vortechpower

iTrader: (1)

So this is a lightened crank pulley? What or how much advantage do you gain from this? Makes sense to have a lighter one...

LatinMax

iTrader: (1)

I think that 70-85% of the power gain comes from being lighter and the rest comes from being smaller. So you don't loose very much power gain without the smaller diameter.
It said that on the Orthdox website.

Broaner

iTrader: (10)

Somebody just needs to dyno with one.

Stephen Max

iTrader: (59)

Lightened engine components don't show much gain in 3rd and especially 4th gear because the engine acceleration rate is too slow for the inertia reduction to be effective.

vortechpower

iTrader: (1)

So, would this part be StephenMax approved? Basically this pulley would give low end performance. Do you think it is worth the $ for the posible gains? I know I could use some help on the low end, my 26lb wheels are not helping at all! Pulley with a lightened flywheel would be a good combo?

Broaner

iTrader: (10)

Its not low end. Its just low gear.

Yeah, I forgot that a dyno won't measure the gains very well. Unless you did a first gear dyno. I'd imagine traction would be a problem for these applications.

ptatohed

iTrader: (12)

I ordered one ($184 shipped) last week. I'll let you guys know how it goes. However, I'll probably just put it on at the same time I put on the supercharger (transfering my SC from my '96 to my '99) so obviously any gains would be hidden with the SC.

dadiesel

So are you saying that it wouldn't be worth it performance-wise, or that it is just to hard to see the difference on a Dyno?

Stephen Max

iTrader: (59)

They make a difference in 1st and 2nd gear, but the higher the gear ratio, the less effect they have on performance. A dyno in 4th gear and probably in 3rd as well will show no discernible performance gain.

dadiesel

Ok, so with running 10psi, this might help the low end before boost? Also, what do you mean by gear ratio?

LatinMax

iTrader: (1)

Iy will help you get to full boost quicker, in the lower gears. In the higher gears you are already at higher rpms, so it won't make that much of a difference.
I really notice it at the lower gears...I hit the rev limiter much quicker now.

Stephen Max

iTrader: (59)

It has to do with the power it takes to accelerate rotating engine parts compared to the acceleration rate dictated by the overall inertia of the entire car and what gear you are in.

A car accelerates fastest in first gear (assuming perfect traction) because it is in its lowest gear ratio. In second gear a car accelerates at a lower rate than in first, and so on as you go up through the gears.

Ooops, time to go home. I will have to finish this tomorrow.

dadiesel

Ok, I understand. Seems that it is a worthwhile mod for sure then .

Stephen Max

iTrader: (59)

Okay, to continue.

The faster a car accelerates down a street, the faster the crank accelerates as well, since the angular acceleration of the crank is coupled to the linear acceleration of the car through the drivetrain.

The power required to accelerate rotating engine parts is proportional to the product of the rotating inertia times the angular acceleration rate. This power is a parasitic loss and decreases power at the wheels. If you can lower the rotary inertia, then you can reduce the parasitic loss. But, the power loss is also proportional to the angular acceleration rate, so a decrease in rotary inertia has a more pronounced effect in lower gears when the crank is accelerating faster.

This also means that the higher the specific power (power/weight) of a car, the faster it can accelerate, and the more effective a reduction of inertia of the rotating components is.

chris'smax

iTrader: (3)

uhhhmmm wow those are some big words , basically it helps you overcome initial inertia?

dadiesel

SO...it IS a worthwhile mod because it increases acceleration, yes?

chris'smax

iTrader: (3)

yes!