27 replies to this topic

[Bobbins]

1" pipe! The water supply for my entire house is supplied by a 1" line! 

 

I have no experience with twin MPi tanks but I have thought about doing it - I even have a couple 5.5 gal tanks stored away. (one was a neat plastic tank I got from a seller from either New Zealand or Australia, the other a regular steel tank.)

 

The idea of a pressurized RH tank being a flow problem I don't understand. I would think that a pressurized RH tank would actually help force fuel into the LH tank. And even any or both tanks were pressurized, I'm not sure how it could block fuel flow, since the fuel pickup is immersed. It's unclear to me how air pressure in the tank could prevent fuel from flowing.

 

Personally, when I thought about doing this, I had wished to put an electrically controlled fuel valve between the tanks so I could start the flow at my discretion (when the LH tank starts reading low.) I probably would be OK with an unvented cap for the RH tank since the sealed cap is for the emissions vapor control system. The ecologically minded would want to connect a RH vent to the LH tank and use a sealed cap to keep things clean.

 

 

Dave

 

This was exactly my thinking, retain the standard LH tank setup and add a RH tank, fully sealed with a "breather top hose" and a "fuel bottom hose" linking the two tanks. I did a little searching though and it appears that with this setup there's instances of the fuel being drained from the left hand tank but not the right, even in one case fuel blowing out of the filler when the RH cap was removed. It doesn't theoretically make any sense but a more substantial link pipe across the bottom of the tanks might be all that is needed to sort the problem, if a problem exists.

 

Stu.

[sonscar]

Link them together and use both at the same time and you will even have a working fuel gauge,Steve..

[brivinci]

MPi tank is 7.5 Gallon. No idea where people are getting 7 from..

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Edited by brivinci, 12 August 2022 - 07:34 PM.

[brivinci]

I'm not crazy...maybe Rover was. This is straight from the original owners manual that came with my 94 SPi. 

I mean, this is the same manual that states the use of 10w 30 oil so I guess you take take it all with a grain.

[bluedragon]

Both the Rover Workshop Manual and the Owner's Handbook for the MPi Minis give the fuel tank capacity as 34 liters (7.48 Imperial gallons, 8.98 U.S. gallons.) I don't know why the above manual lists 7 gals for injection Minis - maybe there was a difference with the SPi models though as far as I know there is not a unique SPi fuel tank.

 

Going off topic, I've never seen anyone scientifically prove 10W/30 oil is bad for the Mini, so far it's all been anecdotal testimony. Whereas I've seen tribologists (oil scientists) who are also Mini owners indicate there's nothing inherently bad about this viscosity of oil.

 

Since Rover had to pay the warranty claims and take the hit to their reputation, they probably actually did testing to verify that 10w/30 was OK. I would have thought after all this time some ex-Rover employee would have come clean if this wasn't a sound recommendation.

 

 

 

Dave

[Steve220]

I'm not crazy...maybe Rover was. This is straight from the original owners manual that came with my 94 SPi.

I mean, this is the same manual that states the use of 10w 30 oil so I guess you take take it all with a grain.

I find that odd as I can get 7.4 gallons in mine.

[brivinci]

I always assumed the heavier weight was largely down to the gearbox being “in the mix”

As for the rover manual and it’s capacities, I never really paid it much mind. I shove as much petrol as I can and hit the roads. I’ve often thought about adding a tank for the added range. It’s rare that I drive more than 200-250 miles in a single trip, but not totally out of the question. I’ve toyed with the idea to drive from my location near NYC, to California. The extra fuel would likely be very handy

[Ethel]

Fears over liability? If they say the tank holds 7 gallons, they can't be so easily blamed if somebody dowses themself in unleaded on a BP forecourt.

 

There is also the evaporative loss system, not sure how much it'd matter if you sloshed petrol down the vent pipe to that, but I doubt it's improved by doing it.

 

Regarding the additional tank, I'd link them at the bottom and the top with sealed caps on both and run all the connections to the front off the original tank. Gravity should settle an equal level in both fast enough, save for filling. If you had to do it without modifying the existing tank you'd need a pump to transfer juice from added tank, unless you could rig up some fancy syphon system & never run it dry.

[Bobbins]

Picking up this thread because I'm again looking at the idea of adding a RH tank to an injected car ....

 

My JDM is having a full back to metal rebuild over the winter so anything that I might want to change later is going to be changed now.  I've always had a "want" to add a RH tank and now is the opportunity, but I need some guidance on what I'll need to do, rather than just the theory.

 

The car is a Spi/Mpi mix but I believe the LH tank is the later shorter neck injection version as fitted to the Mpi cars.  My understanding is the "S" RH tank will be the original longer neck version but should still be able to be fitted with an injection filler cap as per the left hand tank?  I might need to reduce the length of the neck to make them the same (OCD) but I'm sure that's a minor issue.

I plan to have both tanks modified to enable a substantial fuel transfer pipe along the front bottom of the boot floor and a simple breather pipe connecting the two tanks at the top, the LH tank will contain the pump and gauge sender same as currently, the RH tank will just be a plain tank with fuel and breather connections.

 

Does this sound viable?

 

Also, can anyone who's fitted a RH tank to a late model car give guidance as to where they relocated the washer bottle?  I'm sure there'll be no space in the boot with the added tank but my under bonnet space is pretty rammed already.

 

Also, is there a template for the filler neck hole on the RH side?  I know it's not symmetrical to the left side and is positioned further forward, I'm not sure exactly where (yes before anyone says it, I know it's on the rear quarter!).

 

All the associated bracketry should be fine in a late model shell so I suspect the actual install should be straightforward once I have the mods done and the position determined.

 

 

 

 

Regarding the capacity, an in-tank pump is never going to drain the tank dry unlike an outlet pipe positioned close to the bottom, this might be the reason for the 7 gallons being stated?

[Fanfaniracing]

Running a Mpi with righthand Fueltank is very easy if you keep the original intank fuelpump Tank.

The only thing i did, i added a connection pipe in the existing Tank and connected the ventilation of the Original Tank to the Righthand tank. Have serval Cars running like that for more than 10 years without any issues...

[Bobbins]

When you say you connected the vent from the LH to the RH tank, do you mean you vented as normal but include a T connection to the RH tank?
I guess the fuel connection pipe was simply braised into the LH tank?

[Fanfaniracing]

Yes, that's exactly what i did.

I conected the right hand Tank ventilation into the ventilation circuit of the injection Fuel tank with a T-Piece and Fuelhose.

I then turned a connector on the late and welded it into the injection Tank and also connected the Tanks with a Fuelhose.

Works without any troubles for years now

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Edited by Fanfaniracing, 29 August 2023 - 11:25 PM.

[Bobbins]

Fantastic!