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Fuel efficiency
- Thread starter BillyK
- Start date
I'm assuming you are talking the Merc 6.2 Horizon? Your most fuel efficient speed is just shy of hull speed. Beyond that, the only way to tell is with fuel flow meters. Cruise RPM for the 2007 6.2 Horizon is between 3800 and 4200.
I can speak for the 2007 model and V drives. That seems like a lot of prop for that engine. Can you reach the engine's WOT range? I say engine because the inboard and the I/O are the same engine rated at different RPM's. The difference is the V drive max's out at 5K the engine at 5200. If you are not reaching at least 5K WOT, you are overloading the engine and probably burning more fuel than necessary.
YMMV
I can speak for the 2007 model and V drives. That seems like a lot of prop for that engine. Can you reach the engine's WOT range? I say engine because the inboard and the I/O are the same engine rated at different RPM's. The difference is the V drive max's out at 5K the engine at 5200. If you are not reaching at least 5K WOT, you are overloading the engine and probably burning more fuel than necessary.
YMMV
David,
Thanks for your reply. I went for a ride yesterday and the top end was 4400 rpms. This gave me a speed of 27 mph. My transmissions are regular straight out the back of the motor toward the stern. I do not know if they are horizon motors but they are 6.2 merc cruisers. Do you or anyone know how to find out what the correct propellers are.
Thanks,
Billy K.
Thanks for your reply. I went for a ride yesterday and the top end was 4400 rpms. This gave me a speed of 27 mph. My transmissions are regular straight out the back of the motor toward the stern. I do not know if they are horizon motors but they are 6.2 merc cruisers. Do you or anyone know how to find out what the correct propellers are.
Thanks,
Billy K.
- Joined
- Jul 28, 2007
- RO Number
- 27798
- Messages
- 96
Do you still have the original books that came with the boat? It'll be a white hard cover notebook with rings holding the pages in. Inside that will be a fold out form that has every single part onthe boat. Look through that and you'll find the props that were installed on the boat.
Mine came with 22" dia x 26" pitch props, which are too much pitch. My boat wull only hit 4050 RPM instead of the recommended 4200-4600. The carver test boat in 2001 that had the same engines and transmission ratios as mine had 22x24's on it. I'll be re-pitching when the water warms up enought to take them off.
Funny, though. I called and spoke to Carver about it and the guy there was surprised it had 26 pitch props on it from the factory. He too thought it should have had 24.
I would think you would need an even smaller pitch than 23 to hit the correct RPM's for the 6.2 MPI's. Probably 21 if I had to guess.
Mine came with 22" dia x 26" pitch props, which are too much pitch. My boat wull only hit 4050 RPM instead of the recommended 4200-4600. The carver test boat in 2001 that had the same engines and transmission ratios as mine had 22x24's on it. I'll be re-pitching when the water warms up enought to take them off.
Funny, though. I called and spoke to Carver about it and the guy there was surprised it had 26 pitch props on it from the factory. He too thought it should have had 24.
I would think you would need an even smaller pitch than 23 to hit the correct RPM's for the 6.2 MPI's. Probably 21 if I had to guess.