Over 60 mpg due to 40 lbs less rotating wt and aero mods

[moonmonkey]

the extra unsprung weight would have less of a negitive effect if you drive alot of highway, but stop and go could hurt because accelerating the extra mass is the biggest problem not maintaining it, heavier rims once rolling have a flywheel effect that helps cancel out the extra rotating mass (but lighter is always better),, what were the height/gear ratio differances between the two tires?

[ATaylorRacing]

Originally Posted by Gasoline Fumes

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

Ding ding ding ding...we have a winner! This photographer is used to taking pics of the cars as they are doing burn outs and dry hops afterwards...ya right, I DO dry hops to get the right fron tire clean and dry after it was driven through the water (burn out) box or else the rt frt will spin a tiny bit due to moisture still on it.

[Bicycle Bob]

Flywheel effect only helps coasting, not efficiency at cruise. It loads the engine during acceleration, and the brakes when they are used. Rolling resistance is almost linear with load, so 40 lbs can add a measurable increment there. The extra unsprung weight is also bad for efficiency and comfort on bumps.

[ATaylorRacing]

Originally Posted by moonmonkey

the extra unsprung weight would have less of a negitive effect if you drive alot of highway, but stop and go could hurt because accelerating the extra mass is the biggest problem not maintaining it, heavier rims once rolling have a flywheel effect that helps cancel out the extra rotating mass (but lighter is always better),, what were the height/gear ratio differances between the two tires?

On byways I did notice a 2-4 mpg loss of FE using the 32 lb heavier tire/rim set. The 155/80/13s are supposed to be 22.8" in diameter while the 195/50/15s were supposed to be 22.7....the 15s and both sets of the 13s when checked using mile markers on the interstate (which can be off, but I checked out a 200 mile distance that is dead on) show 100.7 miles in a 100 mile distance. The 15s should have been 2/10ths of a % off but all three sets are off by 7/10ths of a %. At the dragstrip (the day this pic was shot) the heavier set of 15s slowed the car down from 19.9s to 20.6s and I had tp pack it up and go home since most tracks require that you run under 20 seconds in the 1/4. I took it out to test and tune and ran the same 19.84 repeatedly where as it was done only once in the past, you need to remember that the car is now lighter by 40 lbs AND instead of shifting at my usual 5700 I shifted at 5400. It should run in the 19.6 range by shifting later and not using 4th at the mph lights...60 feet from the finish line. The car coasts even better now with more modern 13s compatred to the PO craps that were on it.

[ATaylorRacing]

Originally Posted by ojman873

That would do it

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

It ran 19.9s at 65 when I launched at 3300 rpm and shifted at 5700 last year...I always dialed 19.9 and the car at that time was more consistant than the 12 second SRT4 Neon that I normally race in the United Manual Transmission Series. As to my competition, click on the links below and simply go back and forward from my cars pic. I can tell you that getting over a 11 second head start really messes up the minds of a guy driving a 8 second car!!!

My SRT4 Neon
UMTR at Edgewater - May 16, 2009 - Hyper-Performance Motorsports Inc. Photography
Me giving a .14 second head start to a much modified Mustang...check out his tires!
Nat'l Trail Raceway 45th Anniv. - UMTR racers - 5/30/2009 - Hyper-Performance Motorsports Inc. Photography
Me giving a head start to a wheelie popping Mustang
UMTR at Edgewater - June 13, 2009 - Hyper-Performance Motorsports Inc. Photography
Me giving a near 2 second head start to a SHARP old school Camaro
UMTR at Edgewater - June 13, 2009 - Hyper-Performance Motorsports Inc. Photography
Me closer to stock
UMTR at Edgewater - July 11, 2009 - Hyper-Performance Motorsports Inc. Photography
Even the 3 cylinder Geo gets action
UMTR Nationals at Edgewater - 9/26/09 - Hyper-Performance Motorsports Inc. Photography
The White Gnat strikes again
UMTR Nationals at Edgewater - 9/26/09 - Hyper-Performance Motorsports Inc. Photography

NHRA Div 3 ET Finals pics
DSC_0681 on Flickr - Photo Sharing!
Ditto
DSC_0679 on Flickr - Photo Sharing!
Left front corner of hood
DSC_0677 on Flickr - Photo Sharing!

[ECONORAM]

Very interesting. I would like to swap wheels as well, as my factory 20s are 42# each! The 60+ mpg you are seeing is good, even for a 3cyl, I think.

[ATaylorRacing]

Originally Posted by ECONORAM

Very interesting. I would like to swap wheels as well, as my factory 20s are 42# each! The 60+ mpg you are seeing is good, even for a 3cyl, I think.

You could get a set of these that are on sale for only $99 each AND weigh only 28 lbs each!!!!

NASCAR Daytona 8 Black w/Red Stripe

[bgd73]

I assume lack of highway for those little tires. I hope.

Ironically, in another realm of automobile from outer space, I am gaining another 16.9 pound sheet of 18 guage to finish doubling some things on an 87 subaru.

80 pounds of replacements (all doubling- not remove and replace) already added, before counting in 7 reals of mig wire, and 15 inch heavy alloys. the 2750 pounds oem is already approaching 3000 pounds. This next batch should get it over that weight.

I even have a means to a scale locally, looking forward to it. I am going to weigh it with the common tools in the back, between .25 and a half full gas tank, and me inside. It should be closer to 3100..or more.


I found some tricky things about leverage around the struts. Crumpled up in a balll, I bet the car is luycky to be 1700 pounds.. but in a unibody design, weights change dramatically on a scale. Funny stuff.

Is there tricks on the geo to move weight rather than remove? Even the engines fall for this.

The bigger wheels removed on your geo is a surprise relapse.

[ATaylorRacing]

Originally Posted by bgd73

I assume lack of highway for those little tires. I hope.

..................
The bigger wheels removed on your geo is a surprise relapse.

Since I uses the Geo as a delivery truck with some very long distances involved the vast percentage of miles driven is hiway, interstates, state roads, and biways. The around town has not been checked yety since I have not used it more than a handfull of miles, The last 5 tankfulls were all at speeds from 55-60 mph and all of them involved carrying 100-200 lbs of rims/tires to deliveries and near empty wt comming back...since my 45 lb near 4 year old is my co-driver. Last year I found that with either set of 13s or 15s I would loose 1 mpg for every 100 lbs of extra wt.

The ONLY reason the 15s were put on was for looks. Customers seeing a cute Geo with sharp looking rims would think better of my business rather than a normal looking Geo with hubcaps! Now I have decent looks still and better gas mileage. I was going to get front 15x4 drag race rims with a custom bolt pattern of our 4x4.5 added to the available Mustang 4x4.25. Those rims were only 9 lbs, too fragile for the street, very $$$, and I was going to go with the tiny 155/60/15 front tire for the Smart car all around my car. Those tiny 15s were 14 lbs compared to my 13 lb and much less costly 155/80/13s. That combination overall would have saved me only 1 lb per corner more than what my low $$$ effort garnered.