The Saber
A diesel-electric series hybrid on a solid-axle race chassis. The diesel only makes electricity; a single traction motor drives all four wheels through a twin-stick transfer case.
By the numbers
Figures are engineering estimates at a 6,800 lb race weight and will be refined with logged test data.
Powertrain
- Architecture
- Series hybrid, diesel-electric
- Traction motor
- TT-EDU 300D
- Peak output
- 648 kW / 904 N·m
- Continuous
- 146 kW / 387 N·m
- Max speed
- 8,000 rpm (derate from 7,000)
- Generator
- Cummins QSF2.8 diesel genset
- Genset output
- ~50 kW continuous electrical
Energy
- Battery
- 55 kWh NMC, LG E78 cells, 96S2P (~45 kWh usable)
- Fuel
- Diesel, 40 gal cell
- Run time
- ~13–14 hr mixed course
- Fuel burn
- 2.4 gal/hr hard pack · 3.8 gal/hr sand
- Auxiliary loads
- ~4 kW (steering, pumps, cooling)
- Driveline efficiency
- ~88%
Driveline
- Transfer case
- NP205 twin stick
- Ratios
- 1:1 high · 3:1 low
- Front axle
- Currie Extreme 60, 72.5" WMS, driver drop
- Rear axle
- Currie 60
- Gearing
- 4.88
- Axle torque, high
- ~4,400 N·m peak / 1,890 continuous
Chassis & suspension
- Platform
- Jeep JL based
- Wheelbase
- 120.4"
- Suspension
- Rock Krawler Rockzilla
- Front
- 3-link + track bar
- Rear
- 4-link on RK truss + track bar
- Shocks
- Fox 3.0 × 16 coilovers
- Towers
- GenRight
Packaging & balance
Mass placement drove the layout more than any other decision. The battery sits central, at the factory Wrangler 4xe under-seat location, roughly 20" ahead of the rear axle — a position Jeep already validated for balancing a nose-heavy JLU. The fuel cell sits over the rear axle in the caged cargo area, where it doubles as the rear crush structure. A fuel cell can take a hit and keep working. A battery hit from behind ends the race.
Power electronics are racked centrally above the battery and dropped 12" from the first concept to bring CG height down. The spare sits 3" below the cargo-area body line rather than stacked on the cell.
Front axle moved forward 2" — wheelbase 120.4".
- Weight balance
- 45% front / 55% rear at full fuel
48 / 52 empty - CG height
- ~24"
- Wheelbase
- 120.4"
- Race weight
- 6,800 lb (estimate)
Safety architecture
A series hybrid puts a 55 kWh pack and 40 gallons of diesel in the same vehicle. The architecture separates them from each other and from the people, and gives each one its own failure path out of the truck.
- Occupant cell
- Fully sealed six-sided structure — front firewall, floor, both sides, rear bulkhead, top closeout. Center console tied in as a structural spine.
- Isolation
- Fuel cell and HV battery both sit outside the sealed occupant volume. Neither shares air with the cabin.
- Cage
- GenRight, 2.0" × 0.120" DOM. Side closeout by fixed sealed panels skinning the non-opening cage bays.
- Doors
- 16-ga steel, reinforced, dual latch, safety netted.
- Fuel
- Fuel Safe 40-gallon bladder cell. GenRight skid, mounts and bulkhead. Isolation valves on supply, return and vent.
- Battery venting
- Dual burst/vent ports, each sized at 2× requirement for flow margin and redundancy.
- Vent path
- Two fully independent 2.5" stainless channels, each routed out the rear of the truck and exiting rear/down outside the sealed cabin. Two separate exits so one packing with mud doesn't close the path.
Fire is the design driver. Every boundary between the pack, the fuel and the occupants is metal, sealed, and rated above 1,000°F.
Steering
- Type
- Full hydraulic, no box or drag link
- Ram
- Howe 8" double-ended
- Valve
- Char-Lynn orbital
- Pump
- Electric hydraulic, 10 kW
Wheels & tires
- Tires (race)
- Mickey Thompson Baja Boss M/T 40 × 13.50R17
- Tires (road test)
- 35 × 13.50R17 — development and shakedown only
- Wheels
- 17 × 9 beadlock
- Track width
- 76"
Series hybrid
Diesel makes electricity. Electricity makes torque. The battery covers the peaks the generator can't.
Desert conditions at 6,800 lb
Electrical power needed to hold each speed, against the genset's 50 kW continuous output.
| Condition | Force at tires | Power | vs. genset | Range |
|---|---|---|---|---|
| Hard pack · 40 mph | ~360 lbf | ~32 kW | High or low | |
| Gravel · 25 mph | ~510 lbf | ~29 kW | High or low | |
| Loose sand · 25 mph | ~1,050 lbf | ~60 kW | Low · battery assist | |
| 20% climb · 5 mph | ~1,730 lbf | ~20 kW | Low | |
| 40% climb · 5 mph | ~2,900 lbf | ~33 kW | Low · short bursts |
Peak tractive force exceeds available grip in every condition except sticky rock. At 6,800 lb, 5,150 lbf requires a coefficient of friction of 0.76 — the truck is traction-limited before it is torque-limited. Torque is not the constraint; putting it down is.
Performance figures are modeled from first principles at 6,800 lb race weight and will be revised against dyno and terrain test data.
Sand is the test
Loose sand at 25 mph pulls about 64 kW with accessories. The battery covers the gap for roughly 3 hours of continuous sand.
Climbs on demand
A 40% grade needs about 2,900 lbf, well inside the ~5,150 lbf peak at the tires. Short, steep pitches are no problem.
High is for transit
High range handles fast hard pack. Low range does the work in sand, loaded gravel and every climb.
Genset sets the pace
For long sand sections the generator, not the motor, is the limit. That's where development is focused.
13 to 14 hours on one tank. Fuel plans are built from these figures and refined with logged test data.
Three loops
Three isolated cooling loops: the genset, the motor and inverters, and the battery. They can't share a circuit — coolant leaving the generator runs 60–70°C and the pack wants 25–35°C, so putting them on one loop means the generator heats the battery the chiller is trying to cool.
The hard case isn't top speed. It's Backdoor and Chocolate Thunder at 3 mph, where there is no ram air at all, the genset is still making full power, and every core is fed by fans alone. Duct geometry and fan flow decide whether the truck finishes, not core size.