Head modification for more oil return

[Blackmk3]

Hello all

Rebuilding my 7mgte currently, and while ive got it all apart the heads getting a mild port job just cleaning up the casting marks basically
But i have a question, I circuit race my car and always had issues with the engine throwing oil out the cam breathers
i had the PCV removed so it was just venting from the cam covers to a catch can then venting to atmosphere.
I had to do it this way as it was blowing out almost 500mls of oil in a 10lap race

Hopefully with this rebuild it will have minimal blowby as it was getting tired before it was pulled to rebuild, so this should help oil returning to the sump

But im basically asking if anyone here has done any modification to the oil drains in the head to get them to flow easier? get the oil away faster so its not sitting in the head sloshing around and being picked up and pushed out the breathers

Any advice?

Nick

 

[3p141592654]

A lot of productions cars use a oil trap with the oil returned to the crankcase. This seems like the real solution you need, but installing one will take some work.

http://www.fcpeuro.com/products/volvo-pcv-oil-trap-240-740-760-780-940-3501160

 

[Blackmk3]

I considered something like this, and also considered having a return on my catch can back to the sump, so i didn't have to empty it manually.
But i was hoping to try to minimize the issue at the source, stopping the oil in the first place rather than having to do something with it once its been thrown out

Surely others have had the same issues?

 

[suprarx7nut]

"At the source" is tricky. Your engine will always have some blow by and a need for a PCV system of some sort. I'm not aware of a way to bypass that need completely. Assuming that, you can focus on reducing complexity of the trap system. That being said, if OEMs could accomplish it simply without a series of hoses and a trap with a drain to the pan they probably would.

If you get clever with a custom trap of some sort maybe you can trap the oil right near the valve covers and have it drain right back at that spot. Problem is you don't have much gravity to work with at that point.

I think gathering it somewhere else makes more sense and just let it drain into the pan.

Let us know if you find another way though.

 

[hvyman]

Usually when you have a lot of oil coming up there is a lot of blow by.

Could always just put little filters on them so the oil doesn't spray everywhere.

 

[Blackmk3]

There defiantly was alot of blowby the motor was surely tired before it got stripped down for rebuilding.
Hopefully it will be instantly better once its running again, I think i may try smooth up the drains in the head, make a easier track for the oil to run to the drains

Since ive got the die grinder out already

 

[need new tires]

What I did to resolve the oil issue on customers cars was to run a -12 drain from the back of the head and dump it back to the old j tube location. The 7m has a bad problem with sustained high rpm(over 6500 rpm) oil return. On any 7m I put together that will see 8k+ I do this as well as RB series.

 

[chevyguyjoe]

Id say just drain from breather system back to the sump. Some NASCAR engine builders do this. They prefer the valve covers be full of oil to help cool it.

 

[need new tires]

Those cars also run a vacuum pump.....

 

[AcIdBuRn02ZTS]

I would smooth out the casting flash on the oil return ports in the head... you could also polish the inside of the head if you wanted but it would take a good bit of time.

Is this car track only or street driven as well? If its isn't a built track only car, I would say clean up the head and run an oil return off the catch can.

 

[Blackmk3]

What I did to resolve the oil issue on customers cars was to run a -12 drain from the back of the head and dump it back to the old j tube location. The 7m has a bad problem with sustained high rpm(over 6500 rpm) oil return. On any 7m I put together that will see 8k+ I do this as well as RB series.

Sounds very interesting, ive heard of people doing this in RB engines as there common as over here in NZ

You don't happen to have a picture of where you put the return into the back of the head?

 

[Blackmk3]

I would smooth out the casting flash on the oil return ports in the head... you could also polish the inside of the head if you wanted but it would take a good bit of time.

Is this car track only or street driven as well? If its isn't a built track only car, I would say clean up the head and run an oil return off the catch can.

The car is a street car that i just take to the track, maybe once or twice a month.
Im tempted to run a drain back from the catchcan but ive seen the watery nasty looking stuff that collects in the can from when the cars just driven around the streets with minimal open road driving. Id rather that stuff not drain back into the engine and further contaminate the oil
But of course its required when at the track so its kind of a catch 22 situation


ive inspected the head and access is quite limited in a few spots to smooth out the oil track to the drains in the head, but im going to give it ago in the next week or so, ive just been concentrating on the exhaust ports at the moment, Trying to get some actual flow going on!