AD31B - From 130hp to 150HP ?

[Corky]

I've been told by several people that my 130hp AD31B engines are 'easily' converted to 150hp by a straightforward adjustment of the injection pump. Has anyone else heard that and how do you do it? What is required?

 

[QBhoy]

I’m not sure what the technical difference is between the two, but what I do know is they are the same engine and also that a friend took the top off his (130hp) fuel unit and wound it up to just below the point of anti social amounts of black smoke and no more. It made a noticeable difference to performance but more usefully it allowed cruising at lower than the previous “just about full throttle” to keep it planing.

 

[Divemaster1]

Not giving advise on engine tuning, but unless RPM is increased by the excercise, you will need new propellors (propellors move boat, not engine!)...

No point having extra HP on tap and not putting the extra propellor load onto engine which mean you can take out the extra HP you want and thus travel faster at given RPM.

 

[Corky]

Thanks to you both. It's a relief that someone else has heard of this - thought it was a sailing myth. I've felt the boat was over-propped for a while with D6 duoprops. I had a buyer who planned on doing it but we couldn't agree a price.

The question now is - how do you do it? Do I need a VP engine man or is it in the realm of a DIY-er? The engines are in great nick and first time starters so don't want to undo the good.

 

[volvopaul]

Thanks to you both. It's a relief that someone else has heard of this - thought it was a sailing myth. I've felt the boat was over-propped for a while with D6 duoprops. I had a buyer who planned on doing it but we couldn't agree a price.

The question now is - how do you do it? Do I need a VP engine man or is it in the realm of a DIY-er? The engines are in great nick and first time starters so don't want to undo the good.

Remove your injection pumps and take them to a suitable Bosch dealer with all the pump setting details for the 150hp setting , while your at it have the injectors removed and tested , what boat is it ?
Do they make full revs at max throttle ? 3800/3900

It’s not a DIY job at all far from it , only a pump shop with the correct equipment can set up the max fuel setting , it can be adjusted but you have no idea by how much without it being on the pump dyno which accurately measure how much fuel and when it’s going in . I will have the settings in my files but the pump shop should have them too.

 

[Corky]

Thanks. The boat's a Hardy Seawings 305. It's hardly ever reached that sort of revs without a following tide and very clean hull.

Looking for a suitable Bosch dealer I'm struggling. I can't spot any in the area of the boat mooring - Gosport/Portsmouth but have found one without a website in Lewes - East Sussex.

 

[volvopaul]

Thanks. The boat's a Hardy Seawings 305. It's hardly ever reached that sort of revs without a following tide and very clean hull.

Looking for a suitable Bosch dealer I'm struggling. I can't spot any in the area of the boat mooring - Gosport/Portsmouth but have found one without a website in Lewes - East Sussex.

Tried to pm you but won’t send , pm me I’ll sort it.

 

[Corky]

I sent you a PM yesterday but it doesn't show in my sent box. Dunno what's going on.