Prova Air oil Separator is the fastest, most simple, and the cleanest installed unit on the market. It captures the vaporized oil coming out of the heads , allows the fumes to run through the filler neck where the oil can condense back to liquid form and drop back into the motor. This will keep the oil in your motor, instead of having it get burned. This will allow you to keep your motor cleaner, and running better, along with help prolong the life of your motor. There is a reason why many high end sports cars include air oil separators, as it helps keep the motors clean and running at optimal level.

These units can be used on Turbo and NA Subaru motors.

The total install time is about 5-10 min, and requires these things.
1) Prova Air Oil Separator
2) Razor Blade
3) Pliers or something to cut zip ties


These are all the Contents of the Prova Air/Oil Separator kit. As you can see it comes with Hose, Separator, Zip Ties, Instructions, and Plastic T's.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7969_rs.jpg

We did the install on a 2008 STi. However all turbo Imprezas should be 99% the same.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7970_rs.jpg


Start with taking off the oil cap from the filler neck.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7971_rs%20.jpg

Get the Air oil separator. You can see that its a 2 piece design, having the center piece screw into the filler neck securing the outer piece of separator in place.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7972_rs.jpg

Tighten down the center piece hand tight, and then reinstall the oil cap.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7973+7974_rs.jpg

Now move over to the PCV hose that comes from the cross over pipe on the intercooler. Pull off the hose from the metal pipe.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7975_rs.jpg

Now follow that hose, and you will see where it attaches to the turbo inlet hose. Pull it off from there, however be careful not to break the nipple off the inlet.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7976_rs.jpg

The Kit comes with 2 different size hoses. The larger ID hose is for the Turbo inlet side, for the fumes coming out of the separator. The smaller ID is from the metal pipe on top of the intercooler.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7981_rs.jpg

Now get the supplied smaller inside diameter hose that comes with the Prova Separator and attach it to the metal pipe that runs across the intercooler.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7977_rs.jpg

Once attached to the hard pipe, run it over the the separator.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7978_rs.jpg

The hose supplied is about 2X as long as you need, so get the razor and cut it to the appropriate length.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7979_rs.jpg

Once cut to proper length attach it to one of the nipples on the separator. The way this unit is designed, it does not matter what one is in and what one is out. Making this a very easy to use unit.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7980_rs.jpg

Now Get the larger hose and install it onto the turbo inlet side.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7982_rs.jpg

Now run it over to the separator, cut to proper length, and attach it to the separator.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7983_rs.jpg

After all the hoses are attached, make sure that the hoses have no kinks. If everything looks proper get the supplied zip ties and secure the hoses to keep them from moving around and to make it a clean looking install.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7989_rs.jpg

After you are all done. This is what you will have left over. The left over fittings are to be used if you had a NA Subaru. You will notice in the image the pre-bent hose, that is the OEM piece that you pulled off that ran from the Metal cross over pipe on top of the intercooler into the turbo inlet.
http://theattack.rallysportdirect.com/wp-content/gallery/2008_sti_prova_oil_air_separator/IMG_7990_rs.jpg


Now give it a couple days and you will start noticing that the car will start running better as it will be burning off the remaining oil that is in the intercooler, turbo inlet, and inside the intake manifold.


If you guys/gals have any questions do not hesitate to ask.

Kirill
RallySportDirect.com

Are there any valves or anything special to the air/oil seperator that connects to the filler neck? Or is it basically an air inlet and outlet that drains to the filler neck?

Aluminum or Plastic?

what prevents the seperator from simply reinjesting the 'cycled' oil vapor or the oil that spurts up from the pan?

what prevents the seperator from simply reinjesting the 'cycled' oil vapor or the oil that spurts up from the pan?

:confused:

Ever look under the hood of your car?

Are there any valves or anything special to the air/oil seperator that connects to the filler neck? Or is it basically an air inlet and outlet that drains to the filler neck?
No check valves in it. A inlet and a outlet with a chamber to allow the oil to drain.

Aluminum or Plastic?
Aluminum.

Isnt that thing just dumping contaminated oil back into the oil.....? Mabey im missing something.... Nice write up though

Oil recycle.

Very nice writeup. I applaud your dedication to detail.
Very nice machined piece of aluminum.

However I think the bang for the buck ratio on this item is extremely bad.

yes too pricey.

If you guys have any concerns about his product fitting please post in this tread.
If you have any issues with pricing, please PM us or email Prova Japan. This thread is about the product installation not about the price. If you dont agree with pricing please keep it in the PM's and not junk up this thread.

Thanks
Kirill
RallySportDirect.com

nice kit...just wish it came with an oil cap instead of using the ugly yellow stocker to cover up the prova goodness.

nice kit...just wish it came with an oil cap instead of using the ugly yellow stocker to cover up the prova goodness.
The nice thing is sense you can use the stock cap with this, it allows you to use any other OEM replacement cap and it will work :)

wow MUCH MUCH MUCH MUCH MUCHHHHH simpler install than the crawford aos... that one was a pain and i had to take off cruise control for it too.

might have to get one of these soon

I have been looking at this for a bit now and it's simple stupid. Which i like, But i have worries about a possibility of the pressure introduced into the crank case useing this system. I am a novice do it yourselfer with little education in the ways of crank case venolation. Any input is much appretiated.

There will actually be vacuum in the PCV system, do to the negative pressure in the intake system pre turbo.

