My now 30 year old 454's have given me ten great years of service but the boat has always been underpowered (Trojan International, 33', 17k pounds fully loaded). I am looking a pair of 8.1 HO's as a bump up and a compromise between a full diesel re-power which I have taken off the table.
Right now, I'm cruising at about 16-17k knots and by all accounts a 20-21k cruise should be reasonable with the big jump in torque. Has anyone here done same on a boat of similar size and have feedback? I know I'll probably burn less fuel but keeping my expectations here really low. 10% less would be a homerun which should be reasonable.
- Is the footprint of the 8.1's very close to the 454's? I have the taller flame arrestor and still have a few additional inches of clearance above that.
- I have 1.25" shafts now and read that those should be ok if one is aquamet 22. I replaced one a few years ago and it is aquamet , the other is original but just dye tested last year.
- How do I determine the required transmission setup? The ones I'm looking at have ZF Hurth 630 A1 2.0 which I'm told are down angle units and believe that's what I need for my hull. On my model Trojan, the engines are set back and the shafts are pretty short and at a steep angle.
I assume the ratio is 2:1 but will verify. My current tran is 1.5:1.
thanks,
Bob
Right now, I'm cruising at about 16-17k knots and by all accounts a 20-21k cruise should be reasonable with the big jump in torque. Has anyone here done same on a boat of similar size and have feedback? I know I'll probably burn less fuel but keeping my expectations here really low. 10% less would be a homerun which should be reasonable.
- Is the footprint of the 8.1's very close to the 454's? I have the taller flame arrestor and still have a few additional inches of clearance above that.
- I have 1.25" shafts now and read that those should be ok if one is aquamet 22. I replaced one a few years ago and it is aquamet , the other is original but just dye tested last year.
- How do I determine the required transmission setup? The ones I'm looking at have ZF Hurth 630 A1 2.0 which I'm told are down angle units and believe that's what I need for my hull. On my model Trojan, the engines are set back and the shafts are pretty short and at a steep angle.
I assume the ratio is 2:1 but will verify. My current tran is 1.5:1.
thanks,
Bob