On PFI's kit you are told to tap the valve cover. The valve cover has positive pressure therefore, even with a gravity fed line that is angled down from the turbo into the valve cover you are still not going to get a proper drain. Nigel has had his kit for near the longest (next to matthel who doesn't count) and it seems he hasn't had issues, unless he uses another method or hasn't mentioned it.

On Custommaxima's kit you run the oil return/drain line up and into the breather line onthe valve cover and this is just retarded, because even if the valve cover didn't have positive pressure, you still need gravity fed.

On Hal's kits, it's hard to tell what's going on because everyone has completely different setups.

From Jamie (jay25), my dyno tuner and some other folks I've heard that the upper oil pan needs to be tapped. As my car sits I now have a 7/8" hole tapped into the side of my valve cover and would not like to have to deal with finding a plug for that which won't leak.

If I run another line from the turbo to the upper oil pan, then I also have to deal with figuring out how to tap the damn pan because I hear it's quite hard to get to. Nothing too extreme, but a lot of work.

Let's resolve this issue.

Jason

 

The upper oil pan IS the BEST place to do it.

5 different shops in atlanta told me that. That is where I had mine redone at.

I have a few pics. I can take more tomorrow for you. It really is not that hard.


BUT are you having leaking problems?

You need to just be super clean

 

No leaking problems at all.

But my friend who tuned the car stated that due to the positive pressure in the valve cover area, the oil will foam, and not drain as well. Something along those lines. He specializes in turbo cars, so I take his advice seriously. But we'd just like to know if the valve cover tap will cause long term problems, or if it's just one of those things that is not optimal but won't hurt anything.

 

realistically the vacuum pressure in the valve cover when you let off the throttle after boost should suck all the froth out of the drain line. BUT, if i don't let off hard and pull enough vacumm the pressure may hold it in the line.

kirk, it's not the hardest to do, but it's still a pain and a lot more work then i really want to add to my list. tapping the pan involves taking it out, getting long line, running the line, redoing the oil, plugging the valve cover, etc etc..

 

^^^^^ that was me posting.

 

Can someone explain HOW you get positive pressure in the valve cover?

Is it only under boost?

I've seen the valve cover tapped oil return and removed the valve cover immediately afterwards for a leak and saw NO frothing. Definitely, PLENTY of flow. Almost seemed pressurized coming from the turbo.

 

Right, which also seems like it is always getting "suction" on the oil return line itself. I just took my setup apart for my "current project" and I saw no frothing of the oil either......

 

Now here, I am going to throw this out there, myself and Baggs have a valve breather problem, I ran a hose from the valve cover and installed a adapter and placed a filter, oil comes out of there all the times. You guys have the oil coming back into there, I am lost here, oil is suppose to come back into there but I have oil exiting out of there and it sits at a higher position then you guys have the turbo return lines in the lower portion of the valve cover. I am just contributing a fact not an opionion of whats happening with my valve cover breather.

 

I am pretty sure that the breather hose on the valve cover is to releave pressure upon throttle release and under a lot of heat. Some oil will spit out of there, but there is constant spraying and such of oil under the valve cover at all times, it has to drain out sometime as well.

 

I am thinking this....

With the filter at the top of the crankcase, and tapping the oil return below that filter...

I would think that would "vent" the pressure thus making the oil drian freely?

I maybe outta my skull, just a thought

 

The breather isn't really for releasing pressure according to what I've read in the ESM. It's to scavenge blow-by vapors.

These vapors are made up of hot oily residue, which contaminates the intake, throttle-body, manifold, and at shutdown escape through the air filter causing the oily puddle people sometimes find. However, they are recirculated through the "breather" and an EGR valve off the rear bank IIRC.

 

Can someone post pics of the pan tapped or email them to horst_99@msn.com

I researching the best spot to tap and want to see what has been done.

Thanks...

 

This would be why we found a small puddle of very very thin oil on the floor today where the car was on the dyno, because it wasn't thick enough to be regular oil and there wasn't any residue from oil leaking from anywhere else. Also why Jason's oil level was still at the H spot.

And kirk, there are 2 layers to the valve cover, but I find it hard to believe that one could have one type of pressure and one have the other, and the only difference is one is higher up than the other. There was some oil in the drain line today when we pulled the turbo off Jason's car, some say that's normal, some say it's not.. It wasn't too much oil, just enough to make a mess.

 

I am not a turbo/sc guru by any means but it seems that at least 40-80 psi of oil pressure is getting sent from the sending unit through the oil feed line and through the turbo. I just can't see how oil could not keep flowing even if it pooled up until reaching a somewhat overflow point. I have also heard from Nigel directly over the phone that the center section of some/most turbos have a one-way type of check valve that will only allow oil to travel in one direction. The upper pan would be excellent to tap, but most of these turbo kits sit high enough that whatever incline the oil must travel to get into the valve cover is overcome by positive flow. imho of course.

 

Anyone?

 

I have bumped this thread back up because it was brought to my attention that I should tap the upper oil pan..

Ugh. Let me tell you how much I don't want to do that. Thoughts and opinions?

