Street Driving the Lithium-powered Zombie – 48 miles on less than 50% battery use!

It’s always good when actual results verify previously crunched numbers :-) As we were designing and building the Zombie’s Dow Kokam LiPol pack, with 22.7 kWh available @ C2, and with my up-close familiarity with Datsun 1200s ( I have a pair of electrified ones), I had predicted 110-120 miles per charge at easy freeway cruising, and under not-so-perfect conditions 90-100 miles. Many doubt it, when I report that Blue Meanie only consumes about 178-185 Wh per mile, but the reality is, those are the numbers. The Datsun 1200 coupe is a small car, thus it has a small frontal area, and stock the little Datsun only weighed 1587 lbs. Blue Meanie is fitted with 175/70/13 LRR Goodyear tires pumped up to 50 psi, its wheel bearings are easy-rolling, and its rear end has the stock small case pumpkin that again, has little drag. With 700 lbs. of Hawker lead and a hefty quad subwoofer stereo system adding weight, the car weighs 2450 lbs. and can go 40-45 miles at 45-50 mph speeds with a lead acid pack that only has 7.9 kWh of energy.

The Zombie of course, is a different story! In back, everything is wrong for range. There’s a large and heavy Dutchman Street/Strip racing housing fitted with beefy (heavy) parts…there’s a Ford 9 inch differential with its low pinion angle well known to be inefficient, 31 spline racing axles (heavy), large case bearings (heavy), and traction assist devices attached (heavy). Then there’s 15 x 8 wheels (huge for a little 1200 that came stock with 12 x 4 wheels) fitted with 225/50/15 rubber (huge for a little 1200 that came stock with 155/80/12 tires). Pushing 9.5 inches of rubber down the road is not conducive for high efficiency! The extra weight of the sub frame connectors and heavier gauge floor steel added weight. The larger diameter Siamese 9 motor, too, adds weight. Bigger ‘everything’ in the front suspension added weight, but not as much as you might think – read on.

To fight the weight increases hi pro components often add. a lot of thought has gone into the design of the 2010 Zombie – a lot of it! The weight savings actually started a few years ago when I switched out the steel Ford 9 inch housing to a racer’s all aluminum ‘Strange’ housing…28 lbs. dropped from the car. Before last week’s 10.4 runs, we had a special process done to the ring and pinion gears that greatly reduce their friction – the gears came back looking as if they were chrome plated. This year, the addition of monster-sized rear ‘Wilwood’ drag discs & 4-piston calipers that replace the heavy Ford drum brakes, in addition to adding tremendous stopping power, also shaved a tidy 12.4 lbs. off each side for 25 lbs. weight savings. Out of interest, these 11.5 inch rotors are nearly the same diameter as the car’s original 12 inch wheels! Likewise, the new CalTrac traction bar/link type system that replaces the old traction bars, in addition to their awesome hard-launch axle control, it’s only 2 lbs. off each side, but that’s another 4 lbs. off the car. To make room for the w-i-d-e rims in back, I had Dutchman Motorsports chop and narrow the custom rear housing 1 inch on each side…again a small weight decrease, but it’s still 2lbs. of steel gone. Though way bigger than the outgoing 14 x 6 rims with 215/60/14 G. Force tires, the because American Racing has always focused on wheel strength with light weight, the 15 x 8 ‘Torque Thrust D’ rims with 225/50/15 G Force tires are only 3 lbs. more per side. In terms of tire drag, there’ not much to do with this, other than pump them up to 42 psi for street running (we lower them to 20 psi at the drag track).

