KAD44 supercharger cut in and cut out engine speeds

[aerobat]

Hello gents !

if i understand it correctly the supercharger envolope on the kad 44/300 is a bit different than the mechanical kad32/43 .

Not fixed cut in at 1500 and cutout at ~2800 but controlled by ECU depending on conditions .

My question :

the manual says the supercharger range is between 1000-2800rpm .

Is this the envelope where ECU can decide to call for the supercharger depending ln load etc or does it mean that the engine spins the supercharger all the time at anything above 1000rpm,s , so you virtually will do anything below full planing speeds with the charger engaged ?

I know the '44 will spin the charger when engine is cold or will engage it immediately when you "gun the engine" , i ask for a warmed up engine and a steady hull speed trolling on an inland channel

Thank you very much !

 

[petem]

Hello gents !

if i understand it correctly the supercharger envolope on the kad 44/300 is a bit different than the mechanical kad32/43 .

Not fixed cut in at 1500 and cutout at ~2800 but controlled by ECU depending on conditions .

My question :

the manual says the supercharger range is between 1000-2800rpm .

Is this the envelope where ECU can decide to call for the supercharger depending ln load etc or does it mean that the engine spins the supercharger all the time at anything above 1000rpm,s , so you virtually will do anything below full planing speeds with the charger engaged ?

I know the '44 will spin the charger when engine is cold or will engage it immediately when you "gun the engine" , i ask for a warmed up engine and a steady hull speed trolling on an inland channel

Thank you very much !

I believe it varies depending on the exact engine model (i.e. KADP44-A, B, C or KAD300). I have KAD and it's possible to pootle along at 8kts or so with the supercharger disengaged. And also at cruising speed you can reduce throttle at certain engine speeds and get the supercharger to disengage.

I also believe that the KAD44/300 series supercharger is quieter in operation than the KAD42/3 version.

Note that the turbos on KAD engine only last around 15 years so budget for replacements if they're still the original ones (£1000 per side).

We tend to cruise at slow speed or fast enough that the turbo is doing its work and the supercharger has disengaged.

 

[Chris_d]

The 1000-2800 range is the range in which the kick-down function will engage the superchargers, if you just push the throttles open slowly the supercharger will engage at approx 1700rpm and cut out at approx 2600rpm etc.. subject to boost and load.

 

[aerobat]

Ok, great infos , now it makes sense to me !!

 

[aerobat]

Note that the turbos on KAD engine only last around 15 years so budget for replacements if they're still the original ones (£1000 per side).

You are correct , afaik the turbos were never changed so probably they run on borrowed time - 25 years .

Today phoned with the volvo yard for the engine survey . They wanted the exact serials and they told me we need an speed unrestricted spot to load up the engines up to 100% .

Then , hooked up on diagnostics during the ride , recordings of oilpressure , watertemps , charge pressures and temperatures , fuel flow etc will be made and compared to internal volvo specs as well if there are differences on both .

Then a visual inspection , readout of stored fault codes etc .

It will be interesting if the turbos still hold the spec charge pressure or not . Will let you know .

 

[Seastoke]

If the engine results are bad , can you pull out of the deal.

 

[aerobat]

If the engine results are bad , can you pull out of the deal.

Yes

 

[briggs]

Supercharger is the same unit for the 32,43,44,300 series engine. All produce the same annoying whine.
Careful running in the supercharger range for long periods of time. They will overheat and come apart, can cause catastrophic damage. They also produce moisture that is forced through your engine.
The supercharger on those engines is for intermittent use only. Super frustrating that the 1550-2750 rpm range is useless.

 

[ChromeDome]

I'm not a fan of green lumps, but as input to your question Mr. Google finds:

The Volvo Penta KAD44's supercharger engagement/disengagement is managed by an electromagnetic clutch system controlled by the Engine Control Module (ECM). Here's how it operates and common issues affecting its function:

Control Mechanism

• ECM Inputs: The system uses engine RPM, throttle position, and load sensors to determine when to engage/disengage the supercharger[1][7].
• Clutch Operation:
• Engagement: At low RPMs (<1,800–2,000 RPM), the ECM sends power to the electromagnetic clutch, mechanically coupling the supercharger to the engine via a drive belt[1][2].
• Disengagement: At higher RPMs, the ECM cuts power to the clutch, allowing the turbocharger to take over boost duties[1][7].

