I have a old 470 Mercruiser 170hp in my Campion 310. Due to the lack of ready available parts I am going to swap out the motor this fall with something newer. I was wondering if any of you have done this before and what engine would be the easiest to install without too many modifications. I was considering a Volvo Penta 4.3 litre or the Merc 3 litre. The Merc is only 140 horse with far less torque but I question if I need much torque or horsepower on a 7 knot boat. I can modify the mounts and stringers but my big concern is matching to the Borge warner trans.
Pagoo has the 140 hp Volvo diesel. I run it at 1400 to 1500 rpms. I think it is rated at 2400 rpms. Anything over 1500 just burns more fuel. I would be looking at about a 80 hp diesel if I was going to repower. My fuel burn at 1500 rpms is 6 liters / hour. As I under stand it one of the problem with the 470 is the built in alternator which can be replaced with a more standard one such as a Delco.
Thanks... My 470 has had all the improvements such as alternator kit ,electronic ignition etc. I have thought of switching to diesel because my fuel tanks can go either way but the costs have been unbelievable. I got a quote to put a yanmar in it and they wanted $27,000 which is just not going to happen. So do you think a 140 horse 3 litre merc would push it OK ? The torque rating is not very high but I don't think these boats need a lot of torque at 7 knot top end. Do you know what the torque rating is on your engine? When I tell people it has a 470 they all give me the "Oh my god" look and I only feel it will hurt resale if I re-power with another one.
I will see if I can find the torque curve for my engine. Off the top of my head I think 140 horse 3 liter merc would push it, but you may be happier with some thing that you could run slower and still git your 6 to 7 knots