Supercharger....

[dog]

Following on from the belt life post, can anyone confirm whether the supercharger can be disengaged in any way on a kad32. I have heard it rumoured before, but never found any supporting evidence. Would be nice to be able to switch it off whn required. I have had a number of times when its too rough to fully plane, but would be running with the charger engaged if trying semi displacement speed.

Thanks in advance....

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[DavidJ]

On the KAD43 (maybe you're 32 is similar) the supercharger gets it's switch on signal from engine revs (1600 rpm actually) via a little electronic box (€186) you could just switch off the rpm input. As you might have guessed from this reply I've just had to replace my box.
David

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[dog]

Hi, yup 1600 and it cuts in. I guessed it must have been electronically controlled as the charger didnt work the other week when the ignition accidentally got knocked off! I assume the engine will run happily with not damage without the supercharger?

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[DavidJ]

I'm not going to try the modification myself, but my guess is that if the engine is ok at 1500 rpm without the turbo then it will be ok at 2000 without the turbo.
The electronic box for me was situated on the top of the engine and was inside another black box which also has a relay in it.

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[ulava]

How do you switch of the rpm signal ?

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[DavidJ]

dunno and I not going to try it.

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[[2068]]

You're wasting your time. If you were to disengage it, the gearing and injector pump settings are such that the drop in torque would drop you right back into a hole at displacement speeds, but in an overfuelled state.

Try it, by simply removing the belt or disengaging the clutch wire.

If you didn't want the supercharger, you should have bought an AD31...

dv.

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[KevB]

I have Kad43's and when the tide is running I can be pushing 1600rpm just to do 8 knots, surley I wouldnt need the superchargers then. Bloody annoying having them whisling away at such a low speed.

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[sonarbell]

Have seen on the Kad 44?? that the actuating switch is on the throttle linkage and is a purely mechanical/Switch activation. When the throttle position is at a certain mechanical position and the engine revs reach 1600/1700rpm then the switch is activated thus engaging the Clutch. Would be easy to put switch into sensor switch on throttle. Does any of that make sense~????

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[Observer]

I agree it's a pain but (on the S41) maximum displacement speed (~ 10m waterline length = 7.7 kts) corresponds with the engine speed at which the supercharger cuts in anyway. I've just accepted it as an audible warning that I'm burning loads more fuel for no real benefit (and possibly making excessive wash as well).



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[DavidJ]

That really surprises me 'cos I always think of the 44 as being an electronically advanced 43. Wonder why they have gone for a mechanical switch.

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[[2068]]

At 1600rpms, not much difference either way (apart from the whine), but push it to 2000, and without the extra air, you are running much richer than intended.

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[scottie]

back to basics
1 supercharger pushes air in at low revs to give extra grunt

2 supercharger cuts out at high revs as turbocharger is then pushing the extra air in

3 kickdown switch on throttle control can override to boost acceleration



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[kimhollamby]

Caution

I'd urge caution on this; in a get-you-home emergency okay but in regular use on any of the supercharged engines with mechanically governed fuel you would be overfuelling and probably causing damage to the actual cylinders as well as throwing fuel away for nothing.



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[dog]

Thanks to all who replied, I guess that if Volvo had deemed a switchable supercharger viable- then it would be in production.

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