common rail diesel

The reciprocating parts of an engine are all much of a much so no fundamental reason it can't be done. But I can't think of any classics with indirect engined Diesels that'd be worth updating (I say this entirely as a challenge for Adrian to come up with something) let alone ones where the cost & palarver compared to buying a similar sized CR engine and fabricating new engine mounts and sourcing/modifying a bellhousing to fit the gearbox would be worth it.

TBH, I'd be more wondering why anybody'd bother adding all that complexity and potential ball-ache.

There's certainly nothing like Megasquirt for common-rail diesels, that I'm aware of, so you'd have your work cut out on remapping, even assuming the actual hardware was doable. The pressures of common-rail diesels should scare the shit out of anybody.

I'm assuming you're thinking of converting an engine in-situ rather than taking an old engine out and dropping a new one in, which would probably be the simplest way.

You could do some research into the PSA group engines for the Peugeot 306 and Citroen Xantia to see what the difference was between the early mechanical injection and later HDI common rail versions was - these are 2 cars where I know they started out as 'old' diesel but had common rail fitted to later models. Even with these you would be replacing the cylinder head and injectors, high-pressure injection pump, and adding a completely new ECU with plumbing and wiring to suit. I suspect the chances of common rail components fitting and working with an 'old' cylinder block would be minimal.

Not quite that simple - the car might be the same, but that doesn't mean the engine is. The DW10 HDi is a long way from being an XUD-with-common- rail, although it is derived from it. There was a non-CR version of the HDi, the DW8 non-turbo.

No point with indirect, AFAIU common rail injection with a priming squirt civilises direct ignition engines.

Where's the difference if the pump and injectors for a common rail system are used?

Anyway the question was hypothetical for my interest as we are scrapping 4 or more fords every year with fuel pump problems at between 120k and 150k miles where the basic vehicle is sound, when the pumps break up they seem to write off the injectors too.

AJH

So you're starting off with an engine for which bolt-straight-on pump, injectors, rails, manifolds, etc are available...?

I think there's a huge difference between pissing a bit of petrol into an inlet manifold and squinting diesel under very pressure direct into a combustion chamber. I suspect that the economics of an after-market injection system for diesel would never break even.

Tim

And also starting off with cars that are scrapped because their repaired street value is still less than the cost of the bits!

Eh? Well why ask about "converting older diesels to common rail" then? Starting with a CR Diesel isn't converting, it's repairing.

The CR pump itself is unlikely to be a drop-in replacement for a distributor pump. The cylinder head looks very different because CR engines are usually direct injection. Distributor pumps were usually a cable linkage to the accelerator pedal whilst CR engines are almost certain to be FBW via an ECU. The list goes on ...

It's a question I've seen asked on the MegaSquirt forum - and I haven't really cared much why, but it seems it would be a very tricky thing to do.

Petrol injection pressure - ~3 bar. Citroen hydraulic suspension pressure - 70 bar. Common rail diesel injection pressure - 2,000 bar.

Add in that diesel injection timing is critical to combustion - to a far higher degree than petrol injection and ignition combined...

What benefits do you expect?

If its quieter operation then the common rail Diesel will be useful as it can have multiple injection events in one combustion cycle. Pop pop pop pop instead of ka-boom! Emissions? A longer injection period allows more of the fuel to be burnt or more fuel to be burnt without making smoke. If its power you want then you need a variable vane turbo. DOHC and 4 valves / cyl are also a great power booster. Common rail by itself won't give worthwhile power gains.

Benefit of megasquirt on SI engine is that the restrictive manifold is removed and better flowing individual throttle bodies fitted, usually on ported inlets, bigger valves, lumpy cam. Mapping is relatively easy, cheap and accurate compared to all the faff of jetting up a pair of Webbers or a set of Hollies.

Much easier to select common rail engine of choice and drop that in your car. Then you get a modern engine and have a spare boat anchor.

Someone put an engine and gearbox from a BMW 320D in a 200SX. Then as it's top speed was 90mph swapped the diff to get the gearing right. Then ripped it out again as it was an utter abomination (compared to the stock 1988 1.8 SI 16v DOHC turbo).

Though a few other Diesel conversions do still exist, only one is taxed.

I'd guess it wouldn't be a problem to produce a driver for the injectors - but a suitable processor might well be. And, of course, writing the software for that.

But it's probably just down to demand anyway. Megasquirt is used to provide EFI on an older car which was originally carb, or to update an older EFI setup. (Like I've done on my Rover SD1) Modern common rail diesels are probably already 'state of the art'.

It's also basically a DIY system. Starting with the universal base map supplied, you can get any petrol engine up and running quite easily. Since both the AFR and ignition timing ain't that critical just to get the engine running - before proper tuning. My guess is this isn't so with a common rail diesel.

Many seem to think individual throttle bodies are somehow the holy grail - and they might well be on a race engine. But for a road car, a plenum system is generally a far better option as it gives a stronger low end - and is much easier to tune. As you can then use either the engine vacuum or inlet air flow as a parameter to control the fuelling (Speed Density). With throttle bodies you're more or less stuck with just using the throttle position (Alpha-N)

Rubbish.

3 or 4 standalone CR diesel ECU's are available off the shelf if you can mount the hardware, the ECU will run it.

See here for an example:

On Tue, 27 Jan 2015 16:59:48 +0000, "Tim" > There's certainly nothing like Megasquirt for common-rail diesels, that

Well, I did say "that I'm aware of"...

Retails through Simtek, apparently.

makes no mention seems to resell a different product - BodyLogic - - based on the SC Tornado ECU, which SC list under petrol injection - and that's three grand plus for a tailored and (locked-)mapped install. Ouch. Hardly megasquirt territory...

At about 3500 quid, it's not exactly in the MegaSquirt class.

Maybe I've misunderstood but the OPs question was about fitting a whole common rail system, not just a control box.

Does the linked system include HP pump, plumbing, injectors etc.?

Tim