JasonAndreas

(for next time...) The starting point "idle opening" is adjustable in software which is how they getaway with using the same valve on different size engines.

Mark in Baltimore

Really great to see you posting on the 993 board.

dave911rsr

My 96 was primarily a track car, but I still liked to drive it on the street. For me, the lightweight flywheel did sometimes cause stalls while sitting at a light and it was a pain in traffic. You have to be very aware of that clutch when you start the car moving, because it will stall. If I wasn't going to the track, I would definitely not use the lightweight clutch and flywheel.

Drisump

I personally haven't had any issues around driving my LWF equipped 96. Idle good, no stalling. There is a little more noise and vibration at low RPM as well as a little "pulsing" at extremely low RPM while in heavy traffic. All around though, a good mod to do while a clutch is being changed. I wouldn't bother dropping the tranny and spending the money if changing to the LWF/RS clutch was the only reason. Cheers

sand_man

^^^That's a good point. In my case, I'm coming around on 90K on the original clutch. So I've been acquiring the parts as I go, in preparation for a service.

Cupcar

Hi Jason, I thought the same, but noted that others had tried moving the valve and it worked for them and so I tried it...when nothing else had worked... and moving the valve only a small amount worked for me, and worked very well.

What you are saying is that the ISV is always "on" and the ECU maintains a constant open to idle starting position even with the throttle wide open.

For the mod to work though, I think the idle software must only come into play when the ECU is trying to idle the engine, and that the ISV is in its mechanical "off" position until the ECU attempts to drive it when the throttle is closed.

The closer the mechanical starting point is to the true idle position, the more successful the ECU is at idling the engine before RPM drop too far.

Cupcar

Doing another search I ran across this string with a post from John D. on adjusting the ISV, go down to post #3

https://rennlist.com/forums/993-foru...n-for-lwf.html

sand_man

Yes, that's a good one! I also ran accross that one on my research and bookmarked it. That's the thread that eased my worries regarding the install of LWFW on a '95. I just figured if I was unable to dial most of the stalling out with this mod, then a chip from one of the Steves would certainly do the trick.

RBP

Wow, a lot to think about. Not sure having the gear rattle/noise would be worth what seems questionable gains from the mods. I guess the one thing that's certain is the cars will weigh 20 - 30 lbs less. That's something.

Drisump

I think the loosing of 20-30 lbs is the smallest part of the difference in a three thousand pound car. It spools up faster, is simpler and is the very same modification Porsche used in it's highest performance version of the 993 (the RS). Yes, if smoothness and quietness in your car is of primary inportance, it will not enhance your ownership experience. Myself, I prefer a little reminder that I'm driving a 911 and and even with the LWF, RS mounts and PSS9's, it is still smoother and quieter than my stock 85 3.2. LOL! Cheers

Cupcar

Just for completeness of this thread.

Here are pictures comparing the 8.2 pound 997 RS 4.0 (964.102.239.81) to the 11 pound 964/993 (964.102.239.31) versions of the flywheel. Note, in addition to the removed mass on the flywheel, the more narrow perimeter annulus of the 4.0 flywheel which goes with the lighter clutch plate used with it. Unfortunately I did not weigh or photograph the 4.0's clutch plate This is quite a reduction in the moment of inertia in the 4.0 assembly. But I got it to work on a '95.