# The Black Beast: how much HP must it have to reach 70 mph per hour?

33 replies to this topic

### #1 Nemo1965

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Posted 25 March 2014 - 19:15

Yesterday, the American president visited the Netherlands. A newsreport said the car weighed 70.000 kilo's, which made me laugh out loud.

However, according to wikipedia the car weighs 20.000 pounds, which would be about 9000 kilograms. It is estimated that the car can reach 60 mph per hour. Still that must be some engine in it. How much HP would it take to get it too 70 mph per hour?

I tried to do some basic calculations, but I came to ridicilous conclusions...

### #2 desmo

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Posted 25 March 2014 - 19:51

Five minute glass is heavy. Well it'll take whatever a regular commercial vehicle of that weight will need to get to 70mph, certainly nothing extraordinary. The tech in these armored limousines (I am assuming that's what's being discussed) is no doubt pretty interesting--and probably pretty closely guarded. I wonder if they fit active armor?

### #3 Tenmantaylor

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Posted 25 March 2014 - 21:55

Might be a beast but easily stopped!

### #4 gruntguru

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Posted 25 March 2014 - 21:59

Be on the lookout for dark foreigners with inflatable speedbumps in their carry on luggage.

### #5 Greg Locock

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Posted 25 March 2014 - 22:45

I had a 3 ton (laden) truck that could do 55 mph with a 40 hp diesel, so a 9 ton truck at 70 would need rather less than 40*3*70^3/55^3, 250 hp. That's the least powerful engine available in an Australian Ford taxi.

### #6 Catalina Park

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Posted 26 March 2014 - 00:18

The truck I drive is speed limited to 105kph. It has a 250hp Cummins motor driving through an Allison auto box and will pull top speed on the freeway fully loaded with about 24 tonnes all up.

So 250 hp will propel 9 tonnes easily.

### #7 Ross Stonefeld

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Posted 26 March 2014 - 02:02

It's going to have, I'd guess, twice that? It's going to have some acceleration on it, just in case. Hell, it might be Nitrous but it's not going to amble up to the speed limit when it's Go time.

### #8 gruntguru

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Posted 26 March 2014 - 02:40

There is not a strong relationship between mass and the power consumed at a given speed ie a 20 ton streamlined vehicle might do 70 mph with less than 100 hp.

OTOH acceleration might be disappointing.

### #9 Catalina Park

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Posted 26 March 2014 - 06:42

My truck won't win any traffic light drags when empty at 9.4 tonnes but it will keep up with city traffic quite easily.

The problem I see is finding a transmission that will handle the torque required for a 9 tonne vehicle with decent performance.
The Allisons we use can only take about 300hp.

### #10 Nemo1965

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Posted 26 March 2014 - 08:36

According to this calculator it would take 24,2 seconds for 250 hp to drag the beast to 60 mph... I don't know if that is a thrustworthy calculator... but if I imagine an attack on the president that would be watching a snail trying to escape a saltdispenser...

### #11 carlt

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Posted 26 March 2014 - 11:59

The problem I see is finding a transmission that will handle the torque required for a 9 tonne vehicle with decent performance.
The Allisons we use can only take about 300hp.

you should know by now it is not the HP but the torque that kills gearboxes

### #12 MatsNorway

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Posted 26 March 2014 - 13:24

I really like rear mounted gearboxes for that reason. You do not need that huge a shaft between engine and gearbox. as supposed to gearbox to diff. because the Torque is further down in the system. Dumpers and such even have a hub mounted gearing i believe. I find it odd that its not more common with rear mounted gearboxes in sports sedans and such. Only cars i know of now is the Corvette and the Mercedes SLS.

OT: And now i found out that they do indeed do what i was thinking they could do which is to use hydraulic motors for drive: http://www.liebherr.....wfw/id-16519-0

But they only do it on slower machines. I thought one could do it for dumpers and so on to save the usage of massive gearboxes.

Edited by MatsNorway, 26 March 2014 - 13:55.

### #13 Catalina Park

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Posted 26 March 2014 - 13:30

you should know by now it is not the HP but the torque that kills gearboxes

Yep, I fell, for that one!

### #14 Catalina Park

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Posted 26 March 2014 - 13:36

Mats, some of the real big dumper stuff is Diesel electric.

The Liebherr loader at work is hydraulically driven. The motor is sideways across the back with a hydraulic pump on the end of it. Only does 34kph though.

### #15 MatsNorway

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Posted 26 March 2014 - 14:35

OFC! diesel electric like trains. Why not right. jesus!  Where wondering about why the M1 Abrahams tanks was not that some time ago. It has supposedly a giant gearbox.

