Originally Posted by Zippy
We had a steyr 256 in a 9 meter stepped hull cougar and it was about a close to an outboard as I have driven a diesel rib.
High 5 prop and very little turbo lag and never had a problem even towing skiers (mono ski / wake boarders)
The cougar was a light boat so would be comparable in weight to an 8.1 scorpion I would guess?
even with the cost saving for fuel, I would stick with a new petrol outboard but then my boating is in namby pamby south coast where waterside petrol is easy.
Probably the reason for the lack of turbo lag in that set up would be possibly partly due to the engines turbo set up which is smaller dia & will therefore spool up quicker than a yanmar 6lp which runs a relatively large diameter turbine & comp wheel.
But more likely due to you running the bravo 1 drive with a well matched prop
So many yanmar installations run bravo 3 duo props or bravo2 which is essentially a big cruiser leg with a big dia lower unit & huge dia prop which leads to very little prop slip on either drive which prevents the turbo spooling up to get the thing actually going
For a fast rib a far better set up is a bravo 1 drive with a well matched prop of which there are many variations unlike the b3 and b2 which your stuck with mercruiser's limited standard props