TRAKCAR

There you go.
The fixed the issues with the wheel lug bolts and unprotected radiators as well

utkinpol

sport sprung suspended clutch is required in case if you install LWFW to reduce number of harmonic vibrations transferred back to crankshaft, this is a well known issue with M9x motors as they never get balanced well enough at the factory, so, it is not unusual for racing shops to do a manual balancing to make sure it will not end up with a broken crank.

if that has happened on a .2 gt3 it only says one more time what a sh$tty assembly quality those cars are now, with all those other issues like bolts coming out by itself from variocam and apparently flywheel as well as somebody posted here, etc. after reading all this I really lost any interest to buy this model, as it simply sucks to shell out $100K+ on a newer car and then give it to the indy shop to take engine apart to make sure it will not die on the next event, I already drive a car like this now, what`s the point to get into other one if it is a same thing?

all in all - this stuff is highly annoying. may be they will eventually figure out what is the problem with assembly quality and in 991.2 or 991.3 models it will be finally over.

Mvez

Fact is, the engine has a resonance at about 4K RPM's, all you have to do is install a set of urethane tranny mounts, and you can feel it, very pronounced. The soft, stock tranny mounts mask this harmonic resonance, which seems to be generating from when the cam actuators start coming on at that RPM.

I feel it every time you pass through that RPM range. I purposely avoid that RPM range whenever I drive on the street, and have avoided street driving as much as I can lately, because of this.

The question I have always asked, does this ATI damper absorb this resonance at 4k RPM's for a stock, 3.6L engine (with RS single mass flywheel? If so, and is shown to not introduce any other torsional imbalance, I would be happy to buy the ATI damper and use it in confidence.

Alan C.

I put a light weight flywheel in my 93 RSA and never had an issue. One of the few cars I wish I had kept. It was like a Timex. Took a licking and kept on ticking.

utkinpol

parts are indeed same. how those parts were put together and with what deviations from optimum is not the same.
it is a simple law of physics at work here that brakes engine apart and from a corporate perspective - number of man hours to test an assembled product.

cbweaver1

Very sorry to read this. Do you know if the retrofit included all of the new 4.0 parts? This would include:

1.) 4.0 Pressure Plate
2.) 4.0 Clutch
3.) LWFW (3.8RS & 4.0RS are the same)
4.) RS Pulley
5.) RS bolt to hold pulley

Questions:

A.) How many installs had this shop done before?
B.) How many miles (track & street) were on the car after the retro fit?
C.) How many over-revs and what range(s) when the failure occurred?

Thanks

Serge944

You guys can call BS all you want, but the RS 3.8 and RS 4.0 are the least reliable engines of all GT3 mezgers, and many of the failures are attributed to loosening fasteners. Install LWFW - risk goes up.

As long as you're ok knowing that, have fun. I put a LWFW on my 4.0.

If the engine is out, it's good practice to re-torque the cam bolts too.

betonred

note to self - do not install a lwfw

Jamie_GT3

The low-mid RPM resonance is exactly what we designed it for. We've postponed the testing until the new design that fits the .2 is available. We have 4 more of the original here ready to go... I have one on my 4.2 and John Chan installed one on his 3.6 .1 Pumpkin... Have many out there on 3.6L converted to larger displacement (4.0L all bore and 4.0L bore and stroke).

ScottArizona

Is this a known issue on the .1 rs and .1 gt3's with the rs or 4.0 flywheel? I plan to do the 4.0 parts within the next 4-5 months (along with coolant pipe pinning, etc...).

I like the idea of the harmonic balancer but I hate the idea of adding more rotating weight, as the whole point of the mod is to make everything spin up and down quicker. It was an awesome, awesome change on my 996 gt3, and I was hoping for similar results on the gt3.

Jamie_GT3

So for .1 you can use an RS pulley and LWFW and you will be good. Many .1 GT3's no issues.

Balancer is 6 lbs. stock gt3 flywheel is 40+ pounds. LWFW is down to a little over 20. The crank shaft and rotating assembly is around 30lbs. Adding 6 lbs won't change anything about how the car feels.

We had a 4.0L engine (bore and stroke) customer go from dmfw, to our damper and 4.0RS LWFW and loved it, rev'd so much faster and has had no issues...

This assumption that a 6 pound damper will adversely affect revs isn't founded...

ScottArizona

Thanks Jamie. I wasn't suggesting that the 6 pound difference was something that could be felt on a "butt dyno," only that from a psychological perspective, its too bad to have to add 6 pounds back, making the total weight reduction 20 pounds rather than 26-ish, as the whole point of the lwfw is to reduce weight. Of course, everything is a trade off, and if it helps longevity than its a no brainer.

Jamie_GT3

OP sorry for the off topic, but want to clear up a few things if that's OK:

It's not just the amount of weight, it's also a factor of where the weight is located. Imagine standing in the middle of a merry-go round as a kid, It's very easy to get the merry go round spinning very fast. Now imagine having 2 kids that are 1/2 your weight standing opposite of each other right on the edges of the merry-go-round. It will be dramatically harder to get moving.

This is the difference in weight distribution for a rotating mass. if all the weight it at or very near the center of rotation it has much less effect on the objects resistance to rotation. The damper is 6 lbs and it's concentrated very near the axis of rotation of the crank shaft. The Flywheel is far heavier AND it's weight is spread out farther away from the center of rotation of the crank shaft.

This is why the 20lbs you drop with a LWFW change is so easy to feel. The 6lb's on the damper, really can't even tell it's there...

I've heard this question a few times and wanted to try to put it to bed if I can...

m42racer

Heres my take on this.

Porsche as with many OEM are now driven by the profits and the risk factor. As long as they can slide through the warranty period then its up to the customer to pay for repairs. So factor in so many warranty claims and you can cost out the cost. That cost is always lower than actually fixing the problem. Remember when we get these cars new, they are already years old to Porsche, so engineering is done with them and then its up to the warranty dept to deal with it. They are run by directitives from the Attorneys and accountants.

The issues with any bolts coming loose on any engine is never about how tight it should have been. Once you get vibrations happening nothing will stay tight regardless of how tight it should have been. The problem with .1 and .2 engines having bolts come loose is all about the harmonics induced in these engines. The dampener is the solution in my opinion.

RedRSA

Jamie - you make a good point regarding the location of the weight, especially in terms of the distance from the axis. I have no idea how well the ATI unit works, but philosophically it still seems undesirable to add six pounds back in when converting to the LWFW.

You've commented on the redesign of the 997.2 pulley to fit without modification to the surrounding engine components; that is important. Has it also been modified to retain the stock pulley diameter? Using a larger diameter pulley would seem to increase the speed and parasitic losses of the auxiliary systems, and would necessitate a longer, non-stock serpentine belt. Perhaps this can be factored into the final design?

When will a 997.2 unit be available?