29 replies to this topic

[FabianG]

Hey Guys,

I hope I posted this one in the right category, otherwise please move this thread.
As the title says, I have a problem with oil consumption.
I come from Germany and we are a few people which have that problem but we cant find any answer.
So I want to try my luck here and hope you guys have more experience with it than we do.

But at first my engine configuration:
-Saab B207 engine blok (open deck with cylinder wall supports)
-Z22SE (L61 2.2l) crankshaft
-GM Z20LET rods
-GM C20LET Mahle Pistons
-Ported LSJ head and LSJ intake manifold
-ZZP Stage 2 LSJ cams
-Harrop 1320 with 75mm pulley
-680cc injectors
-LS4 thorttle body (74mm)
-Water Injection
-3" exhaust

Boost is between 1.0 and 1.1 bar and it makes 420HP and 430Nm.
Engine has seen ~1.000km.

We all have got slightly different engine setups, but we all have got ~400HP and the engines are nearly new.
The problems are the same.

When driving the car normally on the street, I cant measure any oil consumption.
As soon as the engine gets hot and a lot of load, the consumption rises badly.
The last time on track my engine used half a liter of oil in one 20 minute stint.
But on the way back home (3h ride on the Autobahn with 160km/h) it used nothing.
We all use different oil types (I am using the Motul 300v 15W50).

My first attempt is to close the PCV valve in the intake manifold.
But I dont think that it can press that much oil through there.
I also tested the valve and it seems to function corretly.

My friend disassembled his engine completely, because he thought his piston rings or valve shaft seals are broken.
But he wasnt able to find anything wrong. The other guy did the same and he also wasnt able to find anything wrong.

So our Idea is now, that the pressure inside the crank case is much too high.
As I found out from Mahle, the piston rings need the pressure of the combustion to press against the cylinder wall and make a good sealing.
But if the pressure in den crank case underneath the pistons is also high, the rings might not be able to seal correctly.

Are the channels from the crank case into the cylinder head too small to let the pressure out?
Do we might need a seperate ventilation?

How do you guys do that with "high power output"?
Do you have the same problems on track?

Thank you guys for your help and very kind regards from Germany!

Fabian

[Johnboyhgt]

How is the rocker cover breather system configured ?

Catch can or simple breather filter system ? 

[FabianG]

Its a catch can to open atmosphere.  

[Exmantaa]

Hmm, I hoped your C20LET pistoned B207 would not have these issues.

Same as Chris/Ultimate had with his old one an now the new Harrop engine....

 

Like you said, it cannot be a simple build error as you have a few B207 engines, all slighty different build but experiencing the exact same oil problems.

I think you are on the right track with the crank ventilation on high load. The B207 bock and head vent channels are pretty big, but then the crank vent channels through an oil seperation system in the valve cover. I would start there  and also the internal diameter of the vent hose adapter is quite narrov inside the head.

(Don't just drill random in the valve cover, as that has a few (plastic) oil seperators inside. must have a pic somewhere.)

[smiley]

I would love to have your power, but i get comparable issues with my B207 running 335 hp.
( I even had this on my Z22SE on 250 bhp)
I have a large catch tank that fills up pretty quick with fresh oil due to crank pressure.

 

A few things that have been done or concluded by others, as you are certainly not the first:
- Adding a second hole to the valve cover helps with pressure releave, and less oil spilled out.
- Having that hose to open atmosphere makes it worse. (even with catch can in between)
- Having the hose from catch can to inlet closed helps, but you need to monitor constantly, as when it get's full,
  you start clogging up the throttlebody, and worst case the laminova system.

There are a few people who have worked on a valve based hose between catch tank and inlet, and reported good results.
Let me see if i can find some drawings.

 

Edited by smiley, 13 October 2020 - 04:18 PM.

[smiley]

Here is Chris Hills solution on his 400hp beast:

 

Here is a Dutch guy abusing his oil cap to tap in a second line:

 

Of course welding in a second bung is the way to go, but he wanted a quick fix. Stage 2.

