Question for the KAD experts RE. Supercharger

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When we were without the supercharger for a while (see the posts about my friends belts snapping on his KAD43) last week we were nervous and kept the revs below 1500 incase the engine got cranky by not picking up boost from the supercharger.

However after a while we said we'd give it a try, and we upped the revs. The engine didn't cough, spit or get angry. The only difference, was obviously, that the acceleration wasn't as good. But revs went up to cruising range no prob, and even a quick blast at WOT

I often find the supercharger a little annoying when trying to do slow speeds, and next summer I'll be doing slow speeds for quite a while when on long rivers with speed limits

My question is, would you do any harm removing the supercharger belt and just running with the turbo? Or is the engine 'brain' picking up something bad when there's no supercharger boost?

(Note the supercharger wires are still connected, just the belt disconnected)

The only thing I can think of is that with the clutch engaged between 1700rpm - 2*00rpm it might like not the fact that it's not moving? But don't see how this could do any damage?
 
There is no need to remove the belt , I sure Peanuts will be along at some point, he will be able to tell you how to turn it off with a switch
 
I remember someone mentioning that it can be unplugged, but I thought I rememberd someone saying how the engine misbehaved or something similar along those lines - Hence why we were nervous to give the engine throttle last weekend.
 
Peanuts was talking about doing this not long ago as we are in Poole which has a 10 knot limit in the summer and he would be able to turn them on and off with a switch so they do not keep coming in when in the harbour.
 
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Peanuts was talking about doing this not long ago as we are in Poole which has a 10 knot limit in the summer and he would be able to turn them on and off with a switch so they do not keep coming in when in the harbour.

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Wonder would it be a matter of putting an ON/OFF switch in line with one of the wires going to the supercharger clutch? Surely it can't be that simple?
 
I don't claim to be an expert on this, but I believe the supercharger clutch engages when the voltage is dropped to 0, and dis-engages when it comes back again. Test first!

If it were me, I wouldn't bother at all: there isn't really any brain on a KAD32, and the fuel pump settings and prop choice assume the supercharger is there, so you'll end up running much a much richer mixture (less air) than intended.
 
Re:Supercharger

Excuse coming in at a tangent BUT in thinking my way towards the next boat had thought a consensus reckoned no flybridges or superchargers for European waterways.
Can you really 'switch of'f when cruising at 4 knots without damage?
Petrolia admitted to opening up when no-one was looking but that's hardly the solution - yet getting to France at at speed does have its appeal too!
Let's hear from Jezzbanks and the technical whizzkids.
 
Re:Supercharger

The supercharger does not engage until 1500rpm, which is around 6/7 knots. It provides a boost until 2500rpm, where it cuts out and the turbo takes over.

dv.
 
Re:Supercharger

I don't intend on cutting any wires... it's just a thought in my head to remove the belt next season when i'll be on 'slow' rivers
 
I had a switch put on top of the contol unit so I could switch off the compressors when we went up the river Seine. I didn't do this myself but is a simple job. The (I think it is the white one) wire in the control box is cut and you just connect it through a water proof switch which goes onto the control unit. I guess you could run the wire back to the helm if you wanted. Peanuts came on the boat and had a look. When he comes along he might remeber if it was the white wire
 
Re:Supercharger

My last boat had 2 kad42s. One engine had a defunck brain on the supercharger circuit. I ran it for ages without until i found it was just the small connector carrying 2 wires just before the clutch had corroded. Before I remade the connection I put a switch in it to bypass the brain. Not recommended as if you forget to switch it off at above 2500 revs I would imagine seriouse damage. The chargers dont need to run for the engine to perform adequately at low revs. I would simply go into the black box on top of the engine and pull the multi pin plug out of the charger regulator. if you really wanted to do the job properly put a switch on the power supply to the clutch. Then you can chose if you want them to cut in or not without affecting the cut out at 2500 revs. You will get slower acceleration but still achieve the same top end performance above 2500 revs as you had before.
 
This came up in MBM about a year ago when Neale contacted the Volvo techies. Apparently turning off the compressors is a no -no due to incorrect fuel mixtures and if you need to run at the rev range that the compressor is engaged, you should live with the noise, no harm will come to the compressors but you may need to change the oil more frequently. Volvopaul might confirm this with a bit of luck.

Eddie
 
Disconnect from a 2 wire connector block (should be around the rocker cover) the supper charger will still engage only if you hammer the throttle down as there is a magnet swich connected to yout throttle by your fuel pump. I disconnect all the time when fault finding these engines. /forums/images/graemlins/smirk.gif
 
"Peanuts came on the boat and had a look. When he comes along he might remeber if it was the white wire" Thats right thats when he was talking about it, the connection is made in the box . Just been talking to him and he will be along when he is "allowed " to go on line !
 
OK, stamped my authority and my 12 year old said I can now go on line.
This part is for Alt. First of all, what is the 'slow speed' you wish to travel at, are we talking about below the compressor being engaged, that is 1700 RPM. If the answer is yes then I would leave everything alone.
Moving across to RIN's post, yes you are right, the cable that the switch is wired into is the white one returning from the compressor to pin S1 inside the 'black box'. As RIN states he has a switch wired on his engine on the side of the black box, if or when I wire a switch in on my engines I would install the switch at the helm position for ease rather than having to climb down into the engine compartment.
I hope I have sort of helped.

Steve
 
[ QUOTE ]
OK, stamped my authority and my 12 year old said I can now go on line.
This part is for Alt. First of all, what is the 'slow speed' you wish to travel at, are we talking about below the compressor being engaged, that is 1700 RPM. If the answer is yes then I would leave everything alone.
Moving across to RIN's post, yes you are right, the cable that the switch is wired into is the white one returning from the compressor to pin S1 inside the 'black box'. As RIN states he has a switch wired on his engine on the side of the black box, if or when I wire a switch in on my engines I would install the switch at the helm position for ease rather than having to climb down into the engine compartment.
I hope I have sort of helped.

Steve

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Hi peanuts, thanks for that

I guess i'll be running at about 2000RPM or thereabouts. Hard to tell really, but i'd still love the thought of being able to bypass the charger at times when on the river. However i'd only do it if I DEFINATELY knew I wasn't doing any engine damage

Are you saying it's just a matter of snipping the white wire in the black box and putting in an ON/OFF switch? If this was safe to do i'd being a switch up the the helm, it'd be excellent

I'd have to get a really crazy looking switch though /forums/images/graemlins/laugh.gif
 
Hi
It is as simple as that, cut the white cable and insert a switch or in my/your case extend the cable to a switch at the helm. Regarding the damage part of your question, as RIN said he went to Paris on his boat and had the compressors off all the time, his engines are OK, I suppose at the end of the day it's down to how long and at what RPM you are going to run with it off.
For your crazy looking switch may I suggest a 'Missile Style Toggle Switch Cover' - Maplins N42AT, I have a feeling this maybe just the thing for you??

Steve
 
The easy option is to just turn your ignition switch to the off position (not the stop position) once they are running. This stops the supercharger cutting in. Downside is probably non of your gauges will be working either.
 
Yes also went to Holland on an MBM cruise this year and often had them switched off for canals and slow speed areas. If I did it again I would have a switch at the helm though
 
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