Isuzu npr 4wd

Ultimark

Active member
I think it would turn the same as a 170ext MB sprinter
Hmm, not too sure about that.

Our NPS has what Isuzu calls their medium wheelbase of 3395mm, it's turning circle is 13.6m. This is the only wheelbase available for the NPS in Australia, and probably the world.

The NPR comes in a few wheelbase lengths, however the crew cab version only comes in their LWB format, which is 4175mm, it's turning circle is 15.3m

Making a 4x2 vehicle into a 4x4 could possibly increase the turning circle somewhat as usually the angle of turn is reduced slightly to enable the drive line to live a long and fruitful life.

On the NPS front axle there is a bolt that can be adjusted to reduce the angle of turn, the idea being to further reduce the angle when fitting wider tyres. The NPS is also manufactured for the Japanese military and comes with super singles as standard, this adjustment bolt may be fitted for those OEM super single machines.

Below is an NPS 75/155 crew cab with the longest tray that can be legally fitted to an Australian NPS, (60% of the wheelbase overhang). They were about 80m from where I was earlier this year and are living in this fulltime towing a caravan, which can be just seen in the background.

He had one major complaint, the fuel tank of 140 litres was not big enough. We have two OEM tanks on the right side which gives us 280 litres. Any crew cab variant with two fuel tanks has one either side as the cabin isn't allowed to be over the fuel tanks.

Mick.

NPS_20240420_141119_003_Web.jpg
 

gator70

Active member
Hmm, not too sure about that.

Our NPS has what Isuzu calls their medium wheelbase of 3395mm, it's turning circle is 13.6m. This is the only wheelbase available for the NPS in Australia, and probably the world.

The NPR comes in a few wheelbase lengths, however the crew cab version only comes in their LWB format, which is 4175mm, it's turning circle is 15.3m

Making a 4x2 vehicle into a 4x4 could possibly increase the turning circle somewhat as usually the angle of turn is reduced slightly to enable the drive line to live a long and fruitful life.

On the NPS front axle there is a bolt that can be adjusted to reduce the angle of turn, the idea being to further reduce the angle when fitting wider tyres. The NPS is also manufactured for the Japanese military and comes with super singles as standard, this adjustment bolt may be fitted for those OEM super single machines.

Below is an NPS 75/155 crew cab with the longest tray that can be legally fitted to an Australian NPS, (60% of the wheelbase overhang). They were about 80m from where I was earlier this year and are living in this fulltime towing a caravan, which can be just seen in the background.

He had one major complaint, the fuel tank of 140 litres was not big enough. We have two OEM tanks on the right side which gives us 280 litres. Any crew cab variant with two fuel tanks has one either side as the cabin isn't allowed to be over the fuel tanks.

Mick.

View attachment 843887
Thanks for the info. The truck I'm building has about the same length as the 170ext MB sprinter. Maybe 6inchs longer. The cabover design is better for turning radius.

In the end, I have 5700mm + 440mm on frame length. Some compromise is warranted.

I appreciate the discussion, Thanks
 

DzlToy

Explorer
"Wheel cut" or the angle of the inside wheel, is usually the factour limiting a great turning circle/radius. It is common for pick up trucks, cabover trucks and SUVs to have a wheel cut in the 30* - 35* range. The exception to this, in my notes, is Ford's F450 trucks with Dana's Super 60 axle, a.k.a., the Fat Boy, which has a wheel cut of approximately 45-degrees.

Using something like RCV's Ultimate CV axle gives you 45-degrees of steering, also. This isn't surprising as it's based on 1 ton and 5/4 ton Superduty parts.




Machined, 1550-Series joints/knuckles/housings will get you 50-degrees of steering: (Branik, Spidertrax and a few others offer parts/services to do this kind of thing.)






I am not saying this is reasonable, it's quite an expensive endeavour, honestly. But if the OEMs would simply machine/cast knuckles, housings and joints this way from the start, 32* of steering would be a thing of the past.

In the States, it's common to see 2WD motorhomes, buses and commercial trucks with a 50 to 55-degree wheel cut. Making a CV or U-joint live at these angles is another story.
 

gator70

Active member
Installing 2nd gas tank. The truck is gas. There are many ways to do this, and I want the simplest installation without a fuel gauge. Any opinions?
 

