Common Rail Diesels

Redbay Rover · 30 October 2003, 16:28

Common Rail diesels are undoubtedly the way forward. They are more economical, have bags of torque and have no trouble with the forthcoming emmision regs. Why then is it that only Volvo seem to have a common rail engine (D6 - 310) on the market. I am currently speccing a new Redbay 8.4 but the D6 is too heavy, redbay have recommended the Volov KA300, but I reckon common rail is the only way to go. Anybody know of any other common rail engines on the market?

P.S. The Yanmar 300hp would be a better bet than the Volvo Ka300, right?

Brian · 30 October 2003, 18:41

Could you please tell us, in words of one syllable, what the diference is between a common-rail diesel and, er, the other type?

Redbay Rover · 30 October 2003, 18:52

I'll try. Common rail diesels have a rail that sits above all of the cylinders in the engine. The rail is full of pressurised fuel ready to be injected. A computer controls when the rail injects fuel into the cylinders. It is quicker and more precise than standard direct injection. Diesel car engines have used common rail for a few years now, and it's leading a revolution; making diesel cars much better thatn petrol ones (faster, more economical and fewer emissions). Why aren't more marine diesels common rail?

Petrov · 30 October 2003, 19:09

Have never seen a diesel engine that is faster than petrol in a car, maybe stronger but not faster, and it`s not every country that diesel engines are more economical, they are more expensive to buy and in Sweden for an example we have higher taxes on a diesel engine than on a petrol engine.
You must drive at least 20000 km before it`s more economical than petrol, i think an average person are driving around 12000 km per year.
I know on boats in Norway, both petrol and diesel engines they pay 12 GBP/HP in tax when they buy a boat, it`s unbelivable expensive, so check it up in the country you live in before buying, maybe it`s same rules in UK, but not outside UK.

Regards

Petrov

jwalker · 30 October 2003, 21:01

Quote:

Originally posted by Redbay Rover

P.S. The Yanmar 300hp would be a better bet than the Volvo Ka300, right?

Some may think so.

There have been a few debates on here, do a search.

crazyhorse · 30 October 2003, 21:09

Eve all

In answer to your question why arent all diesels common rail,then its down to development and tooling costs and getting rid of old stock.The D6 will be worth having when its putting out 400+Hp as it has the stroke,At the moment the advantages arnt worth having over a kad300 eg costs and extra weight ect.

All that sort of stuff.

In answer to Yanmar being better than Volvo why do you say that?

jwalker · 30 October 2003, 21:16

Hi CH. Well wot's it like?

crazyhorse · 30 October 2003, 21:21

Brill JW, but real slow at the moment,Having to re spec the windows ect,for self righting.I will be happy when its all finished.

jwalker · 30 October 2003, 21:30

Why not jump to your old Volvo thread and tell us the stories?

crazyhorse · 30 October 2003, 21:32

I will tell all when she is finished,It will make your hair curl.

thewavehumper · 30 October 2003, 21:33

Quote:

Originally posted by crazyhorse
EIn answer to Yanmar being better than Volvo why do you say that?

Youre both wrong. CATS are the best.

KADs are notorious for several weaknesses i.e. valves, pistons, head gaskets to mention but a few.

Yanmar suffer from excessive turbo lag, cracked blocks, breaking drives and creating an impenetrable fog screen wherever they go.

Stu.

crazyhorse · 30 October 2003, 21:43

Hi Wave, sorry I forgot you are now a diesel expert as you needed to fix yours didnt you.?

Hope your well and you got that Big Cat of yours running at over 2500 revs .

Cats are very good engines in the right application,them that run that is.

Redbay Rover · 30 October 2003, 21:49

I read on the Cummins Mercruiser site that Mercury will be launching a common rail engine soon, but it dosn't say exactly when. I think alot of manufacturers will start to churn out common rail engines so that they meet the 2006 emission regs.

Anyway, forgetting about common rail for the moment, what is the best circa 300 HP diesel engine at the moment? I need it to be quiet, reliable and full of torque. I'm not too bothered about fuel efficeincy and emissions.

Petrov · 30 October 2003, 21:50

I think it`s hard to say that one engine is better than the other, a lot depending on what and how you are using your boat and what kind of boat.
Offcourse you can never build an engine that will be the best engine on all boats and use, we all have different experience and good luck and bad luck, exactly the same as with cars.
But i will recoemend an engine that is very reliable, a lot of people have never heard of them but they made engien for tanks from the begining, took a tank engine and made it to a marine engine, they are very light but still strong, the biggest model they have is 246.
Go in to their website and have a check.
I heard that a lot of rescue boats on ships, Pilots etc are using the engine because it`s so reliable.
Steyr engines

thewavehumper · 30 October 2003, 21:55

I'm fine thanks John and the CAT is running fine. It's true that I have been on a steep learning curve. I've no doubt that you will be on the same curve when you get the KAD back in the UK.

This time next year you might be the countrys No1 KAD mechanic.

Nice to hear the eurocommuter is nearly ready. You'll be able to start getting a bit of experience on your CV.

Cheers

Stu

jwalker · 30 October 2003, 21:57

Quote:

Originally posted by thewavehumper
Youre both wrong. CATS are the best.

Stu.

er.... A slight weight penalty Stu.

Redbay Rover · 30 October 2003, 22:00

Thanks for the link Petrov. The single engine jsut isn't powerful enough, but perhaps redbay can squeeze two 164s next to each other

crazyhorse · 30 October 2003, 22:03

Unfortunatly its down to who you listen to.

The Cat is one of the best but ,Cummins/Mercruser is also very highly respected engine for over 300 hp.The problem is there isnt at present a Cat 450 with a good leg,You could go with a Conrad leg but with a gearbox and weight and HP losses and size ,your unit will be around 10 ft long and nearly weigh a ton.The costs of a new leg will be around 7k and 2 k for a box and your left with around 370hp at the single prop end.You then having spent 30k have to find a boat to put it all in with room for yourself.

This is if you dont want to go for a second hand water jet like stuart has. Wave can tell you all about that sort of setup.

I have bought new and gone Kad 300 and I am still real happy,Although I like the new IZuzo 400+hp plus motor comming onto the market soon it still needs a reliable leg and I dont know what the costs are like or the size of the engine and box.

good luck

crazyhorse · 30 October 2003, 22:14

Hay Stuart when did you become a master marina? Ha Ha

gavin · 30 October 2003, 22:48

Unfortunatally Common Rail gives the impression of simplicity efficiency, low emmissions.Unfortunatly these type of fuel injection systems rely on electronics, and individual solineid valves per chamber (cylinder).In order for the system to work,individually operated solenied valves open and close, electronically timed and sensed.This may be good for managing emmisions, however the fuel injection system which predates this system where individual injectors are fed from a mechanical engine driven pump, is simpler reliable, and relys on filtration to keep the injectors free, of deposits, in cars for example injector intervals are approx 60k.For all intensive purposes a single pump pumps fuel to each injector when required.Common Rail is impressive, but interuption in fuel supply to the Rail will affect all cylinders, you are now into electronically controlled valves, again more moving parts fuel sensors and electronic fuel timing, adding to the complexity of a system which in Diesel engines doesnt need to be complex atall.