Volvo sync gauge question

[steve930]

On a twin volvo engined set up, where does the engine sync gauge receive it's data from?

On my boat (twin kad 32's) the gauge registers that the engines are in sync until the superchargers cut out & the turbos kick in. At this point the gauge registers that the port engine is completely out of sync!

Both engines are revving out fine and appear to be making equal power. You can obviously hear that the engines are also in sync with each other, so I don't believe there's any problems but I'm curious as to why this happens!

 

[jrudge]

I dont know about a sync gauge, all i have had is a little blue light on the EDC controller.

There was a thread on this some while ago and I believe sync starts about 1200 RPM which is also the supercharger approx cut in.

 

[steve930]

Yeah this is a simple analogue gauge on the dashboard
View attachment 58585

 

[aquatom]

It won't be a Volvo gauge but will probably get its feed from the W terminal on each alternator. It sounds like the belts are slipping a bit when the super charger cuts in and causing the gauge to read wrong. Check the tension of the main belts between the crank and water pump pulleys.

 

[steve930]

I did wonder if that's where the feed comes from. I'm not convinced it's belt slip though, as it's when the charger cuts out & the turbo takes over, thus less load on the belts?