2 stage injectors on a 2.25 diesel

[wood-gee]

I've been pondering why my 2.25 diesel is quite such a noisy engine, and it led to me thinking about 2 stage injectors, which are said to reduce knock and the possibility of retrofitting them on one. Before anyone shouts 'it can't be done', or 'they're best stock', I recognise this is almost definitely just going to turn out not to be possible, but I enjoy learning about how these things work in the process, and it's nice dreaming about how you'd improve on any design.

Getting into it, my understanding is that the 2.25 uses a single stage injector, driven by the rotary distributor pump, and that the injectors are essentially needle valves that open above a predefined pressure. What I've read indicates that systems like this operate at around 100-150 bar. A 2 stage injector on the other hand is effectively two needle valves combined, where one opens at a lower pressure than the other, and generally runs on higher pressures, ie 200 bar first stage, 400 bar second.

Given that the distributor is also the high pressure pump that means you'd have to replace that as well, so I was pondering the possibility of attaching one from say a 200 or 300tdi, along with their injectors (2 stage).

I was curious what issues spring to mind for anyone reading this. I'm assuming you could get the timing right, and create adaptors to fit the injectors into the block, and to drive the distributor, so thinking more in terms of cracking parts of the engine, buggering up pistons, cranks con rods and the like.

[Ex Member]

It is not direct injection, so that does not work,

[wood-gee]

I new there may be something simple like that, thanks for the input!

[tugboat]

The indirect injection Ricardo pre-chambers in the 2.25 have a Rover patented mod (see link below) for inducing additional swirl and turbulence to give a cleaner quieter burn than other diesel engines of the period. This innovation actually does work well.

Indirect injection diesels are generally much smoother and quieter than direct injection engines (until you get to computer controlled multi stage common rail setups). The Rover 2.25 in good condition and properly set up is exceptionally quiet for its time. If yours isn't, it's very probable that the injection timing is out, quite likely too advanced, set that way to mask wear and to get rid of blue smoke and misfires at idle.

http://www.google.com/patents/US3025839

[Gazzar]

That's the big problem with that diesel - using the petrol style dizzy drive for an IP adds too many wear components to the arrangement. That, plus a 3 bearing set up, isn't a recipe for a long life.

Interestingly LR were working on a DI turbo intercooled diesel in the 1960's but funding was cut off by HQ, probably to conserve funds for Jet engines or some such rubbish.

[tugboat]

^^^^ And one thing leads to another. Bad timing leads to very poor starting, which leads to heater plug and starter motor burnouts and short battery life. Misfires on idle and at low load give rise to diesel vapour condensing on the cylinder walls which causes ring and bore wear. It also results in fuel contamination of the lube oil which, of course, accelerates further the wear in the timing gear.

I agree that the long path from the crank to the injection pump appears to be a recipe for trouble, and in the Rover diesel it most certainly is, but I've a lot of experience with the similarly configured BMC 1.5s and these seem to be very much less susceptible to the problem. It's definitely the Rover's Achilles heel. If Rover had tackled it properly, the engine would rightly be regarded as a classic rarher than a bit of a dog. Too many sexy projects for the boys to play with instead of sorting out their main revenue earner's boring pump timing, layshafts, half shafts, etc., etc.,

[Gazzar]

Always the way - the apprentices were given the job of desigining the defender, while the "chief designer" designs the lifestyle vehicle with the pop star.

Nevermind, if they didn't break so much, we'd not have the fun of rebuilding them properly!

[tacr2man]

The 2286 diesel was a big improvement on the 2 ltr , and is a good workhorse , if not over endowed with power when comparing with a modern engine . I tried over many years to get more out of one , as my 109 got heavier , its slowness became more noticeable. Land rover was doing the same and put a turbo on , which greatly reduced its longevity . If maintained well , they are very reliable , and a lot quieter than a 200 tdi ! They were also a very good engine for bush work as were easily diagnosable , and easy to fix. They can handle a lot of abuse as well. They need to be very precisely built and timed to get the best out . You just have to decide , as I did that flogging a dead horse achieves nothing , and I retrofitted a 4ltr leyland diesel , which would rev lot less but with gearing mods would hold 60 mph with ease .

[wood-gee]

Thanks guys for the input, although I do now feel pretty silly for my first post, which had I taken a little more time to research would have saved me asking the question in the first place, you live and learn, and the other comments posted on this has been really helpful in understanding a bit more about my engine.

Tugboat - do you mean that if the timing is off, this will result in increased noise and misfires at idle, or did you mean it may have been advanced to avoid these misfires: I've currently got a very noisy 2.25 diesel which has a frequent misfire and corresponding puffs of smoke at idle and isn't overly keen to start, the source of which I'd been told may be the timing, and although I intend to try and address it soon, it'd be a bonus to be fairly confident that that is the source.

Also it's very interesting to hear your comment re 200 tdis Tacr2man, I'd been considering one as a future upgrade, predominantly to reduce noise, but also for a little more power, but going by your comment if I get my 2.25 sufficiently sorted I may be better off staying with that and embracing the occasional tailback if I'm trying to keep noise down, although I suppose a valid counter argument is that a more powerful engine would allows taller gears and thus lower revs at cruising speeds. I know noise levels are never going to be perfect, and frankly I feel it's all part of the cars character when I'm driving along on my own, but I am keen to try and find a way around the current situation of having to shout to have a conversation whenever I have passengers. Is the 300 tdi any quieter? I know it has a slightly different block and an exciting piece of plastic on the top, but sadly still don't know enough about engines to know if that makes much difference.