QUOTE(bbrock @ Jun 26 2022, 01:07 AM)
The drive train PLUS rear battery pack and cooling is roughly the weight of a six cylinder engine and transmission according to the vid.
@bbrock You know I can't resist a good debate.
I think we are all over the map. I'm not debating that you can get 100 miles of range out of a 914 with a 26 KWh battery. That is agreed.
What I want to focus on is the falsehood that the EV conversion doesn't destroy the 914 dynamic handling character. I get people will do conversions - that's fine if they want to spend a whole lot of money to build a less capable 914 (less range than gasoline, degraded handling vs. a stock 914, and shitty range as compared to purpose designed EV).
I call
that the power pack unit in the video is roughly the weight of a six:
From information I can find on-line
Tesla rear motor unit: 290 lbs
26Kwh batteries (let's use the Beetle numbers) -- 280 lbs
Two cooling tanks with lets say 4 gallon of water - 32 lbs
Cradle with sufficient structure to support all the weight - 75 lbs (estimated)
Radiators -- 2 @ 4 lbs each = 8 lbs
Fans --4 @ 1 lb each = 4 lbs
Total = 689 lbs.
I'm a little unclear on where the power electronics are - are they in the front battery module or the rear? How much do they weigh (guessing about 10 lbs based on weight of Tesla SiC MOSFET inverter)? That looks like it may be the
inverter DC to DC converter on the side of the rear battery pack?
Now lets talk moments of inertia
Look at this picture - that is A LOT of mass siting up at the TOP of the engine compartment. Not only the coolant but probably also the power electronics (inverter, DC/DC converter, some of the batteries, etc.) that are sitting up high in the engine compartment. This is unlike a boxer engine that puts most of that mass low in the vehicle. That is going to lead to increased propensity for the vehicle body roll as well as fore/aft pitch when braking and accelerating.
Click to view attachmentNow let's look this one
Click to view attachmentSo the motor is well behind the rear axle. This is a 290 lb mass that is going to seriously degrade the handling by adding moment of inertia to the vehicle. Not only because of the mass and it's rearward placement, but also because it's running (and its gyroscopic rotation) laterially across the car. This is unlike the gas powertrain where the crankshaft, transmission gears, and differential, are centralized and rotating along the central axis of the vehicle.
Then of course we have the radiators stuck out at the farthest end. At least they are relatively light.
My main bitch with all this are the flippant remarks by those that do these conversions and gloss over them with remarks that it's about the same weight
The burden of proof is not on me to prove that the vehicle has been degraded. It's PHYSICS. Those doing conversions don't get a pass on physics and math just because it's an EV.
I'm not saying my mass numbers or engineering analysis are 100% correct - I'm working with what I can find on-line. However, I am tired of having to be the one to dig out the numbers while those doing the conversions just spin a fairy tale about how good the vehicle is while driving a straight line down the motorway.
If these conversions are so good, then post numbers (mass, range, moments of inertia). Moments of inertia could easily be modeled with some basic CAD work. The onus is not on me . . . they have the components, they can measure where they are packaged, they can determine with a high degree of precision what the degradation is instead of me doing napkin math. Yet they never tell you that information . . . I wonder why?
I propose the following challenge for those that want to do an experiment to see how mass and its placement degrade vehicle handling.
Go to Home Depot, buy some 50 lb bags of pea gravel. They only cost about $4 a bag. Buy 6 bags (300 lbs). This will cost you all of $30 to learn a very important lesson in Physics. Go have a field day -- move that mass around between the Frunk, the passenger compartment, and the Trunk and see how it changes the vehicle handling. Arrange the mass longitudinally vs. laterally and note the change. If by chance you can't tell the difference . . . an EV conversion won't bother you a bit.