Lighweight flywheel on SRT with Paxton

[Sleeper]

Curious if anyone has done this.
In particular, have you changed flywheels after supercharger was already in place? If so tell me what difference you noticed. I can have one installed for $835.00. Thanks,
TD

 

[VIPER D]

i have a light flywheel but it was on b/f the blower. My advice since the tranny will be out also do the b&m ripper shifter.


vd..

 

[Sleeper]

Dmitry,

At these power levels, I'm not convinced l/w fw is as critical as on lower power applications. For reference, we recently (3/05) installed McCleod clutch and lightweight flywheel on a heavily modded 300ZX TT. This produced faster response in the lower RPM range (say to 3400 RPM or so), most noticable in 1st and 2nd gears. But that motor is only making 300 ft-lbs @ 3400 revs.
Regarding the shifter, in my previous experience ( above '94 Nissan and 2002 Z-06) the install was done from the top. So removing the center console was all that was required. Did you drop the tranny to get your B&M shifter installed?

TD

 

[VIPER D]

Its a nightmare to do it from the top down. its much much easier to go it when you your tranny is out anyway. Also i don't know much about *** cars but in the viper i noticed a differance right away. The car revs up much faster and if you have a weak launce it can recover faster.


vd..

 

[Viper X]

Viper D is right. I too installed the light weight flywheel prior to the super charger but would still highly recommend it. It will allow you to screw up your launch and still recover. Shifting quickly is also easier under boost with the l/w flywheel.

This is a very good mod regardless of your power level.

 

[Sleeper]

Thanks for the responses.
I spoke with a Viper engineer at VOI 8. He said the only reason for the stock cast iron f/w is for warranty protection from owners who abuse the car by dumping the clutch at high rpm, etc. He also recommended changing to a lighter flywheel for performance improvement, although our conversation was not in the context of a supercharged or otherwise higher powered car.

Viper X, not sure what you meant by "shifting quickly is also easier under boost with the l/w flywheel". Could you elaborate? The l/w flywheel allows quicker shifts somehow?
Thanks,
TD

 

[Viper X]

This is just my "feeling" of the way a light flywheel works in this car, but with the heavy stock flywheel, momentum of the flywheel and gear train in general seems to make fast shifting more difficult, both up and down. With the light weight RPS unit I installed in my car, shifting quickly feels better / more precise and is easier for me. This was a side benefit that I did not expect.

Perhaps someone else with a light weight flywheel can elaborate on this.

Dan

 

[joe117]

Spinning up a heavy wheel takes more power than spinning up a light wheel.
I've seen the hp numbers but I can't remember them.

Slowing down a heavy wheel takes more brake power than slowing a light wheel.

Any race car will improve with a lighter wheel. That's a fact. And that includes drag racing.

Street driveability is the only downside.

 

[TCKTPLZ]

Any race car will improve with a lighter wheel. That's a fact. And that includes drag racing.

I don't see how you come to this conclusion. Fact of the matter is, if your at the line with your car revving at 2500-3000 RPM's and are ready to release the clutch as soon as the light turns green, a heavier flywheel will give you more momentum and off the line inertia. It is just a matter of simple physics. Perhaps if you become well versed in the art of launching your car you will be able to circumvent this. But to those who are not masters of this craft, a heavier flywheel will not only make it easier to launch your car, but will yield more positive results as well.

 

[gthomas]

Spinning up a heavy wheel takes more power than spinning up a light wheel.
I've seen the hp numbers but I can't remember them.

Slowing down a heavy wheel takes more brake power than slowing a light wheel.

Any race car will improve with a lighter wheel. That's a fact. And that includes drag racing.

Street driveability is the only downside.

MWAAHAHA!!!!Joe, we disagree on the other thread, but we agree on this one.
1 for 1 not too shabby.
The only downside in terms of street drivability is that the car will be more prone to dieing at idle while cold, and would affect only low speed drivability.
Tis was told to me by a motorcycle builder/racer (750cc), but I have not experienced it. I also am in the car and always let it warm up for a few minutes, give a little gas, so that may be why. And I don't drive 'low'.
Clutch,pressure plate,and flywheel spin in circle(creating centrifugal force).
Lighter aluminum flywheel will have less weight,less force,easier to engage/disengage.
My calculations are already in other threads dealing with this.
EQUIVALENT WEIGHT=0.5x(flywheel weight)x[(flywheel radius x gear ratio x final drive ratio)/(tire radius])above 2(that's squared)
In essence, in first gear you shave off hundreds of pounds of equivalent weight. It does decrease as you shift up, but you're still shaving off equivalent weight in each gear.

 

[joe117]

TCKTPLZ,
Think about it. Sure, you have energy built up in the spinning flywheel when you are watching the lights come down.
But you also have an engine that can break the tires loose even without that built up energy.
It may take more skill, but a light wheel will get you better times.

When you start on your run, you need to spin the flywheel up along with accelerating the weight of the car down the track.

Ever have anyone tell you that adding weight to your car will improve your traction?
That's the same sort of faulty logic.
Sure, more weight will make it harder to spin the wheels, but it will not help you get to the end of the track any faster.

Building up energy in a flywheel will give you extra torque at the start, but that extra torque at the start will not overcome the handicap of having to accelerate the flywheel weight up to shift rpm at each gear change.

There is only one kind of racing that I know of where a heavy flywheel will not be a handicap.
Land speed racing on the dry lakes.

Any purpose built race car will have a light flywheel. There is no street drivability issue there, so they go for light wheel every time.

Have you ever seen any aftermarket speed equipment company selling "high performance extra heavy flywheels"?

If flywheel weight was good, what would make you believe that the Viper just happened to have exactly the right weight?
Why wouldn't someone sell extra heavy ones?

 

[VIPER D]

I know that a light flywheel will prolong engine life due to less stress on the bearings.


vd..

 

[Sleeper]

I appreciate the responses. This is the type of information I was looking for.

It would be nice to drive a lightweight flywheel-equipped Viper first, and then decide. Perhaps someone will let me drive their car at the Southwest Zone Rendezvous this month, or the Midwest Zone Rendezvous later this summer?

There is clearly a tradeoff between the two. I want to optimize my car for the road course, rather than the drag strip (but I still like an occasional street race).

 

[joe117]

A light wheel will help you on the road course. It not only helps you accelerate, it helps you slow down.

At the drags, or street race drags, a light wheel will help you when you learn how to launch with it.

Change your rear to a 3.55 and it will be easier to drive with the light wheel.

 

[Viper X]

There's not much of a trade off. The l/w flywheel is superior at every event, drags, road, street play and normal driving.

Add 100 rpms to your normal take off on the street and it's about a draw. Good mod. Make sure the tech torques and thread locks the pressure plate bolts.