4G63 Block Vent

I have read a few threads on adding a block vent to the 4g63.
I know this not a new idea, and others have had done it before.
I also know that there is a kit so a block vent can be added in at the rear balance shaft timing passage.
Some of the locations I have seen used I did not like, or the size of the fitting being too small to be very effective.
After spending some time looking a block over, and looking at an assembled engine. I believe I found one of the better spots to install a block vent.

If you have not read this thread.
https://www.evolutionm.net/forums/ev...l#post11025185
You should do so, so you will have a better understanding of why I chose the location I did.

Since there is a factory vent from block to head, tapping into this spot makes the most sense to me. It is on the down side rotation of the crank, and is decently covered and high enough in the block not having to worry about oil slosh or oil return from the head. Also this should pull from the head as well as the block.


Also looking at an assembled engine, this vent looks to clear the starter and the intake support bracket.


I chose to use a 1/2npt 45* fitting with a 5/8 hose barb. This should give plenty of cross section and make an effective vent. The ID of the fitting is .530 The reason for a 45* instead of a 90* is so there will be less of a flow restriction through the fitting.

I scribed a simple circle for the location, then did a center punch dot


It is a basic drill and tap install.
For a ½ npt the drill size used is 23/32



Then tap a few thread, care needs to be used since this is a thin cast area.


Test fit the vent fitting and tap until the proper angle for the hose fittings face the desired angle.


Try not to extend the threaded portion of the fitting into the factory vent passage.

 

Only issue I might possibly see is there is no baffling to keep the oil from blowing straight out of the block. I know it's the same pathway that goes to the valve cover but obviously the valve cover has baffles to reduce oil blowing out into the catch tank. I'm interested in how this works out for you.

 

+1

From what I understand, this area is for block relief mainly and not oil drain back. Is that correct?

What if the end of the thread was cut at a 45* angle with the cut side pointing up and threaded in a little further?Would that act as a baffle if oil is shooting up?

 

I had not posted the the internal view thread before I posted this one.

https://www.evolutionm.net/forums/ev...l#post11025185

This walks you through the factory venting for the block.

I can see where you are going with the baffle and yes it would make a good addition. but doubtful it would be needed. This vent uses the factory cast baffle. The port is 2 inches or so up in the vent chamber.

Since this is on the downward side of the crank, oil will not crawl up the wall to it, also since not an oil return (except for what little drips off the intake cam that crosses over the vent tube.) Doubtful that is would suck much oil at all except what has been misted by the rotational engine parts.

 

Thanks for posting this BTW. It got me excited about crank case ventilation. I really want to block the IM PCV. This may work with an exhaust scavenger set up. IDK.

Anyhow, I went to look at an Evo cylinder head, block and VC and it is a little different than the DSM you posted.

I was excited to see that same tapping area on the front of the block as the Evo block is reversed. Then looking at the cylinder head I see Mitsu used this for an oil drain back instead of ventilation.

The tapping area is not as flat, but it should still work. It looks like the turbo may be in the way for the front, but it should clear the water pipe in the rear. However, this will put the crank on the up stroke. Right? I'll have to put my turbo set up on and see if I can clear it on the front.

As you can see the oil drain back on the Evo is twice as big as the ventilation. I wonder why they did this. Any guesses?

 

Yes, it looks like you are on the right path.

Since the EVO has 2 vents (looks like Mits found this same issue) I would closer at the vent tube on the exhaust side. that will still keep it on the down side of the crank.

also that point, if the block is similar cast as the DSM, that tube should be hidden even more than the vent chamber than the DSM.