What PCV system are you running on big single?

[jevansio]

I am curious as to what PCV system people run on their big singles?

 

I'm currently just venting to atmosphere via a catch tank on both outlets, but am thinking of re-introducing a version of the stock system to regain the benefits it provides.

 

I thought I'd start a thread as I will have a lot of related questions on the subject

[johnny g]

If you vent to atmosphere - I think that's fine. If you plumb it back to the intake, the vapours can have the effect of lowering the octane of the mix in the combustion chamber.

 

I don't think there's anything wrong with your PCV setup though - you're running 2 x AN10's into a AN12 line aren't you?

[jevansio]

Yeah, that's the thing though, it might be fine, but it's not great

 

Been reading up on the benefits of having a vacuum source on there (as per the stock system) and I want in

 

But I don't want the downsides (lowing octane, residue in inlet).

[johnny g]

Why not go dry sump? The scavenging action of the pump should evacuate any excess blow by gases in the crankcase

 

You might get a gain by reducing any residual oil drag on the rotating mass

[jevansio]

Why not go dry sump? The scavenging action of the pump should evacuate any excess blow by gases in the crankcase

 

You might get a gain by reducing any residual oil drag on the rotating mass

Too complicated, I just want what the stock system provides, ramped up for single power, but without the octance prob & residue in inlet

[dude]

If your looking for a vacuum why not plumb it into the exhaust using something like a Moroso crank evacuation kit;)

[jevansio]

If your looking for a vacuum why not plumb it into the exhaust using something like a Moroso crank evacuation kit;)

That's what the plan is, but I've read those valves fail pretty quickly with exhaust gas temps.

[JamieP]

Intake side mine is stock, exhaust side i have a -12 to a catch can, mine has been like this for many miles and i see no reason to change it.

[jevansio]

Yeah, mine has been fine too, but I'm starting to wonder what performance gains are to be had.

 

Before I embark on a full rework, I might hook my catch tank upto the inlet and see what sort of performance benefits are to be had.

 

The other beneift is it is supposed to help greatly with small oil leaks, mine has a very small drip that it leaves, it would be good to get rid of that

[Tricky-Ricky]

The idea of using a catch can is that the oil vapours drawn from the crankcase cool slightly and drop out of suspension, so if you use a remote catch can with fairly long ish pipe runs, and have it plumbed back into the turbo inlet, in theory pretty much all the potential octane lowering oil vapour has already gone!

 

Filling the catch can with stainless scourer is supposed to help as well.

[JamieP]

If your engine is good then you should get no oil mist surely?

 

If you get any oil at all in the catch can then you have engine problems id have thought, mine is always bone dry.

[johnny g]

If your engine is good then you should get no oil mist surely?

 

If you get any oil at all in the catch can then you have engine problems id have thought, mine is always bone dry.

 

You've got a good seal then between the rings. Good point though.

[jevansio]

If your engine is good then you should get no oil mist surely?

 

If you get any oil at all in the catch can then you have engine problems id have thought, mine is always bone dry.

Yip, not got a drop in my catch can since I've been running it.

[Wez]

Intake side mine is stock, exhaust side i have a -12 to a catch can, mine has been like this for many miles and i see no reason to change it.

 

Same as mine

[JamieP]

Yip, not got a drop in my catch can since I've been running it.

 

I would leave it as is mate, dont complicate things.

[Swampy442]

Good question as Im wondering what to do with mine. On a slightly related topic what have you done with the intake to the IACV?

[Tricky-Ricky]

Mine never had any oil in it just water with an oily film, mostly during the winter when doing shorter trips.

[jevansio]

Good question as Im wondering what to do with mine. On a slightly related topic what have you done with the intake to the IACV?

I have a Greddy plenum, but the IACV is hooked upto it as usual. I'm thinking of removing the IACV TBH and that's where I'll hook the intake cam cover to

[TLicense]

I had both my inlet and exhaust side connected via a -10 to my inlet (pre-turbo) so they were always seeing vacuum.

I wanted to make sure that the fact that they would have been under a considerable amount fo vacuum wasn't contributing to the blow-by I've been getting, so re-routed both sides to a catch can I made.

I didn't notice any change in performance at all.

[dandan]

I have a dash 10 from each cam cover to the catch can, then two dash 8's into the midpipe via one way valves and slash cuts and then I also have one dash 12 to the turbo intake via a third one way valve.

 

I've done about 5k on this setup and haven't fried any one way valves yet. When Ryan gets back I'll aim to do a back to back on the rollers with and without the vacuum to see if there's any measureable difference.

[Tricky-Ricky]

The only reason i fitted a catch can was due to when i removed the plenum and runners, i found quite a lot of pooled oil sat in the lowest point of the runners, and as the PCV system like many will draw the most oil mist through on idle, due to the high vacuum.

 

You should see the amount of oil that was in my plenum on my new Skyline 350, they run a very short length of pipe from the top of the cam cover to the plenum, so a lot of oil mist gets

drawn in and just sits there until you open the throttle wide, and then it gets drawn in and burnt, not a big deal on an N/A engine (although not desirable) but on a highly tuned turbo engine a sudden drop in fuel octane coupled with big boost could result in detonation, hence my concerns for eliminating the problem;)

[jevansio]

Nice one Dan, I think I'll just wait for your results , it's exactly what I'm looking for in terms of data

 

Quick one, how do you know if the valves are fried? And if they go does that mean you'll get an excessively pressurised crankcase (or is that why you added the 3rd to the inlet as a safety measure)?

[Nodalmighty]

You can buy belt driven vacuum pumps that put the crack case under vacuum to help promote ring seal and reduce pumping losses.

 

http://www.gzmotorsports.com/vacuum-pump-guide.html

[jevansio]

You can buy belt driven vacuum pumps that put the crack case under vacuum to help promote ring seal and reduce pumping losses.

 

http://www.gzmotorsports.com/vacuum-pump-guide.html

Yeah, the fact race cars run dedicated pumps and still see gains is one of the reasons I'm so interested in the subject. There's no way a they would run these power sapping pumps if there wasn't a benefit.

 

I'm thinking if a properly setup system can get me 10bhp, thats free power & 10bhp I don't have to find by stressing the engine out with more boost or higher tune

[jagman]

If you are passing over 750 cubic feet of air every min through the engine, just how much is cranckcase blowby/oil mist ? would this really have any effect that is noticeable on octane?

Strikes me that 750 cubic feet of air is a large room full..