Volvo KAD43 running without compressor

[SimonD]

I have am considering a semi-displacement boat around 33 feet LOA with a single VP KAD 43. This engine was fine in my previous planing boat as at displacement speed, the compressor didn't cut in and by the time I got on the plane, it cut out. On this semi-displacement, I want to be able to use the whole rev range but that potentially means running for long periods in with the compressor running. Apart from the noise this creates, I'm not sure the compressor is intended to run continuously.

The obvious solution is to install a switch to disable the compressor. However, this must make the engine less efficient and it clearly wouldn't develop full power, I imagine that the boat would reach a certain speed without the compressor which would then need to be switched back in to go faster. Does this make sense or would it cause some damage?

Alternatively, the builder put this engine in and must have known what they were doing. Am I missing something?

 

[Portofino]

No .
Find another boat who’s rpm range / speed suits your requirements.

 

[Greg2]

Never really understood why some builders fitted the KAMD / KAD series engines to semi-displacement boats (I am thinking that it is the former as such boats don’t tend to have outdrives)?

We have discounted one or two that have those engines. Should say that I would be happy with them (and have been) in a planing hull.

 

[Portofino]

Never really understood why some builders fitted the KAMD / KAD series engines to semi-displacement boats (I am thinking that it is the former as such boats don’t tend to have outdrives)

Probably money ! They work out cheaper for the builder .
On a few levels , first the shear scale of manufacturing of the marine / Penta range .
Some cost savings using less than the best metals in some bolt on bits .
Hp / £ .
Rumour had it VP offered a credit line to builders to the extent they raised the invoice for payment after the customer bought the boat .As a jobbing small time or indeed a mass production builder more so this is massive .

John Deere , Cummins , Yanmar , Vetus etc want to see the funds transferred first before they pack it and ship it to the yard .
The same Hp would cost a lot more .

If your competition has taken the Nordic Schilling and been seduced then you have to react or sit on an empty stand at boat shows as after viewing the perspex screen , punters despite a nice pretty hired in brigade of ladies - just walk off .

 

[SimonD]

Find another boat who’s rpm range / speed suits your requirements.

I was rather hoping that wasn't the answer as there are very few of this particular boat around.

If it really isn't a suitable engine (and I confess to reaching here) would it be possible to re-engine and, if so, what sort of money are we talking about?

 

[BruceK]

You can safely ignore Porto, his vehemence of Volvo and particularly KADs borders on the psychotic while his love for MAN and Itama panders to a rather perculiar narcissism. Think I'm joking, hang around some more. Moving on, I agree partially with Greg2 but really the deciding factor is the boat and the performance envelope of the boat. If it's a squat heavy beast probably yes in not the best of choices. If it's SD but nimble then no issue imo. At the end of the day no matter what the opinions here are there is no manufacturer that will deliberately scupper their boat and reputation by putting in an inadequate engine, regardless of the back hand, unless Porto would have you believe that the "Nordic Schilling " practically bought the boat keeping the company profitable.

 

[kashurst]

You can safely ignore Porto, his vehemence of Volvo and particularly KADs borders on the psychotic while his love for MAN and Itama panders to a rather perculiar narcissism. Think I'm joking, hang around some more. Moving on, I agree partially with Greg2 but really the deciding factor is the boat and the performance envelope of the boat. If it's a squat heavy beast probably yes in not the best of choices. If it's SD but nimble then no issue imo. At the end of the day no matter what the opinions here are there is no manufacturer that will deliberately scupper their boat and reputation by putting in an inadequate engine, regardless of the back hand, unless Porto would have you believe that the "Nordic Schilling " practically bought the boat keeping the company profitable.

+1 I can't find any mention in any volvo kad manual that you cannot run the engine on the supercharger for long periods. Plenty of other no-no's but not that. Also I believe the kad 43 charger is only on between 1700rpm and 2400 rpm. If they were worried they would not have sold the engine without either a limit or a warning. There seem to be a lot of myths about these engines - no idea why they seem pretty straightforward to me. Lots of cars (mercedes, jaguar etc) run superchargers continuously.

 

[SimonD]

I can't find any mention in any volvo kad manual that you cannot run the engine on the supercharger for long periods. Plenty of other no-no's but not that. Also I believe the kad 43 charger is only on between 1700rpm and 2400 rpm. If they were worried they would not have sold the engine without either a limit or a warning.

