 1psi. This is perfect and exactly what we need in our PCV systems -- a valve that will open easily and close quickly under boost.

The $100 kit comes with two valves -- one that's supposed to sit between the intake manifold and the PCV and one that's supposed to come off the valve cover. The idea is that when under vacuum, the valve cover check is closed and the one on the manifold is open, allowing the manifold to draw a vacuum on the crankcase since theoretically the crankcase is fully sealed at that point. When in boost, the manifold valve closes and if any crankcase pressure is built, the valve cover check opens releasing the pressure.

Pretty neat system -- once I get the motor back in the car this will be one of the first things I play around with!

caseyse

Did you purchase their Turbo or Mini valves?

Tony @ MPH

Mini valves. If you read carefully they tell you all the valves perform the same, just the turbo valves are bigger. I am sure they sell a lot of the larger ones just because the perceived value is greater.

AVB

Aren't those the ones that are supposed to maintain vacuum after the pcv checkvalve has closed? If they do that, maintain vacuum in the crankcase while blowby is entering, then yes. I would say they're worth it.


I was about to order a set a while back and settled for another unit instead.

Let us know and if that's the case cause if it is they've got another sale

Arnel

Blue Lightening

Why do you need them? I would think if they were important the tunners would stick them in? Send pictures.
Norm

vertC6

Trust me, there worth it. I ran with a C5 with 7psi and blew the motor because of crank case pressure. The small vent keep the pcv from leaking back and the big one lets out crank case pressure and when the vacuum comes back it closes.

Tony @ MPH

Arnel -- they won't maintain vacuum after you get blowby unless you have a vacuum pump running on the motor. There aren't many solutions that can keep vacuum at WOT with blowby unless you are relying on exhaust gas to suck the crankcase or have some other mechanical device sucking on the crank case. They WILL maintain vacuum better than most PCV setups I've seen.

As vertc6 mentioned -- the larger valve keeps the crankcase sealed (until it sees any pressure) which allows the smaller valve to keep vacuum on the crankcase. As far as I can tell, all the valve cover breather setups out there won't allow you to pull down vacuum on the crankcase. If these valves work as I think they will, they should be a more intelligent breather setup -- the crankcase only vents to atmosphere when blowby is present.

Tony @ MPH

Hmm, interesting stuff Arnel. I'm not sure how they would do it, but I am just looking at this simplistically... manifold as a source of vacuum, bottom of the pistons as a source of blowby... I didn't see how you could hold a vacuum under boost but if it's true, then awesome! I was just thinking this was a great way to get my part throttle vacuum back and still be able to vent the crankcase under boost.

QuickSilver2002

I've been running these for quite a while with great resutls. I did a post where I logged crankcase pressure... Can't remember where it is or what it was titled (probably has PCV in the title)... I'll search for it here in a minute Think this was it http://forums.corvetteforum.com/show...&highlight=PCV, but some of the pics are missing....

You can maintain a vaccum for x amout of time. If you use a big canister for storage. You can actually hold it through the 1/4 mile if you shift slow LOL.

I think mine is holding a vaccum until about 5.x rpms and then it starts to run closer to atmosphere. I have a vacuum switch to regulate the vacuum. Once the vacuum drops below a specific kpa no more fresh air is allowed in. The crankvent then allows pressure to be released if any positive pressure develops.

I thought the valves were a waste of money, but the cracking pressure is just amazing.

I also noticed improved low end response once the crankcase had a vacuum on it.

AVB

Geez.... none of the posts are in the right order!!!

AVB

Actually during a conversation with (I forget his name) ET, when describing my setup which doesn't use a PCV (capped), it was explained to me how by just using the larger valve, vacuum would be created by internal engine pulses even w/ blowby... as long as the motor was completely sealed.

Who knows I could have just totally misunderstood

Anyways here's some text taken from their website FAQ:

The KrankVent claims include the unique property of releasing crank case pressure and producing, and maintaining, a vacuum in the crank case. This is done with a unique Flow Controlled One-Way Valve that uses aerodynamic principles to move the valve in and out of position.

Arnel

Warp Factor

Such valves can produce a net vacuum in systems with strong pressure pulses, such as on a Harley Davidson where both pistons are coming down and going up at about the same time in a small crankcase.

On a V8, one might find similar strong pulses by tapping in below two cylinders which share a common crank jounal, but getting the oil out of the expelled air might be a nightmare.

It's something I'd thought about on another engine, but wasn't confident enough it would work to drill my block, or weld a fitting onto the oil pan.

QuickSilver2002

Exactly, they don't work as advertised on our cars, but the super low cracking pressure makes for a great one-way release valve. This allows you to pull a vaccum from the intake manifold under non boost conditions and then vent to atmosphere once any case pressure builds.

No stinky engine bay and improved low end response from better ring seal.

Tony @ MPH

Those were the main reasons I bought them, to get rid of that nasty breather, eliminate the smell, and eliminate the need to hose down the engine bay every week due to being covered in oil and dirt. The ring seal was just a bonus.

Zrod

I've been running the Krankvent setup for a while, and believe they work. One of the first things I noticed was a much cleaner rear fascia. Which tells me I'm getting much less blow-by. If you open the oil fill cap just after shutting off the motor, you can hear the vaccum release. Its actually quite loud. Keeping the crankcase under vaccum is a good thing, and these valves do the trick.

Tony @ MPH

Wow... this is excellent feedback! I didn't know it would draw that much vacuum. Can't wait to get the car back on the road to try them out.

QuickSilver2002

The valves themselves won't draw any vacuum. The intake manifold will. You have to close up or restrict the system to get a vacuum (fresh air source needs to be plugged). I was a little concerned about too much vacuum under decel.. (thus the reason for the switch). Just not sure how much vacuum all the seals would be happy with. I tried it without the switch and the motor made a few funky sounds on decel so I went back to keeping the vacuum limited.

clemsondave

Interesting stuff! Would you recommend these on any FI engine? I have a P1 with 7#.

Vetteoholic

Tony @ MPH

Of course the valves won't draw vacuum... neither will the intake manifold to be precise... what I was trying to get across is I didn't know the valves would allow that much vacuum to be created in the crankcase.

What kind of funky sounds did you hear on decel?