CRDI: possible on an old diesel?

[oldbeaver]

For the diesel experts:

What if I take my old diesel engine, with a rotative Bosch injection pump and common mechanic injectors. Then:

a) I take out injectors and injection pump. Easy.
b) Install a high pressure injection pump. Easy.
c) Install a Bosch Common Rail Direct Injection (CRDI) system. Not easy.
d) Install an electronic injection computer. Easy.
e) Install electronic governed injectors. Easy.

Make all CRDI work (not easy) with the necessary pipes, wires and sensors:

Would the engine work?
Is an old block, are old cylinders and pistons so on, able to resist the new efforts?

Old Beaver.

[Ryland]

Does that engine have pre-chambers or is it direct injection?
Making all the bits fit and finding ways to make the sensors work with the old block seem like the hard part, remember that you are also working with ~20,000psi in the common rail... so make sure it all really does fit right.

[oldbeaver]

Tks for replying.

Well, I don´t know. How can I realise that?

The engine is a Nissan RD28 1996, (18 valves) 6 cil in line, aspirated engine.

It has a Zexel (Bosch rotative) injection pump with 6 pipes coming out of it, going to each cylinder. Should be a direct injection system, isn´t it? At least, it sounds to me as such.

So, you think it is possible?

Well, I know, it won´t be cheap. Maybe it is better to keep it mechanic and swap for a mechanic turbo RD28 or such.

The question is the engine is very good, runs smooth, is economic, a little slow, but runs well. Good for the car.

Of course, I would like to improve performance and I will.

Thank you again,

OldBeaver

[Arragonis]

Happy new year!

Interesting thought - I don't think its a simple changeover by any means - it would be a little bit like changing an old petrol engine from carbs to a modern FI system.

If you could get it to work the advantages you would see from the swap will be less noise (the noisy part of an old Diesel engine is the mechanical fuel pump), less smoke under load and will use less fuel. You probably wouldn't see more power though.

If you want more power from a Diesel you have to make a bigger bang - power = size of bang x number of bangs (BHP = (torque (lb/ft) * rpm) / 5252 - I think). You can't make more bangs as Diesel doesn't burn as fast as petrol - hence the lower max engine speeds.

To make a bigger bang you need to burn more fuel. You could adjust the injection pump to do this probably but you will see more smoke and potentially it may make no difference to the performance at all. You also need more air as well, so to really make a difference you will need to go with a turbo.

If you have access to a complete replacement engine then that would probably be the least painful route to turbo boosted happiness.

[user removed]

Does Nissan make a later version of that engine with modern high pressure injection?

I think your engine is based on the L series in line six that was first used in the 240Z here in the US in 1969. They made a 2.4 liter diesel version that was used in the Maxima until 1984.

Pretty sure it is a prechamber design, so you would probably have to use a later version cylinder head, if they even exist.

Best bet would be to check the opening pressures and spray pattern on your existing injectors. In the Mercedes engines we found that the opening pressures would drop from 1800 PSI to about 1500 PSI over time. Replacing the spring the each injector brought the pressures up to 1800, which is the spec for a new injector.

This would reduce the smoke considerably and the noise slightly. A turbo would give you more power and probably some improvement in fuel economy. Those engines are very strong with forged crankshaft and connecting rods. I have seen one that went close to 700k miles before the cranking compression dropped to the point where it would not start without boosting the battery. Guy drove it 85,000 miles a year.

regards
Mech

[oldbeaver]

Tks to OldMechanic, Arragonis and Ryland for the comments and advice.

I wrote an extense response to your comments, which was lost when posted to the Forum, and I am not going to write it again.

Please, refer to Nissan RD engine - Wikipedia, the free encyclopedia for the history of the RD28 engine and it´s versions. It started production about 1984 and ended about 2002, I think.

The Laurel is still a demanded car in cold countries like Sweden, Finland, Russia and in Australia also.

The Patrol (which uses a RD28 turbo) is still demanded in Northern Africa, Australia, South America, Spain, other europeans countries.

Here in Chile the RD28 engine is very well known as a swap engine, for its reliability, smoothness, low noise and low price, even when a few diesel Laurels came as imports specially by japanese diplomats about 15 to 20 years ago.

People prefer the Nissan TD27 for swapping on 4x4 or small trucks. It is smaller, lighter and a lot more powerful. But vibrates more.

One person I know installed that engine on a Mercedes 300SE (it is heavier than mine) and broke the differential, due to the higher torque.

My best wishes for you for the year that start today.

OldBeaver

[Dave's Civic Duty]

I know on my 98 Dodge Cummins, an upgrade kit to common rail is available, so it is possible.

Dave