 

I can't find another Dutch guys valve system. I will ping him for that.

[Exmantaa]

Some reading from the Z22SE forum:

 

https://z22se.co.uk/...he-z22se.28789/

(With a few good in depth links on the other pages)

 

And on the rings:

"Crankcase Vacuum = Better Piston Ring Sealing = More Power.

You may also be having problems with poor ring sealing in your engine, causing more blow-by. A good side effect of lower crankcase pressure is how the extra pressure differential affects the piston oil ring, helping oil control.

With high pressure in the crankcase, when the piston reaches the top of its stroke, the oil ring is flexed in the piston groove, which allows excessive combustion chamber pressure leakage.

When a crankcase vacuum is present, the piston compression rings seat better, rather than wobble in their grooves. Piston ring to piston groove sealing is as important as piston ring to cylinder wall sealing."

 

Our valve cover system:

(Thiis is a Z22SE cover and the vent hoose outlet in the right lower corner has a narrow internal diameter inside the cover. not sure how that is on the B207 cover.)

Edited by Exmantaa, 13 October 2020 - 05:19 PM.

[Nev]

My first guess is that you have high crank case pressure (might be several PSI even). I had this on my engine orginally, but it is fully remedied with a 1" pipe venting the crank case to atmosphere, via a home made condensor (to convert the oil vapour back to liquid which can then drain back into the crank by gravity). Before I built this thing, my car used to leak oil from various sunp gaskets a little bit and burn maybe 1/2 litre per 200 miles of hard driving. Now that I've vented properly it only uses maybe 1/2 litre per 500 miles hard driving.

 

Once you start having such high dynamic compression in cylinders (in order to make 400+ HP), it is inevitable that some of it will get into the crank case, so you really need to vent it very well. Often this matter gets overlooked (I overlooked it in my original setup 12 years ago), but it is one of the subtle but important differences between a Euro 4 engine and a propper power engine.

 

Incidentally, I "think" that on my car it burns the most when using the engine has mid/semi high loads (say 50% to 75%), when I really drive hard I find it does not use so much. I suspect the extra heat when > 80% load means the rings swell and seal better as well as reducing the ring gap. Might just be my imagination, but I've noticed it a few times.

 

 

HTH.

 

Edited by Nev, 13 October 2020 - 07:46 PM.

[Nev]

Its a catch can to open atmosphere.  

 

Just venting from the constricted and narrow rocker cover may not be enough, please read my solution (using 1" pipe) that fixed this issue on my car. Good luck.

[2-20]

You need an exhaust venturi to create vacuum.

This will help the rings to seal correctly.

 

https://www.summitra...parts/mor-97810

 

Read this:

 

https://www.engineba...entilation.html

 

And the link inside

[Exmantaa]

 

Our valve cover system:

(Thiis is a Z22SE cover and the vent hoose outlet in the right lower corner has a narrow internal diameter inside the cover. not sure how that is on the B207 cover.)

 

Did some checking on the different B207 valve cover (which is the same as the supercharged US LSJ engine), but basically it functions identical inside.

The only difference is the position of the valve cover hose connection:

On the Z22SE cover pictured here it can be seen at the red arrow in the lower right corner.

On the B207 cover it is positioned on the opposite side, the right side upper corner in this picture, but internally there is a connecting pipe running from the top right to bottom right, where it connects to the same gas vent chamber as the Z22SE.

 

Some reading the US forums learned that this hose connector seem to have a purposely build restriction (6mm) inside to keep the crankcase under slight vacuum when cruising. (when the PCV valve is open to manifold vacuum and fresh air enters through the hose from the air intake/ filter.)

 

It's tricky to improve the high blowby ventilation on boosted cars (where the PCV valve is closed due to manifold boost and blowby gas goes out through the hose to the air intake /filter) and still keep this crankcase vacuum under cruise condition.

 

The oil cap vent pictured above is just bypassing the stock oil seperators in the valve cover and is not the smartest solution. But one that seems to work on high power track cars is to keep the stock valve cover system intact, but use a proper good quality air/oil seperator in the vent hose with a drain back to the sump...

