Engine Bay Cleanup

The work continues to remove vestigial components that supported the internal combustion engine.


The list of removed parts includes the oil tank (and 14 quarts of oil required for the dry sumped, air cooled engine), the oil cooler, fuel vapor canister, fuel filter, fuel pressure accumulator, cruise control servo, starter motor and electronic ignition module.


Twenty feet (6 meters) of copper pipe comprise the oil cooler. The tubes run from the back engine compartment along the rocker panel to the front passenger wheel well. The coiled bit is sometimes called the trombone.


The right rear engine bay cleaned after removing the oil tank. The grease and dripping oil will not be missed.

Extracting the Flywheel

I need to send my flywheel to my EV vendor so that they can make an adaptor for me. The flywheel bolts to the crankshaft of the gas engine. It is a large disk that smoothes out the pulse of the gas motor and it provides a surface for the clutch disk to transfer power to the transmission. With an electric motor, there is no need to dampen power pulses, but the flywheel is still needed to transfer power to the clutch. The adaptor will allow me to bolt the flywheel to the electric motor.



Unbolting the transmission from the gas motor.



The pressure plate is the first thing you see on the engine once the transmission is pulled away.  Under the pressure plate is the clutch disk, and behind that is the flywheel.  The pressure plate is a spring loaded assembly that applies and removes clamping force on the clutch disk, when the clutch pedal is applied.

 

This is the transmission side of things.  In the center is the input shaft of the transmission.  The fork actuates the pressure plate when the clutch pedal is pressed.  The oil is not supposed to be there.  The clutch is not something that is supposed to be lubricated.  I purchased new seals for the transmission.



The flywheel is top center, the pressure plate is to the right, and the clutch disk is on the left.  The flywheel bolts on with nine bolts.



Gas Engine Removal

The car has been de-iced. (ICE = internal combustion engine). If you are doing this with floor jacks (some of us don’t have access to a car lift), one tip that saved me a lot of time is to jack up the front of the car a bit, to make it easier for the transmission gear selector shaft to clear the tunnel. Otherwise I followed the process in my service manual, and didn’t have any real problems.  I took my time, as this was my first engine removal, and it took about 14 hours working solo.


This is the before picture.



Draining the fluids and removing all of the connections to the engine (eletrical wires, tubes, cables, drive axles).



Lowering the engine to the floor.



Engine is disappearing.



The back end has to be lifted high into the air.  The engine then slides out.



Smelly, greasy, dirty, gas fueled beast has been liberated from the car.



Blank EV canvas.  It's a beautiful thing.



Brakes

The vacuum kit I ordered for the car arrived today.

Most cars on the road have power assisted brakes. When you press the brake pedal, a brake booster increases the pressure in the brake lines in proportion to the force applied at the brake pedal. The brake booster operates on vacuum, which is available from the intake manifold on internal combustion engines. On an electric car, the vacuum must come from another source – a vacuum pump. On some electric cars, the vacuum pump can be the noisiest part of the car. I found a pump kit that has a reputation for quiet operation: VBS-EV-12 . The pump operates from the car's 12 Volt system.  The exhaust of the pump is coupled to an oil filled muffler. This cuts down emitted noise. The pump will be installed with a rubber isolation mount, to keep vibration from transmitting through the structure of the car. If pump noise still proves offensive, then the final contingency is to mount the pump in an acoustic enclosure.

When the vacuum pump is switched on, the pressure in the brake booster drops. Once the proper pressure is achieved, the pressure switch will open and turn the vacuum pump off. Provided there are no leaks, the vacuum level can be passively maintained until the brakes are operated. The check valve prevents the vacuum from leaking through the unpowered pump. After a few cycles of pressing the brake pedal, the pressure will rise, and the vacuum pump will switch on. The purpose of the buffer tank is to store vacuum, and increase the number of times the brakes can be operated before the vacuum pump turns on again.

The electrical circuit will only turn the pump on when the pressure switch measures poor vacuum, and when the ignition switch is in the run position. The main relay is rated for 40 amps. The reason for the second relay is not clear to me. The only thing that comes to mind is that the coil of the main relay must draw a fair bit of current, and the second relay keeps the current drawn from the ignition switch reasonable.

Keys, Locks, and Doors



For Christmas I received a Bentley repair manual. Perfect. This will come in handy.

To replace the worn out duplicate keys that came when I purchased the car, I ordered a couple of factory key blanks from Pelican Parts. At $58 each they are pricey, but a lot cheaper than getting them done at the dealer. They look great. A local locksmith was able to read the key code from my worn key, to make a proper cut instead of just making a copy of a worn out key. They also re-pinned the locks in the door handle to match the ignition switch. I am down to one key for operating all of the locks on the Porsche.

