I'll try to be clear and concise.

Having recently learned about the improved efficiencies with high pressure direct injection automotive diesels (upwards of 20% just on improved atomization alone) I've been forced to wonder about the possibilities of retrofitting the already economical CS model with something comparable.

I thought best to put it out here for all of you with lifetimes of experience beyond mine for some feedback on the variables and implications involved.

Simply put: Why not fit a 2400 bar system (pump, injector and lines) with appropriate simple electronic switches to get one of these beasts ultra-economical?

I understand they aren't direct injection...but is that paramount to the process?
Is the engine otherwise actually in need of the extra lube in the unburnt fuel? What problems would running this much leaner cause?

Thanks in advance!

SES

In a diesel engine one has droplets of fuel which are burning.  The object of the exercise is for all the droplets to burn quickly, generate heat and push the piston down.  One can surmise that the smaller the droplets the faster the burn.  Now in an engine that is running at a low speed there is more time for the fuel to burn so there is no need for ultra small droplets.  It is still important however to have an adequate injection pressure.

One engine that gave its owner great trouble was a Petter Mini Six.  It was the marine version.  The exhaust was grey and stinking of unburnt fuel.  When the injector was tested it had a pop pressure of 1800 psi.  On a Mini Six this is useless.  The pop pressure needs to be between 2200 and 2400 psi.  That extra 400 psi creates smaller droplets which do burn OK before the exhaust valve opens.

Other people's experience of Common Rail seems to be that it is very unreliable.  One person I know spent £3500 on repairs to his VW Caddy van when in all probability the fault was just a  fractured intermittent wire.  The Main Dealer replaced (1) The injectors.  (2) The camshaft.  (3) The cylinder head.  (4) The turbo-charger.   When they did finally fix it they would not say what the fault was!  Another bloke trashed his ultra high pressure pump (normally £800) on his Citroen when he ran out of fuel!  Fortunately a scrap-yard had a good pump on a knackered engine and this saved £650!

Eliminating the "jerk pump" does allow diesels to run faster but as the pistons are much heavier than those in a petrol engine the improvement in rpm is very modest.

That's fine in theory, however the rule of thumb has generally been accepted as no faster than 5000 ft/minute rim speed.  That's based on the tensile strength of good quality fine-grained cast iron (which Indian Listeroids sadly lack) with a generous safety factor thrown in.  There was a discussion on this subject a couple of months ago or so.  Do a search under FLYWHEEL and you'll find it.  Kevin posted the information out of Machinery's Handbook which is the definitive reference.

Quinn

There are so many types of cast iron and unless one has the premium grades its not the most trustworthy material.  Many years ago I was living in London and word was got to me that a friends car had broken down and he needed towing in.  When I got there it was a disaster as one of the engine mounts had torn away a large piece of the engine block and black oil was everywhere.  I seem to remember that the engine had to be roped-up so that it didn't drag along the road.  It was a defective block that had a line of air bubbles in it and it had broken along the line of bubbles.  Normally those 1172cc side-valve engines were very reliable but not this one.  When Ginger complained to the manufacturer they told him that he had has his moneys-worth out of the engine and they basically told him to get lost.  That's business.  Some more expensive makes such as Triumph (cars not motorcycles) would use "Chromalloy" blocks and the engines would last almost for evermore.  As with most things you get what you pay for.