Synchronizing Two Motors?

[donpearsall]

While at BMST this season a builder brought his twin-engine streamliner to display. It had two bone stock Hayabusa engines connected via a chain drive. The two throttles, clutches, and gear shift mechanisms were also connected into the cockpit and controlled with the typical hand controls. I questioned what he did to synchronize the two engines so they were not fighting each other. He said nothing needs to be done. Is that right? I know that two engines have minutely different engine speed and power output just because of the small differences in the way they act. But intuitively it seems to me like the engine that runs faster at the same throttle setting will be driving the other engine, and thus the power output is not twice the output of one.

What needs to be done to synchronize the engines so they are working together instead of against each other? Anything? Any special drivetrain to connect them like a differential?

Thanks
Don

[Seldom Seen Slim]

Ask Jim Knapp how he harnessed THREE Suzuki 1,000 cc bike motors to make the Barnyard Bearcat go 300. It's doable.

[RichFox]

Next time you see a freight train go by, think about what is happening

[Stainless1]

Don, I would guess you don't get double... but you get close.... it may seem 1 engine is working harder than the other because it is, but they are not fighting each other, they are working together. 
If the crankshafts are solidly attached to each other you may have some synchronizing issue but that is not the case with most multi-engine vehicles.

[wobblywalrus]

Both engines are 4 cylinder which have smoother power delivery than twins or singles.  Both have some shock absorbing capability in their clutches and this helps isolate each engine from the other.  Both have their own clutch and tranny so the only doubled power is applied at the final drive.  A lot of double engine setups in the past have not had these features and they often were problematic.   

[SPARKY]

I would do nothing----just let them put out what they can

[floydjer]

Running 2 or more engines into a common shaft it almost seems logical to phase them so that the power impulses are evenly spaced/timed to the shaft. Two 4 cyl. would be timed 90 degrees apart  ( fours fire every 180 degrees) and the shaft would then "see" power impulses  spaced the same as a V-8.  And if you really want your head to hurt...The Lycoming V-8 used in the 810/812 Cord fired the entire right bank first, Then the left bank.

[BHR301]

Floydjer, in the 60's we tried timing our dragster twins as a V8, and as a V16 and at times just hooked them up as they were when we put the engine in the car...found no difference in performance...we settled on V16 as it sounded to damn good on the strip.  

[Crackerman]

Next time you see a freight train go by, think about what is happening

Diesel electric locomotion? If I am not mistaken, any engine running in a train is a powerplant for a large generator, and it drives electric traction motors.

Unless, it is a smaller pup locomotive for moving cars around the yard?

[floydjer]

Someone call Tommy Ivo and get him to chime in But I do wonder what the guys running multi-Harley drag bikes do ?  180 apart or maybe "lead" the front engine a few degrees?

[edjboard]

I worked on train engines for 10 years,with multi hookups a large umbilical cord between each engine makes them run together even if cars are there and engine are in the middle or on rear,and locomotive go just as fast in reverse as  forward

[Rex Schimmer]

About 7 or 8 years ago JimL on this site put together a twin engine bike using Honda 650 vee twins. He built a beautiful adapter plate that utilized gears to connect the engines. The very first time he fired it the connecting gear train self destructed, which was a heart breaker for Jim and all of us that were following the build. He reacted quickly and was able to chain the engines together and run the bike. His build is worth reading especially when he talks about the gear train failure. http://www.landracing.com/forum/index.php/topic,7416.0.html 

Rex

[Vinsky]

Ack Attack has two turbocharged Hayabusas with two transmissions. And it works well.

[RichFox]

Worked OK for Danny this year Too.

[racergeo]

  A brief clarification about RichFox's freight train comment. He simply forgot to capitalize. The Freight Train was one of the the greatest two engine dragsters I've ever seen. Probably one of the most winning cars ever built. Two SB Chevys that ran with numerous drivers and different configurations during the 50's, 60's and I think with Hemis in the 70's. Hopefully I'll see it in a few weeks at Hot Rod reunion.