Hey all! I have a 2000 BMW 328i and my friend and I were interested in converting it into a performance hybrid as project. I was wanting to send all the power from the electric motor to the front wheels and keep the gasoline power going to the rear wheels. I was just interested in the cost I would be looking at and the parts that I would need. I have a basic understanding of auto mechanics and have a friend who can do minor fabrication. I want moderate range but I'm mainly interested in speed and performance. I have looked at the AC-51 motor but I am a complete novice at this and would love to have some feedback on what parts are needed and what parts are the best. My budget is about 10,000. Thanks you for your time.
Planning 2000 BMW 328i to hybrid conversion
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I don't know how this topic was originally written, but I read it (probably mis-read it) as a battery-electric EV conversion, not a hybrid. Sorry for any confusion.
This is still a valid question: What do you consider "high performance"?
The AC-51 continuous power graph shows characteristics similar to a gasoline engine over much of it's range (and all the range used for best acceleration), and a peak of only 45 horsepower with 144 volt power supply. For brief periods it can be run harder and produce up to 88 horsepower (144 volt peak power graph).
Adding this power output to the gas engine's output is good for acceleration, but the weight increase will be substantial... which is bad for all aspects of performance. What are the expectations?
This is still a valid question: What do you consider "high performance"?
The AC-51 continuous power graph shows characteristics similar to a gasoline engine over much of it's range (and all the range used for best acceleration), and a peak of only 45 horsepower with 144 volt power supply. For brief periods it can be run harder and produce up to 88 horsepower (144 volt peak power graph).
Adding this power output to the gas engine's output is good for acceleration, but the weight increase will be substantial... which is bad for all aspects of performance. What are the expectations?
As for parts...
For any electric conversion, you need the motor, some form of gearbox, a motor controller, a battery pack, and some form of battery management system. No difference here; there's also a huge amount of detail to understand beyond that...
Following edited after clarification by original poster:
With the understanding that the entire original powertrain stays intact and continues to drive the rear wheels, to add electric drive of the front wheels you also need a suitable gearbox, halfshafts with CV joints, and front hubs which accommodate being driven.
Since the engine is in the way, the only easy solution is BMW's stock parts from an all-wheel-drive BMW 3-series (model ending in "xi") - final drive unit (differential), and halfshafts, and hub assemblies. The electric motor would probably need to sit beside the output of the transmission, where the transfer case is in the stock AWD configuration... although there still won't likely be enough space. Since you are not going through the BMW transmission you also need a reduction gearbox.. or you could use the electric motor output directly to the front final drive, at a substantial performance penalty especially at lower speeds).
Finally, to make this a functional hybrid - rather than just a car with two unrelated drive systems - you need some way to produce electricity from the engine. Normally in hybrid adaptations of conventional powertrains a motor-generator is sandwiched between the engine and transmission; it acts as a generator for regenerative braking of the rear wheels, as a generator when desired to charge the battery from the engine or shift power to the front wheels for traction or handling, and as a motor to use battery power instead of engine power (although you say you don't want to do this). This is easy when the transmission manufacturer designs this piece, but it doesn't exist for the GM 5L automatic used in this car, and is very unlikely to exist for the manual transmission as well.
The end result, with hybrid drive to one axle and electric-only drive to the other, is a similar configuration to the Highlander/RX and RAV4/NX hybrids from Toyota/Lexus, the current RL, MDX, Pilot, and NSX from Honda/Acura, and some exotics. In all of these, electric drive is available to the engine-driven axle. Also in all of these cases, the electric-only axle is at the other end of the car from the engine, so packaging the electric motor and gearbox is easier.
For any electric conversion, you need the motor, some form of gearbox, a motor controller, a battery pack, and some form of battery management system. No difference here; there's also a huge amount of detail to understand beyond that...
Following edited after clarification by original poster:
With the understanding that the entire original powertrain stays intact and continues to drive the rear wheels, to add electric drive of the front wheels you also need a suitable gearbox, halfshafts with CV joints, and front hubs which accommodate being driven.
Since the engine is in the way, the only easy solution is BMW's stock parts from an all-wheel-drive BMW 3-series (model ending in "xi") - final drive unit (differential), and halfshafts, and hub assemblies. The electric motor would probably need to sit beside the output of the transmission, where the transfer case is in the stock AWD configuration... although there still won't likely be enough space. Since you are not going through the BMW transmission you also need a reduction gearbox.. or you could use the electric motor output directly to the front final drive, at a substantial performance penalty especially at lower speeds).
Finally, to make this a functional hybrid - rather than just a car with two unrelated drive systems - you need some way to produce electricity from the engine. Normally in hybrid adaptations of conventional powertrains a motor-generator is sandwiched between the engine and transmission; it acts as a generator for regenerative braking of the rear wheels, as a generator when desired to charge the battery from the engine or shift power to the front wheels for traction or handling, and as a motor to use battery power instead of engine power (although you say you don't want to do this). This is easy when the transmission manufacturer designs this piece, but it doesn't exist for the GM 5L automatic used in this car, and is very unlikely to exist for the manual transmission as well.
The end result, with hybrid drive to one axle and electric-only drive to the other, is a similar configuration to the Highlander/RX and RAV4/NX hybrids from Toyota/Lexus, the current RL, MDX, Pilot, and NSX from Honda/Acura, and some exotics. In all of these, electric drive is available to the engine-driven axle. Also in all of these cases, the electric-only axle is at the other end of the car from the engine, so packaging the electric motor and gearbox is easier.
Thank you so much, that gave me a lot to think on. I'm thinking now of putting in a smaller engine in before I try anything with an electric motor. That'll free up a little room up there. The car is mainly just to mess around on and tinker with so when i mean't performance I mean't to be able to use AWD at times if I take it to a track. I also wanted to ask how to cut out the motor when I get above a certain speed.
The obvious engine swap would be to put in one of the four-cylinder engines which were offered in the same generation of 3-Series. That will help to manage weight and weight distribution, and room is good, but one of those engines will be just as wide and (although shorter) will still block the space between the front wheels and make it difficult to use anything other than BMW's AWD components to drive the front wheels electrically.
It's good to have realistic expectations.
By "cut out", do you mean electrically turn off, or mechanically disconnect. I'm not sure that there is any reason to turn it off - beyond simply not apply power - but mechanically disconnecting could allow you to gear it for lower speeds, and disconnect it at high speeds which would destroy the motor. I just don't think I would want to lose the front-drive functionality at higher speeds.
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