Common Failure Points

• Clutch Wear/Defects
• Symptoms: Failure to engage (loss of low-end power) or erratic engagement/disengagement[1][7].
• Causes: Worn clutch plates, solenoid failure, or electrical issues (e.g., corroded wiring)[2][6].
• Sensor/ECM Issues
• Faulty throttle position sensors or RPM inputs can prevent proper clutch activation[1][7].
• Example: A loose inlet manifold bung (reported in the search results) may cause inaccurate boost pressure readings, confusing the ECM[1].
• Electrical Problems
• Poor connections at the clutch solenoid or damaged wiring harnesses can interrupt power delivery[2][6].

Troubleshooting Tips

• Boost Pressure Check: Install a boost gauge on the intake manifold or turbocharger outlet to verify if the turbo spools up as expected[1].
• Clutch Power Test: Use a multimeter to confirm 12V reaches the clutch during low-RPM operation[2][6].
• ECM Diagnostics: Scan for error codes related to throttle position, RPM sensors, or clutch circuit faults[1][7].

Critical Observations from User Reports

- A user with a new supercharger clutch still experienced turbo spooling issues, suggesting potential ECM/sensor miscommunication rather than clutch failure[1].
- Loose manifold bungs or air leaks can mimic clutch-related problems by altering boost pressure readings[1].

For clutch replacement or ECM recalibration, refer to Volvo Penta service manuals or professional technicians[6][7].

Citations:

[1] Kad 44 EDC down in power. boat details, condition of hull/props, and observations lis
[2] KAD 44 supercharger clutch
[3] https://www.svb24.com/en/category/_KAD44/inboard-parts-accessories
[4]

[5] https://www.thehulltruth.com/boatin...enta-kad44-marine-diesel-printerfriendly.html
[6] how do I remove compressor/supercharger clutch on Volvo Penta KAMD-44?
[7] KADP44 EDC supercharger engages and disengages please help!!!!
[8] SOLENOID CLUTCH 3581724

 

[aerobat]

The supercharger on those engines is for intermittent use only. Super frustrating that the 1550-2750 rpm range is useless.

SInce i,m new to kad44 i asked with some fear if it is to understand that it will spin the supercharger anytime between 1000 and 2800 - so including 7kt on inland channels - but thankfully not .

not intending to run continously in supercharger range but do we have documented failures from such use ? I would guess there are tons of boaters who do not realise or care the supercharger and just ride the boat

 

[ChromeDome]

SInce i,m new to kad44 i asked with some fear if it is to understand that it will spin the supercharger anytime between 1000 and 2800 - so including 7kt on inland channels - but thankfully not .

not intending to run continously in supercharger range but do we have documented failures from such use ? I would guess there are tons of boaters who do not realise or care the supercharger and just ride the boat

Engines are designed to work. A super knowledgeable forumite (not seen for years unfortunately) said "in the red once a week", referring to the tacho, to keep the engine happy.

The KAD 44 was developed for "Special Light Duty" planing vessels, leveraging its compressor- and turbocharged design for rapid acceleration and top-speed performance. In addition, planing hulls struggle to maintain straight tracking at low speeds due to hydrodynamic design priorities and reduced directional stability mechanisms. A few of them can do the 7-15 knot range in comfort.

Potting around will be possible but personally I'd refrain from it. If on sterndrives you'd have to factor the (eye watering compared to shafts) maintenance cost of these in too. Admittedly, sterndrives are fine for close quarter maneuvering, when you know how to.

 

[petem]

I also believe that the KAD44/300 series supercharger is quieter in operation than the KAD42/3 version.

@BruceK can you confirm this? I think I read it on one of your posts.

 

[kashurst]

Supercharger is the same unit for the 32,43,44,300 series engine. All produce the same annoying whine.
Careful running in the supercharger range for long periods of time. They will overheat and come apart, can cause catastrophic damage. They also produce moisture that is forced through your engine.
The supercharger on those engines is for intermittent use only. Super frustrating that the 1550-2750 rpm range is useless.

superchargers and turbo chargers do not directly produce moisture. They compress air which contains water and that heats it all up. When that warm air is then put through a charge air cooler, it cools down and some of the water content condenses out inside the charge air cooler. The KA(M)D engines have a drain to get rid of it. Most engines just invariably suck the moist air through and it exits the engine as steam. All turbo/super charged engines do this.