Thanks for that. But, in practice, it would be running for quite a lot of the speed range of the boat. Maybe they're not all the same, but the KAD43's on my last boat made an unholy howling noise while running. That's not something I'd want to be hearing for long periods. Unfortunately, the boat in question is currently on the Thames so it would be difficult to run it at speed to see how noisy it is.

 

[Portofino]

Simon Go on face books “ Volvo Penta victims “ for a educated background, well more educated .


Answering your other Q constructively .
You might be able to get away with a lower Hp depending on how you wanna use it .
If they produce more torque( which a bigger displacement will ) the g box + prop may well need changing.
At the end of the day there is no substitute for cubes , a bigger displacement lower revving motor is the way to go .
Super charged + turbo high speed high revving are for light weight sports cruisers , after all do not loose sight it’s what they were designed for .

Marine Inboard engines 100- 200 hp - French Marine Motors Ltd

 

[Momac]

Rumour had it VP offered a credit line to builders to the extent they raised the invoice for payment after the customer bought the boat .

Has that not proven to be good business sense on the part of Volvo Penta ?

 

[DavidJ]

This has been debated before
You may find this interesting
Question for the KAD experts RE. Supercharger

 

[oldgit]

Thanks for that. But, in practice, it would be running for quite a lot of the speed range of the boat. Maybe they're not all the same, but the KAD43's on my last boat made an unholy howling noise while running. That's not something I'd want to be hearing for long periods. Unfortunately, the boat in question is currently on the Thames so it would be difficult to run it at speed to see how noisy it is.

Boating on Ye Thames.
Chum has a Faultline Brava 36 or 37 ( depending on the broker selling it) with pair of KAD 235 HP.
The constant racket and banshee howling of these engines along with the crunching lurch as the compressors cut in and out when the skipper desperately tries to maintain a constant 8 kms speed is less than relaxing !
Main memory of delivering the boat from Limehouse to Bray was trying to hang on as the boat surged back and forth and the racket from the engines while standing on the aft deck even though the patio doors were closed.
Some skippers fit a switch to disable the electro mechanical thingy that makes the blower engage ?
Just saying

 

[simonfraser]

I want to be able to use the whole rev range

you are more likely to be pottering about or on the plane, as long as the boat can stay on the plane without the supercharger i don't see what the issue is

one kad 43 for 33 ft seems small imo

 

[Portofino]

Running with the SC on for extended periods puts undue pressure on the spindle bearings and shafts of the other stuff connected to the same belts .The belt tension suddenly increases .A short 20 sec bursts is do able , but constant running ?? Bad idea .
This leads to premature failure of said items .

The bolt on nature of the SC in the development of the KAD series from its none SC base doner is the issue for prolong running .
The other component s on the belt we’re not specced for the additional lateral SC “on “ loads indefinitely.

There is possibly with some ( you need to do your own due diligence exactly which ? ) an issue with overfilling if you fit a switch or otherwise disable the SC belt.The rpm sensor tells the ECU once above the cut in - say 1400 rpm or what ever ,to feed more fuel in to match the additional air vol it thinks it’s gonna get .
Obviously if the SC is disabled then the fuel air mix becomes over rich , you are risking injector premature failure.

They were conceived for high speed lightweight planing boats to run above the SC range not in it .
For this intended purpose with outdrives they are ideal , compact light , fugal ,easy to install in mass production.

As said there business model made a compelling argument for any FD in the boardrooms of many a struggling builders trying to keep the wolf from the door .

Look at Broom as one example.^^^
Would you buy a KAD 300 example or a Perkins none SC - or what ever none larger displacement SC they did ?

The Brooms aren’t daft they must have known what they were doing , FD , bank , thought of receivership on one hand and desperately wanting to keep the business afloat on the other they ended up taking the “Nordic Schilling “

Arguably a KAD 300 Broom is totally inappropriate for a mixed river / estuary use semi displacement boat .Ask the Broom owners club .

 

[SimonD]

Many thanks for the really helpful input.

I take the point about pottering or being on the plane. She displaces 3500kg, i.e. about the same as a Nimbus 320. The single engine model of the latter has a Yanmar or VP D4 of around 230hp, so the KAD43 would seem the right size. The boat I'm looking at has very similar characteristics to the Nimbus. From that, I believe that at a cruising speed of around 15knots, the engine would be running above compressor cut off revs. Displacement speed would be below the cut in point. So, all I need to worry about is the times I would want to be at an intermediate speed. After all, one of the benefits of semi-displacement is the ability to run at these speeds.

