What I got for Christmas. - Page 2

mbenzman · 2007-01-11 02:06:48

This seems very similiar to an issue that we have with our C Coupes with the Eaton M45 Supercharger. I think that we actually get a vacum condition that pulls oil up from the crankcase and then it gets into the intake and therefore on the MAF. Quite a problem. I ended up using an Oil Catch can to capture oil from the Vent on the Valve Cover, and installing a Breather on the Oil Return line. I would rather find a Check Valve, and install everything to stock. E

02-07-2007, 07:55 AM

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mbenzman

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Quote:

Originally Posted by PTE

mbenzman: I've been watching your post with great interest

. It seems like Crankcase pressure could be a issue. But everytime I've remove my intake manifold , it has some oil laying in the lower plenum. I've looked into why it gets there. There is a ton of oil laying in cylinder head bolt pockets and in valleys , that do not drain well. Clearance for the Cam Lobes. The cylinder head drain back passages to the Crankcase , don't seem to allow all the oil to return. It appears the vents are much larger. AE: Timing chain passages. I was removing the heads . but used a Vet hypo seringe , to suck the oil out of the low lieing areas. To my supprise after I removed the heads , set them upright , MORE OIL FLOWED OUT

With all this oil under the valve covers , My Guess is that when we Chop the throttle shut after a hi rpm run, There is a LOT of vaccum pulled on the hose just after the throttle Plate. May we can find a check valve that closes at Vaccum . then sends that cçase pressure to the exhaust system ??

Lets keep look for Ideas Take care ___PTE___

It really isn't that much oil that gets into the intake manifold, it's just that it hangs around after it gets in there. I believe it's simply vaporized oil from the crankshaft, rods and pistons that is carried out by blowby gases through the pcv system under full throttle application. The hoses to the vacuum side (manifold side) of the throttle body has restrictors to limit the amount of vacuum to the pcv so high rpm manifold vacuum at throttle closure wouldn't have any effect on the pcv.
Ways to minimize it would be; 1. to vent to atmospere during acceleration while having check valves installed in the smaller vacuum side line/s to prevent the backflow, 2. exhaust venting agian in conjunction with #1 plan, 3. rering the engine with zero gap (gapless) rings to minimize blowby gases and the oil carried by it, 4. knifeedge the crankshaft and even coat polish (or coat the surface to shed oil and keep it from beating up the oil and getting it airbourne (lots of ideas here), 5 make the oils path to the manifold longer so that the oil has more time to drop out, 6, use separators, which the could have a mesh to collect the oil and and or centerfuge to sling the oil out against the wall.
Just a few things that could be done. How far are you willing to go? I believe most won't go anywhere near this level. In the long run you and I are likely to play with the bottom ends because we can and will. A little oil vapor doesn't bother me, a lot does as it will hurt the potential of the engine. I've been playing with the bimmer part and may modify it as I don't believe it to be sufficient for my needs.
So what do you use on the outboards?
Rich

Last edited by mbenzman; 02-07-2007 at 08:01 AM.

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