 

 

 

 

Edited by Exmantaa, 13 October 2020 - 10:38 PM.

[smiley]

I can't find another Dutch guys valve system. I will ping him for that.

 

No valves on this stage 2 setup. Only Chris Hill did that.

 

All 3 reported it to either help, or brought consumption to almost zero.
Unfortunately neither of the 3 do regular trackdays right now, so difficult to be conclusive.
If you do work out what works best, let us know.

 

Edited by smiley, 13 October 2020 - 11:00 PM.

[siztenboots]

my z20let only uses a noticeable amount of oil if I use the full 8000rpm limit , but I also have a bigger oil sump capacity with the balancer shafts removed.

 

10w40 oil used, all other oil system parts original

[FLD]

I've had a little read on this one but it was a while ago.  There are plastic combs in the rocker to separate the oil mist from the crank case fumes.  Higher powered engines often over-flow the capability of this system causing higher crankcase pressure, I've even seen one engine with melted combs but it was a one off from what I'm aware of.  The drag car ecotecs which use big boost seem to favour using total seal rings to reduce crank case pressure but these need adjustment to the PCV.  These combine with removal of the combs and change to just a baffle coupled with a large bore breather system and separator.  The large bore is used to reduce the vent gas speed to allow drop-out or condensation.  Some use a catch can with 'filling' of some description and some use a centrifugal separator with a sump return pipe. 

 

This is just my lazy readings and I have not tried any of these routes but thought I'd share in case it's of use or triggers a useful outcome.

[FabianG]

Hey guys, thank you very much for your answers! 

That gives me a little hope to fix the problem. 

 

My thoughts after reading your replys: 

 

As it seems it is necessary to have the most possible negative pressure in the crank case to make the piston rings seal the best way. 

In partial load its easy to get negative pressure from between TB and SC. (there is a connection on the top of the SC) 

On full load (WOT) the pressure is the same like before the TB. Its almost atmosphere. Maybe we can get a little negative pressure from the venturi effect,

because the connection is 90° regarded to the direction of air flow. 

 

So I dont understand why the 8mm hose is connected between the air filter and the TB, and why the 20mm hose is connected to atmosphere ? 

The negative pressure should be completely lost. 

 

I know that you cant just connect the 8mm hose between TB and SC, because the engine would get the wrong amount of air over the 20mm hose. 

But why dont just close that 20mm and connect the 8mm between TB and SC? 

 

Would be nice if you could explain that.  

 

 

 

[smiley]

The 8mm taps in between TB and filter, not at the actual TB.

I don't know what his exact theory behind it is. All i have is that he tracks once a year and is happy with it.

 

Let's be honest; we need some extensive German engineering and testing with clear outcome of all test results.
You can't leave it to the English, who are fine with spitting out oil on track, or some Dutch playing with hoses and hope for the best.

 

I am looking forward to your end report somewhere spring 2021     

Edited by smiley, 14 October 2020 - 11:41 AM.

[oakmere]

A dry sump system would be nice to solve this but very pricey.

I remember seeing a catch can fitted to the large diameter hole on the chain end of the head. I think the plug gives access to one of the cam chain guide bolts.

[techieboy]

I remember seeing a catch can fitted to the large diameter hole on the chain end of the head. I think the plug gives access to one of the cam chain guide bolts.

 

Yup, I remember that too. For some reason, I seem to think it was a French chap who'd done it.

[Ivor]

Is this a problem associated with SC cars or do turbos have similar issues?

[Exmantaa]

 

I remember seeing a catch can fitted to the large diameter hole on the chain end of the head. I think the plug gives access to one of the cam chain guide bolts.

 

Yup, I remember that too. For some reason, I seem to think it was a French chap who'd done it.

 

 

Problem with those "direct" solutions is that you bypass all the oil seperator systems GM designed for our engine. Better improve on what is there...

 

(I'm still driving with the stock B207/LSJ setup on my car without any oil issues. Maybe I'm driving too slow on track, or I simply need more power...  )