Thoughts on lightened flywheels and clutch disks, For performance motor Options

[Boomingbeetle]

I have a 2270 motor that I will eventually be putting into my '71 with a sideshift tranny, once I get some dress-up and parts collected. It does not currently have a flywheel, clutch, or pressure plate.

1. Is there a benefit to finding a lightened flywheel if the motor has lighter internals?

2. I assume I should use a 6-spring clutch disk or an aftermarket performance material, but maybe this isn't necessary for a 150-HP/TQ motor? Ditto for the pressure plate.

[stugray]

Another key concept (apparently completely lost on the younger crowd on the BRZ forums):

Horsepower measured by a Dyno is really measured at a lot of discrete points of constant RPM in the "curve" as the RPMs are raised.
When you look at "dyno pull results" (like this one from Vans 914 build page: http://www.ephotomotion.com/914engine/page50.html)
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.ephotomotion.com-10819-1478183765.1.gif)

It looks like a constantly changing RPM and most people believe that you want to try to do the "pull" as fast as possible and that a faster pull means more HP.
That is not the case, in fact, the SAE requirements for dynamometer measurements are that the dyno is supposed to pause at each discrete measurement point for a specified duration before measuring torque & RPM.
In practice, dyno pulls are done in a dynamic sweep that seems to be one continuous pull, when they are really performing hundreds of discrete measurements.
The most accurate dyno measurements are done as slowly as possible.

What I am getting at is that each discrete measurement of torque is supposed to be done at constant RPM.

So how does the rotational inertia of the flywheel and crank affect the torque measurement at constant RPM (NOT accelerating)?
Answer: It doesn't.

I was essentially unable to convince the naysayers that you could not "feel" the difference of replacing the OEM driveshaft with a carbon fiber driveshaft on a BRZ.
And they REALLY love talking about how they can feel the difference of replacing an 8 lbs crank pulley with a 4 lb one in terms of vehicle acceleration.
I calculated the difference between a 0-100 MPH run with the OEM driveshaft and a run with a "magical" driveshaft that weighs ZERO.
There was a theoretical difference of 10 milliseconds in a 0-100 MPH run, but they were still convinced that you could FEEL the difference with their "Butt Dyno".

Hold on, everyone here has a 914 because they like to DRIVE, right? If you want a well behaved street car, you get a Camry. Snappy engine response is one of the things that makes shifting a joy. Maybe the stock flywheel gives you what you want, but it is at least something to think about.

This IS, in fact, the only noticeable difference a driver will "feel" with a lightened rotating assembly is throttle response when the car is out of gear (again - as compared to removing the weight from anywhere else on the car)