For every 1 kg taken off the crank/flywheel you could expect approximatly 4.6 kw of power
If you lighten the fly the motor can accelerate faster (less resistance) but (and its a big one) your economy will drop dramatically, your gear changes will be choppy (even worse with a short shift kit installed), your cruise control will work over time and your ability to cruise at a constant speed will be reduced, coz there will be less momentum produced.
You asked for it
Apart from all that, if your after a few extra hp .... Nike'
you left out that it also makes for a lumpier idle... and if you have aggresive cams, this will exagerate the problem further...requiring a higher idle speed, so of course more fuel consuption on city traffic cycle...
but don't mind all this, if it gives u more power - i'm all thumbs up LOL
Something else no one has said yet, if you live in a hilly/mountainous area, you will have more trouble going up an incline than before. I would go for it in a heartbeat though.
Of course, Texas is pretty damned flat
I havent ever had any problems with hill and lightened flys, with the exception of "getting a run up" on a really steep one, and usually the steepness would knock of the speed anyway. The advantage is that half way up the hill you know you can kick into it and its gonna respond (unlike the full weight).
Most of Australia is flat as well.
I read a post recently about alloy flywheels with steel surfaces, could be an alternative. In Oz we can take 500g out of the back of a flywheel for about AUD$50, so you guys should be able to do it for less.
Great way to get noticably more hp at very little cost
i dunno woo... my second car was a mazda 323 ss astine import - the 4wd turbo 1.6 (85) - and when i lightened the flywheel in that - it made for a very touch car... the idle was screwed, was difficult to find that piont where u can ride it to stay still on an incline... although it definatly improved acceleration...
i'm 50/50 to it... it definatly adds a lil power...but it can make a heavily modified car a bitch to drive - especially if its a daily driver...
I'm not sure why your idle got screwed-up, unless you took a real lot of metal out of the back of it.
I agree though it does make finding the sweet-spot just that little bit harder. You can overcome this with a slightly higher idle.
I built rally motors for Nissan (curse that word) and by the time you modify the mill to the max, idle is the least of your problems. We would nearly always be idleing at 1000+rpm and as the idle increases so does the momentum of the fly, hence for increased idle the launch would be the same as standard.
I still say do it, with the motor split it would be close to the top of the list of must do's
Yeah I saw the BB on probetalk, it's for 2.2 NA, not turbo though, AU$300 is a pretty good deal, That's about what the underdrive crank pulley costs.
So I was thinking of going for it, but I am worried that it's going to
totally screw up my idle and make the car less driveable.
Would I just have to get the idle speed adjusted to a faster speed, like
1000rpm instead of 750 (or whatever it is supposed to be)
And make sure I downshift going up hills (rather then leaving it in 5th @
2000rpm doing 60kmh )
How much would it cost to get installed in Australia? 'cos I couldn't do it
Benefits, that I've heard:
easier to match rpms when shifting
better fuel economy
less engine wear
worse fuel economy in city traffic
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