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

[pounsfos]

yeah the benefits are small but as they say it all adds up, i might get my other flywheel lightened to like 8-6lb and see how we go, maybe theres a point to where it gets to light and starts to negatively affect F/E

remember a flywheels 2 primary designs is to smooth out engine pulses and convert though pulses into a more linear power curve

Flywheel - Wikipedia, the free encyclopedia

i would also like to say that the toyota k series engines are naturally very torquey engines so even though the flywheels may sound heavy when in use the car still goes "hard",

also this test increased MY fuel economy, it may NOT increase yours as you dont drive a 28 year old car, imporvements on cars have been made since then

[kamesama980]

it also is going to depend on your driving style and drive pattern. how much and how fast you rev the engine will affect how it responds. city driving vs highway driving is also going to respond differently.

It would be interesting to try on my truck (2.4l 4 cyl), stock is 26lbs not including the pressure plate. I have seen them as low as 12 lbs. I've also seen one place that advertises taking 10 lbs off but leaving most of the weight around the outside edge. Interestingly enough stock for my cressida is only ~18lbs with a 3l I6. I'm guessing it's because the I6 is inherently smoother than the I4.

[comptiger5000]

The I6 is a smooth engine by design, and also naturally well balanced, so it doesn't need as big a flywheel.

Out of curiosity, what kind of mpg are you seeing with a 5 speed in a Cressida?

[pounsfos]

this weeks results are in:
43.18mpg. even better.

all i need now is for someone to try a HEAVIER flywheel and see what happens

[Jim-Bob]

So what has been the net improvement in fuel economy so far ( where did you start from?)

[arcosine]

You shouldn't notice any difference at at steady speed with the light fly wheel, consistent with your first observations, there should be some improvement in acceleration. The heavy flywheel helps the engine run smother at low speed and idle. The rotational energy that was stored in the heavy flywheel is now transfered to the forward momentum of the car.

[autoteach]

At steady engine speeds there can be a decrease in FE, but at what point the diminishing returns start to occur is not completely visible to non ICE engineers (with loads of calculations or testing).

[Frank Lee]

At steady engine speeds- shall we assume highway cruise?- it won't matter one bit as the entire driveline and road interaction function as a big flywheel.

[pounsfos]

well its netted me an average mpg of 5mpg
before i recorded my travels on ecomodder i kept it on pen and paper and averaged 35-40mpg. so just by changing the flywheel i am now averaging more than that.
(i know its still early days) but theres something here. and franks right as well when steady cruizing the whole car, (wheels etc...) act as flywheel.

[Jim-Bob]

Thanks for the reply. I do have one other question though: How much of your driving is city and how much is highway? I wonder because it would be interesting to see if the positive effect is skewed more heavily towards situations in which you are accelerating often or driving at a steady state speed.

I am considering this as a mod for my Metro in the near future as the 1.3 flywheel is lighter than the 1.0 and I am changing out the engine in a few months. My car sees mostly suburban delivery driving with plenty of stop and go so it will be interesting to see how much of a difference it makes. 5 MPG is a VERY tantalizing prospect!