Isuzu NRR / Acela Straya High-mobility 4×4 Cab-over Truck

[carterd]

Great to see another 4x4 cabover option in the marketplace. This combines the NRR with Meritor axles, 41 inch military wheels/tires, and optional CTIS. Pricing is not bad relative to Earthcruiser. I wish they had a slightly toned-down NPR 6.6L gas version with 37s. The Acela Straya Isuzu NRR is a Class 5 truck with the somewhat antiquated 6.0L gas engine with Allison transmission.

Acela Straya: North America's First High-mobility 4x4 Cab-over Truck - Expedition Portal

Acela's new cab-over 4x4 truck, the Straya, is a high-mobility platform based on

expeditionportal.com

 

[carterd]

More specs. New Venture 273 transfer case. The Meritor axles have hub reduction, so the center pumpkin has great ground clearance.

 

[Simonroadtrip]

I am thinking about combination between Bliss mobil 13ft box and this Straya truck. Is the fully loaded box too heavy for this gas engine?

 

[carterd]

It would be within the GVWR, but you won't win any drag races and you would be sub-10 mpg.

 

[Blowby]

If the 13' Bliss is doable on a Core chassis,I would think this is definitely within its capabilities!
I am guessing 65-70mph would be top speed with that gearing?

 

[carterd]

It has a 6.5:1 final drive ratio on 41s, which is equivalent to 5:1 on 32s, so it is geared low. Between the low gearing and the 68mph speed rating of the Continental MPT 81s, you won't be getting any speeding tickets.

 

[Simonroadtrip]

Comparing with Earth Cruiser Core chassis, wha’s the pros and cons except the price?

 

[charlieaarons]

Actually, with the gearing including the extremely tall 6th gear ratio of the Allison 1000 (0.614) giving final drive of 3.99, at peak hp at 4900rpm, theoretical rpm limited top speed is in excess of 140mph (!!!). Peak torque is about 4100 rpm, equivalent to 120mph.
IMHO the setup including gearing is perfect for a Cummins ISF3.8. Peak torque 442 ft-lb, 168hp at 2600. Which makes top speed about 75.5mph. Fine since tires are rated at 68 and at 65 it’ll be turning just under 2250. And probably getting 13-14mpg with a 14’ camper box on 150” wheelbase with a single cab.
Only other desirable modification with the small gear spread of Allison 1000 would be a Magnum underdrive/NP205 (or leaving the 273 in place behind the Magnum).
I again reiterate the importance of extremely low 1st gearing and creep speed as vehicle weight and physical bulk (including COG) increases. Sounds like a great choice of axles, to bad the optional (probably no cost) NoSpin isn’t available for rear axle. CTIS is an enormous advantage and puts the Meritor (formerly Axletech) 3000 way above the Danas used by EC. Along with 2 piece (Hutchinson?) wheels with internal beadlocks available.

A swap to a Euro 3 diesel is obviously only possible in certain jurisdictions.

 

[charlieaarons]

PS: for those with math limitations, 335/80R20s turn about 512 times/mile.

 

[carterd]

Some comparisons:



It is a bit of an apples to oranges comparison. The CORE is the same chassis design as used in the EarthCruiser EXP/FX platform. It is very well suited to a composite habitat of around 14 feet. CORE sells a spring mounted subframe specifically designed for a 14' Total Composites box. The transfer case, axles, and wheels are pretty standard 4x4 stuff with widely available parts and could be serviced by most mechanics. The Acela Straya is a Class 5 truck with much higher payload capacity, more wheelbase options, and a military axle/wheel configuration with CTIS.

A full buildout out on either of these trucks is going to put you in a $250K+ vehicle. I think you really have to ask yourself how much technical terrain you really want to tackle in a $250K truck, and will the truck even fit where you want to go? Also, how much highway driving will you need to do to get to your desired destination? I suspect spending days on the highway in an underpowered cabover truck with 41" mud terrains is not a pleasant experience. The awesomeness of CTIS and the off-road capability in the Acela is undeniable, however.

I was about to pull the trigger on a CORE chassis last year, but backed down. I love the concept of the cab-over as it allows for the maximum habitat length with minimal vehicle length, but ultimately you are paying $150K for a Frankenstein work truck. There will be engineering integration issues, there will be warranty disputes, and there will be repair issues. If you are willing to add another 4 feet to your vehicle, you can get a highly capable domestic heavy duty pickup chassis with tons of options, creature comforts, OEM integration, and warranty support for half the cost. They are not nearly as cool, however.

