Common Rail Diesels - Page 4

TIM · 04 November 2003, 07:51

Redbay... all outdrive legs are on the power and torque limit in and around the 300hp mark, its no problem putting a bigger engine on to any of the legs, but they simpily will break......

thats why surface drives have been tried on Scorpion or Revenger ?? I dont know which , But its is basicly to shove out more power, with out jetdrive......... Jet drive can handle the power, but doesnt work in the air, and takes up alot of room, heavy and expencive etc etc... and heaps of advantages, but not really for lesure useage, one of there best advantages is they are uniffected by loads, ie fully loaded or empty, (ie fast ferries) and the shallow drive of course

I have heard about Gary, and aparently he Knows his stuff, I would ask him why Volvo...... they have a second hand 8.4 with yanmar (2000), but it now has new 3X leg, so I can only asume that the previous B3 leg died

I hope I have confused you more now

YANMAR YANMAR YANMAR !!!

Redbay Rover · 04 November 2003, 14:10

Why is the stern drive so power sapping on the Yanmar? A 315HP engine reduced to 285HP at the sight of a leg

. Do you think the 285 quoted for the volvo is with or without the drive? I'm so confused

Dirk Diggler · 04 November 2003, 16:44

I've always thought it a bit strange that the Yanmar was originally quoted as a 300hp motor until Volvo brought one out, at which point the Yanmar became 315hp, without any changes so I am told. All IMHO of course!

gavin · 04 November 2003, 19:01

They just estimate 300hp at the output and allow 15hp for losses incured tro the gearbox, depends on where you measure the horsepower, are you talking about total horsepower or output horsepower , if I have a 130 hp Honda do I have 130 at the prop or 130 in total they merley make an allowance for the losses incured, its quite a lot really to lose tro a gearbox ,Id sooner have it a the props

jwalker · 04 November 2003, 19:48

Quote:

Originally posted by Redbay Rover
Do you think the 285 quoted for the volvo is with or without the drive? I'm so confused

285 at the flywheel, 272 at the prop.

Redbay Rover · 05 November 2003, 17:19

Have spoken to redbay and they too cannot decide between the yanmar and the volvo. They have arranged a comparison test for me with boats fitted with the engines in question, which is solid customer service (if it comes off). I'm leaning over towards Yanmar, purely because 315 sounds alot better than 285. That way i can at least pretend that my boat has 30 more horses than a KAD300 powered one.

ALSO: Anyone know the torque figure for the KAD300? I can't find it anywhere and i may well prove to be the deciding factor.

gavin · 05 November 2003, 19:39

Redbay I was wrong about Movin On one motor just two hatches, however the Redbay with twin motors is the Irishseacruises.com Rib I have two pics Movin on and the one with four ribs shows Movin On and a rare hard top 8.4 Redbay and the twin engined Irishseacruises.com Rib

gavin · 05 November 2003, 19:42

This was in Scotland hard top to left and Irishseacruises rib on far right

jwalker · 05 November 2003, 19:44

Quote:

Originally posted by Redbay Rover
Anyone know the torque figure for the KAD300? I can't find it anywhere and i may well prove to be the deciding factor.

Yes I do, but why do you feel it matters?

The Jackeens · 05 November 2003, 19:46

Gavin,

What make is the yellow rib second on the right next to the redbay

Paul

Jono Garton · 05 November 2003, 19:47

Just to recap whats the best Diesel?

gavin · 05 November 2003, 19:50

Check this for lots of info on Redbay Cabins and pics slightly off the point
http://rib.net/forum/showthread.php?...ght=cabin+ribs

Redbay Rover · 05 November 2003, 21:07

Thanks for the pics gavin

. JW, torque determines acceleration and is more of a "real-life" measurement than power, as power is something which really only affects the top end performance. So what is the torque value? (please tell me no matter .what you think of the previous statement)

jwalker · 05 November 2003, 23:46

Power is the product of torque and rpm. Your notion that the two are entirely separate is incorrect. When an engine is described as being 'torquey', it usually implies that the engine produces a good measure of power at low(ish) rpm. There is no such thing as 'a torque value'. It can only be quoted at a given rpm. It is the turning force applied by the engine.

