Routing PCV system into the exhaust

[Justin]

What is there to know about this type of setup? I tried searching but it appears that when I search for 'Exhaust PCV' it pulls up every result with EITHER word, not BOTH words. Ugh.

As of right now I have nothing setup, at all. Before I get the car ready to run though I'd like to find a good solution...

 

[annoyingrob]

I've only ever seen one car with the PCV routed into the exhaust (A MKIV Supra at that). It's an interesting conecpt though. I might have to try it one of these days.

 

[KicknAsphlt]

What would the effects/benefits be over a standard PCV system? I've never heard of this.

 

[WhtMa71]

If you connect the PCV system to the exhaust you generally use a "slash cut" piece of pipe welded into the exhaust at a certain angle. The combination of the slash cut and angle its welded in the pipe draws a vacuum through the pipe much like it does being connected to the intake. Only the crankcase vapors go into the exhaust instead of all in your intake pipe and turbo and intercooler pipes.
Its usually used for race cars and its not the most environmentally friendly way to run a pcv system.

 

[adampecush]

The Venturi effect is used to evacuate the crankcase fumes as opposed to re-routing them back through the intake system. It eliminates the potential re-circulation of oil if the catch can overflows and it reduces some inlets/outlets of the intake system. As far as downsides go, more hydrocarbon emissions and forget about running a catalytic converter. The ports have to be perfectly positioned in the exhaust system as well for the Venturi effect to take place.

 

[Justin]

Only the crankcase vapors go into the exhaust instead of all in your intake pipe and turbo and intercooler pipes.
Its usually used for race cars and its not the most environmentally friendly way to run a pcv system.

That would be nice, to have the vapors out through the exhaust. No cat here, so even if it was an issue its not any more...

There is not a single thing on my car that is environmentally friendly, matter of fact there's not a single piece of emissions equipment left on my car either

The Venturi effect is used to evacuate the crankcase fumes as opposed to re-routing them back through the intake system. It eliminates the potential re-circulation of oil if the catch can overflows and it reduces some inlets/outlets of the intake system. As far as downsides go, more hydrocarbon emissions and forget about running a catalytic converter. The ports have to be perfectly positioned in the exhaust system as well for the Venturi effect to take place.

Hmmm... So its as simple as running a line from your valve covers to the exhaust port that is welded in at precisely the correct angle?

Seems like a pretty neat way to go.

 

[jdub]

To me, there's not a lot of an advantage to route the PVC this way. The vac produced per above is not very strong...it will work, but is way below the vac produced at the TB. Plus, you will need a one-way check valve in the line from the cam cover to the venturi at the exhaust to make damn sure you don't get ANY back flow.

Emissions wise...Adam is correct, higher HC and it WILL poison the CAT.

 

[Orion ZyGarian]

Thats what I've been thinking as well. I know it could theoretically work, as I've used a vacuum attachment to shop air before, and shop air is 90+ psi. Venturis are our friend...without them, we wouldnt have carb'd engines to get us to EFI!

Its a shame we cant (shouldnt) dump it pre-turbo into the exhaust manifold though to burn it up. I sure as hell dont want any more carbon/oil on my turbine than necessary.

 

[Supracentral]

I've run this sort of setup on two cars.

#1 was on an Outlaw 10.5 car:

This car had a Keith Black Stage XV Hemi running on alchohol:

Due to the type of setup on this engine, there's really no manifold vaccuum to work with so you need alternatives.

#2 was on our NDRA Pro Street Tire car:

This car ran a modded 2JZ-GTE with a big Borg Warner Turbo:

We found that the "header vac" PCV system didn't work well with this setup. We had a 5" open downpipe and never really drew off vac the way we wanted it. In the end we settled for the setup as shown above. But this is a 7 second car. I wouldn't use anything like this on the street.

Stick with the stock type PCV setup, it's far superior and should only be removed if you have absolutely no alternative.

Even then I'd consider some sort of vacuum pump before I tried anything else.

Just my $.02, ymmv.

 

[IJ.]

My understanding is it doesn't work well with mufflers.

 

[3p141592654]

There is not a single thing on my car that is environmentally friendly, matter of fact there's not a single piece of emissions equipment left on my car either

Wow! So you got rid of the ECU and oxygen sensor?

 

[MDCmotorsports]

My understanding is it doesn't work well with mufflers.

Correct Ian.

The PCV system running through the exhaust is the same we use on a lot of race cars.

The exhaust must have high velocity and no restrictions or back pressure.

 

[Rennat]

this is a little OT... but SC do you have some more pics of that mk4 engine bay???

 

[TurboStreetCar]

Also airspeed has to be high enough inside the exhaust pipe in order to even create the venturi effect in the first place, thats why i thought it was only a race car thing where constant high velocity exhaust flow was actually achieved.

 

[MK3Brent]

Be careful also if you plan on competing at some drag strips.

The exhaust PCV's can be considered an "oil down" potential... so they won't pass tech on you.

 

[SevenMKIII]

If you connect the PCV system to the exhaust you generally use a "slash cut" piece of pipe welded into the exhaust at a certain angle. The combination of the slash cut and angle its welded in the pipe draws a vacuum through the pipe much like it does being connected to the intake. Only the crankcase vapors go into the exhaust instead of all in your intake pipe and turbo and intercooler pipes.
Its usually used for race cars and its not the most environmentally friendly way to run a pcv system.

No slash-cutting for wesbeech :momaru:

I've only ever seen one car with the PCV routed into the exhaust (A MKIV Supra at that).

Now you've seen two, and one's an MK3, at that.

 

[MK3Brent]

TunX had his for a while.

 

[figgie]

I've run this sort of setup on two cars.

#1 was on an Outlaw 10.5 car:

This car had a Keith Black Stage XV Hemi running on alchohol:

Wow Mike,

that is a nice car and engine

still own it?
The Supra, is that the AAP supra now? I saw it forsale?

 

[Doward]

Run valve covers - catch can - vacuum pump imho.

 

[supraguru05]

there was a honda tech article on this subject and the vacuum pull by the exhaust versus vacuum by the throttle body were compared. iirc neither really pulled that much vacuum under boost the auther decided the exhaust one was suficent im still on the fence but i have ordered two slash cut pipes to use in my downpipe. if anyone is trying this you want the open side of the slash cut facing away from the flow and the pipe at a 90 degree angle to flow for maximum pull