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Old 13-01-2015, 11:25   #1
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Fuel consumption on rebuilt Westerbeke 4-107

First post for me.

Have rebuilt my Westerbeke 4-107 engine and now need to know it,s consumption. I purchased the boat dry (out of water) and right away rebuilt motor so had no idea of consumption now I want to check fuel consumption. My plan is to have a 2 ltr external bottle of fuel and run down to 1 Ltr at different engine RPM. To make it easier to plumb I want to couple the engine fuel return line to the inlet line before the pump and only have one line to the supply bottle, is this a viable way to connect. I understand that returned fuel goes to the tank to cool down before being re-used in the engine.

John
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Old 13-01-2015, 11:44   #2
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Re: Fuel consumption on rebuilt Westerbeke 4-107

My 4-108 in a 44 footer burned .65 gal/hour for the life of my ownership of the boat. Includes idling and motoring. Quite a bit of motoring actually in currents etc in the PNW.
For some reason I think that was exceptional though from other reports I've seen.
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Old 13-01-2015, 12:16   #3
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Re: Fuel consumption on rebuilt Westerbeke 4-107

May want to use a bigger bottle to get fuel consumption, but yes I believe it's a viable experiment. With that small a sample, it's difficult to get real accurate.
There is a formula to get fuel consumption per HP of small Diesel engine, and it is awfully close. I don't have it, but the BSFC of all these engines is awfully close
Be a little careful with getting number from others, for example I burn .5 gph based on my normal use which is a lot of warming up and in and out of the Marina, but constantly motoring at 6.5 kts, my consumption doubles to 1 gph.

Looked it up, seems to be about .4 lbs of fuel per hour, per HP. Diesel weighs I think about 7.1 lbs? So at 1 GPH, I'm making just shy of 18 HP? My 4JHE is a 40 HP continuous duty motor
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Old 13-01-2015, 12:25   #4
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Re: Fuel consumption on rebuilt Westerbeke 4-107

This seems a good link
Diesel Engine Fuel Consumption - Quick calculation
Wonder, these are Imperial gallons?
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Old 13-01-2015, 13:12   #5
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Re: Fuel consumption on rebuilt Westerbeke 4-107

a64pilot. Yes they are imperial measurements. I need to know cosumption at different RPM because in fresh water I run 6+ knots at 1500rpm on my 37ft sail boat where the max is 7.4 knots. Max rpm of engine is 3000 rpm, to me 1500rpm is to low when evry other owner talks about 22/2300 normal running. I used a litre first because I am in canada and 1 litre is very close to 1 US pint (4 litres=1 us gal) and second I will be travelling to the US this winter and this makes it easy to calculate consumption.
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Old 13-01-2015, 15:06   #6
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Re: Fuel consumption on rebuilt Westerbeke 4-107

OK, first I'm going to guess your overpropped, can you reach or come close to max RPM underway?


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Old 13-01-2015, 15:51   #7
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Re: Fuel consumption on rebuilt Westerbeke 4-107

It had crossed my mind that I am overproped but do not have the size available. I have not tried to go to max because I do not have complete confidence in my electronic Tac. My origional question was more about tieing in the fuel return into the fuel input, I will have to more research in the spring knowing that as you suggested I can connect both together on an experimental basis.

Thanks for the information
John
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Old 13-01-2015, 17:27   #8
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Re: Fuel consumption on rebuilt Westerbeke 4-107

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a64pilot. Yes they are imperial measurements. I need to know cosumption at different RPM because in fresh water I run 6+ knots at 1500rpm on my 37ft sail boat where the max is 7.4 knots. Max rpm of engine is 3000 rpm, to me 1500rpm is to low when evry other owner talks about 22/2300 normal running. I used a litre first because I am in canada and 1 litre is very close to 1 US pint (4 litres=1 us gal) and second I will be travelling to the US this winter and this makes it easy to calculate consumption.
john
I liked about 2400 rpm on my 4-108, that was a sweet spot. I think I could get it to 2700 or maybe 2800, but I never ran there.
BTW 1 litre is close to a quart, not a pint. (4 quarts per gallon)
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Old 13-01-2015, 17:59   #9
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Re: Fuel consumption on rebuilt Westerbeke 4-107