 

[Ultimark]

It seems as though people living in the USA are finally getting some interesting light trucks after a dearth of them as manufacturers/importers pulled them from the market.

Carterd makes a very valid point about CTIS being awesome and extremely desirable; it certainly is. I have an aftermarket CTIS on my Isuzu NPS 75-155 and to say it has transformed the vehicle is a big understatement. Having an OEM unit like being available on the Acela vehicle, with air coming through the axles and having everything neat and sealed, is just icing on the cake. It is also monitoring vehicle speed so I assume that like the Unimog if one starts to drive faster than the selected tyre pressure, the truck overrides this and inflates to a more suitable pressure commensurate with the speed.

The CTIS price is quite cheap at USD $3435, however the cost of a spare wheel and tyre at USD $3205 seems astronomical and if you desire two spare wheels then you are looking at $USD $6410.

The wheelbases offered are interesting, in Australia the Isuzu N series trucks are available with three wheelbases, short, medium and long. The 4x4 NPS is only available in the medium wheelbase version and when I enquired as to why, the answer was: SWB equals too quick handling and with a top heavy truck, the possibility of tipping is greatly enhanced. The LWB version has ramp over issues, understand that the Isuzu N series of trucks all have smallish wheels with duals at the rear, so ramp over with a LWB is an issue. The medium wheelbase chosen by the factory seems to be about right, more so when equipped with aftermarket super singles. The other issue is turning circle, certainly going to be interesting on tight turns if one has a LWB version.

The Acela appears to be a very wide truck at 2387mm, the Isuzu wide cab version it is using is 2040mm wide as far as I can work out from Isuzu literature. My own truck is 2040mm wide on the cabin and with super singles fitted to OEM axles it is possible to have a vehicle with a tray rear that just covers the wheels at 2100mm wide. My own tray is 2200mm wide to carry my slide-on camper, otherwise I would have had the slightly narrower tray.

Overall I like what is being offered, especially if one has a CTIS on board.

 

[Simonroadtrip]

Thanks for Carter's very specific comparisons.
Yes you are right it will cost at least $150k if you want to find a truck chassis with certain level off-road capbility for your expediditon vehcile building up. The most updated starting price for the following choice:
Core DIY: 160k, Straya: 135k, Mounterra: 110k, Unimog 2450 in US:130-220k, Unimog 2450 in Europe: 100k (including shipment). Yes it is relatively expensive for a truck but there is very limited choice in US market, which definetly is different in Europe and Oz.
I do find very few people choose pick up truck (like F550) as expedition vehicle chassis and but I don't know why.
In summary of your comparisons between Core and Straya:
1.The same level of off-road and high way capbility?
2.Easy to repair and maintain on Axles for Core?
3.It looks like that Straya is 20% cheaper than Core
4.Higher payload from Straya
5.Same level of comfortability of cab?
6.Core is more powerful and with more torque
As for the width difference of Straya, I think maybe it is because of the wheel eyebrow rebuilding.

 

[charlieaarons]

2 little things:
1) one doesn’t need 2 complete spare wheels/tires. Just 1, plus an unmounted spare tire.
2) as far as axle width, they chose a wider than stock Isuzu track when selecting axles. Not some deal putting enormous stress on wheel bearings by replacing 32” tires with 41” and using much smaller front offset, and in rear replacing duals with large single with offset similar to outer wheel of duals, deleting inner wheel.
The Straya’s only big engineering compromise is engine choice. Not totally sure why Duramax isn’t optional.

 

[charlieaarons]

Because the GM gas engine puts out 311 hp at 4900 and peak torque at ridiculous 4150, but 6th gear rpm at 70 is only 2400, max available hp at 70 is a mere 160-170. Same as an ISF3.8 for example. Undoubtedly far less economically. That’s my only real “issue” with drivetrain choices. Understandable these days but suboptimal.
It’s NOT “overgeared”.

 

[Ultimark]

One of the things I found out about having CTIS fitted, is the care one needs to do to keep the insides of the tyres scrupulously clean when changing tyres. Dirt or anything else running around inside the tyre can be sucked into the CTIS or maybe partially block the valve stem as there is no Schrader valve. It was suggested by the manufacturer of my CTIS that whenever possible change tyres somewhere clean. I do agree that keeping only one complete spare wheel/tyre and one spare tyre is a nice way to go, and the two piece wheels supplied with the Acela make this a relatively easy thing to do. As far as I'm aware, two piece wheels are as rare as hen's teeth in Australia, I'm not even sure if they are legal here.

Unless I'm missing something, the picture above shows a truck with no headlights, or are they behind those flat white panels?