teener, nice
spindle been machined? looks thinner

question?, observation?
all of the lightening efforts to the rotating bits at the business end of a P car will show up as add'tl hp on a chassis dyno, right?

Bill K

thanks!
na... stock rear spindles.

regarding the dyno.
I think so, if the dyno is a chassis dyno.
and more importantly, that same "power" should have some effect on accelerating and on suspension compliance while on the track.

we dyno'd this car, but more for the intent of dialing in the jetting, and compairing before after to the tuning things we tried.
brant

"all of the lightening efforts to the rotating bits at the business end of a P car will show up as add'tl hp on a chassis dyno, right?"

Err.. not quite. The only device that affects how a dyno reacts is ... the engine, not the weight of the engine container, the vehicle. The same engine that produces 200 ft.lbs of torque in a Suburban will produce the same power in a Fiat Spider.

The main advantage of reduced weight, as Brant suggests, is in acceleration, braking, cornering power and vehicle dynamics.

Sherwood

hmmm...

I kinda thought that if you chassis dyno'd one car with heavy wheels and tires, and then re-dyno'd the same car, in the same conditions with lightweight wheels and tires.....

the chassis dyno would be tricked to show quicker acceleration and one or two extra horse power.

of course I've been wrong before!

only if the dyno is not operating correctly or not designed correctly...

Power is the time derivative of Energy

Wt. will affect acceleration, a in F = ma

Both of you are correct.
 

Making the wheels lighter will aid acceleration, but so will making any portion of the car lighter. As Randy shows, acceleration is a function of mass and force. a=F/m

Increase the torque (force), increase the acceleration; decrease the weight, increase the acceleration.

On the other hand, top end speed is a function of horsepower and the drag coefficient Cd.

Or so I believe.

Brant, what wheel and tire combo are you using?
I was using 15x7 fuchs with discontinued 195/60 yokos 00 something before I switched (necessated by the lack of decent 15" track tires) to the heavier 16x6 fuchs with 205/55 mich sport cups. the current combo feels 6/10 lbs heavier each wheel than my 15's

from a weight perspective, I regret that I am using the kumho's on the track. don't get me wrong, I really like the kumho. They are predictable as anything... and last and last.
I've been using 15x7's and in the last year started my switch from cookie cutters, over to the fuchs. (barely fit into my $50/lb rule).

I've been running the 225/50/15
and I know people running the 205/50/15 on the same rims.
Of course if I could afford it, I'd buy the hoosiers as they are probably 5lbs lighter per tire! (but we run 2 drivers sometimes, and I can afford a set of tires every weekend)

brant