my911rs

Obviousely saving mass and rotating mass at that is good. But how good? people describe LWFW cars as "revving much faster". Well, given the same transmission ratios that would entail much faster accelaration (unless revving in neutral). Few people say that acceleration is actually better. It seems to me that with identical engine output, the main benefit of the LWFW will be in reduced drive line power loss to the rear wheels. But by how much? Did anybody dyno a car before and after installation of a LWFW? Does Porsche shed light on this subject?
Thanks

MJSpeed

Less weight/mass= easier to rev up and down...perception will tell each individual something different...quicker throttle response, quicker to rev up and down...

frayed

Acceleration is only improved in gears 1 and 2.

The real benefit is rev matching.

On an intertial dyno you can see power at lower gears but not in higher gears. On a proper loading dyno, there is no extra hp.

roberga

my: someone did the math last ear. There is no ture HP gain, however do the the weight loss and gear ratios I think it comes to about a 31 virtual HP gain in first then 15 in second.
Do a search and you will find it.
I can tell you without question that the car is faster with the LWFW. 1st and 2nd is unreal.

Carrera GT

Of course there's an HP gain because there's a reduction in parasitic loss in terms of resistance to rpm (aka torque.)

More importantly this is a tangible, seat of the pants difference.

Two things that really perk of a naturally aspirated engine are a reduction in rotating mass and shorter gear ratios. In a 911, the most effective change is a lightweight flywheel and shorter diff ratio (ring and pinion,) both of which are "non invasive" modifications.

In short, do it. : )

my911rs

Thanks all for your input. It makes sense. The faster the engine revs (1st gear) the more work it has to do to accelerate the FW, the greater is the benefit of LWFW. This would not translate into peak HP gain as there is no more acceleartion at this point, but should be visible on a dyno chart in the first 2 gears.

frayed

This is patently wrong. There is no reduction in parasitic losses, which are generally frictional (heat) losses in the drivetrain, from the crankshaft to the wheels. Conceptually, a ltw fly addition is analgous to on ltw wheels, ltw tires, ltw brake rotors, etc. Reduced rotating mass does not affect peak wheel hp. This is why on a proper loading dyno there is NO hp or tq improvement, but in low gears an inertial dyno like a dynojet you can detect some fantom hp. But, in reality, that's all it is.

I do agree however, that ltw flys make sportscars more fun. More 'sportbike-like', more revy, and far easy to blip the throttle on the track.

icon

exactly the way reason i like the idea of the lwfw.
being a former (rarely still) sportbiker i'm used to the quick, free rev.
cgt is the only car i've heard that sounds close to sportbike throttle response.
one of the reason i know i'd love the car so much.
but a lwfw helps on the gt3/rs
the quicker response gives you a little more confidence that the car is doing what you asked, when you asked.
and there's a big dif in lwfw throttle response quick vs. throttle map bogus throttle response quick,
in feeling and the confidence it would inspire.

frayed

icon, I agree. I've installed and run ltw flys on several cars, and there's a step up in car/driver connection. Like the car is more hard wired to you brain, to you right foot. Even though I did not get them, I consider the improvement in throttle response to be very similar to improvement in pedal feel due to PCCBs.

You have precious few input points b/t you and your car, and the ltw certainly helps one of the most important points, through your right foot.

The downside is an increase in NVH though. But on a car like a GT3, I don't think owners will complain.

RS 197

I did not notice a huge difference in the LWFW. In my buddies 996 GT3. It did not have the same throttle response as my cup car. It is an improvement, but not enought IMHO, to warrant a change right away. After I drive an RS I am sure I will have to have one. Until then I will live with what I have.

Carrera GT

If you're driving a Cup car, you're "calibration" is already off the scale of the street-going variants.
If you get a chance to drive a car, then swap the flywheel, then drive it again same day, you feel the difference immediately and it's very appealing, especially the downshifts and 1st/2nd/3rd gear romp from about 6000rpm. (on the track, of course, of course.)
I've gotten into a car and thought it had a single mass (lightweight) flywheel because of the NVH only to drive it and conclude it was the normal setup. My car doesn't have the flywheel upgrade and it idles like a Kenworth and rattles like there's a wrench left in the diff.
I haven't driven the shorter diff ratio, but it's so pronounced on a 993, surely it's a blast on the GT3 and by all accounts, dramatic.

RS 197

I did not realize that about my Cup. Rookie I guess. I will have to go back and drive my buddies 996 GT3 and then my car and see if I can feel a difference.

Nordschleife

An interesting aside, the Mac F1 has NO flywheel, just a beautifully balanced engine.

R+C