Repowered 1998 370
- Thread starter PKONA
- Start date
DeltaEx
New Member
I have that boat 1998 370 EC. I made that same mistake and put 8.1s in her!!! What a pig! I can not afford now to take my baby any where because there is no sweet spot. I am now looking into Cummins or Yanmars. Very sorry your where talked into the same thing I was ..... :-(
techmitch
Well-Known Member
- May 1, 2008
- 8,396
- Boat Info
- 1999 270 DA
- Engines
- Twin 4.3s W/Alpa I Gen II's
Two questions: (1) What are your trans. ratios? (2) What are your props size and pitch?
Air O'Nautical
Well-Known Member
- Feb 5, 2008
- 2,316
- Boat Info
- 1995 400EC. Raymarine E80, Tridata, 4kw dome, Garmin 943
- Engines
- 2013 7.4L Mercruiser Blue water.
Hurth straight shaft 630's,
Westerbeke 7.0 BCG
You are on the right track.
Sound like the new engines are not dialed in yet.
Reprop it correctly and keep the bottom clean.
Big gas boat "sweet spot" ? (Docked maybe)
From my experence the faster you go (as long as you are on plane) the more fuel you will burn.
Smaller boats have a big sweet spot tho....
- Oct 6, 2006
- 12,155
- Boat Info
- 1996 450DA
- Engines
- 3116 Caterpillars
I'm with Mitch on this one. Something isn't adding up.
I sold a 390EC to a guy who eventually repowered it with 8.1's. Since the boat originally had counter-rotating 7.4's, he bought complete engine transmission packages and changed to ZF's from Borg warner gears. I don't know the ratios, but they were different. The otherchange he made was going to 4 blade props pitched to match the engine/transmissions. The top end speed increased to about 26 kts and the boat was quieter and smoother. But, it takes a lot of fuel to feed 500 cubic inches no matter how efficient the motor is.
I sold a 390EC to a guy who eventually repowered it with 8.1's. Since the boat originally had counter-rotating 7.4's, he bought complete engine transmission packages and changed to ZF's from Borg warner gears. I don't know the ratios, but they were different. The otherchange he made was going to 4 blade props pitched to match the engine/transmissions. The top end speed increased to about 26 kts and the boat was quieter and smoother. But, it takes a lot of fuel to feed 500 cubic inches no matter how efficient the motor is.
