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Dear All,

Dave  (Longen) touched on the fitting EFI to a Meadows petrol engine.

In my opinion this would be quite easy and economic to do using a Speeduino as I have done with the Meteor.

A key question is "does the inlet manifold have a separate port for each cylinder?"  If so, it would be easy to fabricate a new inlet manifold to mount the injectors and provide an inlet tract for the fuel to 'rest' in before being sucked into the engine.

When I used an Explorer in the TA in the early 80's, I did not experience any problems with the carbs.  However, the system would have been designed to ensure that the engine ran rich in order to avoid any possibility of the pistons burning when working hard.  With an EFI system the mixture can be kept optimal all the time.  There is provision for cranking enrichment, after start enrichment, acceleration enrichment and cold running enrichment.

There is also provision for electronic ignition.  On the Meadows there is no vacuum advance for the magneto so the timing cannot be optimal.  With Speeduino EFI the ignition timing can be altered to suit both PRM and manifold depression.

The bare Speeduino PCB is less than £10.  The Arduino MEGA is about £30 and is widely available.  The necessary software is open source although I do not understand it.  Thus it would be easy and sensible to have a fully programmed spare ECU on the vehicle.

With the Meteor engines,  I noticed that the Conqueror ARV with EFI used significantly less fuel than the Cent which does not have it.  I would expect a petrol explorer with EFI to be significantly more economic.


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Thank you John.

this has motivated my thinking. The Meadows has 2 identical heads with 3 individual ports for inlet per head. So indirect injection through injectors in each inlet tract. Each inlet connected to an inlet plenum with single throttle valve.

so now to the first questions,

crank position sensing, pick up off flywheel?

injectors, required capacity, is there a 10 litre petrol engine already with fuel injection ?

the above is just me thinking out loud but if anyone has already investigated this I'd be interested in piggybacking off your knowledge.

picture from Explorer parts books.




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Fitting EFI to a military vehicle engine should not be too hard as although the cubic capacity is usually large, the peak power is not that big so the injector size is not unreasonable.

As well as the ECU you would need:

A high pressure fuel pump

a 3 bar fuel regulator with return line to tank

A fuel rail to hold the injectors onto the manifold

Crank trigger wheel

Throttle position sensor

All these bits can be got from eBay

A long time ago I wrote an article for Practical Performance Car on choosing the pump and injectors and I will try to dig it out and put the relevant bits on here.

From memory, when Dave Walker (Emerald M3D ECUs) fitted EFI on a Meteor engine in a Rover SD1 he used Rover 800 series injectors. I can also thoroughly recommend Dave's book Engine Management published by Haynes


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For the RPM and crank positioning I fitted the trigger wheel inside the Meteor's magneto.  The "Scintilla" magneto is quite small diameter and might create problems fitting a trigger wheel inside it.  You could dispense with the magneto and just use the mounting for the trigger wheel.  A hall effect switch is pretty robust and reliable.  The only requirement would be to shield it from accidental mechanical damage.  The ignition and advance would come from the Speeduino.

For certain set ups, you can use the flywheel teeth. However, you might need to have a 'missing tooth'.

The size of the engine does not matter.  The spec for the injector says how much fuel it will pass at normal fuel pressure and its rough horse power.  I had Rover V8 injectors available but the Meteor needed 24 of them to get about 670 BHP which I thought would be enough and it was when I tested it on the heath at Bordon.

This the data for the injectors that I am using:

ROVER PT No ERC 3620  
Bosch Pt No 0 280 150 105  
Flow rate 18.1 Lbs per Hr @43 PSI
  187 cc per min
HP per injector 27.8  
Impedance 2.2 Ohms  
AVAILABLE POWER Is 24 X 27.8 667.2


These injectors have a rubber hose coming off them rather than an O ring fitting.  A firm called Turbo Technix used to have a huge stock and would sell them cheaply.  New injectors are about £40 to £50 each so it might be better to ID which one is required and get them from a scrap yard.  

You are correct in your thoughts about the inlet tracts and the plenum.  A problem could be the clearance from the side of the engine to the bulkhead.  The inlet tract and plenum does not want to be heated as does an inlet manifold with a carb.

The plenum would want to be quite big to ensure even air distribution.  Say 4" in diameter.