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Originally Posted by John Boor View Post
It had crossed my mind that I am overproped but do not have the size available. I have not tried to go to max because I do not have complete confidence in my electronic Tac. My origional question was more about tieing in the fuel return into the fuel input, I will have to more research in the spring knowing that as you suggested I can connect both together on an experimental basis.

Thanks for the information
John
Why connect them, put both hoses into the same container

In order for your 1500 RPM cruise compared to other peoples high RPM, you first must determine if your overpropped, If your making 6.5 kts at 1500 RPM, I believe your way overpropped. I believe it's not good for a motor to be way overpropped.
Put her in neutral and open it up when it's fully warmed up, it won't hurt it,
full RPM is governed, then see if you can get close to that RPM when underway
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Old 13-01-2015, 19:15   #10
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Re: Fuel consumption on rebuilt Westerbeke 4-107

Thanks for the correction about fuel. Most of my sailing is solo and wanted to have the fuel in the cockpit during the testing to see when my level has been reached, also with the returned fuel it may cause inaccurate readings. Again will have to wait until spring to test max RPM I did this once and chickened out at 2000 RPM.

John
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Old 14-01-2015, 11:26   #11
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Re: Fuel consumption on rebuilt Westerbeke 4-107

Quote:
Originally Posted by John Boor View Post
First post for me.

Have rebuilt my Westerbeke 4-107 engine and now need to know it,s consumption. I purchased the boat dry (out of water) and right away rebuilt motor so had no idea of consumption now I want to check fuel consumption. My plan is to have a 2 ltr external bottle of fuel and run down to 1 Ltr at different engine RPM. To make it easier to plumb I want to couple the engine fuel return line to the inlet line before the pump and only have one line to the supply bottle, is this a viable way to connect. I understand that returned fuel goes to the tank to cool down before being re-used in the engine.

John
I could be wrong? I believe the return line is only because the supply is intentionally more than the injectors can use. Install a day tank. I don't think your idea is necessary unless you can find a dead calm and a place with no current. Monitor the day tank usage that will give you a real life usage. Or do it old school and stick your tank with a stick literally, stick marked as you fill the tank, gal. by gal. or liter by liter. You don't even need to start with an empty tank. Just stick and mark gal. by Gal. on fill up, since chances are the tank is not symmetrical.
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Old 14-01-2015, 12:38   #12
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Re: Fuel consumption on rebuilt Westerbeke 4-107

I have a day tank and thought of using it as you suggest but would be a long drawn out event. I live on Lake ontario north of Prince Edward county and we have no current and a lot of calm days. My calculation would not be super acurate but would give me bench mark to get started.

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Old 14-01-2015, 16:33   #13
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Re: Fuel consumption on rebuilt Westerbeke 4-107

Geez Guys. Fill Your tank; run it for an hour and fill the tank again, noting how much was consumed. You can test it idling for a hour or motoring for a full hour, or mix it up. Just common sense.
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Old 14-01-2015, 17:15   #14
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Re: Fuel consumption on rebuilt Westerbeke 4-107

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Geez Guys. Fill Your tank; run it for an hour and fill the tank again, noting how much was consumed. You can test it idling for a hour or motoring for a full hour, or mix it up. Just common sense.
, yeah.... Unless your are attempting to motor the Atlantic immediately, keep a fuel/hours log....
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Old 14-01-2015, 17:30   #15
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Re: Fuel consumption on rebuilt Westerbeke 4-107

Assuming your propped correctly you can make rated HP
Then you can use the formula on that link I sent you and determine fuel usage at different RPM's and be awfully close.
If as I think, your not even close on your prop, then you can't make rated HP
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