Cruise Reports Isuzu 3.1. Prop help

[Kevmca]

Hello all
I have just fitted a 3.1 turbo diesel Isuzu engine in a rinker 182 (I think) it is I’m running it with the Alfa 1 gen 2 leg and was wondering if anyone would have help or advice on what prop to run it on it’s currently on a 14-1/2x17 and it struggles to get up on plane unless at top revs and it’s no pull on the engine at all? I have got my hands on a high 5 stainless steel but haven got back out for a test yet

Thanks in advance for the help

 

[QBhoy]

Oh jeez. This is a problem faced by many doing this.
Put simply...there are a couple of issues. It’s neber going to be perfect without changing the drive ratio. Your two main issues are
The original petrol would be set up with a drive ratio and prop to see 4400-4800 or similar. With a linear power curve almost.
The diesel will produce peak power much further down the rpms and will rev much lower flat out.
Further complicated by the fact that often a diesel needs a lot of load on the engine to spool up the turbo...by using a higher pitch prop. But then there is the fine line of too much pitch that won’t allow the boat to plane. 9/10 times this idea doesn’t work unless you put in a diesel with similar rpm peak power range. That’s why the bmw 3.0d engines are sometimes a good fit. They do rev to similar rpm as the old GM petrol and produce peak power at similar rpm too. Good luck but it’s difficult.