Can't believe someone would try this ?

[Draggon]

Yea, but the freight train and showboat had a purpose. Those others, not so much....

[Harry P.]

Yeah

How were these engines hooked together and synchronized, and how were they connected to the rear axle?

[Ace-Garageguy]

How were these engines hooked together and synchronized, and how were they connected to the rear axle?

Notice the positions of the distributors. The front engines are installed facing the normal way, while the rear engines are installed backwards. The left and right pairs of engines are mechanically coupled at the flywheel end, and a transfer case takes the output to the center of the car (and apparently only one clutch). Driveshafts run to front and rear differentials much like in a conventional 4-wheel drive vehicle.

Ivo's 4 Buick-engined Showboat used two engines on one side facing the normal way, and two on the other side installed backwards. The flywheel end of the front engine of the forward-facing pair was mechanically connected to the nose of the other engine in the pair, and a flywheel / clutch assembly connected it to an offset driveshaft running to an offset Halibrand champ-car quick-change center section in an otherwise conventional axle.

The rear-facing pair of engines in the Ivo car were connected together the same way, but drove a heavily modified 4WD truck front axle, again with an offset Halibrand QC center.

Engine synchronization is achieved by very careful setup of the mechanical throttle linkage.

Edited October 22, 2014 by Ace-Garageguy

[Harry P.]

So was all of that fancy engineering (and the weight of the extra engines) actually worth the bother... or was it more a sense of "look at what we did?"

In other words, we did it because we can, not because it makes any mechanical sense?

BTW... how did one clutch pedal connect to four separate engines? Was the clutch system hydraulic?

[Ace-Garageguy]

The 4-engined drag cars were really too heavy to run as quick as some single-engined cars, and were primarily built for exhibitions. The 4-engine Mustang was supposedly capable of 7 second passes, but there's no documentation to back it up. Ivo's Showboat was insanely impressive, smoking all 4 tires, but it wasn't a real "race" car,

Some of the two-engined cars WERE fast and quick enough to make it worth the extra weight and complication...but only until engine development made it possible to get as much power from one engine.

Thompson's Challenger used 4 separate 3-speed LaSalle transmissions as well, all shifted together by some incredibly complex mechanical linkage. At the time, since the Challenger was built for maximum terminal velocity at the expense of acceleration, it was worth the extra complexity. His son's car though (rebuilt from Mickey's Challenger 2), only uses two engines. More power, less weight, lower frontal area. Much-reduced frontal area = vastly reduced drag, so a lot less power is required to go faster.

It would certainly be the most logical to use hydraulic clutch linkage on any multi-clutch car, but I honestly don't know if Showboat and Challenger used hydraulics. The technology certainly existed at the time.

Edited October 22, 2014 by Ace-Garageguy

[Harry P.]

I can't imagine a mechanical clutch linkage operating four engines simultaneously. It would almost have to have been hydraulic.

Crazy stuff.

[Ace-Garageguy]

It wouldn't be all that hard to do it with cables and pulleys, really. But you should see the shifter linkage for the 4 transmissions in Challenger 1. That IS crazy stuff.

Edited October 22, 2014 by Ace-Garageguy

[Greg Myers]

From Hot Rod Magazine http://www.highperformancepontiac.com/features/hppp_0905_1959_mickey_thompson_pontiac_challenger_i/clutches.html

[Ace-Garageguy]

Interesting photo Greg, and it shows up a lot in Challenger-related articles, but that was not the final configuration of the Challenger 1 driveline.

The as-raced versions had two Pontiacs mounted backwards in front of the car, each one driving through a conventional clutch, 3-speed 1937 LaSalle gearbox, and a Cyclone quick-change rear gear carrier. Same layout at the rear of the car, but the engines were mounted facing forwards in the usual manner. EACH engine had its own 3-speed gearbox and QC rear. 4 clutches, 4 transmissions, 4 QC rear ends.