Landracing Forum
Tech Information => Technical Discussion => Topic started by: donpearsall on September 28, 2018, 12:25:41 AM
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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
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Ask Jim Knapp how he harnessed THREE Suzuki 1,000 cc bike motors to make the Barnyard Bearcat go 300. It's doable.
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Next time you see a freight train go by, think about what is happening
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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.
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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.
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I would do nothing----just let them put out what they can
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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.
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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. :-)
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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?
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Someone call Tommy Ivo and get him to chime in :cheers: But I do wonder what the guys running multi-Harley drag bikes do ? 180 apart or maybe "lead" the front engine a few degrees?
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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
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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
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Ack Attack has two turbocharged Hayabusas with two transmissions. And it works well.
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Worked OK for Danny this year Too.
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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.
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Somewhere on a two-engine setup the torque will be doubled. That is a weakness when two engines are linked to one clutch, primary drive, or transmission and any of the three are designed for one motor. It is easiest for the home builder to engineer and design the final drive. In any case it is a good idea to do some calculations when designing the system. The easiest way is to start with a final drive that is proven to work for one engine and to double the strength for two. This provides some added and probably not needed robustness. Any factor of safety in the single engine final drive is also doubled.
The alternative is to calculate the failure strength and safety factor for the double engine final drive. This is difficult to do. The first method is most practical.
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Seems to Rich he was referring to multi-engined railroad freight engines and cars. I see them go by; the Freight Train, not so much.
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The Odd Couple was a good demonstration of two engines of different potential working well together. As well as the Bustle Bomb. Really not much difference between an eight cylinder engine and two four cylinder engines. Not all eight holes are putting out the same amount of effort. But it all adds up. If you had a tug of war and your side had some big strong guys and some less so, They all do what they can.
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Don't think the 777 Kenz and Leslie streamliner synced its 3 flatheads back in the 50's :cheers:
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Oops, my bad. On my comment to Rich I left out :wink: :evil: :lol: :-) :-D and also WTF
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The ground sinks up everything together. :-D
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Rich, the Odd Couple was the dual engine car I was thinking about when someone mentioned gear driven. Doesn't the coupler have to be forgiving because of the difference in crank twisting. Something like a chain with lots of backlash. I would think gears would bind things up. Or am I thinking too much??
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The only twin I was ever involved with used a Mark Williams splined coupler. It was not a really snug fit. But didn't have lots of slop. I would not call it "forgiving".
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I originally started building my liner with two engines using Greek Couplers then changed the design to just one AA.
In the Herbert-Steen 4 engine liner the front pair are facing backwards driving the front trans & diff. The rear pair are facing forward driving the rear trans & diff & there are clutches before the trans inputs. The engine pairs are coupled with chain sprockets on each with a double row chain being the link. Between the center two engines is a reverser box to hook it all together. Engines are 500" Rodeck's. It is unlikely it will ever run again.
Sid.
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Excellent article re; The Bustle Bomb in Hot Rod a few mo.`s ago...Talk about a combo one would not think would work , But did...And rather well