Im putting together L14 Turbo engine for my 140J and was trying to work out if i lighten the flywheel before i put it goes together.

I know a lighter flywheel will rev faster which is great but between gears when you come off the gas the revs drop quicker to.

Has anyone had any experience in this area and can recommend anything.

Another downside is if the flywheel is lightened it will need to be balanced.

If i don't lighten it it would just need a grind and would be ready to go back in.

Feel free to through up your opinions and if you think it should be lightened what would the target weight be?

Flywheel is currently 10.6kg.

Brett

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Past:
A10 160J Coupe
R30 Turbo Manual
Present:
KP710 160JSSS Coupe (My Standard Car)
KP710 160JSSS Coupe (My SR20DET 6Spd Car)
KP710 140J Delux (New Road Car)
KP710 Parts POS

Rev drop between gear changes also helps out on the synchros. Thousands of race cars can't be wrong, send it to Jenny Craig.
Homologated weight for a Hyundai 1500cc twincam is 6.4kg.
I think a good 180B flywheel (stock flywheel machined down) is probably going to be a touch over 7kg.
Have a look at the diagrams on the Datsport site, respect the guidelines on face thickness, remove as much as you can from the outer diameter, it's where it counts the most.

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Happiness is watching the race.... in your rearview mirror

I would seriously consider the wisdom of lightening a cast iron flywheel - yes, of course it can be done, and then rebalanced (mandatory) and, sure, it will give you all the advantages that are outlined but you might want to do some research on the consequences of a flywheel that disintegrates under sustained high RPM, "quicker" rev up or a combination of these two and during launch with clutch loads as well...I would recommend, unless you are limited by a racing class rule where you cannot change the standard flywheel (and I have yet to see one that mandates a standard flywheel - I don't mind being corrected here), then go and find a purpose made steel flywheel. Most "lightened" steel flywheels will be as light or lighter than can safely be achieved with the cast iron version - you really do not know (again welcome any one to correct) how much material will affect the durability of the stock wheel...just far too risky, in my opinion. Search "flywheel explosion" and view with amazement....yes, some of those would be steel, but I would guess the majority were the stock version.....

I agree that a lightened cast flywheel does pose an increased risk of failure, though sticking with the minimum thicknesses as shown in the picture on the Datsport site, you'll be safe as houses. The old racers have been doing this for years. I wish I had photo's of the Toyota 2TG flywheel that I helped lighten, at the time it seemed like a huge amount of material we were taking off (pocket milled in between where the pressure plate mounts), though newer stock 4AGE flywheels were actually fairly similar. That flywheel has seen 7000rpm duty in a rally car for several years and still going well.
Further to that, I've seen flex stress marks in an aftermarket steel EJ20 flywheel.
Billet steel is the better option, but cast iron done moderately/safely is quite fine. It's not exactly crappy grade cast iron that they're using in a flywheel. But at the end of the day, if you don't feel comfortable, don't do it.

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Happiness is watching the race.... in your rearview mirror