SInce i,m new to kad44 i asked with some fear if it is to understand that it will spin the supercharger anytime between 1000 and 2800 - so including 7kt on inland channels - but thankfully not .

not intending to run continously in supercharger range but do we have documented failures from such use ? I would guess there are tons of boaters who do not realise or care the supercharger and just ride the boat

I had a pair of KAMD 300s in my previous boat. They are almost exactly the same as the 44s.
I read the official volvo user manual which covers the 44 and 300 engines front to back and back to front many times. I generally do my own servicing.
Volvo make no mention at all about operating the engines with the superchargers engaged. I have done so on numerous occaisions and they work well. If you go out to sea it is impossible not to on some occasions. You cannot always be planing if it gets rough.

I do not know what the source of this myth is. However there are many tales of KAD engine clutches and belts failing. Pay close attention to the shims in the clutch if you replace it and always use a decent torque wrench to set to the volvo specified belt tension - otherwise they shriek and don't last long. I think some people treat them like a car cam belt and don't set the tension tight enough.

The supercharger silencers on the 44/300 are quieter than the 42/43. They are a different design

 

[aerobat]

Pay close attention to the shims in the clutch if you replace it and always use a decent torque wrench to set to the volvo specified belt tension - otherwise they shriek and don't last long. I think some people treat them like a car cam belt and don't set the tension tight enough.

The supercharger silencers on the 44/300 are quieter than the 42/43. They are a different design

Great informations , thank you ! How often did you have to replace the belts ?

 

[kashurst]

Great informations , thank you ! How often did you have to replace the belts ?

I put new official volvo belts on when I bought the boat. I kept that about about 5 years and I did/do about 30 - 50 hours a year. I never adjusted them or changed them in that time. They didn't squeal or other odd things. I did check them regularly. If/when you change yours make sure all the pulleys are really clean, check the idle/tensioner wheel feels very smooth and not loose on its bearing. I use the volvo belts as the supercharger application is very demanding.
I can't remember what the Volvo manual says about changing but stick to that. There is all sorts of anecdotal stuff on the internet about changing them every two years etc or spraying them with some sort of gunk to stop squealing, ignore it all follow Volvo's specification and method in the manual.

 

[BruceK]

@BruceK can you confirm this? I think I read it on one of your posts.

Yes. Earlier iterations did not come with the supercharger silencer. However the 44 and 300 silencer fits the 42 and is what I put in mine and so are as quiet / noisy.

Supercharger is the same unit for the 32,43,44,300 series engine. All produce the same annoying whine.
Careful running in the supercharger range for long periods of time. They will overheat and come apart, can cause catastrophic damage. They also produce moisture that is forced through your engine.
The supercharger on those engines is for intermittent use only. Super frustrating that the 1550-2750 rpm range is useless.

Thats nonsense. The superchargers are Ogura and ours in particular are rated to run at 10 000 rpm continuously. Anything else you read on the internet is best taken to source first

Ogura S.A.S. - Official European Electromagnetic Clutches and Brakes WebSite

 

[BruceK]

...... always use a decent torque wrench to set to the volvo specified belt tension - otherwise they shriek and don't last long. I think some people treat them like a car cam belt and don't set the tension tight enough.

More often than not the belt shriek is coming from the crank to water pump belt which in turn drives alternator, compressor and hydraulic steering pumps on top of that. The compressor is just the final straw when it kicks in as it has a lot of resistance spooling up..

 

[BruceK]

The roots charger on these engines is simply a mechanism to avoid turbo lag. They are designed to help spool up a smaller turbo in what would otherwise be a turbo lag in a larger turbo right in the point you are trying to clear the hole shot and come on the plane. Where as the roots charger can be run continuously within it's designated speeds, as these speeds occur at the transition point between displacement and planing speeds that may dictate that its "not a good idea to run the roots charger for longer than necessary" not because of the roots charger overheating but instead because you are lugging the engine.