For the KAD300, max. torque occurs at approx. 3350rpm and it's value is about 573Nm.

Something else you need to consider is the duty rating of the engine. This is related to the length of time the manufacturer considers it is advisable to run the motor at full power.

The Yanmar 6LPA-STZP's continuous max. power is 255hp @ 3600rpm. The KAD300's is (reading from a wee graph) approx. 262hp at 3400rpm.

Somthing else, again, is the power produced before the turbo becomes effective. This will determine the driveability of the boat in a biggish sea where you need to be able to climb the faces of the waves. This is the reason Volvo use a supercharger on the KAD motors.

Redbay Rover · 06 November 2003, 01:06

That's significantly less torque than the Yanmar. It manages 740Nm at only 2600 rpm and has above 700Nm between 2200 and 3200rpm. That's hard to argue against.

That has definetly got me leaning more towards the yanmar, but the point about the turbo kick in point means i'm still not entirely sure.

JW, do you use the diagnostic ability of the EDC equipped KAD? Is it useful? The EDC offers so many other benefits that make the engine more refined, quieter and more economical than the Yanmar, which is a big plus. However the boat will be based on a reasonably remote island where the simplier technology of the yanmar makes more sense. But then the volvo is £1500 cheaper. This ain't going to be an easy decision

.

Alan · 06 November 2003, 07:22

Quote:

Originally posted by Redbay Rover

That has definetly got me leaning more towards the yanmar, but the point about the turbo kick in point means i'm still not entirely sure.

.

Point is that if you a driving heavy on the throttle as you invariably have to in a big sea and you need to rapidly apply power to lift the bow to meet a sea the turbo lag could really give you a problem. Those few seconds delay could make all the difference.

I've driven a Yanmar 300 equipped boat and its not an insurmountable problem but you do need to keep the revs in the the turbo band for better response. Problem is that conditions might mean that this is too fast to be comfortable.

I'm no expert on diesels and its your hard earned at the end of the day. My only comment would be to be wary of Bravo 3x drives on the Yanmar - they are very much the weak link!

Rene · 06 November 2003, 09:17

Well all this talk about engines just got me more confused.

What about this baby, it will run on allmost anything.

http://www.turbokart.com/turbineboat.htm

Oki, I know it's not a RIB, but just take a look at the engine, stuff that in the RIB and your out of here. Not too heavy, but you might need to do something about the noise.

Rene

DGR · 06 November 2003, 09:57

I might be missing something here, but if the decision is between the Yanmar and the Volvo KAD300, what's wrong with the Mercruiser?

Any horror stories out there?!? Or is it merely that the Yanmar and Volvo are just 'better' in some way?

Answers on a postcard......

Dylan...

Julian · 06 November 2003, 10:02

I have seen 2 mercruiser diesels go bank and a few in Belgium where the bearings have blown which is quite common on these engines and it costs about £1900 to replace them. I personally dont like them as.

Julian

jwalker · 06 November 2003, 11:51

Quote:

Originally posted by Redbay Rover
But then the volvo is £1500 cheaper. This ain't going to be an easy decision .

Not when I bought mine! The Volvo was close to £2500 more expensive. You're either getting a poor deal on the Yanmar or a good deal on the Volvo. However, you can get a KAD44 a good deal cheaper and this is also an option, given that both the Yanmar and the KAD are not rated to use full power for prolonged periods.
If it were me, at this time I'd be waiting to see how the new engines pan out. The D series Volvo looks very good but it's more weight and, at present, more cost. It's capacity is big so it'll produce good low-down power. Volvo have produced a new, allegedly, drive to go with it.

Just over a year ago, I was where you are and it's a difficult decision. What swung it for me was the failure rate of the Bravo drives and the benefit of the supercharger. If you are down on the South Coast where you are likely to get help without difficulty, then a leg failure is just a leg failure. Up here, when out on the water, it is rare to see other boats except for commercial traffic. A leg failure is going to mean a rescue. If you are travelling in a remote area, you are f***ed. For that reason, I have a diesel outboard. It's still in the back of my car at present,

but it'll be mounted soon.