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| Performance problem - 18x48 w/ 37EFI https://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=41&t=66938 |
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| Author: | usherjs [ Sat May 21, 2016 5:13 pm ] |
| Post subject: | Performance problem - 18x48 w/ 37EFI |
I have a new 1848 custom made duck boat with a new MudBuddy 37EFI HDR. By all accounts, the boat should be able to hit 30mph with a moderate load but the best I can do is 25mph. It gets up on plane easily and turns 4500 RPM with no problem. As I trim the prop lower into the water, the best speed I can attain is 25mph but the RPMs never get below 4350. Any thoughts on why this is? Should I consider more prop? Say, the Hammer? Or, maybe change the belt ratio? BTW, I have a 21 inch transom and ordered the tall transom configuration of the HDR. Any way to verify that I have the right model? |
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| Author: | JD145 [ Sat May 21, 2016 7:17 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
Tall transom should have 8 bolts in the clutch cover. What about your current prop? Is it worn bad? Could be part of your issue. |
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| Author: | JD145 [ Sat May 21, 2016 7:24 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
In my experience the hammer doesn't gain you speed. Is it a heavy boat? Open or full of boxes? |
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| Author: | VooDoo Daddy [ Sun May 22, 2016 9:18 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
I am having the same problem, my boat has recorded 31 before, always did about 30. I noticed last year that I cannot get it past 26. Boat Dr is looking at it now. Could be prop, could be governor spring, could be valves, could be one of about 6 or 7 things probably. |
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| Author: | usherjs [ Sun May 22, 2016 2:02 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
Thanks. I do have eight bolts in the clutch housing cover so I'm good there. And, the prop (as well as the entire rig) is new so that's not a factor. As for the boat, it is mostly open but the style of construction probably makes it a little heavier than a GatorTrax of similar size and shape -- but not that much. I did have two kids (125 & 50lbs), a dog, and a six gallon gas (in addition to the 10 gallon built-in tank) near mid-boat just to simulate a near hunting load. I would figure that if the engine weren't running well, I wouldn't be able to keep 4300+ RPM. Is that right? And I was thinking if slippage was the issue with the big blade, then maybe a hammer would grab more water. Sounds as if you don't agree. What is the benefit of the hammer blade then? Any other thoughts come to mind? |
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| Author: | JD145 [ Sun May 22, 2016 2:42 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
Hammer will step a load quicker and just handle a big load better. If you're talking top end speed the big blade will be the one that provides the most out of the two. Im not sure a stock 37 can sufficiently spin a hammer either. Maybe try shifting the weight around in the boat, different boat/motor combos like different things. I doubt its your valves because it sounds like your RPM are good. Im also not sure should necessarily expect a steady 30 mph with a stock motor but you definitely have some speed left on the table. |
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| Author: | bdavis85 [ Mon May 23, 2016 11:53 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
i have an 1848 prodigy with a 35 gtr and can only hit 26.5. I have even decked the heads and gutted the exhaust. |
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| Author: | TPerkins [ Mon May 23, 2016 2:26 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
That sucks, im assuming its a loaded out boat? Sent from my SM-G920V using Tapatalk |
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| Author: | Matt Boyt [ Mon May 23, 2016 7:10 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
1854 prodigy 4400 HDR runs 30 all day with 2 people Sent from my iPhone using Tapatalk |
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| Author: | krazo [ Tue May 24, 2016 8:47 pm ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
| Author: | txmudcutter [ Wed May 25, 2016 5:30 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
| Author: | dead animal [ Wed May 25, 2016 6:07 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
don't beleive most of the bullsheet on here. 25 is a good speed for a lawnmower engine on a big ass boat. 30 unloaded with the wind to your back in 18'' of water = 25 in deep water with regular load. enjoy the boat, there will always be somebody with a faster boat, it is all some folks live for. lol |
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| Author: | TPerkins [ Wed May 25, 2016 6:15 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
I wouldn't call 1848 a big ass boat, but agree with what others are saying in regard to inflated speeds. Sent from my SM-G920V using Tapatalk |
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| Author: | North LA Hunter [ Wed May 25, 2016 7:06 am ] |
| Post subject: | Re: Performance problem - 18x48 w/ 37EFI |
The 1848 boats that I've built run about 27-30 with stock motors. I built a 1852 loaded out and it hits about 27-28. Don't think your speeds are horrible but the could be better. Who built the hull? Sent from my beeper |
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