Could a Bike Motor Work in a Performance Green Car?

BillS

I'm not a bike guy, but maybe some of you can help out. If a bike can make 175 hp (?), and a bike weighs 700 lb with rider (?), could that motor be used to create a 1200 lb (1400 with driver) car? If so it would seem to be pretty fast (a Mini S has about that power and twice the weight and is fast enough to be fun)? How efficient are these motors (gas mileage)?

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0tto

Probably wouldn't get as good of gas milage as you'd think. While motorcycle engines make incredible horsepower numbers for their size, they are weak as far as torque goes. They make up for this with light weight and short gearing. In a car the weight factor would be gone, and you'd be left pulling high RPM's on the highway. Those 175hp motors you refered to would have to be 1-liter or larger, most likely from a super-sport bike, which aren't exactly stellar fuel misers to begin with.

If you want to see what it'd look like a number of people have put Hayabusa motors in a Smart ForTwo, pretty crazy: http://www.youtube.com/watch?v=45i_YsSv3bE

Fri, 07/04/2008 - 00:53
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BillS

Thanks 0tto. Bike specs are harder to find than cars specs, but I found this for the Kawasaki Ninja ZX-14:

113 lb-ft torque at 7500 rpm

35 mpg

475 lb.

175 hp?

I see that the mpg isn't so hot.

Fri, 07/04/2008 - 09:18
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0tto

Yeah, but it would be a lot of fun. =D

Fri, 07/04/2008 - 11:54
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BillS

Are there more efficient engines if I looked at something that is less of a screamer? Could I get more torque if I didn't go for max power? I mean a Lotus makes 140 lbft of torque and something like 180 hp and weighs 2000 lb and gets 23 mpg. So is there a bike motor that makes 100 lb ft and 125 hp?

Fri, 07/04/2008 - 12:57
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Mena

Just use a car motor. You'll get more torque at a more reasonable rpm. The base motor on an Ariel Atom (1400 lb car) is a GM Ecotec 4 putting out 145 hp and 155 lb-ft of torque. That engine gets 25/36 in a 2600 lb Cobalt. I'd imagine a much lighter car will do better than that. I've read that even the supercharged 300 hp versions still get 30 mpg.

Mon, 07/07/2008 - 12:30
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BillS

Yeah, you're probably right. I was hoping that a bike motor would weigh less but give decent power. But bike motors seem to be inefficient. 25/36 would be fine in my view; I wanted the light weight for performance (but in a real car, not an Ariel or Caterham).

Mon, 07/07/2008 - 16:24
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Mena

"I wanted the light weight for performance (but in a real car, not an Ariel or Caterham)"

I understand. You could always get a 92 Civic hatch and swap in a 160hp Honda K20A3 engine from a 2002 Civic Si. A 92 Civic weighs under 2300 lbs. You'll need an aftermarket header and exhaust but otherwise leave the engine stock. The 02 Civic Si engine gets 26/30 in a 2700 lb car.

Tue, 07/08/2008 - 00:20
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tbmshark

1150 lbs, 500bhp from what is essentially two blown bike motors on one crankshaft:

http://www.nextautos.com/aftermarket/caterhams-rst-v8-packs-v-8-ungodly-...

Yes, it can work

Mon, 07/07/2008 - 12:56
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BillS

Very cool, but not exactly green?

Mon, 07/07/2008 - 16:25
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CMartens

I have often wondered if it might be possible to use the 1,832cc flat six boxer engine from the Honda Goldwing, complete with shaft drive assembly, as the core platform for a high mileage, high fun factor, modern day update of the classic Morgan three-wheeler (two wheels up front, one out back)

At first glance, the Goldwing motor might seem to be an underachiever (118bhp, 125lb./ft. of torque), but I believe it is capable of much more output, is just spooky smooth, and anvil strong. Also, it was born to haul around a pretty heavy vehicle in the first place (Goldwings weight about 900 lbs., I think), so that the jump up to a small two-seater car shouldn't be too hard to handle.

Yet another compelling piece of the puzzle is that the Goldwing drivetrain includes an already-developed beefy transmission and a slick and simple single-sided swingarm with built-in shaft drive. So, it doesn't take a whole lot of imagination to picture bolting the Goldwing drivetrain into a low, light, sleek "seating platform/front suspension" assembly of some kind. Thanks to the Goldwing engine's boxer layout, the CG would be wonderfully low, as well.

I think it could yield a highly entertaining, "green" vehicle. Thoughts?