You would also need a lambda sensor in the exhaust and as high up as poss.  Finally, the throttle position sensor.  You could use one off a car or use an ordinary potentiometer.  I tried the latter but found the former gave the ECU values that it expected.   

If you were to swing round to me I can show you the Meteor's modified magneto which I call a discombobulator.  Alternatively, you could come up to the barn at Basingstoke and see the complete engine.

I thought that your Explorer had a 680 Leyland in it?



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Thank you both for your replies. Very encouraging.

pc1959, I've seen videos of the SDI Rover but nothing about the build.

John, good detailed information. I admit the websites for the ecu's are a little confusing and I need to continue to research that. Interesting you appear to use 2 injectors for each cylinder, I assume to get sufficient capacity. I hadn't considered that. I assume your triggering 2 from the same ecu output.

the Explorer currently has a Leyland 680 and it works well. However I also have a complete Meadows in the garden shed which was an insurance against the previously discussed possibility of loosing historic tax status if major changes had been made to a lorry.

my intention was/is to get the Meadows running on a test rig and then decide wether to change the Leyland over. 

regarding your offer to see the discombobulater and complete engine, I'd like to take you up on that next time your visiting the barn. I've got a phone number for you ending 926. If correct I'll message you my number and you can contact me when convenient for you to arrange the visit.


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On the SD1 Rover,  that was done by Charlie Broomfield and I have spoken to him about it.  I think he used an OMEC controller that was professionally installed so it would not be cheap but I did not ask any impertinent questions!

For a big truck engine, a Speeduino or a Megasquirt controller will do all that is needed.

For the Meteor I did indeed need two injectors per cylinder.  It would have delivered nowhere near enough fuel otherwise.  I had to make what is called a 'peak and hold' injector current control system using LM1949 chips. The data sheet for the chip explains all.

On historic vehicle exemptions.  The EU Road Worthiness Directive was predicated on the needs of the accession states that still had numerous old and unsafe vehicles in commercial use on their roads.  They wanted as tightly drafted historic exemption as possible.  From my own experience I know that our Department for Transport wanted to bring as few vehicles as possible into goods vehicle testing because of the very limited road safety benefit in doing otherwise.

If a Scammell Explorer is 'historic' I don't know what is!  However, having the right petrol engine in stock is a good insurance policy.  Equally, a 680 Leyland is a 'historic' engine itself and it is hard to think of anything better to fit to an Explorer.

Once I have finished my current work schedule on Meteors, we could put your Meadows petrol into my run-up rig.  You will find that it takes quite a bit of time to make one up!

Dave, you have the right number for me.  Give a ring anytime soon and we can arrange a visit to the barn.  Meteor should be running again at the back end of the week.




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  • 1 year later...

Hi Guys,
Bit of a thread revival so I apologise.
I was discussing armour and making them more reliable for sporadic civilian display use (read: reduced manpower, funding and spares availability) with a friend recently and they mentioned your EFI and Electronic Ignition efforts with the Meteor John, sounded very interesting!

When my Explorer was Meadows powered I intended on fitting an electronic ignition system from Megasquirt to help with starting etc.
I still have the kit in the shed actually along with the Meadows with the intention of making a running display engine to pop onto an Arrows trailer.

Recently I have stumbled across two things that may be of relevance and interest in this thread:

First is a company doing Fuel injection conversions on classic cars via a couple of different methods but one of which is a replacement "carb" which has built in sensors, butterly and injector and doesnt detract from the classic appearance of the engine in any great manner

The second is a bloke on youtube who has created a device called a "CarbCheater" which is basically a closed loop PWM control of an off the shelf idle control valve from a modern vehicle which adds air to the intake after the carb to lean out the mixture to 14.5/1 accurately. Parts count was about $100 for the circuit board, valve and AFR sensor.
He is looking to make it an open source project like Speeduino.

Hope this is of interest!

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My preference would be to go for electronic fuel injectors.  I am aware of Classic Fuel Injection's work from the net but I have not seen an example.  I expect that it is aimed at a market where originality is very important.

The leaning out technique sounds very interesting and very clever although great care would need to be taken to ensure that the added air was properly mixed.  The advantage is that the original carb system would work perfectly well on its own.


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