Edited by MatsNorway, 26 March 2014 - 14:36.

### #16 Kelpiecross

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Posted 27 March 2014 - 06:32

I really like rear mounted gearboxes for that reason. You do not need that huge a shaft between engine and gearbox. as supposed to gearbox to diff. because the Torque is further down in the system. Dumpers and such even have a hub mounted gearing i believe. I find it odd that its not more common with rear mounted gearboxes in sports sedans and such. Only cars i know of now is the Corvette and the Mercedes SLS.

OT: And now i found out that they do indeed do what i was thinking they could do which is to use hydraulic motors for drive: http://www.liebherr.....wfw/id-16519-0
But they only do it on slower machines. I thought one could do it for dumpers and so on to save the usage of massive gearboxes.

Oz V-8 Supercars have the gearbox at the back.

### #17 indigoid

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Posted 27 March 2014 - 10:11

Oz V-8 Supercars have the gearbox at the back.

Current Nissan GTR too AFAIK

### #18 MatsNorway

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Posted 27 March 2014 - 10:20

That is correct. I forgot that one too.

http://images.hemmin...2/Cutaway-1.jpg

### #19 GVera

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Posted 27 March 2014 - 14:10

I remember Alfas from the 80's with the gearbox at the back and De Dion suspension...

### #20 Magoo

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Posted 27 March 2014 - 21:01

The presidential limousine is called the Beast, not the Black Beast. I believe we might be...projecting.

I think I mentioned earlier that I accidentally stumbled into the Beast (or a prototype) when it was under construction several years ago. I can say that it is not a car at all but an extensively modified GMC C4500 medium-duty truck, which among other things, has been heavily armored top, sides, and bottom. The body is carbon fiber styled to resemble a late model Cadillac DTS sedan, more or less. with various Cadillac production car doodads including the grille, lamps. etc. The engine is, I believe, a Duramax diesel V8 that produces somewhere between 360 and 450 hp, coupled to a 5-speed Allison automatic transmission.

### #21 Nemo1965

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Posted 28 March 2014 - 20:30

The presidential limousine is called the Beast, not the Black Beast. I believe we might be...projecting.

I think I mentioned earlier that I accidentally stumbled into the Beast (or a prototype) when it was under construction several years ago. I can say that it is not a car at all but an extensively modified GMC C4500 medium-duty truck, which among other things, has been heavily armored top, sides, and bottom. The body is carbon fiber styled to resemble a late model Cadillac DTS sedan, more or less. with various Cadillac production car doodads including the grille, lamps. etc. The engine is, I believe, a Duramax diesel V8 that produces somewhere between 360 and 450 hp, coupled to a 5-speed Allison automatic transmission.

I am sorry, I am not projecting anything. The Dutch press called it like that and I reproduced it, my mistake.  Thank your for the interesting info! Most internetpages imply that this information is kept close to the chest.

### #22 Lee Nicolle

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Posted 28 March 2014 - 22:19

Oz V-8 Supercars have the gearbox at the back.

As did many Oz Sports Sedans 2 and 3 decades before. And most are half a ton lighter too!

### #23 Lee Nicolle

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Posted 28 March 2014 - 22:21

The presidential limousine is called the Beast, not the Black Beast. I believe we might be...projecting.

I think I mentioned earlier that I accidentally stumbled into the Beast (or a prototype) when it was under construction several years ago. I can say that it is not a car at all but an extensively modified GMC C4500 medium-duty truck, which among other things, has been heavily armored top, sides, and bottom. The body is carbon fiber styled to resemble a late model Cadillac DTS sedan, more or less. with various Cadillac production car doodads including the grille, lamps. etc. The engine is, I believe, a Duramax diesel V8 that produces somewhere between 360 and 450 hp, coupled to a 5-speed Allison automatic transmission.

I knew it was a GM V8 diesel but was not aware of the truck underpinnings.

Maybe they should just use a reinforced duallie instead. Go down very well in some quarters.

### #24 rdyn

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Posted 29 March 2014 - 00:05

I really like rear mounted gearboxes for that reason. You do not need that huge a shaft between engine and gearbox. as supposed to gearbox to diff. because the Torque is further down in the system.

The outer shaft diameter is selected based on critical speed - torque is usually not the problem.

Rear mounted gearboxes provide better weight distribution.

### #25 Kelpiecross

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Posted 29 March 2014 - 03:54

As did many Oz Sports Sedans 2 and 3 decades before. And most are half a ton lighter too!

