Who can lighten the flywheel of an Impreza and what can I expect
Or do I have to get steel one

kurt

 

I won't shave the stock flywheel. The easiest is to go for the STi one, just fit straight on and it works. JUN makes a good chromemoly one. Are you planning on racing? Overlight ones are too twitchy to drive normally.

 

I had my flywheel lightened. I was told it was taken from 12kg to 7.5/8.0 kg. I felt absolutely no difference.
Now I have the engine out the flywheel has been machined but weighs 9.2 kg.
With hind sight this was a mod with no discernable benefit.
There could be another issue in that the lighter the fly wheel the less the shock absorption/cushioning. This may have a bearing on main & big end bearing life.(no pun intended) STi v6.
Except for racing engines with frequent rebuilds do not bother. IMHO.

 

That is very unusual, some cars wont event idle with lightened flywheel. Did you change anything else when you lightened your flywheel? like bigger clutch or something that offsetted the weight saving?

From all the Integra Type Rs I have seen with lightened flywheel, I think NA cars feel the effect more than turbo cars.

Shock absorption is handled by the clutch plate.. those little spings within the disc itself.

 

I had my flywheel lightened when I had an AP clutch fitted, I sure there is a slight benefit with spool/pick up time compared to before. I've noticed no difference to the idle or with drive shunt. It maybe slightly more prone to stalling but that could be the bite of the clutch.

Mark A

 

Must agree with markA, had mine taken down to 8Kgs

 

Barge: Were you told it was 8kg as I was or did you weigh it?
Alfer: The exhausts were supposed to be ported. Not much metal was removed & I am doing properly myself as I now have engine out.
As I said I felt no difference. A more radical reduction of 35% may have shown up.
Hope this is helpful.

 

Harvey: Did you port match your exhaust ports? or did you leave a step into the exahust manifolds? Apparently, the exhaust ports are just slightly smaller than the gasket/manifold, it actually increases low-midrange torque without losing top-end power... the step actually acts as a one-way valve during low engine speeds.. reducing backflow.

How much a step.. I dont know...

 

I was shown mine before it was fitted, & I felt the weight or it compared to a normal unit, I also had the headers & down pipe ported, I was shown the before & after units so I'm happy it was doen.

 

The ports were only chamfered. I doubt it would make much if any difference. I have now cleaned out to match the gasket profile & extended into the manifold & cleaned out rough cast marks all of which I think I could have reasonably have expected in the first place from a reputable Scooby tuner.
I will know inside the next week whether my subsequent work has been worthwhile.

 

Please let us know Harvey

Thanks
Richard