NH SWB Replacement Fuel Tank

[AndyNH91]

Hi there,

I've just replaced the fuel tank in my 91NH SWB in preparation for a gas conversion. Pics as attached.

The main petrol tank that sits behind rear axle has been removed and a smaller tank has been placed in front of the rear axle, next to and around the tail shaft and muffler. I call it the tetris tank... it really is squeezed in. It's only 48L but it enables me to keep the Pajero duel fuel without loosing cargo space.

I'm quite happy with the conversion so far. Next step is a VSI gas conversion. I'll pretty happy not to be paying $1.49/L again!!

Cheers,

Andrew

[t-rex1995]

hi mate i've got a nh v6 manual lwb running straight gas its a sprint gas system 80 litre tank but only holds 60 litre i mainly do h/way kms best i've done 323kms with 6 litres still left in the tank have just recently purchased a aux tank out of another pajero the same as the guy was wrecking it tank and all hoses and brackets $175 delivered

So what type of gas system you willing to put in and are your heads suited for gas i presume it a v6 3litre???????????

[AndyNH91]

You are right, it's the 3.0L V6 which normally suffers after a gas conversion. Mine has been rebuilt with hardend valve seats (from HM Gem) so it should be okay. At this stage I'm looking at the Prins/Parnell VSI conversion. Pricey, but I'm driving 30,000km a year, so it will still repay itself quickly.

[AndyNH91]

hi mate i've got a nh v6 manual lwb running straight gas its a sprint gas system 80 litre tank but only holds 60 litre i mainly do h/way kms best i've done 323kms with 6 litres still left in the tank have just recently purchased a aux tank out of another pajero the same as the guy was wrecking it tank and all hoses and brackets $175 delivered

So what type of gas system you willing to put in and are your heads suited for gas i presume it a v6 3litre???????????

Nice job on getting the auxillary tank so cheap. Hey, is your sprint system the venturi type?

[t-rex1995]

not sure what you quite mean lol?????

[AndyNH91]

Sorry I'll explain. The venturi gas type has a single mixer on the intake. The vapour sequential injection (VSI) has six gas injectors on the inlet manifold which allows for more control. The venturi type uses a bit more gas (+30% when compared to petrol) and the VSI uses less (+10% when compared to petrol) but you pay a lot more for the conversion. It really depends how many km you do and how much you want to pay upfront to find the best solution for you. No wrong answers in other words :-)

[t-rex1995]

mine just has a upper lubricant bottle and sucks lube into the the manifold next to throttle body must be venturi type system???

[Nakk]

Hi Andy, that looks great. I too have a SWB NL and the limited fuel tank is driving me crazy. I would be interested in the dimensions of that tank if you got it.

BTW did you explore the idea of fitting a gas tank instead as the aux to run on LPG instead of dropping the main tank? I know it would mean more fuel stops for LPG.

Currently on 33" i dont get much k's.

Cheers

[AndyNH91]

Hi Andy, that looks great. I too have a SWB NL and the limited fuel tank is driving me crazy. I would be interested in the dimensions of that tank if you got it.

BTW did you explore the idea of fitting a gas tank instead as the aux to run on LPG instead of dropping the main tank? I know it would mean more fuel stops for LPG.

Currently on 33" i dont get much k's.

Cheers

Now that I have my gas conversion, I can answer your questions pretty well. It is useful to have a larger tank for lpg as you'll go through it quickly and after going to the expense of a conversion, you'll want to use lpg as much as possible to recoup the conversion costs and to start making savings.

I'm not sure if their exists an lpg tank that will fit in front of the rear axle due to the shape the tank needs to be. A custom scuba tank might do the trick, but you'd be paying $$$ for it.

The 'little' auxillary fuel tank that I've install gives me about 370km out of the 48L useable @13L/100km. The 60L lpg tank that replaced the main petrol tank gives about 420km @14.5L/100km. I'm not convinced these two fuel consumptions were taken under the same conditions! I have had fuel consumption down as low as 11.5L/100km on petrol, so as far as 4bees go, the little swb pajero can be pretty efficient.

[AdReNaLiN]

Hi Andy, can you tell me the model number of the Aux tank you bought? was it an LRA one?

Do you have photos of the mounting points of the Aux tank in the SWB? Did you have to drill holes or weld to the chassis?

[AndyNH91]

Yes it was an LRA one. I spoke to their Lilydale office in Vic (03) 9739 5667. The model number was MPNHS6GC... apparently the GC means that it's designed to take your fuel pump as it becomes your primary petrol tank as opposed to your auxillary.

Just a word of warning, the tank didn't fit the vehicle initially for some reason (tailshaft wound up being too close to the tank to drive safely). They pulled the tank back out, cut the corner off and rewelded it. Can't really tell, the modification is in the pick above, the vertical panel that runs next to the tail shaft. LRA covered this cost so it really wasn't any impact to me.

The other teething problem I had was the standard mitsi fuel gauge is too long for the tank and fouls on the opposite side of the tank, so the needle in the cabin doesn't shift as the fuel level drops. The fuel lamp worked though. Seeing they had done the hard yards cutting and shutting the tank so professionally I fixed the fuel gauge myself by using some fencing pliers and putting a few kinks in the float arm until it was the correct length and angle. Again, a bit of messing around.

But in the end, I think I got a quality product.

Gas conversion... I went for the Prins VSI. It runs beautifly and I get reasonable economy out of it for gas but I think I would have done as well from the older venturi type. I had to return it twice to get the tune right. The first time I had awesome power, but it was using 19.5L/100km driving one person around. The second time they tuned it it came back using 21L/100km. Third time lucky and I got around 14.5L/100km. With the VSI there are no starting issues, backfiring, stalling or change over issues. Not sure if people with venturi systems get these, perhaps others could help you here.

The gas tank is mounted pretty low too, so that's another thing I'll need to fix prior to going and doing any serious off-roading. Currently the tank is sitting lower than the rear diff and I think that's thoroughly inappropriate for an off-roader.

So if you're up to a bit of messing around it is a good conversion to do. But be aware that its pretty major surgery. The end product will be just what I wanted, but it has taken much longer than I ever expected. If I had my time again I would have spent my cash on a couple of ARB airlockers and had some decent fun on the weekends!

[AndyNH91]

Both tanks are mounted through the floor pan. Quick and dirty, I know, but this is how manufacturers and installers roll these days.

I note the OEM petrol tank that was removed was mounted to the chassis.

The floor pan of the Pajero is pretty thick, I think you'd have to be doing something seriously wrong to pull a tank loose. Videos anyone??

[AndyNH91]

Just completed a long term test on the Prins VSI fitted to my vehicle. The warning light for the petrol tank came on after 5000km. Plenty of tanks of gas used in this time.

It works out to be less than $10/100km running on gas, add another $1/100km for the cold start petrol. All in all about 33% cheaper than if running on 91 unleaded.