if i hade a large peice of alluminium could i get it machined into a copy of a std 4k one and have it just as strong?

casey: that sounds very scary. aluminium shock hardens and becomes very brittle, that's why planes are pulled to bits every year and checked. They are so stringent that they won't even let you draw on the aluminium with a pencil because it causes micro-fractures.

 

It seems you can lighten any steel flywheel, but take it to a pro. The best ones I've seen are CNC machined and leave ribs at full thickness that link to a think outer rim around the ring gear.

I realise this is resurrecting an old(ish) topic, but I think the discussion is still relevant. Has anyone actually gone to a lightweight aftermarket flywheel (and not just a lightened standard one)? I'm wondering if you notice any idling problems. TODA make as light as a 3.7kg flywheel to suit the 4A-GE, and I'm just wondering if you need to increase the idle rpm to keep the engine running or what the deal is.

more than likely ancullen. few months back we put a lightened flywheel on a s4 rx7, now needs a re-tune as it won't idle when its cold. as soon as it get some temp into it, its fine though.

My 4A-GZE won't idle when cold at the moment anyway. Plus I don't think I'd put the new flywheel on until I swap heads, which will definitely require a retune anyway.

on a 4agze i would be saying yes. it seems they are bastards to get to idle at the best of time