Lighter engine
 

Some times I wonder what Porsche was thinking?

I have my engine apart again which started life as a 2004, 3.2 L. I had it modified in winter of 2012-2013, to a 3.6L by LN. I ran low of funds while assembling it so a couple of things I wanted to do didn't get done. Consequently I didn't replace the tappets and ended up with a tap this summer which seem to be getting louder this fall. While apart the first time I had the crank balanced but skipped replacing the rods.

I removed the motor and started by removing the cams to check the tappets finding 4 that did not seem to pump up and were lower in the tappet housing than the others. The tappets at this point had 65K miles. The rebuild has 18K and I calculated 4500 of those were on track. So there are now 24 new tappets being installed. In the end I wanted to check how the rest of the engine looked and so I took it down to the crank. There was no wear measureable on the lower end. The thing that gets me is the weights variation of parts. Why would they have so high a variation on moving engine parts. The original part 3.2. 93 mm pistons with rings and connecting rod pins. Compared to the LN JE piston 3.6 99 mm pistons with ring and moly connecting rods, No comparison.

Stock piston------------- Stock -----------JE pistons/W --------------Carillo
/W rings & pins....... Rod /W bearing .....Rings & pins ..............Molly rods /W Bearings
1. 649 g................ 635 g. ......................491 g. ......................565 g.
2. 649 g................ 639 g. ......................491 g....................... 564 g.
3. 656 g................ 638 g....................... 491 g. ..................... 565 g.
4. 653 g. .............. 639 g. ..................... 491 g. ..................... 565 g.
5. 654 g. .............. 638 g. ..................... 491 g. ..................... 564 g.
6. 650 g. .............. 638 g. ..................... 491 g. ..................... 565 g.

Stock moving weight 7738. g. The low total assembled rod 1284g highest 1294 g.
Modified moving weight 6333 g. The low total assembled rod 1055g highest 1056g.

Previously the crank was out of balance as well by over 20 g. No wonder you need a 34 pound sprung flywheel

Because time spent dynamically balancing the engine costs money. Accountants hate that, and they are in charge. It takes me 6-8 hours to fly dynamically balance an M96 engine before assembly.

Also, that heavy assed, 37.5# dual mass flywheel will mask the imbalance. Thats what the factory thought.

My LN R&R rods are 511 g.

The other reason I'm taking the time now, was a felt how bad the balance was as soon as I installed a semi solid mount. It was like sitting in a massage chair.

http://i1199.photobucket.com/albums/...pspnsfwhxg.jpg


http://i1199.photobucket.com/albums/...psljixchmc.jpg


http://i1199.photobucket.com/albums/...psjuk50zoh.jpg

"God is in the details'. Love the pics, details and seeing where all the money goes...

Here is some more for ya.

With a reduction of 3+ pound internally, and a improved balance will this allow the use of a SMFW and sprung clutch plate, or are their still to many harmonics from the opposed pistons.

You can, but you need to be certain the crank has no issues and all of the components are balanced including the clutch and PP.

Hey, that work bench looks familiar.. I hear the guy that owns the place is a real ****************************!

And that built crank, it might cost 6,500.00 and have that ****************************'s name on it, but it is 4 pounds lighter than stock and won't snap in half.

OP of those photos was ltusler. I can only dream I had a crank like that.

They were thinking: how can we manufacture this engine cheaper?


Because they were thinking: how can we manufacture this engine cheaper?


Because a flywheel damper is cheaper than high tolerance machining.


And thanks for all of the photos and weights - very cool!

When accountants are in charge of mechanical things, nothing makes sense. It gets worse and worse with every year and every model.

So true! It systems are the same. I am living that hell right now and it's going to cost alot more to fix then we "saved".

Jake,

Nice, is this a forged crankshaft?

He meant to say billet crank. Those pics are of the guts of my FSI 4.0. It is one SWEET engine.

THANK YOU JAKE RABY!!!!!!

I want something like that crank inside my 99 mm LN sleeved 3.2 -> 3.6 engine .........if possible I would like to get one the next time I have it apart.....maybe I could stroke it to 3.8 or bigger at the same time? But I fear that Jake will only supply it with his own rebuilds....arg. It sure is thing of true beauty

I think 3.8 is the Max you want to go. At 3.8L you will need head porting for 5-chain heads. Maybe Jake will sell you a package with Crank & heads. I'll vouch for you if that helps.

I don'tsell any parts. Been there, done that and never will again. If you want it my way, you have to buy the whole combination, assembled and perfected.

Selling parts was a disaster.

Thanks Bill and thanks for the offer Jake, but I don't think I will take you up on it in the near future. Like I have expressed before, I have great respect for your achievements and reading your homepage got me into the Boxster in the first place. Like you I find big joy in trying to understand how these things work.
I always dreamed about finding a crank from a m96-3.6 to install together with some strong custom rods for a stroked engine. Noe offence meant, but this gives me the idea to find someone to make a custom stroked well balanced crankshaft that will be much stronger than the Porsche equivalent. But my self-assembled 3.6 engine is still going strong, so I hope it is not coming apart in the near future, as I have some other P-car related money gulping projects going at the moment.

Thats where component compatibility experience comes in. The 3.6 crank has larger main journals, to increase the rod journal overlaps and build strength. The 82.8mm stroke cranks are the weakest of the bunch.

The guys like you are the ones who have already booked my first M96/97 Performance Engine Class to 3/4 capacity before I even released the registration. One thing I cover in depth is engine combinations, and how to reduce compromises while increasing performance.