Rev counter kad 32

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Dover Escape

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Good evening
V P KAD 32

Always had a few issues getting on the plane and thanks to a great engineer whipo found an air leak much better now
My question is that when the s/c kicks in at around 1500 the revcounter drops straight away down to 1000 then starts to climb I am not 100% sure if the actual revs drop by that much but is it because something is drawing current from it i am not really sure
I have always had a terrible unburnt diesel issue which i still have but am hoping that a dam good thrashing/ chinese service now the air leak is sorted may solve that and I have always lived in hope.
I have looked at what I think is a red and a white wire that comes from the top of the supercharger and would like to track them back to check the connections but have not a clue where they end up as they disappear down the block a bit
I changed the supercharger oil yesterday and it is actually much quieter which is nice.
Any advice appreciated
Thanks
Steve
 
Two things spring to mind.
First is it's not unusual for the revs to drop when the SC kicks in. It creates a lot of parasitical drag and never more so when spooling up. However the drop in the rev counter is significant and if all the belts are tight i.e. that drag isn't causing momentary belt slip, then the current draw on the clutch may be excessive indicating that clutch wear is at it's limit. In my experience and this is not from manual but experience only you should see only 12A when the clutch kicks in dropping to about 3 A to hold it in. On worn clutches I have seen this shoot up to 30A to kick in and hold with predictable results. If you suspect a worn clutch change it, it could save your black box of tricks.

Note S1 ground to SC burnt through

S8hhOFa.jpg
 
Last edited:
BruceK said:
Two things spring to mind.
First is it's not unusual for the revs to drop when the SC kicks in. It creates a lot of parasitical drag and never more so when spooling up. However the drop in the rev counter is significant and if all the belts are tight i.e. that drag isn't causing momentary belt slip, then the current draw on the clutch may be excessive indicating that clutch wear is at it's limit. In my experience and this is not from manual but experience only you should see only 12A when the clutch kicks in dropping to about 3 A to hold it in. On worn clutches I have seen this shoot up to 30A to kick in and hold with predictable results. If you suspect a worn clutch change it, it could save your black box of tricks.

Note S1 ground to SC burnt through

S8hhOFa.jpg
Click to expand...

Bruce, how did you measure the current drawn to the SC clutch ?
clip Amp meter on which wire ?
Simon
 
Dover Escape said:
Good evening
V P KAD 32

Always had a few issues getting on the plane and thanks to a great engineer whipo found an air leak much better now
My question is that when the s/c kicks in at around 1500 the revcounter drops straight away down to 1000 then starts to climb I am not 100% sure if the actual revs drop by that much but is it because something is drawing current from it i am not really sure
I have always had a terrible unburnt diesel issue which i still have but am hoping that a dam good thrashing/ chinese service now the air leak is sorted may solve that and I have always lived in hope.
I have looked at what I think is a red and a white wire that comes from the top of the supercharger and would like to track them back to check the connections but have not a clue where they end up as they disappear down the block a bit
I changed the supercharger oil yesterday and it is actually much quieter which is nice.
Any advice appreciated
Thanks
Steve
Click to expand...

I think you are being too gentle with the control and maybe you just need to push the control a little further forwards
I don't recognise the big drop in revs you describe. But I think there is some other underlying issue.

There is flap valve in the air box. With the supercharger operating the pressure from the supercharger should close the flap valve . Check that flap valve is functioning. If the flap isn't able to close fully the supercharger pressure will not fully effective. If the flap is okay perhaps the supercharger is not creating enough pressure.
Is the fact you changed the supercharger oil and it made a difference not concerning? What was the old supercharger oil like ? Was the supercharger oil level too low before you changed it?


.
 
The flap was ok as is the pressure as I just had that tested.
I have only also noticed this while revving up on the berth so maybe different at sea but too cold to try !
Supercharger oil was not that low bit dark in colour
I think as you recommend I will change the clutch as a good service item to do anyway is there anything else that should be changed at the same time too do you think. I have had a new speed sensor fitted recently
I basically have a load of unburnt fuel that appears about 30 foot behind the boat when I am trying to get on the plane and I have done the following
New props
Injectors overhauled
New fuel and air filters
New speed sensor
Turbo overhauled
Clean bottom
Tappet clearances to be checked this week
Intercooler cleaned
Throttle linkage checked

I have only just identified a big air leak as it was always a struggle to get ot in the plane and have not had a real thrash since that has been identified and unburnt fuel issue I have had for 3 long years
It also only ever reached 3100 rpm and 22 knots when it should do 3900 and more like 30knots
I have uploaded a picture of the unburnt fuel to see what you thinks you think the air leak would resolve the problem straight away or only after a long time.
Thansk
Steve
 
if you were doing this in neutral then I dont see anything wrong with the rev drop as the SC engages. In gear under load you normally power right through that with plenty fueling going on
 
Sounds like a test run required before any further major expense. Maybe the air leak being fixed has solved it.
If not..
Compression test perhaps?
Fuel injector pump issue (not a DIY fix) .

What props did you fit - A4's?
 
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