So, the question for me is: how much running at 'intermediate speeds' would I be doing. If it's significant, I can wire a switch to disable the compressor. The helpful link provided by DavidJ discusses this and the downsides associated with potential over fueling. However, there didn't seem to be a firm conclusion and I think I need to talk to a Volvo expert before going further.

 

[Portofino]

Here you are - Kashurts point - the written manual guides why do VP not write something up this SC use age regime?

So what ? Just cos they do not write “ do not cruise @ SC engagement speed “ or what ever does not mean it’s ok .
Think back the first principles and go from there .

Like an engineer peering at them day in day out .

Volvo kamd 300

Ps Carb classic Ferrari returned form a valve+ belt job recently and the tickover was reduced from 950 to nearer 600 rpm .
When I turned the aircon on it lowered further .
Alarm bells ring in my head .Yup oil pressure in the crank journals .
Bit of Ferrari forum back ground reading and yup I was right .The tickover should be set relatively high ( to other cars ) because the oil pump is configured for the higher rpm range ( red line near 8000 ) and it does indeed plum it below 7/800 rpm risking crank journals .
So adjusted it up to 1100 rpm without the AC on which drops it back to 950 rpm at standstill with the AC on .

Adjustments have to made with a thoroughly warm engine , difficult to do without a good run .So I can see what’s happened.
They tick over fast when cold , cold idle jets in the Webber’s take over until hot . .

Back to KADs ……once again happy to repeat = high speed planning boats !!! - which they a good at btw .I had one !

 

[SimonD]

I'm happy to knock on the head the idea of running the compressor for long periods. Not for esoteric technical reasons but because I couldn't stand the noise!
From the other thread, it appears I can fit a switch to disable the compressor. The only question now is: does running the engine at the engine at 'compressor speed' with the compressor switched off for more than a few hours cause any problems?

 

[BruceK]

I'm happy to knock on the head the idea of running the compressor for long periods. Not for esoteric technical reasons but because I couldn't stand the noise!
From the other thread, it appears I can fit a switch to disable the compressor. The only question now is: does running the engine at the engine at 'compressor speed' with the compressor switched off for more than a few hours cause any problems?

I fitted the silencers off a KAD44/300. Made a massive difference to noise output. Ogura make the SC. It has an rev operting range that so long as it is not exceeded can run indefinitely. If I recall correctly that is 11k rpm. Obviously that is the SC rpm and not engine rpm. The SC is designed not to get you onto the plane quicker although that is a side benefit, it is designed so there is no turbo lag you get with a bigger turbo. It fills the gap it takes a smaller turbo to spin up and in addition helps a smaller turbo spin up earlier. i.e. your turbo will be making about 1 bar of pressure at 2500 rpm with the SC having given it boost but without the SC boost may only spin up to make 1 bar once you've reached 3k rpm on initial take off. Can you run without a SC or even turbo? Sure, if the pump smoke limiter is functioning properly it will sense a reduction in boost and retard the amount of fuel delivered accordingly. Opting for a smaller or finer pitched prop could absolve you of needing to run the SC at all if you dont need the torque to get over the hump. The previous owner of my boat disabled the the SC's and had finer pitch props on. The boat would leap onto the plane, wasnt fast, but could travel any speed within it's range effortlessly. The above being true for the 42 and 43 but not for the 44 and 300 where the SC becomes an integral part of ECU operations.

 

[Greg2]

Look at Broom as one example.^^^
Would you buy a KAD 300 example or a Perkins none SC - or what ever none larger displacement SC they did ?

The Brooms aren’t daft they must have known what they were doing , FD , bank , thought of receivership on one hand and desperately wanting to keep the business afloat on the other they ended up taking the “Nordic Schilling “

Arguably a KAD 300 Broom is totally inappropriate for a mixed river / estuary use semi displacement boat .Ask the Broom owners club .

We considered a Broom 38cl that had KAMD44’s and concluded that they were just the wrong engines for that type of semi-displacement cruiser. Not many had them - most were Perkins or Yanmars.

 

[Portofino]

We considered a Broom 38cl that had KAMD44’s and concluded that they were just the wrong engines for that type of semi-displacement cruiser. Not many had them - most were Perkins or Yanmars.

Contradicting nicely what Bruce infers in his diatribe of post #6 . .