GTPNewsWire
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This is the discussion thread for a recent post on GTPlanet:
This article was published by Andrew Evans (@Famine) on January 29th, 2020 in the Automotive News category.
Mercedes Unimog Breaks the World Altitude Record for Wheeled Vehicles
- Thread starter GTPNewsWire
- 22 comments
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- 23,872
- It/It
- GTP_TheCracker
Great. Now you've got me looking up prices and availability (actually quite reasonable and seemingly not uncommon) for used Unimogs.
That's the zombie apocalypse sorted then. :tup
That's the zombie apocalypse sorted then. :tup
- 14
- United States
- xprojected
Can't be long before MB puts the Unimog brand on SUVs, for people who think their G-Class isn't rugged enough for trips to the mall.
- 86,534
- Rule 12
- GTP_Famine
Cooling would likely become a significant issue. I'd need to look into how the ID R coped with 650mbar on Pikes Peak without significant derating, but to beat the Unimog a car would need to survive 450mbar. I think that it wouldn't be a great environment for a pure EV after getting it up there.
A hybrid might do well - ICE up to 21k feet and battery to lift it past 22k.
- 8,704
Turbos are only helpful up to their maximum pressure ratio. So beyond a certain "thinning" of the atmosphere, absolute cylinder pressures will eventually start to decrease under certain load / speed conditions, and so will the absolute quantity of fuel that can reasonably be injected to maintain best AFR (power). Unless you start compounding 
Regardless, this is very impressive. Just navigating a way up must have been tricky, never mind actually driving it and not breaking anything on the way. And then getting back down again.
Regardless, this is very impressive. Just navigating a way up must have been tricky, never mind actually driving it and not breaking anything on the way. And then getting back down again.
- 364
- United Kingdom
- ZedNinetySix &
Pure badass, they all should be knighted!
- 11
- Brazil
Wow, they beat the record by 6 meters! The previous record was a held by a Suzuki Samurai at 6,688 meters (versus MBs 6,694m) in 2007 at the same location: https://www.autoblog.com/2007/04/27...ord-with-modded-suzuki-samurai/#slide-1581132
Wanna know what's even more funny? The record before the Suzuki was the SAME DRIVER from the MB Unimog, Matthias Jeschke, on a Jeep Wrangler at 6,464m, also 2007.
Now what's more impressive, a rugged purpose-built MB with a big team and bigger wallet, or a friggin Suzuki mini-jeep with no financial support?
Only way to beat that now is with an electric vehicle - Im looking at you, BMW.
Wanna know what's even more funny? The record before the Suzuki was the SAME DRIVER from the MB Unimog, Matthias Jeschke, on a Jeep Wrangler at 6,464m, also 2007.
Now what's more impressive, a rugged purpose-built MB with a big team and bigger wallet, or a friggin Suzuki mini-jeep with no financial support?
Only way to beat that now is with an electric vehicle - Im looking at you, BMW.
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- 86,534
- Rule 12
- GTP_Famine
Oddly, the same guy also drove a Mercedes-Benz Zetros lorry up the same mountain in the same place in 2014 to 6,675m (which was the truck record), and the Wrangler Rubicon beat his own previous record from 2005 in a Toyota Land Cruiser at 6,358m... also on the same mountain.Wow, they beat the record by 6 meters! The previous record was a held by a Suzuki Samurai at 6,688 meters (versus MBs 6,694m) in 2007 at the same location: https://www.autoblog.com/2007/04/27...ord-with-modded-suzuki-samurai/#slide-1581132
Wanna know what's even more funny? The record before the Suzuki was the SAME DRIVER from the MB Unimog, Matthias Jeschke, on a Jeep Wrangler at 6,464m, also 2007.
Now what's more impressive, a rugged purpose-built MB with a big team and bigger wallet, or a friggin Suzuki mini-jeep with no financial support?
Only way to beat that now is with an electric vehicle - Im looking at you, BMW.
Guy loves his mountains.
LeGeNd-1
Premium
- 7,264
- Australia
- GTP_LeGeNd-1
Really impressive, reminds me of the Top Gear Bolivia special where they also got quite high up in the Andes (obviously not as high as this though).
Totally crazy thought, but would a turbine engine car have better performance at high altitude given they are designed to work on planes?
Totally crazy thought, but would a turbine engine car have better performance at high altitude given they are designed to work on planes?
- 8,704
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- a baby, candy, it's like taking.
- TexRex72
Would this principle also apply to a turboshaft engine that would be necessary for a wheel-driven vehicle?
- 2,684
- Knoxville, Tennessee
Well, remember there are turboprops which don't really utilize the ram air effect that can fly in excess of 41,000 ft. The Pratt & Whitney PT6 for example can handle high altitude flight just fine, as can the APU in pretty much any commercial airliner. IIRC it is more about engine pressure ratio than forward speed that determines how high a conventional turbine engine can go.
Also this makes me want a Unimog even more than I already do. I love the Unimog
- 8,704
Yes, the overall internal pressure ratio is the key for maintaining power as the air "thins" - so it is similar to turbocharged engines in that sense, especially since you can make a Brayton cycle "engine" out of any turbocharger. Jet engines (or any Turbo-whatever engine) of course are usually multi-stage (i.e. compounding), and not normally with the same number of expansion as compression.
"Ram air" technically occurs at any speed, although it is negligible below about 70 - 100 mph, and you do need special designs to "recover" the extra pressure properly (as seen anywhere piston engines currently race against each other), but obviously we're not talking about actual ram-jets here.
So I don't think a turboshaft engine would be of much benefit over a compounded turbocharged piston engine in this application.
"Ram air" technically occurs at any speed, although it is negligible below about 70 - 100 mph, and you do need special designs to "recover" the extra pressure properly (as seen anywhere piston engines currently race against each other), but obviously we're not talking about actual ram-jets here.
So I don't think a turboshaft engine would be of much benefit over a compounded turbocharged piston engine in this application.
LeGeNd-1
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- 7,264
- Australia
- GTP_LeGeNd-1
Interesting, thanks for explaining. I'm no engineer but I can get the gist of it. So basically a turbine engine (turboshaft, like the one in Howmet TX) is like an oversized turbo without the actual engine, and instead connected directly to the driveshaft. So it would also encounter the same issues with thin air as a turbo+ICE right?
Whereas a plane engine (turbojet or turbofan) creates drive force from the expelled air behind it, and needs air moving fast into it, which is obviously not a practical choice for cars.
- 12,864
- Cambridge
- Moglet85
- Moglet
I spot quite a few Unimogs on the roads near where I live, utility companies and farmers use them to be able to access flooded areas while carrying all of their equipment. Coming face to face with one on a tiny country lane is always fun.
- 23,872
- It/It
- GTP_TheCracker
They're fairly common near me too. A lot appear to be owned by tree-surgeons. Unimogs utilise the engine when not on the move to run ancillary attachments, like wood chippers, so they don't have to haul around portable generators. But yeah, they're lorry wide not Transit wide so not ideal for threading down narrow roads.
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