Hello everybody,
pleasure to be here on the forum.
I have a 1976 Bertram 31 with 2002 Mercruisers MPI 350 hp.
I'd like to understand what is the best cruising speed (how many rpms?) and what is the maximum range.
I need to go to Napoli from Sardinia stopping in Ponza island (155 Nm + 45 Nm).
So from Olbia (Sardegna) to Ponza is 155 Nm.
My boat is 1976 so I should have the 215 gallons tank.
Do you think I can make it?
Thank you for your advices.
Ciao!
Luca
Mercruiser 7.4 MPI Consumption and range
Moderators: CaptPatrick, mike ohlstein, Bruce
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franzmerenda
- Posts: 110
- Joined: Nov 15th, '22, 10:17
Re: Mercruiser 7.4 MPI Consumption and range
Ciao Luca.
At cruise speed, let's say 25ktns, you should burn some 24 gal/h (90 litri/h) for a total consumption in between 155 and 160 gallons (550-600 litri).
What you should check carefully, is if your tank (that on a boat manufactured in 1976 shouldn't be less than 215 gals) is clean and the fuel inside as well
A couple of 50 liters canisters onboard would do the rest.
francesco
At cruise speed, let's say 25ktns, you should burn some 24 gal/h (90 litri/h) for a total consumption in between 155 and 160 gallons (550-600 litri).
What you should check carefully, is if your tank (that on a boat manufactured in 1976 shouldn't be less than 215 gals) is clean and the fuel inside as well
A couple of 50 liters canisters onboard would do the rest.
francesco
Re: Mercruiser 7.4 MPI Consumption and range
Hi Francesco,
thank you for your help.
At 3000 rpm I'm around 23 knots and fuel consumption should be around 80/90 lt/hr.
I've calculated a conservative 4 liter/Nm...
The problem is if I get big sea and I have to throttle back to 2800 rpm that means 19 Knots, in this case I think that the liters /Nm becomes much worse.... but I don't know how much....
Yes, the fuel tank has been washed and the fuel is new and clean.
I'm going to refuel in Ponza so I think 155 Nm can be done in safety but there not so many MPI gassers around so I'm curious to know the experience from other people with same engines.
I'm very happy with these engines because are simple, super powerful and silent.
I've tried many 31s with diesel and they vibrate a lot, are. super noisy and fuel consumption is good but with the actual diesel cost I don't see the deal.
And the sound of the V8 is orgasmic.
Thank you!!!
thank you for your help.
At 3000 rpm I'm around 23 knots and fuel consumption should be around 80/90 lt/hr.
I've calculated a conservative 4 liter/Nm...
The problem is if I get big sea and I have to throttle back to 2800 rpm that means 19 Knots, in this case I think that the liters /Nm becomes much worse.... but I don't know how much....
Yes, the fuel tank has been washed and the fuel is new and clean.
I'm going to refuel in Ponza so I think 155 Nm can be done in safety but there not so many MPI gassers around so I'm curious to know the experience from other people with same engines.
I'm very happy with these engines because are simple, super powerful and silent.
I've tried many 31s with diesel and they vibrate a lot, are. super noisy and fuel consumption is good but with the actual diesel cost I don't see the deal.
And the sound of the V8 is orgasmic.
Thank you!!!
-
franzmerenda
- Posts: 110
- Joined: Nov 15th, '22, 10:17
Re: Mercruiser 7.4 MPI Consumption and range
Ciao Luca,
I recently bought a 1970 Sportfish with 6.2MPI DTS 320hp and I do confirm that at 3200 rpm, boat runs at 24ktns.
I sailed from Maddalena to Olbia, put the boat on a truck and the truck on a ferry to Livorno.
I'm now refurbishing the boat from stringers and since engines had no fresh water heat exchangers, I chose to upgrade them with 6.2L 350hp.
Considering insane fuel costs here, silent, light and smokeless performance of these Mercs, has many advantages and modern technology offers very reliable fumes detectors.
May be at the of the day you spend some extra Euros but as I like thinking:
"More fuel costs mean more time spent boating; more time spent boating, more pleasure... "
I recently bought a 1970 Sportfish with 6.2MPI DTS 320hp and I do confirm that at 3200 rpm, boat runs at 24ktns.
I sailed from Maddalena to Olbia, put the boat on a truck and the truck on a ferry to Livorno.
I'm now refurbishing the boat from stringers and since engines had no fresh water heat exchangers, I chose to upgrade them with 6.2L 350hp.
Considering insane fuel costs here, silent, light and smokeless performance of these Mercs, has many advantages and modern technology offers very reliable fumes detectors.
May be at the of the day you spend some extra Euros but as I like thinking:
"More fuel costs mean more time spent boating; more time spent boating, more pleasure... "
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