KAD 44 - Limp Mode

Portofino said:
It’s a Swedish to Eng translation the book .
Some things are lost in the syntax
It says you run irrc 3000, 3200 or the arbitrary “10% less WOT “
This is what it recommends .
We need a copy of it posted for all to see .Over to you Peter ?
It tells you the function of the SC ,s and I,am sure suggests don,t hover in that zone if you don,t need to or words to that effect .

It’s not the same as a Merc Kompressor or any other auto part , that you all seem to be clinging on to in the belief it’s ok to run it constantly ad infinitum.
It’s origin is irrelevant, it’s it use and designer / engineers intention that you need to know .
“ High speed planing craft “

Let’s face it VP bolt on parts ( wether in house or bought in ) are not famous for longevity,

Btw give me an example in the auto world of a superchrger ( to get going ) and the turbo that takes over once above a rev range ?
Click to expand...

https://en.wikipedia.org/wiki/Twincharger
www.volvopenta.com/marineleisure/en-en/for-owners/your-engine/manuals---handbooks.html
 
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Portofino said:
It’s a Swedish to Eng translation the book .
Some things are lost in the syntax
It says you run irrc 3000, 3200 or the arbitrary “10% less WOT “
This is what it recommends .
We need a copy of it posted for all to see .Over to you Peter ?
It tells you the function of the SC ,s and I,am sure suggests don,t hover in that zone if you don,t need to or words to that effect .

It’s not the same as a Merc Kompressor or any other auto part , that you all seem to be clinging on to in the belief it’s ok to run it constantly ad infinitum.
It’s origin is irrelevant, it’s it use and designer / engineers intention that you need to know .
“ High speed planing craft “

Let’s face it VP bolt on parts ( wether in house or bought in ) are not famous for longevity,

Btw give me an example in the auto world of a superchrger ( to get going ) and the turbo that takes over once above a rev range ?
Click to expand...

Be my guest!

https://www.volvopenta.com/marineleisure/en-en/for-owners/your-engine/manuals---handbooks.html

You can use my serial number: 2204409430
 
petem said:
Be my guest!

https://www.volvopenta.com/marineleisure/en-en/for-owners/your-engine/manuals---handbooks.html

You can use my serial number: 2204409430
Click to expand...

I took page 31 of the book the bit on cruising rpm as mentioned by me ^^^ .
It’s silent on the sub 3000 i was understood is not a green light to go there - say cruise @ 2300 for example with the SC screening away all day .
It recommends N of 3000 and “ high speed planing craft “ earlier in the preface .
There’s really two issues to watch if you want to cruise in the SC activation range

1- buruning out the control wiring for the clutch in the black box
2- low EGT,s sooting up ,- if you are a high hrs boater ?

KAD 44 and KAD 300
I,am sure I read in a technical bulletin ( Ok not this book ) words to effect of only say in the SC range for short periods .
Unfortunately I can’t find that .
Tbo my KAD 300 s we’re serviced by the book official Vp and I operated them by what I thought was the book .
Did 800 uneventful hrs , expensive hrs though .
 
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As said the twin charge system is an answer to a large turbo's lag. Personally I think this whole argument is moot because the times the root charger cuts in (at least on my KADs) is when climbing out the hole or you're about to fall back into it, with the exception of kick down boost of course. Now why anybody would want to ride in a constant state of climbing out the hole, lugging the engines etc is a bit of a mystery to me. A planing boat is either planing or displacement, that is it's limitation, it's not a SD. Now if somebody could show me an heavily SD biased boat with root chargers then the argument might have legs. At least for me whether or not you should run constantly off root chargers is superseded by other factors which are equally undesirable.

edit spelling
 
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petem said:
Do you have any evidence of 1) apart from BruceK's post?
Click to expand...

Hey, please reread that post before I'm misquoted on it. :D
That info came from a engineer who then added to electrical wizardry to mine to prevent a recurrence. When I approached our local engineer about it because I was dubious he said he couldn't fathom why Volvo didn't just design it this way.
This is just a short exert from the correspondence

The clutches are apparently operating correctly, though we are confident that one transient suppressor is open circuit. these suppressors are permanently moulded into the clutch cables, so the official line would be to replace the clutch assembly, at considerable expense. We can fit a suitable replacement unit to the cables with a very considerable saving, ( only £5 ) but this might not be considered original, we could also fit a standard relay between the speed relay and the clutch to separate them electrically, (also about £ 5 each). which would considerably reduce the chances of this happening again. For information they already use a standard relay adjacent to the speed relay for the starter circuit. They do not use 'transistor' relays on the starter circuit due to the high reverse e.m.f from the starter solenoid, precisely the suspected reason for the port speed relay failure!

