Horsepower at the wheel

flatus

Active Member
I was looking on the web at some of the R&D projects the military are doing in all electric vehicles. I was interested in the designs that have an electric motor at each wheel -- this allows the vehicles to have a much lower center of gravity and a lot more freedom in designing the suspension.

So, of course, I started wondering what someone could do for a monster truck with a similar approach. However, the electric motors used in these vehicles are about 140hp each. 560 hp is a far cry from the 1500+ hp engines currently in use. But how much of that 1500 hp is actually translated to the wheels?

I'm sure there would be a ton of other technical reasons this wouldn't be practical. But I don't know enough about mechanics to get a feel for how much horsepower would be needed to get equivalent performance. Any ideas?
 

Brandon Clark

Benchracer Extraordinaire
Nobody really knows how much power is made to the wheels. Cause alot of it is lost between the tranny, transfer case, rear end, planetaires etc. etc.

the biggest problem is, nobody even knows the exact numbers taht their engines are putting out, since no one ever engine dynos a monster truck motor.

why not? why would you? most teams jsut dont bother with it, and nobody really knows their exact horsepower, its always just a very estimated guess based on air/fuel ratios, blower overdrive, and altitude.

as long s the truck has enough to get it moving and off the ground, i really dont see where it matters.
 

flatus

Active Member
It doesn't matter. I was just wondering if anyone had a guesstimate, thats all.

I'm just playing around with ideas in my head about how one could make a 'better' monster truck. This is one of the articles that I read that got me thinking about the horsepower thing.
http://www.designnews.com/article/CA6358116.html

by the curtness of you response I take it I hit some sort of sore spot? hopefully you can relax and see i have no ill intentions in the questions I asked.
 

71m07hySm17h

Well-Known Member
Of course it's not a bad question at all but the real problem with that, like Bowtie Bandit said, is they don't necessarily need to do any of that. Not much innovation has went into monsters since the popularity of freestyle. If a real racing series took off a lot more innovations would occur. But again, a very tough electric engine right now puts out about 300 horsepower, so the truck would still be down on power. We'd need more time for the invention of more powerful electric engines, until the situation calls for it. Also, the complication, plus the equipment. I don't know much about electric motors, and it may just be plug-n-go, but it really doesn't sound as such. Just like independent suspension, electric motors need to get a racing series and better technology under their belt. Sure would be neat to see, however.
 

KD58

Well-Known Member
I would say the biggest thing standing in the way would be practicality and ease of maintenance. While a blown motor of any kind isn't exactly practical or easy to maintain, they are far more likely to perform reliably in inclement weather than electric motors are. The axles of a monster truck take the brunt of the abuse while on track, and that abuse comes not only in the form of jumps and bumps, but also in the form of water, mud, oil, dust, etc. I think that keeping these units sealed and cooled off would be quite the challenge.

Not only that, but part of a monster truck's classic appeal is the noise. You simply won't generate that with electric motors. I just don't see electric race vehicles becoming a mainstream entertainment comodity until fossil and alternative fuel sources have been exhausted. Loud noises inspire the "fight or flight" hormone trigger in people's bodies...that's part of what makes racing so exciting on an elemental level. The noise is as critical as what's actually happening on track in many cases.

-kd
 

Sinister '32

Well-Known Member
My biggest concerns with electric drives have always been weight and packaging. In the case of the HEMTT featured in the linked article, they ditched the drivetrain and put large AC motors on each differential. Realize the HEMTT has fully independent suspension so it was easier (though not easy, I'm sure) to package that setup since the diff is mounted up in the chassis. Adding one of those motors to an axle on a live axle MT would be a packaging nightmare and would add a ton (Quite literally) of unsprung weight. As Kyle wisely points out, the axles on MT's, as we know them today, take alot of abuse. Hanging a big motor off of the diff would leave it in a VERY vulnerable location. Also realize that the HEMTT's motors are liquid cooled so using a similar motor would mean running cooling lines down to the axles! Huge potential for failure there.

Now, if you were thinking of doing something with independent suspension, like what the HEMTT has, then possibly there would be merit. But you would still have the weight of the motors, capacitors or batteries, and generator(s) which are still usually heavier than a mechanical drive system of equivalent capacity, given today's technology. That may change in the future but it could be a while.

Having individual motors right at the wheels themelves would possibly solve some of the packaging and vulnerability issues but I have not seen anything small enough to package that way and still provide the torque these things need.

Now one possible concept that might be easier to do on an MT would be hydraulic drive. I've been considering this since high school when I worked for a Caterpillar dealer. Lots of agriculural and earth moving equipment have these kinds of setups already. And the hydraulic motors are right at the hub, not much weight difference, if any, than a planetary hub. Plus you don't have a differential or axle shafts so there's weight gained there. This system can be ran from an engine driven pump up in the chassis, no tranny, transfer case or drive shafts and no heavy generators or batteries to deal with. It would also have endless possiblities in terms of controls and would package well with alternative suspension designs.
 

tromoly

Well-Known Member
Now one possible concept that might be easier to do on an MT would be hydraulic drive. I've been considering this since high school when I worked for a Caterpillar dealer. Lots of agriculural and earth moving equipment have these kinds of setups already. And the hydraulic motors are right at the hub, not much weight difference, if any, than a planetary hub. Plus you don't have a differential or axle shafts so there's weight gained there. This system can be ran from an engine driven pump up in the chassis, no tranny, transfer case or drive shafts and no heavy generators or batteries to deal with. It would also have endless possiblities in terms of controls and would package well with alternative suspension designs.
I agree wholeheartedly with that thought, it would be an excellent idea and I have also thought about using hydrostatic drive in vehicles. The main thing I saw a few years ago (and I may be wrong) is that the motors do not have a very high top speed (35-45 mph or whatever in revolutions/minute), which is one of the reasons I gave up on the idea; with advances in technology I'm sure the motors are more powerful now, that would be a sight to see on an MT in the near future.
 

