# Convince me making a hybrid vw beetle is impossible



## Davinchy (May 10, 2013)

Hey guys I'm new here. I am a software designer and was previously a helicopter engine and power train mechanic in the army. I was looking at selling my vw beetle for a more fuel efficient car. Unfortunately selling it will net me very little and a car that gets the kind of mileage I want is very expensive. 

I got to thinking and looked into these conversions that you guys on this site do. 20 mile range sounds ok most of the time but I don't want to get stuck out on the road without juice. I then thought why not use my programming ability and my mechanical skills together to make a hybrid system for my bug instead. 

I have a 1200cc engine in the garage that probably only produces 25hp or so. It is from an older beetle I think. I know very little about what would happen if I were to put power through the crank shaft of a running engine. My idea is basic. I would put the motor parallel to the engine and run a belt to the crank shaft. I would need to work out how to synchronize the two through fuel regulation and torque resistances. 

Rather than a motorized engine assist I am thinking of a motor with engine assist. I would use the motor to do all it is capable of and when the resistance is too much for the motor; I would start pumping more fuel and opening the throttle body of the engine. 

I am thinking controlling fuel could be accomplished with a modern fuel injector for a larger vehicle in line with the fuel line connection to the carb. I am thinking the butterfly valves controlled with a simple servo. I would work out the math and use a rasberry pie linux computer to control everything. That or figure out the programming required to run an old 80's throttle body fuel injection system for one of those little chevy pickups with the 4tech engine. I remember them being about the most basic fuel injection system in the world.

If any of you have any Ideas as to why this sounds impossible please let me know. I will probably start with a little 4 horse lawn mower engine and a dc motor to test the thing out if you guys can't come up with a game ending problem. 

Thanks in advance for any opinions or ideas you may have.


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## Woodsmith (Jun 5, 2008)

I guess anything is possible....

One thing to take into account, if the motor is driving the ICE crank shaft with a belt then the motor is not only running the car but spinning the ICE against its compression and internal friction too. That would be very inefficient.

It would be easier to have the motor connected to the transmission and then the ICE can drive the tail shaft of the motor, via a one way clutch. The clutch would allow the motor to spin faster then the ICE when the ICE is not running but when the motor needs help the ICE can then spin up until the clutch starts to drive the motor (within the motor's maximum speed range).

I am trying to imagine where all this will go under that little hood at the back of the Beetle though.

You might be better saving the effort and cost and going full electric with a greater range. You can also to a trailer with a generator set, when needed, in case you really are somewhere where there is no where to charge up. Saves lugging all that weight of fuel and ICE around for the 90% of the time that you may not need it.


Anyway, welcome to the forum, your skills and experience could lead to an interesting EV.


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## TEV (Nov 25, 2011)

Or you can make a pusher trailer http://www.evalbum.com/753


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## poprock (Apr 29, 2010)

or leave the vw motor in place and attempt to fit a small DC assist motor with belt drive onto crank pulley .


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## Woodsmith (Jun 5, 2008)

poprock1 said:


> or leave the vw motor in place and attempt to fit a small DC assist motor with belt drive onto crank pulley .


I think that was the OP's plan. I figured the friction and compression of the ICE would make the motor very inefficient.


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## poprock (Apr 29, 2010)

Sorry, a better explanation is needed.The electric motor is only used as an assist when accelerating and normally freewheels . Depending on motor type re-gen could be set up on braking. I had this setup on a Dyna 150, but connected to the brake drum of the transmission. The extra boost was good for hills.


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## toddshotrods (Feb 10, 2009)

I'm building a hybrid race car. My solution was to power the axles independently, gas in back/electric up front. That way I can pick and choose which does what, and when, and whether I want to control/link them through driver control and/or electronically. The only other way I think is reasonable is a front-engine/RWD vehicle with the electric motor inline to the rear axle; either before or after the transmission, in the tunnel. My reasons are based on the practicality of connecting everything, and weight distribution.

The biggest issue is weight. Combining gas and electric adds a lot of weight to the vehicle. The both drivetrains become less efficient, than they would be in ideal circumstances, because they have to move the other one around, in addition to the vehicle. Honestly, I don't think the numbers add up anyway you shake them. The "micro hybrids" (Prius, etc) that are so popular now really aren't that good, in terms of fuel economy. My 96 Saturn sedan gets the same numbers, because it's lightweight. If I were to add electric to it, that number would go down, and the electric drive's numbers would be compromised... I'd probably spend a ton of money to get back to where I was. 

I decided to build a race car, with a high-power, lightweight, LiPo pack because economy isn't the goal. It's a marketing tool, and the electric drive system up front is clean and neat; plus gives me the ability to go off the deep end with the ICE, without concerns of practicality on the street, because the electric can faithfully pull it around town and in traffic. In truth, it's still adding hundreds of pounds to the car that compromise its mission a bit.

I say do the numbers, and carefully explore the "why" that's propelling you to go this route. If it's purely for economy, you'll likely find that you're losing money. If it's for the experience and knowledge, the question is what is that worth to you?


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## onegreenev (May 18, 2012)

I think the first thing that will need to be known is how much driving would you be doing in reality on a daily basis? In reality I rarely ever go more than 50 miles in a single day. For those days I do need to go further I just get into my gas hog. It is gathering dust rather quickly and rarely ever gets used but it does get used. That is how I did my hybrid. It is just split between two vehicles. Not likely that your little beetle is your only vehicle. because of space constraints you may have a hard time building a hybrid. If you must I would go with the pusher trailer or a trailer with an extra pack of batteries for the days you need to go further. You can actually put in quite a few cells to make a decent distance Bug. Check out Corbin Dunn's Bug. 

http://www.corbinstreehouse.com/blog/category/electric-bug/

http://www.evalbum.com/3665

Many other examples of bugs too. 

My bet is you really don't need a hybrid.


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