 






The new Porsche key blank looks good.  The difference between the worn out and newly cut key is dramatic.


The interior door trim and panels had to come apart to remove the door locks for the locksmith. As long as I’m in there, I might as well fix a few problems. The stock interior door handles are shockingly thin and flimsy plastic. I’m amazed they managed to last 30 years. I’m replacing them with black anodized aluminum handles.

After market anodized aluminium interior handles on the left.
Flimsy plastic stock door handles on the right.

The door panels have damage from what appears to be an old speaker installation. I can only get affordable replacement panels in black, but much of the door trim, the dash, and rear deck are black. I think it looks good.

Original door panels.

Replacement door panels.

Electric Motor

Component selection is something I’ve thought about a lot over the years. The goal is to select a combination of parts that will work well as a system. One of the key goals for me is to maintain performance that is comparable to the original. In 1983, this car would do zero to 60 mph (96.6 km/hr) in 7 seconds. This may seem tame by today’s standard, but it is plenty quick for me. The electric motor will be key to meeting this goal. Once the motor is installed, I will have a better idea of how much space is available for other components, especially where all 56 of the batteries are going to live.

Today I placed the order for an electric motor and adaptor kit. The electric motor is called the WarP9 from NetGain. It is just over 9 inches (235 mm) in diameter and 16 inches (400 mm) in length. It weighs 156 lbs (71 kg). It delivers 32 horsepower. That may not sound impressive, but it is a continuous output rating. In short bursts, the motor is capable of coming close to the stock gas engine output of 170 horsepower. A key advantage of an electric motor is that virtually all 200 ft lbs (270 Nm) of torque are available at 0 RPM, where a gas engine develops maximum power above 5000 RPM.

The adapter plate is a chunk of metal, typically aluminum, which mechanically fastens the motor to the transmission. It must be machined to tight tolerances to align the motor shaft and transmission shaft so that they spin along the same axis. A hub clamps onto the motor shaft and provides a means of attaching the flywheel. The clutch mounts to the flywheel the same as it did with the gas engine. Some people choose to go without a clutch and couple the motor and transmission rigidly. Going without the clutch has the advantage of less rotating mass and it’s much simpler mechanically. However, I think the driving experience will be better with the clutch.

Fixing Up the Car – Gear Shift Bushings

Over the last few weeks I’ve been enjoying the 911 under gasoline power. I want to have a performance reference to compare against once the car is under electric power. I also want to identify and make as many repairs as possible before starting the conversion.

I love the feel of the manual steering. It is more precise than any other car I’ve driven. The acceleration is terrific too. Adding to the exotic feel of the car, the pedals are hinged at the bottom, so shifting and braking are different than I am accustomed. What I hate is the smell that fills the garage, a mixture of oil and exhaust, which reminds me of an old pickup truck I once owned. There is also the feeling of uncertainty as to if the car will start up on any given attempt. Maybe the starting battery is getting weak. These will soon be non issues.

So far the repair list is small – minor looseness in the shift pattern, the car only has duplicate keys, different keys are required to open the door and operate the ignition switch, flimsy interior door handles, damage to the interior door panels from oversized stereo speaker installation, and a cigarette/12 volt outlet with intermittent power outages.

I will be keeping the stock transmission. The electric motors that meet my application requirements and my price range do not have a wide enough torque band to use with a fixed gear ratio. So the electric motor will be mounted to the transmission along with the flywheel and clutch. The car will shift much like a manual car, with a few noteworthy differences. At a stop the motor will not be spinning. With one foot on the brake the entire time, you could put the car into gear and release the clutch and the car will not move until you release the brake and press the accelerator. This means there will be no clutch slipping like on an internal combustion engine (ICE) as you try to coordinate releasing the clutch and pressing the gas pedal to get the car moving. Also, the electric motor does have a wider torque band than the ICE. A lot of electric car owners report starting the car in second gear, and leaving it there until up to 40 MPH (65 km/h). They shift to third for higher speeds.

While clutch usage will be reduced, it will still be used. To tighten up the shift pattern of the gear selector, I replaced the four bushings in the shift linkage. Pelican Parts sells them in a kit for about $23 USD. It looked like three of the bushings had been replaced recently, but the fourth and most difficult to access bushing was in poor condition. The result was a significant improvement in how the gear box shifts.



Rear Shift Rod Coupler and Bushings



The front shift rod bushing on the left was in
poor condition.  The others were OK.