DzlToy

Explorer
If you want an Isuzu tank, phone up a wrecking yard like Busbee's or even a local truck yard if you just want something that isn't off a passenger car. If you can weld or know someone who can, a tank almost any size and shape can be made from aluminum or stainless. Plastic welding is also an option, HDPE is impervious to gas and diesel, but has a high coefficient of (linear) thermal expansion. So, this must be taken into account. Fiberglass, Kevlar and Carbon are all options if you don't mind working with those products. Epoxy resin is impervious to gas and diesel. Using a pan or finger brake and sheet metal, 'baking pans' can be made, then bonded together to eliminate welded seams. Cover the whole thing in Polyurea when you are done. Finally, COTS aftermarket tanks for Jeeps, rock buggies and pickup truck beds, usually made from roto-moulded plastic, are all options.

A 12VDC transfer pump fills your main tank, from the auxiliary tank, when required.
 

Ultimark

Active member
The simplest way is as our extra tank has been done. Place another OEM identical tank immediately behind the original. This way nothing fuel wise with regard to pumps, filters or plumbing to the injection system is changed; it's also the cheapest.

You may have to move the original forward slightly, this will depend on exactly where your OEM tank is situated. Then attach a hose between both tanks underneath. Cover the hose and anything else with a solid bit of metal. Ours is aluminium tread plate, the same as our tray material.

The rear tank will essentially double the OEM tank capacity. The OEM tank for the NPS series is 140 litres, so you end up with 280 litres of fuel. The fuel gauge works perfectly normal, you will have ½ a tank when it indicates ½ a tank. As we received our truck with two tanks fitted, we've never known anything else.

The accompanying picture is immediately after the ATW build, prior to shipment to Melbourne, some 2,000 km's away. Due to COVID we were under lockdown (March/April 2020) so we couldn't fly up and drive it home. If you look under the tanks you can see the equalising system.

If you open the below image in a new window, you should have access to the non reduced size; viewing the tanks is much clearer when viewed at full web resolution.

Mick.


Truck_Build_IMG_4882_Web.jpg
 

SkiFreak

Crazy Person
As has been noted above, you have numerous options when it comes to a second fuel tank.
On my truck I have 2 tanks, but only one is monitored by the truck's fuel gauge. There is a custom made stainless steel centrally mounted 200L tank between the chassis rails and another 110L custom stainless "reserve" tank on the driver's side. The two tanks are connected via a manually controlled fuel transfer pump.
Although not really necessary, I also built a smart transfer system, which ensures that it is not possible to overfill the main tank.
I rarely ever need to fill both tanks, so to negate the potential issue of having stale fuel in the reserve (and to reduce weight), I normally just fill the reserve tank, then pump that into the main tank.

 

mog

Kodiak Buckaroo
I rarely ever need to fill both tanks, so to negate the potential issue of having stale fuel in the reserve (and to reduce weight), I normally just fill the reserve tank, then pump that into the main tank.
Great Idea! 🏆
 

gator70

Active member
It seems most of you guys have diesels. Mine is gas.
So far I found a new gas tank from a 1974 blazer that fits between the frame rails. It is 10 3/4 deep, 25 gallons.
Meaning if mounted at frame rail level height, it protrudes only 10 3/4 inch deep.
I don't see a need for a fuel gauge on that tank. If when my primary tank shows almost empty, with a transfer pump (switch on dash) I can fill the primary tank somewhat. Then watch the original fuel gauge increase.
 
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SkiFreak

Crazy Person
Realistically, it does not matter if the fuel is diesel or petrol/gas; the concepts are the same.
I actually like Mick's setup, as it simply makes 2 tanks into 1, negating the need to do anything manually. :)

Be mindful that if you do intend to use a transfer pump, it is technically possible to put more fuel into your main tank than actually fits.
Going by your main fuel gauge alone could be problematic, as the ECU has built in dampening, meaning that you do not get real time monitoring while filling.
A simple safety system would be to connect a suitably sized pipe/hose between the tops of both tanks. If this were done it would negate the possibility of pressurizing the main tank, as it would simply pump any excess fuel back into the secondary tank if the main tank was overfilled.