Up front, weight savings were thought of throughout the design process of the new suspension and brakes. We started with much more robust (heavier) Datsun 280ZX struts that come with big 10.75 inch, ventilated rotors (stock 1200 are 8 inch solid). These at first, really increase the weight, going from the 1200′s 37 lb. strut/brake assembly to the Z’s 54 lb. assembly for each side. Again, we worked to make things better. We had to create new hubs to convert from the Nissan 4 on 4.5 bolt pattern to the new Nissan/Ford 5 on 4.5 bolt pattern, so we made the hubs from high strength aluminum…nearly 4 lbs. off each hub. The new ‘Brembo’ rotors were custom cross-drilled to knock 1.7 lbs. off each ventilated rotor. New aluminum caliper brackets replaced the stock steel ones. Eibach adjustable coil-over springs are lighter but stronger…the list goes on. The new ‘skinnies’ up front replace the old fatter 13 inch setup comprised of 13 x 5.5 rims with 185/55/13 rubber. The new 15 x 4 American Racing ‘Torque Thrust D’ rims with 145/65/15 LRR EcoContact tires are 5.5 lighter per side! Of course, all new bearings ensure smooth rolling, too.

My thoughts in this design process, were to make the Zombie handle better, stop better, and roll easier down the track track, while also doing the same on the open highway. The super low rolling front end should help make up for the sins of fat drag tires and beefy axle assembly in back.

I had predicted that while not as thrifty as its brother Blue Meanie in terms of lowest rolling resistance, with its lighter curb weight of ~ 2300 lbs. vs the Meanie’s 2450 lbs. and all the above tricks, the car might come in at 190 – 210 Wh per mile, and if so, with a max. of 22.7 kWh capacity in the tank, the car could do 110-120 miles on the open highway, and less at around 90-100 miles in mixed style driving round town.

Yesterday morning, I had a meeting with Bob Fagliano and a body/paint shop, so off I went for a fairly long street drive in the Zombie. It needs to be noted, that I forgot to re-air the rear tires that were still dropped to a baggy 20 psi for track racing. The lithium pack was fully charged over the weekend and sitting at 395V, as is normal for this 355V nominal rated pack. It settles in at a lower 191V or so, and hangs in the 180V range initially driving on the freeway. This was the pack’s 6th cycle. so the cells are starting to get broken in a bit more. I haven’t repaired all the ‘Murphy’s law’ problems we had last weekend, so the car’s dash was dark….blown Emeter, blown EVision system…only a trusty 0-15V gauge analog was left functioning to tell me the ~ voltage point of the 13.4V Thunder Sky 12V system battery. Anyway, off I went in the Zombie with a lot of faith in the Dow Kokam cells to not let me down.

Distilling this story down a bit – I traveled from Portland, past Oregon City, into West Linn, then into Lake Oswego, then back home for 48 miles of driving (checked on Bob’s Mercedes odometer who paced me the entire way). About 2/3 of it was at 65 mph freeway speeds, and the rest was stop and go with some pretty good hills along the way near Lake Oswego. Near home at the 45 mile point I had some guys in a Mitsu Eclipse running along with me on the 205 freeway, and to change lanes and so gave them a little demonstration of Zombie go-power. I stabbed throttle to accelerate away and over two lanes….HUGE power instantly with not a hint of power loss! Arriving at the Wayland EV Juice bar, the Siamese 9 was warm but far from hot, and aside from a nice com. patina, looking as new. The pack was at near nominal voltage with the cells at 3.68V (they can go down to 2.6V) and all the modules were at ambient temp…not even warm, and not a single low set point (2.6V) red LED was glowing :-) It was as if the car took a walk in the park! It took exactly one hour at 27.5 amps start current that dropped to 26.5 amps, then ramped to 25 amps near end of charge – 27 ahrs to get to a full charge with all the reg boards winking away and remarkably all in sink within 2 minutes at 3-5 amps finish current. This pencils out to 208 Wh per mile.

Considering that the pack is rated at 64 ah @ C2, the car used less than half the capacity of the pack to do close to 50 miles…with the rear tires at 20 psi for half the trip – we aired them up at the body shop. Of note, there is also a very bad drive line/universal vibration that both Tim and I are certain is robbing lots of power…being attended to this week. Additionally, the front end has not yet been aligned…again, being attended to this week.

It seems the Zombie can do 90-100 miles as it is right now, even with unresolved issues that keep it from being 100% for range driving…not bad! How cool is it, to have a low 10 second electric car that also has a 100 mile range?

See Ya…John Wayland

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