Build Thread: Burni

[Dansale]

With the go faster pedal down you can hit 17psi from 1400 to 2500rpm. The wastegate is set to ~17.5 so it may otherwise be higher. From 2500 to 2700rpm boost falls to about 16psi.

I let the EGTs get to 550*c and then back off. That happens on 1km plus at 5 degree incline or larger inclines. Interestingly at 86kph (2500rpm) it stays cooler longer than at 80ish kph (2350rpm).

Very interesting.. having to back off on hills is so annoying and distracting.

More revs = lower EGTS because of higher air flow.
On 4btswaps and the Cummins forums they say that EGTS of about 1200*f sustained up hills are ok, subject to coolant temps staying acceptable. Even if you tuned your engine to limit max EGT to about 600*c 1100*f seems fine.

Only really two ways to go from here, more air or less fuel.
You could bump up the boost by a few psi, hit that same hill to see if EGTs are reduced.

You could drop a gear and scream up the hill at 3000rpm, or reduce the fueling, but wheres the fun in that?

 

[SPF40plus]

At 10.5t you have to accept a change down every now and then from a 6.5l engine.

As standard a 5% incline would probably mean 4th gear.

 

[SPF40plus]

Towbar:
Sooooo....
The rural fire dept did this to my chassis


And that meant that noone wanted to supply me with a towbar. Further, to get a towbar they required that we had a chassis extension done first.

The chassis extension meant that there wasn't enough room for a super single spare.

So, we designed and fabricated this and got it engineered.


And the spare tyre goes here

It's rated at 3500kg, but if i want to have the rating increased i have to get it retested at the higher load. I'll see if there is any need.

The internal part slides inside the chassis rails and the rear spring hangers, cross member, and load spring rests all bolt through it and the chassis rail. There is an additional plate on the outside of each rail that supports angles on the top and bottom flanges so the connection is as strong, but as torsionally flexible as possible.

 

[SPF40plus]

House/ Camper:
Ok, so when this all started the objective was to not tow a caravan, and have a slide on camper that could be removed with little effort.

In the end this just wasn't achievable. The biggest issue is the height that the camper is off the ground.

Jacking the camper up is achievable with four jack stands or hydraulic lifts.

However, to get the camper high enough to drive out, the rails on the outside need to be 1550mm off the ground. That is really high when you are standing next to it. Even when lowered down to 1300mm off the ground, the 75 x 75x 5mm shs allows too much sway in windy conditions. My family members get sea sick, and that happened.

So, we decided to bolt it to the truck and get on with it for now.

It is a bit of a pain not being able to leave the house behind, because it is limiting as to where and how fast you can go.

Options at this stage are get a 4wd to tow, or take the camper off and make it into a caravan. Or maybe neither of those.

Our family of four fits in with two bunks and a king size bed.



There is a toilet and shower, kitchenette, u shaped dinette, and a deck.

We have a diesel water/air heater, 220l of water, a butane stove and a microwave.

Everything electrical runs off the LifePo4 battery and that is primarily powered by solar only.

In three weeks we have only had to use the 240v charger once and that is because we parked in the shade for three days.

The deck makes the size of the camper livable. It's good to be able to get outside and sit in the sun, and with the mesh screens up with no bugs.

 

[ITTOG]

Why don't you set it on the ground when you take it off? Or if the jacks won't go that low set it on four saw horses?

 

[SPF40plus]

Why don't you set it on the ground when you take it off? Or if the jacks won't go that low set it on four saw horses?

Hey ITTOG noone makes saw horses strong enough, and we can take it off and secure it in all sorts of ways but doing that on the move just takes too much time and effort.

 

[Dansale]

SPF, thanks for the pics, very nice build!

Are you reusing the fire service gal base frame?
Are you using any sort of torsion free / pivoting tray mounts?

I absolutely love the rear deck concept, used by you and Omar. Fly mesh is clever too.

 

[Kingsize24]

Hey ITTOG noone makes saw horses strong enough.....

Pfft!!! Hold my beer! 😂

 

[Peter_n_Margaret]

So, we decided to bolt it to the truck and get on with it for now.

In South Australia if it is "permanently" bolted on, it can be registered as a "Caravan vehicle" instead of a truck and that is a lot cheaper.
Cheers,
Peter
OKA196 motorhome

 

[SPF40plus]

SPF, thanks for the pics, very nice build!

Are you reusing the fire service gal base frame?
Are you using any of torsion free / pivoting tray mounts?

the tray has a three point linkage with gimbal at the front, and this was under the gal tray already.

 

[SPF40plus]

In South Australia if it is "permanently" bolted on, it can be registered as a "Caravan vehicle" instead of a truck and that is a lot cheaper.
Cheers,
Peter
OKA196 motorhome

Because the GVM is over 12t the NHVR rules apply and you have to have a whirly bird or hatch in the roof to register as a motorhome. We took alot of time and care to keep water and dust out, so cutting a hole in the roof was a deal killer for us.

 

[Peter_n_Margaret]

As far as I know, there are no such requirements in SA.
Cheers,
Peter
OKA196 motorhome

 

[SPF40plus]

Roof rack and brush bars:

When this all started, I had thought that we would be doing alot of off road driving without the house on the back. That hasn't happened yet. Anyway the brush bars were designed to stop branches hitting the A-pillar and scraping along the gutters. The roof rack was designed to take a load of 200kg. A call to Isuzu resulted in a completely unfounded and undocumented roof rack load limit of 100kg and i was not satisfied that this was enough, or that the cab had enough structure to take any real load off road.

AS1235 doesn't apply to heavy vehicles, so I didn't need to comply with that, but it was interesting to read what the requirements were. I did some research and found that heavy vehicles in an emergency braking situation see deceleration of 1 to 1.5G. The design for the rack was FEA tested with a 7,000N vertical load to simulate suspension hitting the bump stops at speed and a 7,200N forward load to simulate emergency braking. With these forces we still have a minimum safety factor of 2.4. And generally a safety factor in excess of 4.

In the end the brush bars and roof rack have worked really well and all the little things that I did to stop wind noise seem to have worked. The bars themselves weigh about 120kg and then they are engineered to take 200kg. We currently have about 130kg of stuff on them.

The brush bars replaced all the grab handles on the side of the cab, and used all the existing holes and panel nuts. We had to drill holes in the rear panel and insert steel plates, and the same on the firewall. We used an existing hole in the roof to fit a bolt above the windscreen to help limit sway at the front.

The main tubes are 1 1/4 " pipe or DN32, and the pipes on the side are 1" pipe or DN25.

Under the guards, there are substantial brackets that hold up the guard and front of the bars. Previously the guards would deflect if you stood on them. Not any more.

As a last minute addition we put broadbeam work lights on both sides so that when we turn up to camp at night we can turn on the lights and read any signs, and check for snakes and other problems on the ground before we get out.

 

[SkiFreak]

The design for the rack was FEA tested with a 7,000N vertical load

You mean that you didn't just guess... where's the fun in that?

 

[SPF40plus]

You mean that you didn't just guess... where's the fun in that?

I did, but i did the analysis before I welded on the attachment points for the roof rack. There is only a difference of 300mm between bolt centres for a minimum safety factor of 2.4 and 1.1.

The safety factor could have been higher but that would have required the load to be further forward, and that affects windage and front suspension loads.