Engine update...

[MikeD]

A little history as most already know this, but some may not. The #757 Boxster S motor broke at California Speedway during the CFoS Sunday Sprint Race. Coming out of T5 it sputtered, and as I pulled off to the inside of the track it died. Spectators say that was the same point where a little blue puff of smoke appeared from the exhaust.

Since the car only has 47K on the motor (mostly weekend driving mind you) and is less than 4 years old, I figured I would see if Porsche would at least help with a new motor. No such luck. You could probably hear the laughing from Stuttgart if you had listened close on that day. But I figured it was worth a shot.

So, now the car is at Mind Over Motorsports and the engine is out. Attempted to do a leak-down test on #6 cylinder. But that didn't work out because the piston does not move when the crank shaft is turned. It would appear as though the connecting rod has come unconnected. Not much noise coming from the crankcase during this process, so I am holding out hope that the disconnected connecting rod hasn't caused a lot of collateral damage. Also, the center ceramic piece of the spark plug was shattered. Leading us to believe that there was detonation. Which could have also caused the connecting rod to break (possibly??).

My intent is to get another motor and have it installed into the car as soon as I can get it done (few weeks probably). Then keep this motor, rebuild it and hold onto it as a spare. At least that is my current plan. We'll see how that works out in reality.

[MVZ944T]

Mike,

Good luck. The guy I just bought my new car from recently purchased a 97 RSR clone from a guy that had bought a new Cup car and is racing IMSA. He took the engine to a shop in Phoenix and had it rebuilt. It lasted less than one hour before it tossed a rod through the block. He went back to the shop and they told him he must have missed a shift, so sorry. He sent the whole car up to Chris Cervalli in Denver. Chris found one of the con rod bolts had not been tightend and had fallen out. Total loss on the engine, 30k to replace it. Felt sorry for the guy.

Mike

[sean996]

Myself and a couple of club members pulled apart a Boxster S motor that had suffered an intermediate shaft failure . . . rear intermediate shaft bearing was grenaded and there's a bunch of bent valves . . . we took a bunch of pic's that I think Brad R. was going put on a website.


Haven't taken the crank out of the cradle yet to see if pieces made it to the crank . . . fun stuff . . . neat seeing what's inside!!!

Having a backup motor/motors is also my plan if I ever buy a 996 again

Sean

[kary]

Mike, sorry to hear that Porsche would not support you with anew motor! That is a real drag. I will keep my eye out for another motor and let you know if I find anything.

[lowyder993s]

Well...I was going to post a smart a$$ remark, but seeing as how I destroyed my motor a couple weeks ago I'll just keep quiet. When you gonna be back on the track? Looks like we'll be ready for Tribute. How 'bout Ethan's ride? Anywhere close to being done?

[MikeD]

Well...I was going to post a smart a$$ remark, but seeing as how I destroyed my motor a couple weeks ago I'll just keep quiet. When you gonna be back on the track? Looks like we'll be ready for Tribute. How 'bout Ethan's ride? Anywhere close to being done?

Nope, not going to make Tribute. Might make BW, but not holding out a lot of hope for that either. Should be at Laguna Seca, and Spring Mountain though. Haven't made a single PCA TT this year. Would be nice to put my $10 to use, even it's it's the last event of the year.

Ethan is working on his car. Don't quote me on this, but he might be at BW also.

[Brad Roberts]

OK. So I now have all the pics in one place of yet another failed BoxsterS engine! I wanted to thank Birgit and Sean for all the pics. Birgit took apart 90% of the engine. Sean had started on one side prior to our arrival. Thanks for the use of the shop Sean. I think we are onto something with a few different engine combinations for these new engines.

Enjoy the shots and feel free to ask questions.






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[Brad Roberts]

I'm going to post two at a time. Each shot will have arrows and some minor descriptions for those of you following along at home with no engine experience





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[Brad Roberts]

In the picture above you can see the two black plastic "tubes" in the back corners of the engine. These are the returns from the small external scavenge pumps.





The shot above shows the "witness" marks on the tops of the piston and one in the cylinder wall.

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[Brad Roberts]

Here is the tech info on a BoxsterS engine. I compared all the Boxster engines with the 996 3.4 and the 997 3.8. It is very interesting what bore and stroke combo's they used to come up with the different displacements. It appears everything (so far) 3.2 and up can easily be bored to the 3.8 cylinder bore of 99mm's.

Here are the all the specs.






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[Brad Roberts]

Lots of room to bore this out.. This is the 93mm bore. Stock 3.8 is 99mm as mentioned above.





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[Brad Roberts]

Here is a shot of the head. It is upside down in this picture (I should have flipped it before applying the arrows and TXT)




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[Brad Roberts]

This is what sets the late engines apart from the early engines. The early air cooled engines are slowly beating the main bearing saddles out of every engine Porsche built. The early 6 cyl cases are MUCH worse about this. Porsche addressed it by installing iron/steel inserts RIGHT were the main bearings sit in this new "cradle" design for the crank/rods.

Pretty COOL!!




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[Brad Roberts]

Ok. Here is a shot of the entire crank/rods cradle. This sits inside the two case halves. We are looking from the flywheel end in this shot.




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[Brad Roberts]

OK. Just a few more. Hang in there

This is a shot of the head as viewed from the "cam side". You can see the cam journals in the picture.




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