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MG MGB GT V8 Factory Originals Technical - Injection conversion

Currently i have a V8 roadster which i converted 6 years ago. I used the originaal set up with 2 SU. Now i want to convert it to injection system. I have acces to a Range Rover injection system.
I believe i need a swirl pot in my tank, a thicker fuel pipe, a return fuel pipe, a pump with more pressure and fit the lambda sonde in my exhaust system.
Where do i need to fit the lambda sonde and what other problems will occur beside the height of the injection system as described in the other thread?
Thanks
Regards
Peter
Peter

Peter,

The Range Rover system has two Lambda sensors , one in each exhaust side, I had mine mounted next to the sump facing inwards, several people have not bothered with sensors, the system then works in 'limp home' mode and runs rather richer than normal.

Good luck with the conversion,

Mike
Michael barnfather

Depending on your intended use of the car - you can use a large filter instead of the swirl pot - with a Volvo 240Turbo (Bosch) fuel pump and very high pressure flexible hose in place of steel or copper as your main feed (recent archive material tells you more).

The lambda sensors are only needed if your car has to meet current emmission rules otherwise you might need to change the tune resistor (in a 14CUX system) to tell the computer that the sensors are not fitted. A number of vehicles left the factory without these sensors fitted so the fuel mapping still works pretty well in this mode.

The inlet manifold gasket is another issue and since you will be replacing it anyway, there will be an opportunity to up-date it with the current version.

The speed sensor is sometimes overlooked and changing the drive from the gearbox and adding a second wire drive from the sensor to the speedometer is a bit of a fag however the system does need it.

You mention the plenum chamber height issue - a thinner LH engine mount is helpful if you have an RV8 style exhaust through the inner wings but you will still need to cut down the component units (again in the archives) to achieve height clearance under a standard B bonnet. There is of course the RV8 alternative.

E-mail if you have particular problems.

Roger
RMW

Michael,

Thanks for your reaction. I was planning to use the lambda sensors. I was a little surprised to find 2.
Normally 1 should do but it can be done. I thought that lambda sensors alway need to be fitted vertical but i don't remember where i heard this. What is your opinion on that statement?

Roger,

I was reading the archives yesterday and found your name with "the other Roger" (Parker) quit often.

Michael, Roger,

I was reading the book "How to convert your MG to V8" and the author seems to prefere the hot wire system as being a simple and good system. The fuel injection system where i have acces to, is a Airflow Meter System of a 1988 Range Rover. What is your opinion on this system? Should i let it go and wait for a hot wire system or should i use it.

Is it possible to test test the system or the components when not fitted to the car? The system was on the car and the car was running, but as most of these big cars in Holland, on LPG so i couldn't check if the system works.

Roger,
I had a closer look at it yesterday but as far as i remember, i didn't see a speed sensor connected. The car is an automatic (or are they all automatic?)
Your advice on the swirl pot is a very usable one.
The body is now with the bodyshop, totally dismanted so i could install a thicker diameter pipe instead of the hose.
The Bosch pump is a good advice. I was looking for the Range Rover fuel pump yesterday but i found out that this is fitted in the tank.

Thanks
Regards
Peter

Peter

I have run my fuel injection system with & without the O2 sensors using the appropriate resistor & did not notice any real difference- this is with the later '90 RR system- but chose to use the sensors as I think the provide a bit better fuel mixture.

I really don't like the idea of using the thinner motor mount, but driving as a "lefty" I may not have the same problems. Using as a guide the info in the archives, I had all 3 pieces machined & the trumpets shortened & have no problems clearing the hood (bonnet) with the V8 pucks. I do have a bit more setback acheived with the motor mount adapters from D & D here in the U.S. I recommend as much set back as possible for front clearance- room for an electric puller fan.

