Lighter flywheel + pulleys = less power required to start car?

[Anthony]

Does anyone know if having a lighter flywheel and lighter pulleys installed will cause the starter to pull less power from the battery when cranking the car?

I'm reeeally hoping it would be possible to get away with a Super B 7800 since I'll have a 10 pound flywheel, Raceseng S2 kit, and no sound system. Here are the manufacturer's specs on a 7800:

Nominal voltage (V) - 13.2V
Charge method - CCCV
End of charge voltage (V) - 15.2V
End of charge voltage (V) for endurance (cycle life) - 14.4V
Charge current (A) - 30A (4C)
Charge current (A) for endurance (cycle life) - 9A (1C)
End-of-discharge voltage (V) - 8V
End-of-discharge voltage (V) for endurance (cycle life) - 10V
Discharge current (A) - 210A (30C)
Discharge current (A) for endurance (cycle life) - 6.9A (1C)
Discharge pulse current (A) (10 seconds) - 360A (52C)
Discharge pulse current (A) (1 second) - 450A (65C)
Discharge performance at 20 °C (rated capacity) - 6.9Ah / 91.08Wh
Discharge performance at –20 °C (capacity) - 6.21Ah / 81.972Wh
High rate discharge performance at 20 °C (capacity) - 6.555Ah / 86.526Wh
EqPb (Equals Lead acid battery) - 12 to 20Ah

[Porsche]

Weird... I try to quote you and there's no text in the editing box.

You don't suppose there's some disease spreading around, do you?

You may remember that just recently, @Nevermore was unable to quote me.

Anyway...

What are you building here? A race car?

[Muskokan]

heres a completely uneducated guess from a user that knows nothing about batteries...

Probably would work at first, but as the battery gets older/weather gets colder you might experience problems.

EDIT< just looked at your location, so cold weather shouldnt be to much of a problem.

ps. your profile pic disturbs me... lol

[Anthony]

Originally Posted by Porsche

What are you building here? A race car?

Pretty much.

Originally Posted by Muskokan

ps. your profile pic disturbs me... lol

I do my best.

[nelsmar]

The majority of the stress on the starter is due to the compression stroke, not the weight of the flywheel and pulleys. I am sure it would make a small difference in crank power but minimal at best.

[Anthony]

Originally Posted by nelsmar

The majority of the stress on the starter is due to the compression stroke, not the weight of the flywheel and pulleys. I am sure it would make a small difference in crank power but minimal at best.

That sounds pretty accurate. Thanks!

[diss7]

I think it would make a difference. Even more so if pulleys are underdrive.

[Anthony]

Yeah, I thought about that, but they're not. Same diameter as stock. I think nelsmar hit the nail on the head though. The compression stroke is probably the biggest strain for power.

[diss7]

I definitely agree about the compression stroke being the biggest strain. But I still think the pulley/flywheel weight, can only help.

[Anthony]

Oh yeah, definitely. The real question is would it help so much I could step down to the next smaller battery model. If I knew I could just return it if it didn't work, I'd just roll the dice and buy one. I doubt any vendor would be having all that though.

[StormTrooper]

How light is that and how much difference between the next step up?

Have you looked at the shorai lfx batteries

[Anthony]

I don't know how much the stock flywheel weighs, but supposedly the flywheel I bought weighs 10.1lbs. So whatever the difference of those are + an additional 5.02 of lightness with the pulleys.

So if the stock flywheel weighs 20lbs, I've already shaved off ~15lbs as it is.

[diss7]

My oem flywheel was 9.39kg. Or for those in the new police state, 20.7lbs.

[Anthony]

So then 15.62lbs of weight loss.


EDIT: Or 7.09kg for those on little islands with bad attitudes.