I have one, it goes something like this.
Take two offset-shaft-drive three-cylinder bike drivetrains. Mount side-by-side, longitudinally.
Have one engine drive each rear wheel though some simple gears. No differential.
Somehow link the two shifters together. Or better yet, did anyone make a decent small CVT in the right orientation?
Install in middle of VW chassis, or build a tube frame. Attach crazy late-'70s kit car body.
...
Profit?
What do you guys think? I'll probably never do it, but is it doable? Two fully-independent engines seems like the ultimate way to avoid the drawbacks of every type of differential. You could maybe have them share carbs to simplify the throttle linkage, but that's it. Talk me down now before this idea worms its way into my brain any further.
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Oct. 6, 2009 9:11 a.m. Jay Dork
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Oct. 6, 2009 9:14 a.m. aussiesmg SuperDork
As for the thread title, head to Gainesville to see about 100 such ideas
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Oct. 6, 2009 9:26 a.m. 914Driver SuperDork
Sounds like a lot of work that is prone to fail. Look at a design that's been worked out, like Legend or Dwarf with a short driveshaft.
What you propose is a horizontal 6 cylinder with no reverse, look at modding a FWD anything.
There's gotta be better things keeping you awake at night....
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Oct. 6, 2009 9:27 a.m. Ian F HalfDork
or take one VW and install two complete engine/transmissions in it... rig up a shifter and throttle to operate both at the same time... and leave the driveway....
berkeleying sideways..
http://www.durocco.com/index.html
(I kinda miss the original build story that seems to be gone from the site... that was some fun readin'
)
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Oct. 6, 2009 9:49 a.m. foxtrapper SuperDork
Aw heck, I think it's an interesting idea that you should pursue. I especially like the idea of the common carburetor for synchronization.
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Oct. 6, 2009 9:56 a.m. walterj Dork
It is a bad idea that is doomed to fail... like placing the engine behind the rear axle of a sports car.
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Oct. 6, 2009 10:00 a.m. Jay Dork
I took the liberty of making a diagram in case my original description was infused with too much awesome-stupid (awepid? stusome?) to be clear.
Keep in mind this is a totally 100% accurate schematic of what the final product would look like. (Note: the previous statement is not by any means true.)
So what engine/drivetrain should I hypothetically use? The more I think about this (which I really shouldn't be, now should I?) the more I like the 2xCVT idea, but that would probably rule out two complete bike drivetrains. Snowmobile? ATV? Anything in the size/weight/power ratio you'd need for this?
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Oct. 6, 2009 10:04 a.m. 914Driver SuperDork
How do you get both engines revving and on power at the same time. Throttle steer if one is quicker or just stumbles.
Dan
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Oct. 6, 2009 10:06 a.m. Autolex HalfDork
man! I thought I was crazy for wanting to put a massive turbo on the new 3.6L H6 in the new subarus and drop it in a 2000ish 2.5RS Body!
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Oct. 6, 2009 10:15 a.m. poopshovel SuperDork
You don't have a hair on your balls if you use anything less than 1 motor for each wheel.
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Oct. 6, 2009 10:18 a.m. aussiesmg SuperDork
Is that why all motorcyclists have hairless nads, Bob Costas
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Oct. 6, 2009 10:19 a.m. walterj Dork
I propose you do something like this... allowing the small wheel to pivot and using the engines for direction change as well as power.
EDIT: in-fact, move the pivot wheel behind the engines...
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Oct. 6, 2009 10:34 a.m. Gearheadotaku Reader
Shouldn't that be 2 Miata engines?
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Oct. 6, 2009 10:48 a.m. scardeal New Reader
I had that bad idea once... you just reminded me of it. It just seems too complicated to me...
You'd have to figure a way to adjust the two engines' throttle positions based on steering wheel angle. Not easy mechanically. Very difficult electronically.
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Oct. 6, 2009 11:02 a.m. slantvaliant HalfDork
Will it all fit in a Berkely body?
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Oct. 6, 2009 11:02 a.m. Jay Dork
scardeal wrote:
I had that bad idea once... you just reminded me of it. It just seems too complicated to me...
