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Old 10-16-2009, 07:07 PM   #19
Scooby Newbie
Member#: 225500
Join Date: Oct 2009
Chapter/Region: SCIC
Location: Chino, Long Beach CA
2013 WRB WRX Sedan
11 Mazda 2


Originally Posted by Subie-Zero View Post
I don't really know where this question would be posted but how much do any of you think our flywheel weighs? 09 impreza sedan 2.5i.
And if we were to upgrade to a leighter one how much whp would we get?
or where can i post this to get more accurate answer if not here?

a lighter flywheel doesn't necessarily net you more WHP. What it allows you to do is go through your RPMs faster. Because a lightwheel flywheel is well...lighter than your OEM flywheel, there is less rotational mass associated with it.

Meaning...because it's lighter, it's easier to turn/push/throw/pull(however you wanna see it) your flywheel.

My example would be(TOTALLY HYPOTHETICAL), lets say you floor it in 3rd gear and it takes you 10 seconds to take you from 30mph in 3rd gear to 90 MPH in 3rd gear. When you install the lightweight flywheel it only takes you 7 seconds. Your power curve should look relatively similar if not identical to your past power curves, but it allows you go through the rpms in a shorter amt of time in order to reach the peak points in yer powerband faster.

Some down sides to having a lighter flywheel, is it won't hold inertia as well due to it's lighter weight, so in the normal time it takes you to shift gears right now, lets say 1.5 seconds for you to shift gears, and in that time your rpms would drop from a 4k rpm shift point to 3k rpm originally, now your rpms will be at 2600 in that same 1.5 seconds instead of 3k which is where engine speed is supposed to be at in that gear at that rpm.

A stock flywheel is figured out and tuned to your average drivers shift speed. They figure that it takes xxxx number of seconds for the average person to shift, so xxxx weight flywheel will hold enough inertia to keep the flywheel going until you re-engage the clutch for a perfect shift. You change that dynamic with a lightweight flywheel and not much else.
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