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

[theycallmeebryan]

Can we get something straight on these forums? The mod didn't give you a mpg # increase, it gave you a % increase. Telling people your fuel efficiency increased 5mpg may give readers false hope. A 5mpg gain on a vehicle that previous got 15mpg is a 33% gain. In your case, its a 14% gain. When you talk % it's more universal and more people can relate.

[pounsfos]

Originally Posted by kamesama980

That's what my truck has and why I was wondering. I considered it when I was doing my clutch this summer but didn't have the spare $250-300 or time to wait for the 11 lb fidanza I wanted. one of those clutch slipping in all gears and towing 5k lbs next week situations. It takes FOREVER to rev with no load and I can take my time shifting and still hit the next gear before the revs drop that far.

why buy an aftermarket one when you can just go to wreckers and grab another flywheel and then pay an engine shop $50- $80 for them to machine and balance the new one for you. thats what im going to do with my spare flywheel and make it nice and light and see how we go with that.

[AeroModder]

Percent increases are deceptive as well. A 10% gain for a car getting 50 MPG is far greater than a 10% gain for a car getting 20.

[arcosine]

A gain of 10% for a 20 mpg car is more that twice that of a 50 mpg car, .5 gal/ 100 miles saved vs .2 gal/100 miles saved

[AeroModder]

I might be looking at things differently, but I was looking at 10% of 50 MPG is 5, and 10% of 20 MPG is 2, and 5 > 2. It might look different under another scale, but I'm not accostomed to using gal/100 mi. or l/100km.

[Fr3AkAzOiD]

Why don't people just provide both?
The more info the better.

[darcane]

Originally Posted by AeroModder

I might be looking at things differently, but I was looking at 10% of 50 MPG is 5, and 10% of 20 MPG is 2, and 5 > 2. It might look different under another scale, but I'm not accostomed to using gal/100 mi. or l/100km.

The conventional way mileage is calculated in the US is really not intuitive. It's calculated on a per gallon basis, but you don't drive until you've used a certain amount of fuel, you drive until you get where you are going (i.e. a certain distance).

Look at it another way.
If your vehicle runs at 50mpg for 100 miles, you've used 2 gallons of gas.
If your vehicle runs at 20mpg for 100 miles, you've used 5 gallons of gas

If both improve by 10%:
The 55mpg vehicle uses 1.82 gallons to go 100 miles for a savings of .18 gallons.
The 22mpg vehicle uses 4.55 gallons to go 100 miles for a savings of .44 gallons.

Which is the bigger gain?

It's still far more useful to talk percentage than absolute mpg improvements.
If you instead improved each by 5mpg:
The 55mpg vehicle uses 1.82 gallons to go 100 miles for a savings of .18 gallons.
The 25mpg vehicle uses 4.00 gallons to go 100 miles for a savings of 1.00 gallon.

For a Prius, 1mpg is statistically insignificant. For my full size truck, it's huge.

[NachtRitter]

I'd also like to think that most folks on this forum can figure out for themselves that if someone like pounsfos says he has a 5mpg improvement, it's relative to the FE he (and only he) is currently getting... which may or may not be reproducible by your own vehicle under your own conditions, etc.

Back to the topic at hand... have the results been consistent? Fuel log indicates it has not.