I have not been able to install a speed sensor & the only problem experienced is a bit of fast idle when stopping the car. Slightly annoying but better than going back to a mechanical speedo & screwing around with cables & adaptors. If you use a mech speedo & can get the cables, you will be happier.
Jim Stuart

Peter - good advice from Jim - in answer to your question about the type of FI system to fit, there are (at least)two considerations; firstly that 'the word' here is the earlier flapper system was never really 'sorted'. I do not speak from experience but those close to the trade made comparisons with other contemporary systems and found the early RR wanting. The second point concerns lifespan; the 14CUX system was widely used by Landrover and by MG - it is well documented for both makes of vehicle and that means you should be able to find people who understand it - and can find parts for it, for many years to come. I believe that is a very compelling arguement for the later system (basically the next owner can tell a garage that the mechanics are RV8 or LRover and expect them to sort it). For the same reason, I support the American variations on the V8 theme - the knowledge base and parts situation in the States is different and they will be able to keep the say the Ford V8 going for much longer.

Anyway that's my twopennorth - many will disagree and if you are doing a lot of autoroute driving, it might be wise to consider the oil price and whether a bifuel conversion might be a sensible compromise - we are heading for a 5 gallon and the price won't stabilise there.

All the best

Roger
RMW

Peter,

I originally had the flap-valve (83 Vitesse) system, and converted to hotwire 14CUX at the end of last year.

I cannot do a direct comparison between the two systems, as I also installed an uprated induction system from a TVR, which has much shorter trumpets,and bigger bore inlets, and throttle plate.

I can confirm that both power and fuel consumption improved dramatically, and there was a further improvement in fuel economy when the Lambda sensors were fitted this Spring ( I can now get 33+mpg at 60/80mph cruising speeds).The sensors were fitted by a firm which constructs exhausts, who I assume knew what they were doing when they fitted them horizontally.

I did not connect the speed sensor, but wired it to earth with a resistor (can't remember the value, but could check it up).I did not suffer from fast idle problems when I disconnected it to test, and I know not everybody bothers with it, so it's probably not critical.

Mike

Michael barnfather

The tubing you need is called "Bundee" tubing (not sure of the spelling). It is similiar to brake line but much larger. It can be got from ay hydrolic hose shop. I got mine from ENZED. You are sure to have some place similiar locally.
It's fairly malluable and you can bend it with your hands (use thick gloves) but a small pipe bender would make life easier. I forget the thickness i used, but I just matched it so it could be easily connected to the end of the fuel pump with an appropriate bit of rubber hose. A size up from the existing fuel line I recollect.
You can solve your fuel supply very quickly and cheaply by fitting a very late model MG sender to your existing tank. This incorporates a fuel line pick up. You use the old pick up on the side of the tank as the return line. The high pressure pumps all draw fuel very poorly and may become noisy if you are trying to draw through a filter, and you MUST have a filter. You may need to use a "feeder pump". If you use a high volume ,low pressure pump such as an Auto suction rollervane pump (which draws fuel very well) pierburg #12001) pulling through a large filter, thence to the larger high pressure pump(which draws fuel very poorly); you will not need a swirl pot. The big filter acts as one. If you've economy and speed /ease of application in mind this is probably best, I found it so.
If money and difficulty isn't a factor then possibly the best approach , is to get a flange, swirl pot with filters and "in tank" pump welded into the tank. Keep in mind that you will need to get at it to change it should it fail.
An intermediate approach (in cost and difficulty)is to use an external swirl pot(small tank). You need a pump to pump fuel to it and a return line to the tank to bleed any fuel vapor which builds up (ie you still need that late model sender and feeder pump). You need a line from the external pot/tank to the high pressure pump and a return line to the pot from the engine. Some folks have adapted the remote oil filter to this purpose and have a combined swirl pot and fuel filter which is a smart notion I think. Your swirl pot obviously must have four lines, two in and two out. Put the return line to the main fuel tank at the top to bleed any fuel vapor. build up.

Some people have found that the high pressure fuel pump with filter (no feeder), mounted on the battery box works for them. I found it noisy and irritating and getting much noisier in the summer.
Peter

Roger,

Thanks for your advice. I assume the injectors and the inlet manifold are more or less identical so i can do the modifications to the inlet manifold and trumpets and if i get problems with the AFM system, i can fit a hot wire system.

Michael,

I was planning to fit the lambda sensors and its good to knowi, can fit these in a horizontal position.

Peter,

Thanks for the additional information which gives me a lot of usefull information.

Regards

Peter
peter

This thread was discussed between 10/10/2004 and 16/10/2004

MG MGB GT V8 Factory Originals Technical index

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