Issue is exactly same and fact that they have TSB issued for GT3 cars about this does not make it in any way different for 997 'S' and base cars.

It is same concept/issue and works exactly the same way. The crankshaft is subjected to one-sided loading, causing stress peaks that can result in damage to the crankshaft.

And perhaps if your engine started to rattle out of the sudden - there is a certain reason for this and this reason is well known and documented. The fact that YOU choose to ignore it all and believe it is normal does not change the simple fact that it is not.

 

Go find some one that has one and listen to the rattle, it isn't the block, it is the flywheel that makes some noise. Once again you offer information based on hearsay, and and a totally different engine design. I suggest that before you offer anymore advice on this matter, go find someone that has one installed and listen to it yourself...it isn't the block, the sound is way to light or tinny sounding.

 

Once again you put a lot of words together while not saying anything at all. I suggest you start speaking facts instead of suggesting anything.

Issue is not with what makes sound. Single piece flywheel rattles because it receives vibrations from UNBALANCED crankshaft, so yes it rattles, and as it RATTLES it pushes vibration waves back into crankshaft where they collide and at that happy moment when those waves add up above of steel braking limit point your crankshaft will transform itself into several nicely shaped metal pieces.

Purpose of dual-mass flywheel is to absorb those vibrations (hint - no rattle) and do not let them to go back into the crankshaft.

So usually together with LWFW people get sprung-suspended clutch disk installed to partially assist with those vibrations as it reduces amount of waves going back but as clutch disk does NOT HAVE enough inertia to absorb those vibrations - it does not really help completely. All that got nothign to do with what 'people say' - those are straight laws of physics explaining why Porsche has heavy dual-mass flywheel. To work around this you need to cease the reason that causes those vibrations - to balance the engine to its best which is heck of $$$$ to pay for.

 

You are right, you know more then anyone and don't need to believe anything that anyone with first hand experience. Thank you for the warning that you are providing to all the 6speeders, I would also suggest contacting Alex at Sharkwerks and letting him know that there is a potential problem with the kit that he sells http://www.sharkwerks.com/products.php?pid=151 and that the harmonic vibration will destroy the M96 and M97 engines.

As I have said to other 6speed members, any discussion with you on this forum is a waste of time, your in a lot of threads, and then you surprise me and actually contribute from time to time. This however is a thread that you have no positive input in.

 

So you have nothing to say again? Too bad, I was hoping to hear about alternative set of basic laws of physics or something, who knows, one can always expect a miracle to happen.

And yes, I do know more than most people do. It is a result of a lot of money spent on my education and good memory I have.
If you are also smart - speak facts you can prove and explain from mechanical engineering standpoint. If some merchant sells any self-made part to masses - it does not mean Porsche was too stupid not to do it in a first place, it is actually a complete opposite.

All your 'first hands' experience is good for it that your crankshaft has increased stress level not yet at braking point. I however did a search and found enough cases with 996 cars where issues did happen, then I spoke to service manager at Porsche, Jerry Pellegrino at EPE, another mechanic from shop nearby and those people together have about added up of 100 years of experience working with Porsches and they all repeated me same thing and now some forum poster with 'first hands' experience is trying to lecture me with tongue in cheek saying nothing at all about the subject.
Good grief...

 

I have had 3 race motors built for me over the years and all of them were dynamically balanced to .2oz inches. This includes flywheel, crank, gears, connecting rods, etc.

Just bolting a flywheel to the end of the crank does not put the assembly into a balanced state. Probably why factory uses dual mass FW.

My last motor even had the flywheel and PP bolts indexed to ensure proper balance upon reassembly.

I think SharkWerks is a good outfit but I wouldnt put any kind of lightweight flywheel on my otherwise stock motor unless is was totally torn down and balanced first.

 

Same exact thing I am saying. Everything is possible if done right. But it costs pretty penny and to do it for a non-cup car IMHO is a bit of an overkill.

I wonder if it should be a pre-requisite for FI to be done. Not so sure, as FI does not introduce new types of stresses, just intencifies old types so I think probably rods bolts may need to be changed for enforced ones, but overall re-haul and balancing is not really needed if I am not going to run this engine at 7K+ rpms for hours. From other perspective to get to rod bolts means taking everything apart anyway. Go figure...

I sort of already committed to it but so far all knowledgeble people I know locally tell me it is a pretty stupid thing to do and I will end up with a broken engine. or
Would be nice to have something more here than a mere luck to get prepared.

 

Sometimes a picture helps.

http://www.flat6innovations.com/broken-crank

Read the words too.

 

Nice, somebody even took time to put it into web.
But it is hardly a secret, any mechanics who deal with cup cars do know all that.

 

Problem is I know of 1 race team in California that uses AAsco LWFW on all their race cars and none have had this issue.

I also track my car with many 996 & 997 owners with upgraded LWFW and none have had any of the issues listed stated or in the article above.

I agree that many try to out engineer porsche, and I dont agree with that but there are many reasons why they don't put LWFW on stock cars, because they ARE STREET CARS.

So what you are saying is that each GT3 RS engine is perfectly balanced by porsche because they put a LWFW on that car from the factory..... but a regular 997 GT3 engine is not balanced because they do not use one on that car???

Im pretty sure the 2 engines are built exactly the same, with the ONLY difference being the RS has a different pulley.

There are 2 sides to every argument, and each has its merits and proofs, the only difference is which one to believe....

Everyone can do their OWN research and makes their own decision.. because at the end of the day ITS MY CAR and my money.

my .02 cents

 

I guess key issue here is (probably) if LWFW gets installed with stock clutch or with sprung-suspended clutch. Having solid stock clutch seems to be a core factor here.

Any mod introduces certain level of risk and essentially assessing level of that risk is the most difficult part. In this case we have 2 unpredictable elements as risk factors - for how much exactly was your engine unbalanced and what was level of deviation from norm during production of your crankshaft. In case of forged parts you at least may expect some predictability, but for powdered metal - it is all game.

So if your karma was tainted in any way you may end up with a broken crankshaft, even if you use sprung-suspended clutch disk. At least as I discussed that stuff with mechanics - all people I spoke to saw it happened more than once. Again, it all is just a conceptual talk, I was simply annoyed yesterday about the way NorthVan started lecturing me. Or may be I just was in the *****y mood. Water under the bridge...

Anyone chooses for himself what to do and how to do it. I just prefer to maintain certain level of civility in any conversation, that`s all. did not mean to harm anybody.

 

Off topic.....BUT
Why do you say stuff like this.....there are hundreds of FI kits out there (as well as LWFW)with 1,000's of miles on them and even a few that have gone beyond what the off the shelf system offers...
Are you telling us that there are hundreds of cars that need new engines because of their FI?
Statements like that are what cause problems and make NO sense at all....Sorry!
These statements also hurt the vendors that allow us(who want to) mod their cars.

If you feel like this IS your destiny(broken motor) why do the FI?
If I were you I would ask TPC for your money back.....I don't see anything good coming from this purchase for you or them....BUT that is just my opinion!
And you may want to keep your car stock......


Stacy

 

We're all soooo fortunate to have enough $ to purchase expensive cars and often to spend even more on mods! And while that earning power is typically the result of smarts, hard work, wisdom and ability to get along with others at the end of the day we can still fall short.

I've often not lived up to my late father's frequent advice to praise in public and criticize in private, but I think about it often and when I fall short I know I could do better.

If my turbo explodes, which I doubt, I'll count the exhilarating performance and the enjoyable socializing on this forum as still making it all worthwhile!