Project-Scuderia

Well, we are officially getting close to a new battery technology that is production-ready. BMW just announced a battery pack upgrade for the 2017 i3. 50% more energy (+ 11kW-hr) in the same size battery compartment. No cost or weight data yet, but the article suggested no significant increase in weight or cost, so BMW is making good on their word, and they are right on schedule as well.

 

After this most recent round of upgrades to the car, I am setting it up for street/show, rather than pure track use. To deal with local TX roads and parking lots, as well as the reduced ground clearance of the front skid plates, I raised the ride height up to 136 mm front / 156 mm rear. I took the Scud into Soulspeed in South Austin, where Colin is quickly becoming the local go-to guy for alignments to spec. He set the car up to a street/stock alignment, which was tougher than expected for the minor increase in ride height. I then checked the corner balance and made some minor adjustments. The OEM sway bar drop links are back on the car, and they are not adjustable, so corner balancing was less effective. Nevertheless, the results were acceptable.

Corner Balance Results
198 lb driver
Fuel – half tank (12.5 US gal)
Sway Bars – OEM drop links (non-adjustable)

LF – 734 lb RF – 699 lb
LR – 917 lb RR – 916 lb

Cross Weights – 1650 lb (50.52%) / 1616 lb (49.48%)
Total Weight – 3266 lb
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Now that the Scud is re-assembled and has an all-new setup, it's time to set another baseline:

Curb Weight Results
- No driver
- Fuel: full tank (25 US gal)

LF – 670 lb RF – 665 lb
LR – 889 lb RR – 923 lb

Cross Weights – 1593 lb (50.57%) / 1554 lb (49.43%)
Total Weight – 3147 lb

Changes from Original Baseline
- CF Rockers
- CF Decklid
- CF Under-Body Panel
- CFRC Brake Rotors
- Titanium Brake Rotor Hats
- 16M Forged Wheels
- Pirelli P-Zero Rossa Tires

 

The difference is dry weight vs. curb weight, as discussed back on the first page of this thread (many months ago). If you pull out the 25 gallons of fuel (at 6.1 lb/gal = 152.5 lb) and 1.8 gallons of washer fluid (at 8.0 lb/gal = 14.3 lb), the 3147 lb curb weight is reduced to 2980 lb, which is very close to spec.

 

Looking back at the original baseline in post #1:

And considering the current changes to the car:

CF Rockers -8 lb
CF Decklid -7 lb
CF Under-Body Panel -6 lb
CFRC Brake Rotors +5 lb
Titanium Brake Rotor Hats -2 lb
16M Forged Wheels -2 lb
Pirelli P-Zero Rossa Tires +14 lb
=========================
Total Change -6 lb

So, the curb weight of the car should be 3125 lb - 6 lb = 3119 lb.
But, the curb weight was 3147 lb on the scales, which is a 28 lb error in the wrong direction. Upgrading from the OEM battery to the Optima Yellow Top when the original battery died may account for a few of those pounds, but the more likely culprit is an inaccurate fuel or other fluid fill.

 

Not sure of the source of the image that you pasted in, but it appears to be third party marketing data, which is different than engineering data. But this is an interesting discussion. See the following posts.

 

From Wikipedia, the free encyclopedia

Curb weight (US English) or kerb weight (UK English) is the total weight of a vehicle with standard equipment, all necessary operating consumables such as motor oil, transmission oil, coolant, air conditioning refrigerant, and a full tank of fuel, while not loaded with either passengers or cargo.

This definition may differ from definitions used by governmental regulatory agencies or other organizations. For example, many European Union manufacturers include the weight of a 75 kilogram driver to follow European Directive 95/48/EC.[1] Organizations may also define curb weight with fixed levels of fuel and other variables to equalize the value for the comparison of different vehicles.

The United States Environmental Protection Agency regulations [2] define Curb Weight as follows: Curb weight means the actual or the manufacturer’s estimated weight of the vehicle in operational status with all standard equipment, and weight of fuel at nominal tank capacity [grey area], and the weight of optional equipment [another grey area] computed in accordance with §86.1832–01; incomplete light-duty trucks shall have the curb weight specified by the manufacturer [this is established by OEMs to serve more as a limitation than a specification].

Unladen mass depends on the manufacturer and can be the same as curb weight, however it is often the total mass of the car without a driver, fluid or any additional equipment [this is where the marketing department comes in].

 

From Wikipedia, the free encyclopedia

Dry weight is the weight of a vehicle without any consumables, passengers, or cargo.

It is one of the two common weight measurements included in road vehicle specifications, the other one being curb weight.

By definition, dry weight does not include any of the following:

Gasoline, diesel or any other fuel
Engine oil
Coolant
Brake fluid
Power steering fluid
Transmission fluid
Washer fluid

The difference between dry weight and curb weight depends on many variables such as the capacity of the fuel tank.

 

From Wikipedia, the free encyclopedia

Over time, most domestic vehicle manufacturers have more commonly used the term 'shipping weight', which refers to the vehicle in as-built, no-option condition. This would include engine oil, coolant, brake fluid and at least some small quantity of fuel, as vehicles have traditionally been driven off the assembly line and these fluids were necessary to do so.

 

I monitor this market periodically, but I have not seen a product that meets the project's constraints:
- No loss of vehicle utility or street-ability
- mandatory use of advanced technology and/or materials
- Increased performance
- Competitive cost/pricing relative to OEM

The titanium exhausts I have seen so far are not technologically advanced enough yet. I'm waiting for something really aerospace-grade. Think inconel forgings, hydro-formed titanium tubing, and Bose dynamic sound-canceling.

The same argument applies to my search for a battery solution.

 

See posts #212 to #280 (June 2013 to February 2014) for our discussion of lightweight batteries for F430s.