They usually used a Hewland of some kind I seem to recall.

### #26 Lee Nicolle

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Posted 30 March 2014 - 07:12

They usually used a Hewland of some kind I seem to recall.

Yes, in the early days many used DG300 or the heavier 4 speed sports car box that I have forgotten the designation. Later cars used the more modern boxes, generally from big Sports Cars. Euro or US. Some small engine cars used VW based transaxles.

### #27 Joe Bosworth

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Posted 30 March 2014 - 13:59

By one very well documented and usually accurate set of formulas you find that a 9000 kg vehicle powered by a real 250 HP will do the standing quarter mile in 26 seconds and be doing 55 MPH at the end.

If the HP were a real 450 the time and speed would be 22 seconds and 66 MPH.

Take that data for what it is worth.  It sounds about right.

Regards

### #28 Magoo

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Posted 30 March 2014 - 18:04

I don't know this but I am given to understand that one of the contract requirements was 0-60 mph in 16 seconds.

### #29 gruntguru

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Posted 30 March 2014 - 23:12

Max, min or exactly?

### #30 Lee Nicolle

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Posted 31 March 2014 - 09:13

By one very well documented and usually accurate set of formulas you find that a 9000 kg vehicle powered by a real 250 HP will do the standing quarter mile in 26 seconds and be doing 55 MPH at the end.

If the HP were a real 450 the time and speed would be 22 seconds and 66 MPH.

Take that data for what it is worth.  It sounds about right.

Regards

A Ferret Scout car at its best does 26 sec quarters,, I dont remeber the MPH. And yes somewhere I have pictures

I suspect the thing must have moderate accelaration and speed as both of those are often more handy than all the armour in the world.

Personally If I was having something like that built it would be the most powerfull engine available with bullet prooff glass, tyres and lots of kevlar armour. And probably weigh in under 3 ton. Something strong powerfull with good road manners that can 'run away' is far more usefull than a lumbering tank.

I believe MB make such a thing, probably GM too in the limo range.

### #31 Kelpiecross

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Posted 31 March 2014 - 10:11

By one very well documented and usually accurate set of formulas you find that a 9000 kg vehicle powered by a real 250 HP will do the standing quarter mile in 26 seconds and be doing 55 MPH at the end.

If the HP were a real 450 the time and speed would be 22 seconds and 66 MPH.

Take that data for what it is worth.  It sounds about right.

Regards

Oddly enough the 22 seconds/66mph performance is somewhat better (literally) than the 850cc Mini I drove many years ago. On the subject of scout cars (and their escaping ability) I seem to recall some have automatic/hydraulic transmission that can be but into reverse at any forward speed to reverse out of ambushes etc.

And an Austin Seven (from the twenties/thirties) is lucky to reach 45mph top speed.

### #32 RogerGraham

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Posted 31 March 2014 - 13:28

Something strong powerfull with good road manners that can 'run away' is far more usefull than a lumbering tank.

I daresay that depends entirely on what sort of threats you're most likely to be protecting yourself against.

### #33 Canuck

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Posted 01 April 2014 - 02:27

That limo need only provide a window of protection long enough to allow the heavy artillery to arrive.  Remember, those support vehicles are rumoured to be carrying some staggeringly heavy-duty firepower, and I would guess that significant air support is not very far away from that limo at any given moment.  It doesn't need to go anywhere as it (appears to be) capable of weathering the kind of attack that could be launched within the pre-examined and protected route it travels.  The only thing that's capable of harming the occupants is going to require far more presence than can be hidden from a massive security detail.

### #34 Nemo1965

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Posted 02 April 2014 - 11:36

That limo need only provide a window of protection long enough to allow the heavy artillery to arrive.  Remember, those support vehicles are rumoured to be carrying some staggeringly heavy-duty firepower, and I would guess that significant air support is not very far away from that limo at any given moment.  It doesn't need to go anywhere as it (appears to be) capable of weathering the kind of attack that could be launched within the pre-examined and protected route it travels.  The only thing that's capable of harming the occupants is going to require far more presence than can be hidden from a massive security detail.

True. I told my students (I teach in Amsterdam) that all around the Rijksmuseum (where Obama was going to visit 'De Nachtwacht') there would be snipers hiding. They looked at me sceptically. The day after the visit, one of my students told me they were having a coffee in a nearby cafe. They watched a live-broadcast and the camera happened to pan across to the roof of the Concertbuilding (opposite of the Rijksmuseum). He said: 'You could not see the rooftop for the men laying in prone position.'

Edited by Nemo1965, 02 April 2014 - 11:44.