Fuel burn numbers for 350's, 270 hp in Bertram 28?

[reel trick]

Looking for the fuel burn for these engines/boat, carb Marine Powers, I put a friend on to one for sale and they have signed a contract, trying to help them with answers to questions.

Thanks

[lilbert2]

one n.m. per gallon on average for an offshore trip, including warm up. Basically, running 18.5 knots going out and 20.5 coming home (at 3200 rpm), I was burning 9.2 gph per side, sometimes 8.5 or 10, but average low 9's.

Ran 183 n.m down the ICW one day. Fill up was 181 gallons on the nose.

Carbed 350's, B-W 1.5 to 1's, clean botton, with regular tune ups and carb rebuilds.

Dump some of the weight, run with half fuel and no water, take only skinny crew members, one might see 1.1 n.m. per g.

[prockvoan]

I man at my marina has one with the same set ,says he gets 1.3 mpg@ 3100 rpms.
I have a wellcraft sportsbridge(30'),with the same set up,boat dry weight with tower is 12,700 lbs,run mine at 3200 rpms,6 people loaded down,26 mph,burn 23 gph in 3' to 4' seas for both engines.

[dwg2116]

I also have carbed 350's,
BW 1.5:1,
17/16 three blade props on my B28

lilbert2's numbers above are almost exactly what I get,

3000-3200 rpm = 18-24kts = 9-10 GPH per side
Speed depends on weight

According to floscan my most economical speed is 2600 rpm at 16 kts, I can get 1.2 nmpg or better if the boat is light.
But I can not stand to run there, it sounds like the engines are laboring and the boat is sluggish.

It really loves to run 3200 rpm plus. It just feels 100% better.

4000 feels even better still, but I don't like to run the engines there for more than a minute or two

[cgmiller]

Good Morning Guys,

The fuel burn numbers are right in line with my experiences. I have run 5 different 350's. The first one was a 240 hp Pleasurecraft in a 26 Shamrock. And at 2900 to 3100 rpms, it burned 9 to 11 gallons per hour as per the Flowsan. I replaced that with a 5.7 330 hp EFI Crusader and after taking 2.5 inches out of the pitch, it burned 11 gph at 3,000 rpms and 12 gph at 3200, which Crusader Tech support say was right one. I was very disapointed with the fuel burn and "less balls" of the EFI engine, which I paid an extra 3 grand for. I had a pair of 350 270 hp Crusaders in a 34 Silverton. At 3200 rpms, the port engine bruned 9 gph and the starbord engine burned 12 gpm. I currently am running a 24 Rampage with a 350 Merc (260 hp) and it burns 11 gph at 3000 rpms and 12 gph at 3100 rpms. So despite the boat, they are all burning within the same range..9 to 12 gph. The Silverton only cruised at 15 knots and average 0.7 miles per gallon. It was a bigger boat, but only weighed 12,500 plus 220 gallons of fuel. It does not has a deep a hull as the Bertram, but performance review books indicate a 21-22 knot cruise with 260 hp engines.

[reel trick]

Thanks for the numbers,

The guy the talked with about repower(in a year or two) told them that efi's(same hp) would burn 30 percent less!! I say no way, maybe 15% if they are lucky, any numbers on efi's?

thanks

[cgmiller]

In 2001, I had replaced a carburated 351 with a brand new out of the crate $8300 5.7 Captains Choice EFI Crusader - top of the line...I put it into a 26 Shamrock. I had received test reports from Shamrock for a 300 hp EFI engine in the same hull with the same 1.5:1 tranny. They were posting cruising speeds of 22 mph burning 7.5 gallons per hour. That would have been awsome. That is almost 3 miles per gallon and I was getting 2 miles per gallon with the carburated engine. So in theory, I would be able to run faster burning less fuel and would have more range. So I forked out the cash. My first season with the new engine and new tranny soinning the same wheel was very disapointing. I was burning 14 gallons per hour at 3000 rpms running the same 18 knots as before, which kind of makes sense since I was spinning the same prop at the same speed...what really picked me off was the additional 5 gallons per hour that I was burning. After spending almost 10 grand, I went from a 2 mile per gallon boat to a 1.5 mile per gallon boat. I was not happy. The following spring I had to prop reworked to reach the WOT required (5,000 rpms) which required 2.5 inches of pitch taken out of the 16"x17" 3 blade prop. That had a big effect on my fuel consumption and only dropped my cruising speed about 1 knot. After the prop work, I was able to cruise at 3,000 rpms burning 11 gph and running at 18 knots. 3100 rpms netted me 19 knots at 12 gph and 3200 saw 20 knots at 14 gph. I was still worse off then before the repower in terms of fuel economy and did not feel that the additional cost for the EFI system, the additional returnless fuel system, etc was worth it. Total additional cost over the 5.7 carburated engine was about $3,000. I was really confused with the lack of appreciable performance gain. Afterall I installed an engine rated at almost 100 additional horsepower..but that HP rating was at 5,000 rpms not at crusing speed. Crusader recommended cruising the engine at 75% of WOT, which was 3,750 rpms. I was not comfortable running it that hard and the fuel burn would have been about 18-20 gallons per hour. I probably would have been humping along at 25 knots, but the boat only held 100 gallons of fuel.

I have been comparing the performance and fuel burn of the 5.7 in my 24 Rampage to the new 24 and 26 Albemarles. In the 3000 to 3500 range, I am hitting about the same numbers and they are running EFI 5.0 and 5.7 respectively.

The starting of the efi was nice, but once warm, the carburated 5.7 in my Rampage starts when I hit the key. It starts right up when cold, but the choke is one and it smokes until it warms up and comes off. I bought the boat in August and put 60 hours on the engine in 5 trips. It never missed a beat. The 1987 270 Crusaders in my former 34 Silverton fired right up every time as well and they still had points. My position is that the EFI upgrade is not worth the extra cost at this point in time...

Maybe someone else has had a different experience...

Chris Miller
Mystic Islands, NJ

[SeaJay]

I do not believe that you will get more than a 10% improvement from EFI's over Carbs.

[TerpHeels]

I concur on the statements regarding 350's. I have a 34 Silverton (t/350's) and a 24 Albemarle and all the engines burn in the neighborhood of 12 gal/hr at 3200. Like was said though, my Silverton is making a paltry 15kts where the Albe is moving along at 21kts. These are all carb engines.

[cgmiller]

How do you like that 24 Albe?? I have an eye for the newer version with the raised deck house and the engine moved up from the transom. I like the roominess of my 24 Rampage with the 10' beam, but the 26 Shamrock that I had with an 8' beam would really run through the chop very comfortably. The Rampage has a much stiffer ride and I can't run as fast when it starts getting nasty or in any kind of seas, which pretty much slow the boat down on their own (it needs a 454). It bogs down in the waves and I have already put a smaller prop on the outdrive. Although the Rampage runs with her nose up (needs trim tabs) and does not take much spray. The Shamrock was like a submarine on nasty days, but still comfortable to ride in as long as the widnows were kept closed..

Chris Miller
Mystic Islands, NJ