These are a high quality piece from Prova as usual. Machined from a solid piece of Aluminum. I have been running one for over 15K and it has been great! No problems and as usual my UOA's have been showing that everything is running very healthy. Enjoy! :D

Is there two hose with have oil vapor out? That's why ppl are running dual catch oil setup? This is only route one hose, how about the other one that route back to the inlet?

This only attaches to the head system, the Crank case system is left to work like stock.

how much does this cost?

Pricing for these units can be seen on our site.

Could you connet fittings for steel braided lines

Should be able to, but we never took one apart to that extent.

This is kind of strange. seeing how i have a new beat rush can. and it actually uses the oil refill as a added crank case venting point.

at high rpm wouldnt pressure be coming out ward of the oil refill?

I was contemplating this kit before the beatrush btw.

On a healthy motor, there should not be any high amounts of pressure.

i never get oil coming from there

This only attaches to the head system, the Crank case system is left to work like stock.

That means you're still getting oil in the intake tract. The stock system pulls gasses from the crankcase through the PCV and into the intake manifold when a greater pressure exists in the crankcase, and shunts them into the turbo inlet under boost when the PCV closes. Prova is only addressing the head breathers, which is better than nothing I suppose, but still leaves one side of the system unaddressed.

That means you're still getting oil in the intake tract. The stock system pulls gasses from the crankcase through the PCV and into the intake manifold when a greater pressure exists in the crankcase, and shunts them into the turbo inlet under boost when the PCV closes. Prova is only addressing the head breathers, which is better than nothing I suppose, but still leaves one side of the system unaddressed.
Yes you are correct, that oil from the the crank case will still get into the intake track.
However if you look at a turbo inlet, majority of the oil is coming from the heads and not from the crank case.
After install of these units, there is almost no noticeable oil in the intake or in the intercooler. Where with no catch can/ air oil separator you can tilt the intercooler and see oil come out. No such case after install of these units.

Yeah these are pretty damn sick... it's using the vac pressure to draw the oil back into the system. The way its designed is it has little holes with a lip so you don't have oil blowing back up into the turbo inlet line.

Edit: Nice write up RSD :)

Wow, great looking product and finally an excellent and easy setup!!!! Oh and Nice write up too :)

These things are great, except for the fact that the hose that comes with the kit is really weak and flimsy (A small price to pay for such a great product). Plus if you try to bent the hose at all it will pinch off and won't recirculate air/oil (I know all hoses will do that, but this stuff did it a lot sooner than any other regular hose). I had mine in/on my car for about a year and both of the hoses already cracked and dry rotted. I had to replace the hose with a higher quality hose that wouldn't dry rot as quickly. That's the only down side to this product that I have seen - otherwise it worked great.

this thing looks awesome and would love to get one but with my catch can and funds being low it will be some time before a prova aos goes on my sti

However if you look at a turbo inlet, majority of the oil is coming from the heads and not from the crank case.


Yeah right! ;)

These things are great, except for the fact that the hose that comes with the kit is really weak and flimsy (A small price to pay for such a great product). Plus if you try to bent the hose at all it will pinch off and won't recirculate air/oil (I know all hoses will do that, but this stuff did it a lot sooner than any other regular hose). I had mine in/on my car for about a year and both of the hoses already cracked and dry rotted. I had to replace the hose with a higher quality hose that wouldn't dry rot as quickly. That's the only down side to this product that I have seen - otherwise it worked great.

Can you comment on if it actually works? I.E. have you pulled the line - on both ends - that runs from the prova unit to the turbo inlet to see if there's any trace of oil or buildup after using it over time? It should be easy to tell. I'm looking for a somewhat unbiased opinion.

Sucks about the hose. They should include top-of-the-line oil safe hose considering the price for what's included.

Can you comment on if it actually works? I.E. have you pulled the line - on both ends - that runs from the prova unit to the turbo inlet to see if there's any trace of oil or buildup after using it over time? It should be easy to tell. I'm looking for a somewhat unbiased opinion.

Sucks about the hose. They should include top-of-the-line oil safe hose considering the price for what's included.

The ends of the hoses were not in fact covered in oil. As a matter of fact - they pretty much only smelled like oil. By no means is my motor stock though, so perhaps someone who has/had blow by issues would have a different story. I DID have breathers on the crank case and both cylinder heads at one point and the motor did spew a decent amount of oil out of the breathers (mainly the crankcase breather). I did away with that setup a long time ago and the car ran much better because the metered air was once again circulated into the system.

That brings me to this - I haven't seen any oil buildup yet, but I sure as hell know that the air is being recirculated. The final thing that I NEED to add to this is that the Prova setup of mine only saw about 100-300 miles of regular driving time, not consistent high RPMs or anything.

Thanks for the great write up Kirill.
Install takes less than 5 minutes, seriously.
And the piece is beautifully crafted.

This is kind of strange. seeing how i have a new beat rush can. and it actually uses the oil refill as a added crank case venting point.

at high rpm wouldnt pressure be coming out ward of the oil refill?

I was contemplating this kit before the beatrush btw.

I must have missed this post before.

You will feel pulses of air coming from the oil fill cap at idle if removed fwiw. So yes, pressure would come out of the oil refill under heavy load. This shouldn't be a problem if the a/o unit works (i.e. it seperates the air from the oil).