Bavnavkad
New member
Hi guys, wondering if you can help me as I have a bit of an issue.
I have twin kad32 done 640 hours each, both engines not long serviced.
The issue that's arisen over last few outings is this:
Hi guys wondering if any one can shed any light on an issue that I'm having. Or if any of you have solved it before now, basically it's this.
Last couple of trips, I have noticed that the starboard engine is low on rpm, I.E when both throttles are at cruise of 3000rpm everything is sweet.
If I advance the affected engines throttle to WOT, it increases only around 100rpm, but if I leave that throttle WOT, and advance the good engines throttle. The good engine advances to 3600 perfectly and in turn slowly brings up the rpm of the starboard engine to nearly 3450, if I then only back of to 3000rpm on the good engine, the affected engine also drops back to circa 3100rpm.
So no actual issue until WOT. Otherwise everything else is performing as it should. Planes perfect, no noises nothing.
So coming back to dock, stripped down the air side to check turbo shaft, but cast elbow screw snapped so it wouldn't come off with out removal of turbo. So I've managed to put it back as it was whilst checking all air joints from air box and supercharger to turbo, all appears OK.
However doing an idle check let's me know both super charges work as expected and cut off at the right time. Both engines with NO load rev to 4000rpm as they should, however on the affected engine. After the supercharger has cut off, I get a small cloud of black smoke.
Both intercooler have recently been removed and serviced.
Filters and belts oils etc all brand new genuine.
Good engine had new turbo 80hrs ago ( 1 year ) wonder if its now time for other side
Aim to take it out this week with boost guages, but that won't tell me what the issue is exactly will it? I already think I'm down on boost as both engines always were perfect to 3600 @ 35kt I'm now cruising at 3k @ 28kt
--------------
So today I took the boat out for a boost test with calibrated pressure guages and nipples to test each engine and my results are as follows.
Basically this is the threshold I should be getting from both engines boost according to workshop manual.
I made a nipple and had a professionals guage and calibrated. So. This is the minimum requirement for each engine. Under load
Supercharger at 2000rpm ( no turbo ) 10.1psi
2500rpm - 25.1psi
3800rpm - 23.9 psi
Bearing in mind my starboard won't get to 3800 I had to just compare engines boost.
It's as follows
Starboard engine ( suspected down on boost )
Supercharger at 2000rpm I got 17psi ...
2500rpm I got 18psi
3100rpm I got 13psi
No black smoke under load
Port engine ( with new turbo from GA 2021 )
Supercharger at 2000rpm 20psi
Turbo
2500rpm - 25psi ( bang on )
3000rpm 21psi but then once on plane dropped to 14 consistent...
So I'm not really any further forward other than I am certain boost is down on stbd.
However Supercharger should only give 10.1psi however more I can't see being an issue?
Any input from you guys is really appreciated as I'm at a bit of a loss now as to where the issue may lie.
Thanks in advance
I have twin kad32 done 640 hours each, both engines not long serviced.
The issue that's arisen over last few outings is this:
Hi guys wondering if any one can shed any light on an issue that I'm having. Or if any of you have solved it before now, basically it's this.
Last couple of trips, I have noticed that the starboard engine is low on rpm, I.E when both throttles are at cruise of 3000rpm everything is sweet.
If I advance the affected engines throttle to WOT, it increases only around 100rpm, but if I leave that throttle WOT, and advance the good engines throttle. The good engine advances to 3600 perfectly and in turn slowly brings up the rpm of the starboard engine to nearly 3450, if I then only back of to 3000rpm on the good engine, the affected engine also drops back to circa 3100rpm.
So no actual issue until WOT. Otherwise everything else is performing as it should. Planes perfect, no noises nothing.
So coming back to dock, stripped down the air side to check turbo shaft, but cast elbow screw snapped so it wouldn't come off with out removal of turbo. So I've managed to put it back as it was whilst checking all air joints from air box and supercharger to turbo, all appears OK.
However doing an idle check let's me know both super charges work as expected and cut off at the right time. Both engines with NO load rev to 4000rpm as they should, however on the affected engine. After the supercharger has cut off, I get a small cloud of black smoke.
Both intercooler have recently been removed and serviced.
Filters and belts oils etc all brand new genuine.
Good engine had new turbo 80hrs ago ( 1 year ) wonder if its now time for other side
Aim to take it out this week with boost guages, but that won't tell me what the issue is exactly will it? I already think I'm down on boost as both engines always were perfect to 3600 @ 35kt I'm now cruising at 3k @ 28kt
--------------
So today I took the boat out for a boost test with calibrated pressure guages and nipples to test each engine and my results are as follows.
Basically this is the threshold I should be getting from both engines boost according to workshop manual.
I made a nipple and had a professionals guage and calibrated. So. This is the minimum requirement for each engine. Under load
Supercharger at 2000rpm ( no turbo ) 10.1psi
2500rpm - 25.1psi
3800rpm - 23.9 psi
Bearing in mind my starboard won't get to 3800 I had to just compare engines boost.
It's as follows
Starboard engine ( suspected down on boost )
Supercharger at 2000rpm I got 17psi ...
2500rpm I got 18psi
3100rpm I got 13psi
No black smoke under load
Port engine ( with new turbo from GA 2021 )
Supercharger at 2000rpm 20psi
Turbo
2500rpm - 25psi ( bang on )
3000rpm 21psi but then once on plane dropped to 14 consistent...
So I'm not really any further forward other than I am certain boost is down on stbd.
However Supercharger should only give 10.1psi however more I can't see being an issue?
Any input from you guys is really appreciated as I'm at a bit of a loss now as to where the issue may lie.
Thanks in advance