Boost pressure values KAD42 - Technical data

[BruceK]

I know boost pressure values change with temperature but does anyone know what the correct boost pressure according to the Technical Data manual should be? Typically I have all the manuals apart from that one.
A google search has drawn a blank. Everyone talks about boost pressure but nobody actually mentions what it should be at what ambient temp or rev so I can calibrate it against a published graph.

 

[vas]

no idea for your motors, but I doubt ambient will have any effect on WOT boost once engine is warm that is and that's when you'll be able to do wot tests anyway

I'd expect 2bar to be enough, if there were 2.5bar senders and gauges I'd go for them but I think you then go up to 5.

V.

 

[BruceK]

I have, probably prematurely, purchased 2 bar gauges and senders. I'd be surprised if they are 2 bar and above as the SC's are only 1 bar of boost. And when they kick in you certainly feel it. I am anticipating a figure of about 1.7 bar at max rpm but am not sure and then also what it should be at my cruising and lower revs?

Apparently ambient temps do make a difference. Quite a lot in fact. They have a correction graph chart in the manual to help you work out what you would / should be getting at various temps. Only the Volvo manual covers the entire range of the 3 and 41 series engines upwards and to get data specifics you need the technical data manual.

 

[vas]

I have, probably prematurely, purchased 2 bar gauges and senders. I'd be surprised if they are 2 bar and above as the SC's are only 1 bar of boost. And when they kick in you certainly feel it. I am anticipating a figure of about 1.7 bar at max rpm but am not sure and then also what it should be at my cruising and lower revs?

Apparently ambient temps do make a difference. Quite a lot in fact. They have a correction graph chart in the manual to help you work out what you would / should be getting at various temps. Only the Volvo manual covers the entire range of the 3 and 41 series engines upwards and to get data specifics you need the technical data manual.

is that air intake temp at the filter Bruce, or compressed air temp after the turbo?

V.

 

[BruceK]

The Book of Words says
NOTE! In the KAD32 and KA(M)D42/43/44/300 the
boost pressure is checked only with engine speed
(RPM) exceeding 3100 rpm so that the compressor
does not contribute to the boost pressure.
See Workshop manual “Technical Data”.
The boost pressure should not be less than the
minimum value given for the engine type.
Check the engine speed (RPM) with a workshop revcounter.
NOTE! It is important that full load is retained for as
long as it takes for the boost pressure to stabilize so
that the result is accurate.

then that graph

A. Boost pressure measured
B. Correction graphs
C. Intake air temperature (IAT)
The boost pressure is given at +20°C/68°F, which
means that the measured value must be corrected
according to the diagram, if the intake air does not
have that temperature at the time of measuring.
Example: A pressure of 100 kPa (1kp/cm2/14 psi)
registered at 0°C/32°F is equivalent to 92 kPa (0.92
kp/cm2/12 psi) at +25°C/77°F.

And that's it. Please dont tell me I need another sensor to tell me the charge air temps. I am beginning to despair.

 

[vas]

And that's it. Please dont tell me I need another sensor to tell me the charge air temps. I am beginning to despair.

dont be silly.
You'll be fine with what you've got. Just use a thermometer to check what's the ambient temp like.

Don't forget having two gauges on display all the time, you'll learn what they should be showing at any given moment, and will be alerted if anything different appears on screen!

V.

 

[BruceK]

Not being silly, just a poor attempt at humour while getting a bit stressed. I really do have the boat in pieces sorting stuff out. I had to completely dismantle the engines to put ram pins in or face having the engines lifted. My drives are in shop. My control levers all need replacing along with new gear cables so that's also in bits and I am having a whale of a time with the starboard steering yoke which has decided not to let grease through (salted up). I need to replace 1 trim pump as it doesn't hold the good rams up for long under power, the carpets need replacing and I have to install some solar panels to the deck. Finally I have to also service the engines. The Surveyor comes 20 March and lift in is a week after with no possibility of a delay. I'm a little stressed tbh.

Anyway ....Finally found two corroborating values. A 25 dollar membership to boatdiesel something or other and got the answers :

RPM KPA Bar

1800 115 1.1
2500 145 1.45
3800 175 1.75

PSI
1800 16.6 1.1
2500 21 1.4
3800 25.3 1.7

 

[vas]

I'm a little stressed tbh.

OK, get on with the work and stop faffing about with the pressure sensors...
You fit them at the last moment (or a few moments after you're back in the water)

good luck, looks like a few things to do
what panels btw, how big, where and what mppt controller to what batteries?

V.

 

[BruceK]

I am limited by panel size so this was the biggest I could get..
https://www.photonicuniverse.com/en...s-solar-panel-with-self-adhesive-backing.html

It will go on the foredeck where the sunpad cushions go between the rails. At 2mm thick and able to be stood on it will hopefully be as unobtrusive as possible

https://imgur.com/a/vj4QGul