You'd have to figure a way to adjust the two engines' throttle positions based on steering wheel angle. Not easy mechanically. Very difficult electronically.
I don't think you would. That's the whole reason for not coupling the left & right drivetrains in any way. As you go around a corner, the inside wheel/engine will either bog or spin, depending on traction, just like an open diff in a normal car. Meanwhile the outside wheel will keep putting the powah down. There's no tradeoff. Unwanted throttle-steer would be kept in check by having both engines attached to CVTs, so that they're always in the same part of the powerband.
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Oct. 6, 2009 11:07 a.m. 2002maniac Reader
Sounds like a great idea! Just think up a way to make it FWD!
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Oct. 6, 2009 11:09 a.m. MrJoshua SuperDork
This is done. In fact I think the crazy mini swap company has one. There is also a thread somewhere out there with a crazy aussie race series that uses bike motors where some of the cars have 2 motors. They all mount them parallel to the axles with some sort of belt or chain drive. The problem with no diff is if you break a tire loose you bounce off of the rev limiter for that engine. A really soft viscous limited slip joining the halfshafts would encourage the rpm to stay somewhere in the same vicinity.
My evil idea was to do the same type of thing but aim one motor forward and one backwards with driveshafts connecting to diffs for crackhead 4wd. The problem I found (for me of minimal fab skills) was that little 4wd cars almost never have a front diff.
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Oct. 6, 2009 11:46 a.m. Ian F HalfDork
MrJoshua wrote: My evil idea was to do the same type of thing but aim one motor forward and one backwards with driveshafts connecting to diffs for crackhead 4wd.
When I first read the thread, this was what I was thinking as well... have the engines side-by-side with the exhausts outboard. Synchronize the engines by simply running them both off the same intake and throttle body. Sort of like a "V" engine without being connected... in other words: "I I"
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Oct. 6, 2009 2:42 p.m. Jay Dork
Ian F wrote:
When I first read the thread, this was what I was thinking as well... have the engines side-by-side with the exhausts outboard. Synchronize the engines by simply running them both off the same intake and throttle body. Sort of like a "V" engine without being connected... in other words: "I I"
I like that idea too. The only problem is redirecting the output of the "backwards" engine so it drives a rear wheel, without creating Frankenlinkage from Hell and a huge amount of driveline loss with it. Maybe it would be best to have them transverse, with one pointing left and the other pointing right. Could gain some interior space that way too.
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Oct. 6, 2009 3:51 p.m. Capt Slow Reader
Why not turn both engines 90 degrees and run them off a chain or a belt drive, you could still mate the intakes that way...
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Oct. 6, 2009 3:55 p.m. MrJoshua SuperDork
There is a company that makes a driveshaft flange that slips onto the sprocket output. It is only about $75 and greatly simplifies using a bike motor.
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Oct. 6, 2009 10:48 p.m. mad_machine SuperDork
I would definatly link them with some sort of differntial based clutch. If you don't, the first time you make a tight low speed turn, you are going to stall the engine on the inside wheel
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Oct. 6, 2009 11:53 p.m. NYG95GA SuperDork
I've always wanted to mount a slant six engine midship in a Neon sedan, weld the front doors shut, and drive it from the back seat. Mostly because I have all the raw materials on hand (but not the fabicaton skills).
Talk about a bad idea that will never happen!
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Oct. 7, 2009 9:25 a.m. andrave HalfDork
This is my vote: 1) Nothing less than one engine per driven wheel will do. Motorcycles prove this theory.
2) Only 2 stroke engines qualify. Because this is for great justice.
3) Each engine shall have its own CVT transmission stolen from a fourwheeler. Each CVT transmission shall have its own engine.
4) Throttle control must not be done in anyway that would encourage engines to make the same (or even similar) power levels at the same time. This would negate the ability of multiple engines to thrill and amuse and maim.
4) Throttle control must therefore be done in a way that allows each engine to contribute to handling, cornering, and antics. For more information, see: zero turn lawn mowers, skid steers, bulldozers, and the six wheel max.
5) Front wheels, if deemd necessary, may be mounted on castors for maximum hoon.
