the flywheel test (switched to 2 kg / 4.4 lbs lighter flywheel)

[pounsfos]

ok so i have been reading this and that on flywheels and everyone has a different opinion. so i thought i would do some testing of my own

my starlet has the heaviest flywheel out of all the kp series engines so i thought i would try something lighter (theory being less rotational mass, less work)

so i sourced out a flywheel of the 1.1L motor which ways 2kg's less and installed it yesterday

so far i have noticed a throttle response increase and a quicker time to reach 58kph using 15inches of vacuum as usual.

my cars sweet spot is 55-60kph (about 32 -36mph) at this speed i can cruise using just above 20 inches of vacuum, with the lighter flywheel in it still uses the same but every now and again it drops down abit so have to give her about 22" of vacuum to keep her steady

i will post up results as they come. but its looking good i reckon

vacuum gauge is in inch hg if you must know.

[slogfilet]

Thank you for taking this on... I know it's been discussed at length. The clutch on my VX is starting to chatter, so I may need a replacement soon. I know the VX has a lighter (by 3lbs?) flywheel than other Civics of its generation, so there must be *something* there!

[some_other_dave]

They may be able to turn or cut your flywheel to remove the bad parts. If not, you could get a standard Civic flywheel and get it lightened. Any machine shop can do that. But it may be cheaper to just pick up a VX flywheel, unless you have a good cheap source of standard Civic FWs.

-soD

[pounsfos]

****update*****
flywheel is going really well, only time my car struggles now is in the 80kph (50mph) zones but even then its only buy a little bit apart from that engaging and disengaging the clutch feel exactly the same if not easier. 0-35kph is alot quicker using the same amount of gas.

i have driven 220kilometers (136ish miles) and my fuel gauge is sitting higher than it usually does but will wait for confirmation when i fill her up

[autoteach]

How much did the original flywheel weigh? What was the difference in MOI? Just curious.

[Fr3AkAzOiD]

Please keep us updated on this. I am very interested in your results.

[pounsfos]

Originally Posted by autoteach

How much did the original flywheel weigh? What was the difference in MOI? Just curious.

sorry what is moi??

original flywheel weighed approx 12.5kg
new flywheel weighs 10.2kg

data is in, fuel economy for this week is really good it is
41mpg

now thats not bad, thats better than 35mpg isnt it
so far so good guys will update next week on my next fill up to see some consistancy

oh and yes any shop can machine your flywheel lighter for you if you want. while your their get it balanced as well. it doesnt cost much and its something you should do as OEM manufacturers dont get it 100%

[autoteach]

Moment of Inertia, or MOI is a measure of the rotating structures resistance to acceleration. You could have a 10 lb flywheel that has a higher MOI than a 15lb by having that weight at a larger diameter, if that makes sense.

[pounsfos]

Originally Posted by autoteach

Moment of Inertia, or MOI is a measure of the rotating structures resistance to acceleration. You could have a 10 lb flywheel that has a higher MOI than a 15lb by having that weight at a larger diameter, if that makes sense.

yeah i here you, all the weight on these flywheels are on the outer diameter of the flywheel. is this a good thing or a bad thing?

the flywheel i am currently using looks exaktly the same (the weights still on the outside) but has less mass there

(wish i had a camera to take photos)

[autoteach]

All in all, your reduction was minimal compared to an 8lb flywheel. The reason that I have been asking these questions is that there was a pretty detailed discussion on the topic without any real evidence prior to this and there was a lot of speculation. I am glad that you have seen benefits from this, I just dont want people to think that there is validity in "less-is-more" and shoot for the lightest possible, as there are significant problems with ultra light flywheels. It is amazing how heavy that flywheel is for a 1.1L engine, I would think that you could almost get away with a 18lb, or ~8kg flywheel on such a small engine. And by get away, I mean that it would function as was intended without any drawbacks. It is alot like the over 20 lb flywheel on a BMW opposed twin motorcycle, not really necessary.