Now I'm no electronics expert. All I had was a fried black box and the root charger was responsible.
 
To add fuel to the fire none of the Ogura root chargers ever fitted to cars were factory fitted to run constantly. All operate from a clutch. Which begs the question because on many a turbo being added was an after market conversion.
 
BruceK said:
Hey, please reread that post before I'm misquoted on it. :D
That info came from a engineer who then added to electrical wizardry to mine to prevent a recurrence. When I approached our local engineer about it because I was dubious he said he couldn't fathom why Volvo didn't just design it this way.
This is just a short exert from the correspondence

The clutches are apparently operating correctly, though we are confident that one transient suppressor is open circuit. these suppressors are permanently moulded into the clutch cables, so the official line would be to replace the clutch assembly, at considerable expense. We can fit a suitable replacement unit to the cables with a very considerable saving, ( only £5 ) but this might not be considered original, we could also fit a standard relay between the speed relay and the clutch to separate them electrically, (also about £ 5 each). which would considerably reduce the chances of this happening again. For information they already use a standard relay adjacent to the speed relay for the starter circuit. They do not use 'transistor' relays on the starter circuit due to the high reverse e.m.f from the starter solenoid, precisely the suspected reason for the port speed relay failure!

Now I'm no electronics expert. All I had was a fried black box and the root charger was responsible.
Click to expand...

That's all gobbledygook to me! But I do wonder whether this is a problem that could be partly related to the environment that the engine is in (space, air cooling, etc)?

Incidentally, I don't like running at compressor speed, primarily because of the noise but sometime you have to (in my boat at least) if the sea conditions dictate it.
 
I would concur with that. I dont presume they are going to blow if used for an hour or two, just that prolonged and abusive use should be avoided in that range for a host of reasons and that doing so represents aggressive wear and tear to the entire engine, root charger being no exception.
 
One thing I would like to add here. My early KAD 42's did not come with engine rev sync. I fitted a sync guage to replace the jobsworth speedo. At displacement and planing speed it's actually quite a fiddly job with tiny throttle adjustments to sync the engines. Forget about doing it by ear and harmonics, I was surprised by how far out you could be. Anyway small movements of throttle could easily see a 400rpm difference between engines. This never happens when climbing out the hole. Regardless if there is an inch difference in the throttles. When the compressor is on, the sync tach sits dead centre like it was glued there. Now I surmise that this is because the engines being paired and matched are both loaded to their max under that throttle/rev setting. I've also said in the past it's at that range that I first notice any overheat issue. My temps rise 10 degrees at that range from 80 to 90 C during the displacement to planing transition and will cool off to ~85 once on the plane dependant on sea temps
 
"That info came from a engineer who then added to electrical wizardry to mine to prevent a recurrence. When I approached our local engineer about it because I was dubious he said he couldn't fathom why Volvo didn't just design it this way.
This is just a short exert from the correspondence

The clutches are apparently operating correctly, though we are confident that one transient suppressor is open circuit. these suppressors are permanently moulded into the clutch cables, so the official line would be to replace the clutch assembly, at considerable expense. We can fit a suitable replacement unit to the cables with a very considerable saving, ( only £5 ) but this might not be considered original, we could also fit a standard relay between the speed relay and the clutch to separate them electrically, (also about £ 5 each). which would considerably reduce the chances of this happening again. For information they already use a standard relay adjacent to the speed relay for the starter circuit. They do not use 'transistor' relays on the starter circuit due to the high reverse e.m.f from the starter solenoid, precisely the suspected reason for the port speed relay failure!

Now I'm no electronics expert. All I had was a fried black box and the root charger was responsible."

Whoever told you that is not an electronic engineer either. I do understand all of that and your "engineer" is missing a very important point. When large solenoids are used in machines etc they need two operating currents - the "pull in" current - to get the mechanism to close, then you need to lower the current by about 50% to the "holding current" This reduces power in the solenoid coil and reduces heat. Volvo engineers designed the electronic speed relay to do this. Its very common to see this design approach on fuel shut off solenoids on injection pumps fitted to engines for boats, cars, generators etc.

If you wire in an extra separate relay this will no longer be possible and you may end up running the "pull in" current through the solenoid all the time it is engaged and it will get pretty hot - not what it was designed to do.

How did the engineer determine the transient suppressor was not working? Its very difficult to tell without specialist kit.
 
Pass. Electronics was his speciality. I sought a second opinion and got it. As for current draw the clutches pull 3 Amp. That much I have checked and verified
 
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