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MG MGB GT V8 Factory Originals Technical - Converting to EFI???

How involved is it to convert a carbureted V8 to electronic fuel injection? I'm a pretty decent mechanic, but by no means a great one or a well-equipped one. Questions:

- where does one source an EFI system, e.g. a HotWire setup? ... from a Land Rover perhaps? Do you simply use the chip that Land Rovers have? ... I ask because I find it hard to believe that they'd be the same.

- how many O2 sensors must one add?

- is there any place in the U.S. that one can purchase an MGB fuel tank with a swirl pot pre-installed? ... it seems to me that'd be one of the issues I could not easily surmount

- is this a foolhardy project to try to tackle by myself?

Damon, I make up all the parts & have 4, hot wire systoms on the road & will have an early 80 sdi going next week. Yes I use the Rover goods & mod. them to my needs. It is so neat to have a 4.2 F.I. go down the pike at 80 m.p.h. & do 25 m.p.g. on 87 oct. WITH the A/C on. You should come down & see what you can do with this F/I to get it in your car.
Glenn Towery

I have a Rover EFI system from a 3500 Vitesse which I have overhauled and fitted to my rebuilt engine. The flowmeter and ECU have been checked OK but I have one installation problem I would appreciate assistance with. It concerns the fuel pressure regulator - is it connected upstream or downstream of the injectors? The connection points are obvious, but the direction of flow is not so I'm not sure whether to connect it in the line from the fuel pump (i.e. before the injectors) or in the return line (after the injectors). I I have the the Rover SD1 workshop manual and one for the Range Rover. Both are ambiguous. Can anyone help?
Roger Trett


Your fuel pressure regulator is fitted to the outlet end of the fuel rail and sends excess fuel back to the fuel and or surge tank(s). The fuel line at the opposite end of the vacuum line on the regulator is the return line. Make sure this line is not kinked in anyway as it will effect the fuel flow rate through the injectors.

andrew robson

Thanks for the answer Andrew. That's the way the Lucas literature shows it, but the Rover/LandRover and Haynes manuals are confusing.
Roger Trett

Damon the Land Rover sourced parts are the standard way to go. Unlike the Vitesse all the mapping done for these had fuel consumption (and emissions for later ones) as a main consideration. I used to have contact with the guys at the Lucas PI Lab and speaking with the chap, who was responsible for the Airflow Meter system mapping for the Viteese and early Range Rover Efi, he said that the Vitesse fuelling was 'very generous' since competion aspects were behind this car.

Later Airflow Meter systems on the 3.5 Range Rover does provide an ideal basis for an MG conversion. Form 1989 (1988 in the US) the Hot Wire systems appeared on the 3.9 first followed by the 3.5 Discovery. These are far more accurate systems and offer a slight power advantage from a less restrictive air intake through the airflow meter.

One thing to bear in mind with the Hot Wire systems is that when fitted to a Land Rover (or MGRV8 from Japan) there is a speed restrictor incorporated within the ECU. This hold speed to 112 mph. Elimination can be done via an ECU mod, or more simply by elimination of the road speed input that is part of the Hot Wire system.

The main reason for the raod speed input is however to better extra idle speed control through detecting when the vehicle is at rest. In practice the effect of not using this doesn't make a significant difference to the normal operation of the engine.

Another aspect for all injected engines is the simple fact that a constant high volume fuel supply is needed to keep the engine running. If the fuel pressure in the rail drops to below 12 to 14psi (normal pressure range is 28 to 36psi) the this has the effect of cutting the engine dead like you swithced off.

Now picking up air, even momentarily, does just this and so you have to consider the fuel supply from the tank. When the level in the tank drops below half and you do any spirited cornering, or in some cases acceleration, the fuel surge in the tank uncovers the fule pick up and the engine cuts out. Not ideal as I can vouch for.

The solution is to internally baffle the tank (as is done with Land Rovers), fit what is knwo as a swirl pot (a bowl inside the tank from which fuel is drawn and excess fuel spill returned, as is the case with many Rover injections), or use an external swirl pot of about a gallon capacity which can't suffer surge.

The provision of an extra fuel line and adoption of a suitable high pressure high volume EFi pump have to be worked into the system too. On the positive side conversion of any Rover (and probably it's predecessor) to use this injection set up is simple as all the system is conatined in the inlet manifold assembly. Only little notches in the top of each inlet port are needed to give full clearance for injector spray path, unless the ports are enlarged.

The wiring for the system is also user friendly as it is a separate harness which can be easily adapted and mated to the existing cars wirting with only a few interface connections. It is of benefit to create a completely separate power feed circuit for the injection though.

There are many other detail considerations but essentially this is a genuine DIY project for the competent mechanic. However you need to have some background knowledge in the make up and operation of the system to be able to make the instalation simple.

I think your first move now is to visit Glenn.

Roger Parker

Rog. I would have typed the same as you IF I could type. I have gotten into the F/I a bit & I think it is so neet! Thanks from me & the others, for it would take me 6 weeks to type this info. out.
Glenn Towery

I'm using a Rover 3.9 with the Hot Wire EFI. Glenn? Roger? would either of you or anyone else know of where one could purchase an RV8 fuel tank with the swirl pot? Any idea what it costs?
Dan Bogdanski

Dan, I make up the tank unit. I use the inline fule pump, with 1/2" hose to the pump, that mts. were the chrome cars pump was. Give me a call at 302-734-1243 10-3 E.S.T. if you would like
Glenn Towery

This thread was discussed between 03/01/2001 and 22/01/2001

MG MGB GT V8 Factory Originals Technical index

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