 

I again don't have a turbo but it seems that the lower pan will work as I know on_alerts custom built kit was done this way and he never had any problems. As the engine is running the pickup in the pan at its lowest point is probably only seeing ~2qts of oil maybe less. I would assume if a large enough 6-8an drain is used that it will drain fine due to the effect of flow and gravity on the return line trying to equal the height of the oil in the pan. Again this has been done on the lower pan with no issues.

 

IDEALLY, you want the hot turbo oil to return UNDER the oil level in the pan at the FARTHEST point possible away from the pickup.

Hot oil entering the valve cover or upper oil pan is exposed to air, which causes oxidation and foaming. Not good! However, the concern about putting the return BELOW the oil level line is that this will cause pressure and a backup of oil in the return.

I saw oil flowing UNDER PRESSURE from the turbo flange to the valve cover, so I doubt backing up in the return would be an issue. It may slow the oil some, but I doubt gravity is the ONLY factor when the maximum angle we could get from the turbo-to-valve cover was maybe 15-degrees. The discharge pressure from the turbo center section was PUSHING the oil, not just gravity drawing the oil IMO.

 

Well, the oil feed to the turbo is under a good deal of pressure. On Hondas it's like 65 psi, not sure what it is on a Maxima. So the return is under a good deal of pressure too. It's definitely not just a gravity line. You just can't have the force of gravity be greater than the force of the oil pressure leaving the turbo or else it will back up.

I think tapping the lower oil pan would be fine if you do it in the right spot. I've seen plenty of cars tapped in the lower pan and they're all fine. They usually do it on the opposite side of the pickup like you're saying.

 

With just looking at the return line and how pressurization works in the valve cover it would seem to me that there is plenty of pressure to suck the oil out of the line into the valve cover and drain it accordingly. The only issue I could see is that if I drove the car really hard for a good amount of time and then let the car sit for a few weeks and then starting driving hard again right away, frothing could occur.

I just don't think the upper oil pan is that much better of a solution, even to the valve cover. Maybe the lower oil pan is the best solution, but now I have to figure out how high up I would need to tap it if I do that, getting a new valve cover, etc etc..

 

I agree...however once the oil works its way through all the tiny passages in the turbo center section and spills into a big ole return line, it's no longer flowing near 65psi or whatever it was on the supply side.

Still has some serious flow though and should push oil out of the way if the return line is dumping under the oil level to prevent frothing and oxidation IMO.

 

In every drain application I've seen, the drain line MUST be lower than the turbo's drain outlet. If there were significant pressure OUT of the turbo's drain, then it would be okay to have the oil drain into a spot higher than the turbo's drain outlet. But I've never seen this done. I also don't think it's wise to have the drain under the oil level.
I'm going to have use a hydraulic pump to solve my problem because I'm not satisfied with my oil pan drain location. But it's another thing to go wrong and another thing you have to install in an already cramped engine bay.

 

I've only got around 10 psi at idle and 35 when cruising at 3k rpm.

 

I moved my oil return to the upper oil pan a few weeks ago. The ONLY reason I moved it was to accomodate the GT turbo I had. It could only be clocked in 90 degree rotations for some reason. WithThe slight angle that the turbo sits at, it would have pointed up. I don't think I agree with the oil oxidation stuff. The air you are exposed to in the valve cover won't be a whole lot different from that in the crankcase area. You will get oil oxidation no matter what you do, you will get oil degradation whatever you do, I think the effects of putting it to the valve cover vs putting it in the upper oil pan is minimal. Having it going to the breather is boneheaded. There's a reason why we decided to go to the trouble of drilling and tapping another hole ... No wait, we thought we would spend extra time and effort and parts just for the heck of it! Doing it to the breather is just plain lazy! Doing it to the valve cover is somewhat lazy but it works.

We designed an oil return recently that does not require tapping of the oil pan. You just dril a hole in the oil pan and screw this in - no tapping required so you don't have to worry about screwing up your oil pan if you tap incorrectly.

Other methods we have thought of is using an electric oil pump to pump back up to the valve cover for those people who really want to have the oil drain vertically down but don't want to remove the oil pan. The oil pan is not difficult to remove just a pain in the a$$ to get to.

 

I don't see a different in the upper oil pan and the valve cover. I really think if anything it should go in opposite side of the lower pan at a low point. Realistically just having the AN line that long to reach the oil pan will help because more oil will flow out, but i don't see what difference there is with the upper pan.

I plan on checking my drain line now and again, but I think the best solution is a lower pan tap i guess?

 

Oxidation of super hot oil being introduced into air is a valid concern and many OEMs, such as BMW, have designed to prevent super heated oil leaving the hottest parts of the engines from simply being dumped on top of the oil level in the pan. I'd consider oil leaving the turbo center section to be pretty hot although I've never seen anyone measure it.

The valve cover vs. upper oil pan still exposes the oil to air causing increased oil oxidation and frothing. Only returning the oil below the oil level in the lower pan will help reduce both, however as Jeff stated that would probably require an additional pump so most people won't bother.

As for the return to breather hole, you couldn't get enough downward angle from the turbo, so the only solution I've seen was to tap the valve cover on the front/lowest portion possible. This gave around 15-degrees of decline and was VISUALLY verified to flow plenty of oil.