Will transverse engine mounting counteract wheelstand in a hi-power bike or dragster?

[DasKleineWunder]

For a transverse engine, rear wheel drive bike or dragster.

A revving-up engine engine creates "counter-torque". Not sure if there's a technical name for it.
But it is the torque the engine exerts on its MOUNTS opposing the direction of rotation.
It can clearly be seen while revving-up the engine with the hood open in a car with worn mounts.
It can also be seen on how Top Fuel dragsters load one rear wheel more than the other during launch, usually also leaning to that side.

Will this counter-torque reduce or eliminate wheelstand?
Of course engine must be mounted so that its rotation direction lowers the car nose.

 

[Tmoose]

Some reasonable (and some unreasonable as well) points and pictures here.

http://www.jalopyjournal.com/forum/showthread.php?t=813228&highlight=sidewinder

 

[GregLocock]

Yes, accelerating the crankshaft rotationally will produce an equal and opposite torque on the body.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[TheBlacksmith]

I'm a little fuzzy on this, but someone tried that with a funny car in the late 70's. However, since the drag slicks were designed to flex quite a bit (they didn't call them "wrinkewalls" for nothing) the car pounded the heck out of the tires and the concept was abandoned.

 

[TheBlacksmith]

Sorry, it was John Force and the chain was literally the weak link.

"John Force’s first funny car was a major flop. Not only was "The Night Stalker" a rear engined car, but the engine was mounted sideways. John and Louie Force purchased the Mustang from Jack Chrisman. Chrisman had built the car but never raced it. The car’s weak point was the chain drive. Irwindale starter Larry Sutton was so tired of being hit with chain links, he had John banned from the track. The car had a SOHC 427 Ford to begin with, but a Chrysler Hemi took its place."

 

[pontiacjack]

As Greg said, the acceleration of the engine creates an opposite-direction polar moment (inertial) on the vehicle. Note, however, that the basic torque reaction (not inertial) is totally resolved within the machine. Today's drag vehicles don't accelerate the engine very much during the actual run, due to the advanced state of development of drivelines- high-stall converters (up to around 6,000 RPM) and programmed/staged slipper-clutches.

 

[LionelHutz]

The engine torque driving the wheels and not the torque forces accelerating the engine components cause most of the chassis twist. However, there is an equal and opposite torque at the differential. So, solidly join the engine to the differential and the engine torque driving the wheels does not create any twist in the chassis or unequal loading of the wheels. In other words, solidly joining the engine and differential has the same basic result as running a transverse mounted engine. Of course, to do this you either have to run IRS or no rear suspension.

The above was done in the Corvette starting with the C5 in '97 by using a torque tube to solidly connect the front engine to the rear mounted transmission and differential and also running a LSA IRS. The drive train in these Corvettes lifts the front end straight up when accelerating. C5 and C6 Corvettes stay level and straight when drag racing, even when running 800+ HP and 8's in the quarter.

A similar net result is achieved in Top Fuel and Funny cars. The engine and differential are both solidly mounted in a very rigid frame section and there is no suspension. You may see the chassis flexing on these cars, but the section mounting the engine and diff is not.

 

[LionelHutz]

I posted too quickly only addressing your points about the chassis rolling to one side and not if turning the engine would eliminate wheel stands. Any roll over to one side you see in top fuel is due to the engine and connected parts accelerating. You can see it there because those engines accelerate so quickly coming off the line. However, the force causing that roll over is gone once the engine hits it's high rpm power band and the clutch starts to work accelerating the car. So, it might help a bit coming off the line but I would suspect most of the force due to the engine accelerating would be gone very quickly, likely in well under a second.

 

[Tmoose]

Funny car data from sometime in the 2000s

http://www.horsepowermonster.com/wp-content/uploads/2009/01/craftgraph.pdf

red trace is engine rpm. Max engine in rpm in less than 1/4 second.

 

[Pancholin]

Since the lowest point of the vehicle is the ground and everything else is above the ground, the weight shift will occur. Front wheel drive included. Engine rotation may try to bend the frame but weight transfer will still occur.

 

[NormPeterson]

Rearward load transfer always happens. It sounds like OP wants to know if transversely mounting the engine can use acceleration of specifically the engine + flywheel rotational inertias to offset any of it by causing a moment in the opposite sense to exist.


Norm

 

[LionelHutz]

I thought he was asking if the output torque of the engine would push the front of the dragster down.

The force caused by accelerating a few pounds of rotating mass in the engine won't counter the 1000's of ft-lbs of torque at the axle shaft that is trying to rotate the front of the vehicle into the air.