I should also mention that fuel tanks are not designed to be filled to the top. There should always be a void above the fuel, to allow for expansion.
Without a safety system of some type, if you were to transfer too much fuel into the main tank you would turn your tank breather into a fuel sprayer! That wouldn't be ideal...
 

Ultimark

Active member
Isuzu Trucks Australia, and Isuzu Ute Australia, supply all of their vehicles with dieseleum fuel, none of their vehicles are powered with petroleum. Petroleum powered light trucks and D-Max type utility SUV's, are pretty much a USA type of thing.

With regard to your tank fitting between the chassis rails, I would be very careful about ensuring chassis rail twisting clearance. The chassis rails of my NPS really twist and creak. There was a 2013/14 NPS that I watched being built not too far from my place. They placed three water tanks inside the chassis rails attached to the underside of the floating tray. The tray had the camper bolted to it, making it look very much like a motorhome.

Over time one of the water tanks started to leak, the leak was sourced to a small section of the middle tank. Eventually they worked out that the chassis rails were twisting so much that they touched/grazed the tank in the same place and wearing a hole in the wall of the tank. I cannot remember if they mounted that tank more to one side, due to cabling, pipes or whatever, but wear a hole in it they did.

Mick.
 
Isuzu Trucks Australia e Isuzu Ute Australia suministran todos sus vehículos con combustible diésel, pero ninguno de ellos funciona con petróleo. Los camiones ligeros y los SUV utilitarios tipo D-Max que funcionan con petróleo son más bien algo propio de Estados Unidos.

En cuanto al ajuste del tanque entre los rieles del chasis, yo tendría mucho cuidado de asegurarme de que los rieles del chasis tengan espacio libre para que se tuerzan. Los rieles del chasis de mi NPS realmente se tuercen y crujen. Vi cómo construían un NPS 2013/14 no muy lejos de mi casa. Colocaron tres tanques de agua dentro de los rieles del chasis, unidos a la parte inferior de la bandeja flotante. La caravana estaba atornillada a la bandeja, lo que le daba un aspecto muy parecido al de una autocaravana.

Con el tiempo, uno de los tanques de agua comenzó a tener fugas, la fuga se originó en una pequeña sección del tanque central. Finalmente, descubrieron que los rieles del chasis se estaban torciendo tanto que tocaban o rozaban el tanque en el mismo lugar y hacían un agujero en la pared del tanque. No recuerdo si montaron ese tanque más hacia un lado, debido al cableado, las tuberías o lo que sea, pero hicieron un agujero.

Mick.
The normal thing is to use free torsion subframe, otherwise you are exposed to breakage of the box due to the torsion of the original chassis, if you use subframe goodbye torsion problems
 
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gator70

Active member
Realistically, it does not matter if the fuel is diesel or petrol/gas; the concepts are the same.
I actually like Mick's setup, as it simply makes 2 tanks into 1, negating the need to do anything manually. :)

Be mindful that if you do intend to use a transfer pump, it is technically possible to put more fuel into your main tank than actually fits.
Going by your main fuel gauge alone could be problematic, as the ECU has built in dampening, meaning that you do not get real time monitoring while filling.
A simple safety system would be to connect a suitably sized pipe/hose between the tops of both tanks. If this were done it would negate the possibility of pressurizing the main tank, as it would simply pump any excess fuel back into the secondary tank if the main tank was overfilled.

I should also mention that fuel tanks are not designed to be filled to the top. There should always be a void above the fuel, to allow for expansion.
Without a safety system of some type, if you were to transfer too much fuel into the main tank you would turn your tank breather into a fuel sprayer! That wouldn't be ideal...

Good points. Yet if my aux tank is 22% smaller than the main tank, some of those issues have solutions
 

SkiFreak

Crazy Person
Yet if my aux tank is 22% smaller than the main tank, some of those issues have solutions
Absolutely, but there is still the slight possibility of it happening. As I said... it is relatively simple to include a basic safety system.
I did this with electronics and a couple of capacitive switches, but a tube between both tanks would also work.
 

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