ElectricSubaru


Last update: Jul 2 2015

Motor

The motor is a Netgain WarP 11. I estimate with 1000A at 160V this motor produces about 300 ft·lb torque and 160 hp.

1000A × 160V × 88% (voltage sag) × 85% (motor efficiency) × 1 hp / 746 watt = 160 hp

I believe the NetGain Warp 9 would have been a more sensible choice than the WarP 11. Although the larger motor produces more torque, it does so at a lower RPM. Both motors have the same efficiency, about 85%. For any amount of electrical power you put into the two motors, the mechanical power output is the same. The WarP 9 is 90lbs lighter, 1.7in shorter, and $1000 cheaper. The smaller diameter might be the difference in fitting a few extra cells. The 9in motor power band might match the driveline better than the 11in. The one plus with the WarP 11 is that it looks impressive.

Cutting Aux Shaft

The motor was a very tight fit to install in the car. Long after it was installed, I decided no pulley would be mounted on the front of the motor and so I cut the auxiliary shaft down from 2.25in to 1in, just enough for an RPM sensor. The shorter shaft allows clearance for the motor to come out more easily, and for the A/C condenser to be reinstalled. To cut the shaft, a 12V power supply was connected to spin the motor, then a grinder with cutoff wheel was applied.

Cutting Aux Shaft Cutting Aux Shaft

Mount

Mount

The motor mount basically consists of a band (2in x 3/16in) welded to a flat bar (2in x 1/4in), welded to two lengths of angle (2in x 2in x 1/4in). The material is aluminum. On this basic frame are added the bolting flanges, gussets and reinforcements. This design allowed me to have all the welding performed at a local shop, since I have neither a welding machine nor the skill required to weld aluminum.

Mount Mount

The motor mount attaches to the cross member using Subaru engine mounts without the metal brackets.

Subaru Engine Mounts

If I were to do it again, I would consider integrating the motor mounts with the adapter, as with the Rebirth adapter. This would leave more space along the sides of the motor to mount battery cells.

Cooling

A blower forces air through the motor to keep it cool and to clear out carbon dust from brush wear. The blower is a Jabsco 36740-0000 DC 150 CFM Flexmount 3in Blower, with a K&N RA-0990 Filter.

Blower Blower

The mounting bracket included with the blower does not provide any good opportunity for vibration isolation, so I fabricated a mount that puts some rubber grommets between the blower and the car. A length of aluminum angle (2in x 0.125in) is bolted to the frame via an existing threaded hole and a rivet nut. Four vibration isolation grommets are installed in the aluminum angle, with wood screws passing through them into a block of wood. The blower is strapped to the wood.

Blower Mount Blower Mount Blower Mount

The vibration isolation grommets and spacer inserts are from McMaster-Carr:

Grommet

The duct is black flexible plastic with reinforcing wire, concisely named Universal Washable And Durable Chrome 3 Inch Multi Flexible Adjustable Motor Turbo Cold Air Intake Inlet Pipe Hose Tube Kit. It comes with hose clamps and aluminum ends that have a small bead to help the clamp keep the duct from slipping.

Duct Duct

The shroud is made from sheet metal, backed with synthetic felt rated to 300°C from McMaster-Carr. The short tube where the duct attaches is one of the aluminum end pieces that came with the duct, cut down to length.

Shroud on motor Shroud back side Shroud duct

At full power, the blower screams and squeals. A small 12V PWM speed controller from eBay allows turning the power down just a bit so that the blower still moves quite a lot of air, but with just a tolerable whooshing sound.

Blower Speed Control

A delay module reduces strain on the 12V battery for the few seconds after the ignition is turned on but before the DC-DC powers up. This module is sold on eBay by deselectra. As supplied, the module has two power input wires and two white wires connected to relay contacts that close after the delay elapses. A little soldering reorients the module so that it simply passes power through after the delay.

Delay Module Delay Module Delay Module

Terminal Connectors

Lugs: Genuinedealz Heavy Duty Cable Lug 4/0 AWG 5/16 in Stud
Insulators: VTE 415N0V02, 415N0V14

Terminals

A1 to S1 Terminal Bridge

The NetGain 11 motor A1 and S1 terminals are connected by a 3/4in X 1/4in copper bar. This size has a cross sectional area greater than 4/0 AWG cable. After cutting drilling and bending the bar, I tinned it to protect against oxidation using Tinnit Tin Plate. The terminal bolts are fastened with Nord-Lock washers.

copper bar Tinnit Tin Plate copper bar on motor