Sinister '32

Well-Known Member
...The main thing I saw a few years ago (and I may be wrong) is that the motors do not have a very high top speed (35-45 mph or whatever in revolutions/minute), which is one of the reasons I gave up on the idea...
I agree that's a concern as well. But then again, what kind of RPM's are Clarks, Pettibones, and ZF's "rated" for ;).
 

flatus

Active Member
Now one possible concept that might be easier to do on an MT would be hydraulic drive. I've been considering this since high school when I worked for a Caterpillar dealer. Lots of agriculural and earth moving equipment have these kinds of setups already. And the hydraulic motors are right at the hub, not much weight difference, if any, than a planetary hub. Plus you don't have a differential or axle shafts so there's weight gained there. This system can be ran from an engine driven pump up in the chassis, no tranny, transfer case or drive shafts and no heavy generators or batteries to deal with. It would also have endless possiblities in terms of controls and would package well with alternative suspension designs.
Hmm, thats an interesting idea. how does the size of the engine/pump compare to a regular engine?
 

KD58

Well-Known Member
Great point Scott. Not only those parts, but consider as well that the tires from Goodyear and Firestone are only rated at 35mph or something along those lines. Pushing beyond the limits of factory ratings is one of the Monster Truck industry's Ten Commandments.

But as fun as it is to discuss electric motors and things of that nature being used in an MT application, I highly doubt they will ever be used to any extent, if at all. I'm not saying "bah, you're all dumb for talking about it!" but here are a couple points that stand in the way of the idea, IMO:

1.) People are trying to make a living in this sport. It is far easier to take a known combination that works and put it to use than it is to re-invent the wheel, as it were.

2.) Maintenance. Most trucks are under-maintained as it is, so I don't see a high-demand electrical system and its motors getting the love they need after a point.

3.) Wiring. For an idea like this to become commonplace, 96% of the monster truck industry will need to attend a "How to Safely Wire a Vehicle" class.

4.) Cooling. As Scott touched on, cooling would be a major issue. Not only do large electrical motors generate a great amount of heat under normal operating conditions, imagine someone like Dennis Anderson, who is constantly peddaling the truck and jamming the brakes running an electrical motor truck. That's hotter'n liquid fire right there, baby. I see no reliable, user-friendly way to cool these motors.

5.) Custom housings. Most teams are *still* shying away from custom housings for one reason or another. Asking them to abandon the stuff they know and love-to-hate is tough.

6.) Know-how. The first recorded instance of a man finding affection for a combustion engine dates back to the early days of Rome. Guys (and some gals) like combustion engines, they know how to work on combustion engines, and they enjoy using combustion engines. As complicated as a combustion engine can be, you still don't have to be a rocket scientist to own/operate one in a "hot rod" situation.

7.) Sex Appeal. I threw this one in here...why not??? There's nothing exotic, romantic, daring, or dangerous about using electrical motors other than the potential for severe electrical shock. A big, bad, and blown alky-snuffing, oil-spitting, fire-crackling, crew-shirt melting, hat-blowing-off, ceiling-insulation-rattling V-8 on the other hand...well....let's just say that a monster truck engine is the redneck sex appeal version of Burt Reynolds in Smokey & The Bandit. Yeah, that's right.


I'm sure I can go on and think about 50 other reasons why it wouldn't work out, but please understand that I'm not putting the idea down....just offering up the devil's advocate point of view. That, and I like combustion engines :)


-kd
 

Demonmt

Well-Known Member
Think on how many batteries it would take to run electric motors or one big extention cord:D And what is the fun of not hearing horsepower??????
 

Sinister '32

Well-Known Member
Hmm, thats an interesting idea. how does the size of the engine/pump compare to a regular engine?
I don't think the pump is overly huge, not much bigger than an automatic tranny. And you could still hook the pump to a big V-8 engine. Look at Santanimal, it was hydraulic driven and used a big block V-8 to drive the pump. Hydraulic drive has been used in at least one motor sports application as well. There was a mud racer called the Black Widow, back in the '80's, that used it. It was basically a VW sand buggy, but the engine also drove a hydraulic pump that fed two motors in the front wheels to make the car all wheel drive instead of just rear wheel drive. This made for very capable mud racer that was still incredibly light compared to anything else. It was extremely competitive against the big, blown V-8 racers to the extent that other competitors were complaining about it and trying to get it outlawed. It was featured in "4WD Action" Magazine.

Between, those two vehicles, and what I was seeing at the Caterpillar dealer I worked at, it really got me thinking about using hydraulic drive for an MT. I agree, it would be a DRASTIC change from what everyone's used to and probably won't happen anytime soon. But it just might be closer than you think. I'm not the only person to consider it for an MT.
 

flatus

Active Member
But we need someone in office that will allow us to cling to our monster trucks. Because, sometimes, guns and religion are not enough.
 
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