View Full Version : Info on New 4 stroke
14-01-2002, 02:37 AM
I bought a new rig back in July 01 a new Merc EFI, 115hp, 4 stroke (now done 80 hours) on a 5.6m (Alloy) Sea Boss, I have never been able to find anyone that has a similar set up to compare fuel efficiency, I would also like to get some figures from Optimax owners to compare fuel figures. I do a lot of bottom fishing throughout the year and in the season a lot of game trolling. I read and hear a lot of conflicting info re fuel efficiency from the dealers, but what about from the owners.....
here is another one .....is my motor the same as the 115 4 stroke Yamaha, some dealers say yes (identical) some say no ???
16-01-2002, 05:40 PM
I fish quite a bit out of a mates 5.5m Plate Alloy JBS (Joshua) Classic Cutter. It has the 115 4-Stroke Yammie on it. It is spinning a 17" prop because of the loads we are pushing and because we do bar crossing. It has a Navman fuel flow meter on it so we know what we do. It is nearly 2 years old and has about 250 hours on it. At 98 hours we had the impellor chew out on it 10 Nm off Wide Bay Bar requiring a tow. We have since found out you need to flush them with ear-muffs or the flush port. The impellor is in the middle of the leg. He was flushing it in a plastic 200 litre drum.
At trolling speed we try and keep under 10 l/hr. This gives us 6.5-7.5 knots - perfect for trolling skirts. 2 years ago we fished a game comp with lots of current and trolling a bit faster was all the rage. To produce speeds of 8.5-9.5 knots pushing the current and pushing a lot of weight we were burning 12-14 l/hr. At idle, livebaiting for billfish and Spaniards it uses 2 l/hr. On the plane, the best consumption I have seen it do is 24 knots for 24 l/hr whilst travelling with the swell. It is usually 19-20 knots for 24 l/hr and a bit over 4000 RPM. Its top speed is 30 knots. We get worse fuel economy than any figures I have seen published for these but we are all big guys and we carry big loads of fuel, ice, bait, drinks etc. We know some guys swinging 19" props and they are getting phenominal fuel economy. This combo averages about a Nm/litre. A bit worse for trolling. The Navaman is extremely accurate when calibrated. The Yammie/Merc 4-Stroke is a winner. Not sure what componentry they share. The carbeied models with slightly less horsepower give nothing away to the EFI 115's either.
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