Individual wheel drive (two rear motors)

[Mydogisshaggy]

Let's face it, it's 2023.... The biggest baddest cars, some with total full interior are pushing 1500-2500 horsepower... Factory vehicles making 800+... Where is it heading? Well you could think there's limits, or electric, well. Then there's me. Always a mile outside the box....

First kind of unrelated but something I've been thinking about a lot lately , aerodynamics has come a long way and been a big focus for decades now but often neglected or ignored because it can make vehicles not as beautiful to some, understandable. I think obviously besides wind tunnels and lots of R&D , Aircraft are often looked at for inspiration or downright copying because well, no one knows better. But what people ignore (in my opinion) is thrust/exhaust back pressure as a means to push the vehicle forward that ever so .05 seconds faster... But back to my main point of this post... The end for power/aero/ faster times on a heavier vehicle will almost certainly never stop (at least for some) while that's not me, I don't like a good idea go to waste...and really it's nothing new or totally unheard of, just something nobody would be willing to try or think about readily. So my idea was after seeing a turbo Harley motor do 220hp ,I wondered if I had two of those , one powering each wheel, it would be like 400DRhp but maybe less losses, I have ideas to join 2 8.8 rear ends and use a short axle between the two differentials to balance the difference of tire spin.

Which led me to believe well using a f250 frame, with two smaller motors in the rear(because my budget) if successful though it's possibly why not two coyote motors , each making 1500+ HP per wheel..... , With a turbo system thats intertwined ? Even. Making things take up less space overall... Any thoughts.

 

[Mydogisshaggy]

Two driveshafts two pumpkins, cut the one side axle and weld them together with like 2 feet or so in in between them where the axle with two spline ends would sit connecting the inner spider gears. The fuel take would have to go in the front (no longer engine ) bay.

Does this mean one motor could have one ginermous intake ? V-16 power !!!

 

[aussie7mains]

1500bhp would completely overwhelm the traction of one wheel, even if it was heavily weighted.

 

[pmuller9]

The present-day thinking is to eliminate transmissions and rear ends and is the reason why electric motors are placed directly at each wheel.
Each transmission and rear end represents at least three things.
A power loss
Weight
A point of failure

Adding an additional transmission and rear end is the wrong direction.

Same with multiple engines.
It is lighter and less complex to make 3000 hp with a single 632 cu in engine than with two engines at half the displacement.

The only time I have considered two engines is when I was approached about competing in the hydroplane unlimited class of boat racing that uses a T55-L7 turbine engine that produces 3000 hp and weighs about 600 lbs
For the sake of longevity, I would have needed two V8 engines that produce over 1500 hp each on Methanol.
But here again, two V8s are much heavier and take up more room than the single turbine engine.

 

[Mydogisshaggy]

The present-day thinking is to eliminate transmissions and rear ends and is the reason why electric motors are placed directly at each wheel.
Each transmission and rear end represents at least three things.
A power loss
Weight
A point of failure

Adding an additional transmission and rear end is the wrong direction.

Same with multiple engines.
It is lighter and less complex to make 3000 hp with a single 632 cu in engine than with two engines at half the displacement.

The only time I have considered two engines is when I was approached about competing in the hydroplane unlimited class of boat racing that uses a T55-L7 turbine engine that produces 3000 hp and weighs about 600 lbs
For the sake of longevity, I would have needed two V8 engines that produce over 1500 hp each on Methanol.
But here again, two V8s are much heavier and take up more room than the single turbine engine.

My first thought was transverse or smaller motors and no transmission or driveshaft but I'm not as familiar with fwd axles and all that... While you might be right for production vehicles, they don't make 1500hp per wheel.... So I think 2 transmission handling 1000 per wheel vs 1 transmission handling 2000+ . Is possibly better. Maybe even only 2 gears like power glides. To be continued

 

[pmuller9]

While you might be right for production vehicles, they don't make 1500hp per wheel.... So I think 2 transmission handling 1000 per wheel vs 1 transmission handling 2000+ . Is possibly better. Maybe even only 2 gears like power glides. To be continued

Production vehicles may not make 1500 hp per wheel, but some power tour vehicles that have to travel 1000 miles on public roads do.

There are many aftermarket transmissions that have no problem handling 3000+ hp
The only time you can apply that much torque to the wheels is on a well prepped racetrack.
Most public road surfaces are lucky to support 600 hp.

Secondly, an automatic transmission contributes to a very substantial loss in power to the rear wheel under acceleration.
Adding another transmission adds a lot to that power loss and also adds a lot a weight to the vehicle.

 

[pmuller9]

Let's say you still want to put two engines and two transmissions in a vehicle with 3000 hp combined power.
Let's also say that peak power is at 7500 rpm.
That would equate to 2100 lb ft of torque at that rpm.
The peak torque will probably be back at 5500 and be as high as 2500 lb ft.

The 1st gear overall ratio including the rear end gearing is around 10:1.
Not accounting for any losses, the torque on the rear axles is 25,000 lb ft.
If you have a 20% reduction for drivetrain losses, the axle torque is still 20,000 lb ft.

You would need one of the aftermarket rear ends designed for that power level.
We used Mark Williams rear end assemblies for drag racing at that power level but we didn't need a differential and just use a solid spool.

 

[pmuller9]

What I want you to conclude from the previous posts is that, if you want to use multiple engines it is best if they are coupled together before there is any torque multiplication rather than at the rear end where the torque is at maximum.
The coupling should be done just after the crankshafts, before the transmission.
The gearbox used for coupling will be handling the minimum torque and only one transmission is needed.

A lot of the unlimited modified tractor pullers use 4 engines making around 2500 hp each and are geared together after the centrifugal clutches and then to a single planetary rear end.

 

[benchracer]

how about 2 300s running generators and Tesla electric motors (hybrids) drive people crazy? no gear problems