Absolutely frustrated with this Mercruiser engine

Hoplite , please report if the engine performs fully normal at sea trail . Hopefully yes and than it was a good learning for us all . Hopefully we all fought the devil in your boat and all will be fine ;-)
 
aerobat77 said:
Hoplite , please report if the engine performs fully normal at sea trail . Hopefully yes and than it was a good learning for us all . Hopefully we all fought the devil in your boat and all will be fine ;-)
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I will let everyone know once I can make some time for a proper sea trial. Got a bunch of family stuff this weekend and work needs me 0500-2300 for most of the week. Hopefully next Saturday the weather will be clear enough for me to do a proper run with it.
 
This weekend's weather report was not looking good so I got everything together and went down this morning before work and took her out for about an hour today. It felt much better than before and I ran her at full throttle with no apparent bogging down or other issues for most of the hour I was out for. I think I can call this fixed. Perhaps when she was brand new it went a bit harder and faster but for a 27 year old engine and boat I think this was okay. One engine and with a dry weight of at least 6,500 lbs. she's a bit of a fat bottomed girl anyways so I don't expect it to be any sense of a speedster.

Anyways, some good music then to end this thread with.
 
This makes me so happy! Glad you stick with it and didn’t sell and start with another boat. Enjoy it, I hope you have a great summer! Planning on my first trip to Hawaii next April

Hoplite808 said:
This weekend's weather report was not looking good so I got everything together and went down this morning before work and took her out for about an hour today. It felt much better than before and I ran her at full throttle with no apparent bogging down or other issues for most of the hour I was out for. I think I can call this fixed. Perhaps when she was brand new it went a bit harder and faster but for a 27 year old engine and boat I think this was okay. One engine and with a dry weight of at least 6,500 lbs. she's a bit of a fat bottomed girl anyways so I don't expect it to be any sense of a speedster.

Anyways, some good music then to end this thread with.
Click to expand...
 
So I take it planes no problem and like scoflaw said how's the top speed
 
Is his boat really that heavy that it wouldn't have a top speed of 28 30 mph. Or is it because of the condition of the engine
 
Scott215 said:
Is his boat really that heavy that it wouldn't have a top speed of 28 30 mph. Or is it because of the condition of the engine
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it should absolutely go mid-20's or higher, it's not that heavy of a boat and a B3 has plenty of lift to get the rear end up and out of the water. I'm also curious to hear current top speed/RPM after the latest valve findings
 
My boat supposedly weighs over 5000 pounds and will do 40 mph with a 5.0 MPI and 17 pitch prop. Plenty fast for me . I would rather just chill at my cruise speed of 27 to 29 at 3100 RPMs
 
Per the manufacturer she has a 6,500 lbs dry weight. Gasoline is about 6lbs per gallon and I had about a half tank and with a 40 gallon fresh water tank which when full is another 320ish lbs. With all the other random kit I have aboard plus the weight of people on board I would estimate she's sitting in the water now as least 8,000 lbs. to get underway. The engine is rated when it was brand new at 330 horsepower. With the engine and trim tabs set right and the ocean conditions smoothing out enough for me a bit I was able to get her to rev up to about 4000 for the fasted short run but it was happiest in the sea state that day holding around 3500 RPM's at about 19-22 knots.

Googling what the top speed should be for this boat I couldn't get any clear answer and the numbers were between 26-43 knots and it looks like they got faster the newer they are and there were other variables such as twin engines and other things to find a comparable for my own boat. I did a bit of studying and found and equation created by Naval Architect George Crouch which claims to calculate the theoretical speed of a boat using this equation: S = √(P / D) × C. S = Speed, P = Engine Horsepower, D = Displacement, and C is Crouch's constant of 150. So for my 270 in its current configuration it calculates as S = √(330 / 8000) × 150; which makes S = 30.46 MPH which translates to a theoretical top speed of 26.46 knots. So I think I can say it's good.
 
The 270s were never extremely fast. That sounds about right for that model. The engines were rated for 4000-4400 rpm from merc.
 
Glad you got it going enjoy
 
We don't need another 25 page thread. Wow
 
99 270da here (9.5ft wide beam) with 7.4L MPI and BIII with 22p props. My WOT Rpms is 4200-4300 and top speed somewhere around 35-36mph depending on how clean the bottom is. Hopefully that gives you at least a little reference as to what you're looking for
 
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