Two engines, One kart

[CoyCaller]

I was just wondering....
How do you get two engines to run close enough to the same rpms, to run them together?

Does the weaker engine and the stronger just average out?

Does the hp double or does it produce a higher hp then the sum of the rated power of each engine added together? (5hp+5hp=10hp or more?+)

Can you build a manifold made for a larger engine to feed 2 smaller engines?

Sorry for all the questions but this interests me.

 

[1992suburban]

I would think that the weak engine would pull down the strong..

it will not run any faster TOPEND with TWO motors then it would with 1. unless you take advantage of the extra power and change gearing..

example. 1 motor turning 5700 with a 5:1 ratio turning a 11" tire will run about 36mph
2 motors will do the same but get there FASTER
but you may be able to drop gearing to 4:1 with 2 motors and gain topend?


I would try and get the linkages as close as possible
run a tack on each motor sync up the rpms.. as close as possible

I am sure others will chime in..

 

[ckelp]

i agree with the guy above i'd try to sync the engines so there cycles are 180 out (one just starting the power stoke and the other is starting the intake stroke..

i'm i considered an "other" because i chimed in?

 

[Kaptain Krunch]

You could never get them to stay 180 out, every time you start them it would change, unless the engines were physically linked together.

 

[Russ2251]

Can you say 'self synchronizing'?
I cannot explain it...but it does indeed happen, consistently!!!

 

[1992suburban]

i think it will still be 5hp..

 

[Russ2251]

Actually it doubles.

 

[1992suburban]

why do you want 2 motors??

 

[Russ2251]

why do you want 2 motors??

Unless experienced, it cannot be described.
I wish I had done it years ago. Just slightly more complex and requires patience when adjusting carbs/linkage.

 

[1992suburban]

i would rather have 1 motor making 10hp then 2 5hp ones.

JMO

 

[Russ2251]

I'd rather have 2 10's.

 

[1992suburban]

yeah.. you right!!!

 

[Russ2251]

Seriously...I had two 7hp Briggs flattys that I wanted to use, but footprint was too big for kart.
I opted for two 2 cycles instead. Advertised hp was 6.5 each, but with some mods are probably closer to 7.5 or 8 each, or 15-16 total.
One 7hp Briggs 4 cycle is about 2 thirds the weight of two 2 cycles.

 

[brendonv]

U dont double the hp but (in theory) it has double the acceleration. Once u start both engines they will start to self synchronize as when u go they will both be running on the same shaft and therefore have to eventually run the same. U cant run them 180 out unless u weld the two shafts together so u make urself a twin engine. If u got the patients to tune em correctly and blah blah blah then twins are awesome but im not that patient, i would rather one 10hp.

 

[Russ2251]

U dont double the hp but

Hp is indeed doubled, hence increased acceleration. High school physics.

 

[Kaptain Krunch]

U dont double the hp but (in theory) it has double the acceleration. Once u start both engines they will start to self synchronize as when u go they will both be running on the same shaft and therefore have to eventually run the same. U cant run them 180 out unless u weld the two shafts together so u make urself a twin engine. If u got the patients to tune em correctly and blah blah blah then twins are awesome but im not that patient, i would rather one 10hp.

HP is definitely doubled, where would it go if it wasn't? and if my thinking is correct, a twin 5hp engine kart with two centrifugal clutches (one per engine)would have better acceleration than a single 10hp engined kart.

 

[anderkart]

if my thinking is correct, a twin 5hp engine kart with two centrifugal clutches (one per engine)would have better acceleration than a single 10hp engined kart.

That makes sense to me too, especially if higher quality clutches were used. Lots of people seem to buy the cheapest centrifugal clutch avalible and then they're all disappointed when it doesnt seem to preform/hold up very well.

 

[oscaryu1]

Run them both to one carburetor?