Good Question: Why did Porsche.. - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Brad Roberts · 01-26-2012, 02:21 PM

Porsche **only** used the oil pipe on the left for the M97 2.7 and 3.4 engine in the 987 and 987C

The M96 3.4, 3.6 and the M97 3.6 and 3.8 utilize the same oil return pipe as the 2.5/2.7/3.2 Boxster engines.

What gives? Why change only on the mid engine late cars?

I know what it does.. and I know which one **technically** should work better

Anyone out there "know" why they did this?

B

wvboxst3r · 01-26-2012, 04:57 PM

no clue but I am chiming in to not miss answer

Brad Roberts · 01-26-2012, 05:03 PM

I was all excited when my email "dinged"..

The canister version on the right helps to get the air out of the oil before it returns to the oil pickup area.

The one on the left would help promote getting the oil back to the pickup sooner, but it would have more air in it.

What did they learn? Why did they only use this method on the 987's?

B

Brad Roberts · 01-26-2012, 05:04 PM

Sad..

I just noticed all the GT3 shims on my desk in that picture.

I'll do a better job of cropping my pics

B

san rensho · 01-26-2012, 05:20 PM

Quote:

Originally Posted by Brad Roberts

I was all excited when my email "dinged"..

The canister version on the right helps to get the air out of the oil before it returns to the oil pickup area.

The one on the left would help promote getting the oil back to the pickup sooner, but it would have more air in it.

What did they learn? Why did they only use this method on the 987's?

B

To prevent oil starvation?

Brad Roberts · 01-26-2012, 05:25 PM

That is my best guess, but why would they not use the same part in the 3.8X51 engines? Both have the same oil pumps, or the 3.6?

B

healthservices · 01-26-2012, 05:54 PM

Quote:

Originally Posted by Brad Roberts

Sad..

I just noticed all the GT3 shims on my desk in that picture.

I'll do a better job of cropping my pics

B

At least you don't have a box of tissues and a reflection of something indecent on your monitor...

Brad Roberts · 01-26-2012, 05:57 PM

That is a good point

Floating around on the web somewhere is a picture of a naked guy reflection. he was taking a picture of his couch for eBay.

I personally have not seen it..

B

jaykay · 01-26-2012, 06:08 PM

Well I purposely kept the old style in my sump, as I had heard of Cayman guys retro fitting the older style swirl pots to reduce foaming. Had holes put in my windage tray.

Sounds like change had something to do with engine placement. Perhaps oil return speed in the mid engine location was found to be dominant/more important than taking time to defoam. Perhaps foaming was found to be a predominantly rear engine problem .....something to do with the dynamics of the car

san rensho · 01-27-2012, 01:02 PM

So Brad, don't keep us hanging. Enquiring minds want to know.

Brad Roberts · 01-27-2012, 01:51 PM

I honestly don't know

I know which ones I'm going to use...

B

san rensho · 01-27-2012, 03:20 PM

Ok, I'll bite. Porsche has had a problem (that I've heard of, mostly with Caymans) with 987 motors developing cylinder and piston scoring in cylinders 4-6, leading to engine replacements under warranty. Thinking that the problem was oil starvation, Porsche got rid of the swirl pots and just dumped the oil directly into the sump with the straight pipe.

For what its worth, Hartech argues very pursuasively that the problem is not oil starvation, but overheating caused by a revision to the head gaskets which makes them cheaper, but which leads to higher temps in the 4-6 banks, especially cyl 6, which is compounded by the Porsche coolant thermostat that runs at too high a temperature.

http://www.hartech.org/docs/buyers%20guide%20web%20format%20Jan%202012%20part% 205.pdf

Brad Roberts · 01-27-2012, 06:12 PM

I'm buying some of it, but not all of it

The 3.4 CaymanS block is the same block as the 3.4/996 and 3.6/996

I'm reading..

B

tonycarreon · 01-27-2012, 06:29 PM

the sofa came after the tea kettle...

**NSFW**
snopes.com: Indecent Exposure

Brad Roberts · 01-28-2012, 03:04 PM

Both of these are 3.4 Head Gaskets. The top one is 996 3.4, the bottom one is 3.4 CaymanS

The 996 3.4 has the smaller holes for the water passages, the CaymanS has the larger.

Technically the water for a 996 has to travel further prior to entering the engine after the radiators.

Brad Roberts · 01-28-2012, 03:05 PM

I do have a 3.4 CaymanS block with cylinders 5+6 bad

B

jaykay · 02-02-2012, 12:45 PM

It looks like the 996 head gasket has some kind of flow control orifice function where the 987 does not. One hole is really small. Sooo if they are the same blocks then this would make a difference in what heat transfer occurs via the coolant yes?? Both are putting out the same power; same oiling system; same torque; same water pump.

I am not sure what advantages 996 rad distance would give...got to think about that

Are there Cayman guys that gave swapped in the 996 head gaskets? Are there differences in the heads particularly the coolant passages?

jaykay · 02-02-2012, 12:54 PM

Quote:

Originally Posted by san rensho

Ok, I'll bite. Porsche has had a problem (that I've heard of, mostly with Caymans) with 987 motors developing cylinder and piston scoring in cylinders 4-6, leading to engine replacements under warranty. Thinking that the problem was oil starvation, Porsche got rid of the swirl pots and just dumped the oil directly into the sump with the straight pipe.

For what its worth, Hartech argues very pursuasively that the problem is not oil starvation, but overheating caused by a revision to the head gaskets which makes them cheaper, but which leads to higher temps in the 4-6 banks, especially cyl 6, which is compounded by the Porsche coolant thermostat that runs at too high a temperature.

http://www.hartech.org/docs/buyers%20guide%20web%20format%20Jan%202012%20part% 205.pdf

Ahh it's all in here!

san rensho · 02-02-2012, 12:59 PM

Quote:

Originally Posted by jaykay

It looks like the 996 head gasket has some kind of flow control orifice function where the 987 does not. One hole is really small. Sooo if they are the same blocks then this would make a difference in what heat transfer occurs via the coolant yes?? Both are putting out the same power; same oiling system; same torque; same water pump.I am not sure what advantages 996 rad distance would give...got to think about that

Are there Cayman guys that gave swapped in the 996 head gaskets? Are there differences in the heads particularly the coolant passages?

Yes, the hole differences are for coolant flow control. Cyl 6 is the hottest, since it is furthest away from the WP, so on the 996 HG, 6 has the biggest hole for extra cooling. 996 HG are not interchangeable left to right banks. For the 997, Porsche decided to save a couple of bucks and made the HG interchangeable, but to do so, had to equalise the coolant flow orifices. According to Hartech, the refised HG is why Caymans experience left bank cylinder failures.