Over 60 mpg due to 40 lbs less rotating wt and aero mods - Fuel Economy, Hypermiling, EcoModding News and Forum

ATaylorRacing · 05-03-2010, 10:02 AM

Background:
My 96 1.0 3 banger Geo has had several 57 mpg best mpg fills in the last two years. The original 155/80/13s rated at only 35 psi max were swapped out for 195/50/15s that had a 51 psi max. The new tire/rim package was 8 lbs heavier than the old stuff so I removed an extra 32 lbs from the interior so the total wt of the car was still 1630 lbs. I was still getting fuel fills at a best of 57 since the new stuff had lower rolling resistance. Where I used to be able to coast to the next red light now can be done from a longer distance away. I added a grill block and headlight covers but I started to have EGR issues and couldn't get a good mpg reading. I FINALLY ironed everything out but now winter weather and winter gas was here. Spring has sprung and I decided that a MODERNset of the lighter wt 155/80/13s would be the next ticket to better mpg. I got some 44 psi Kumho Powerstar tires in that size and mounted them on 11 lb Primax rims for a total rotating wt reduction of 10 lbs per corner from the 15s...40 lbs removed in just a few minutes. My last four tank fills have netted over 60 mpg with two being63.0!!! The attached link shows the car on the 15s with the aero mods in place.
http://hyperperformance.smugmug.com/...64413387_6htrP

Gasoline Fumes · 05-03-2010, 12:44 PM

I have a pair of those Power Stars in a 185/65-14 on the front of a Civic Wagon. I'm very pleased with how well they seem to roll. One (made in China) is rated at 44 PSI, the other (made in Korea) at 36 PSI. I currently have both at 52 PSI.

I hear they are awful tires in snow, by the way.

Red Lion · 05-03-2010, 02:02 PM

Mind if I ask which Primax rims you have?
The loss of unsprung rotating mass has a big effect on MPG (at least, noticeably in city driving) and handling. I'm looking for some 11lb-ish wheels myself, be it Miata wheels or Civic HX rims.

NeilBlanchard · 05-03-2010, 07:12 PM

FYI, the Edison2 VLC rims that they custom made are ~6 pounds each. Sweet...

ATaylorRacing · 05-04-2010, 12:02 AM

Quote:

Originally Posted by Red Lion

Mind if I ask which Primax rims you have?
The loss of unsprung rotating mass has a big effect on MPG (at least, noticeably in city driving) and handling. I'm looking for some 11lb-ish wheels myself, be it Miata wheels or Civic HX rims.

Ptimax 333 is the model...they look a great deal like the American Racing Estrella. The 333 were a bit over 11 lbs, but the tuner lug nits are about 1/4 lb lighter than the reguar ones.

I drove over 300 mile today and squeezed out a 61.7 mpg. Keep in mind that I carry at least 100 lbs of extra wt consisting of rims or tires that I sell AND deliver.

ATaylorRacing · 05-04-2010, 07:01 AM

Quote:

Originally Posted by Gasoline Fumes

I have a pair of those Power Stars in a 185/65-14 on the front of a Civic Wagon. I'm very pleased with how well they seem to roll. One (made in China) is rated at 44 PSI, the other (made in Korea) at 36 PSI. I currently have both at 52 PSI.

I hear they are awful tires in snow, by the way.

All 4 of mine were made in China and I complained to Tire Rack that their web site said Korea so they gave me $20 back!

This car is T E R R I B L E in the snow and I am not going to go out and buy a seperate set of rims with snow tires since my 12 second (soon to be 11s) SRT4 Neon does really well with snows.

Phantom · 05-04-2010, 01:34 PM

I do not know if it is just the angle of the pic but it looks like the car sits a bit high up. It might help to improve FE if the front end is dropped and inch or two. I did not suggest the back since you load it down for work.

Gasoline Fumes · 05-04-2010, 03:01 PM

Quote:

Originally Posted by Phantom

I do not know if it is just the angle of the pic but it looks like the car sits a bit high up. It might help to improve FE if the front end is dropped and inch or two. I did not suggest the back since you load it down for work.

I believe it looks high because it's launching at the drag strip.

ojman873 · 05-04-2010, 03:20 PM

That would do it

How does the metro...perform...on a drag strip? Do you race against other metros?

Bicycle Bob · 05-04-2010, 07:12 PM

I think the improvement is more from a lower rolling resistanace tire than lower rotating mass. A coast-down comparison would clairify that, by rolling farther with heavier wheels at the same RR. A coast-down on smooth pavement, followed by rough pavement would further clairify the issue.
I'm surprised at the snow report - mine seem to do just fine.