Looking for a few MPH
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2000 Scarab twin 350 Mag MPI with 23* Mirage Plus Props.
Just looking for a couple MPH on the top end, that is all. Any ideas.
I posted something about a programmer a friend sent me a link to in the boat on a budget section. Looked like BS but figured hey why not at least ask.
Not looking to tear down the engine or anything. Some sort of tuning maybe, or full roller rockers, ect, just basic bolt on stuff. What works on these boats to get just a little gain?
Just looking for a couple MPH on the top end, that is all. Any ideas.
I posted something about a programmer a friend sent me a link to in the boat on a budget section. Looked like BS but figured hey why not at least ask.
Not looking to tear down the engine or anything. Some sort of tuning maybe, or full roller rockers, ect, just basic bolt on stuff. What works on these boats to get just a little gain?
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It's a $1000 per MPH to 75.
$2000 per MPH to 80.
$5000 per MPH after 80.
Seriously, I've noticed something about the MPI Merc small blocks. I have a Chaparral with 5L MPI. It runs the same top end with a 19 or a 23. Holeshot is all that changes, but the computer seems to "adjust" for the props. I think alot could be done with programming on that motor.
$2000 per MPH to 80.
$5000 per MPH after 80.
Seriously, I've noticed something about the MPI Merc small blocks. I have a Chaparral with 5L MPI. It runs the same top end with a 19 or a 23. Holeshot is all that changes, but the computer seems to "adjust" for the props. I think alot could be done with programming on that motor.
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Go with after market exhaust manifolds, Imco Thumper or Stainless Marine...saves weight which translates to 1-2 mph. Dart or AFR aluminum heads, a buddy ran a 350 small block with these in an identical boat to mine with a 454 and he would pass me, so 1-2 mph. Also the shorties have been posted about many times here as being very effective on the 29 hull for several mph. I've read of improvement boring to .030 over, getting you about 5 horsepower per motor...maybe see another mile and hour from it, but don't think it is worth the trouble doing. Whipple may have a bolt-on stage 1 kit (not supercharging) for the 350MPI, which reprograms the ECU, giving you 5600rpm and 5-8% Horsepower gain, so 2 mph. CMI exhaust headers, good for a couple horsepower, 1-2mph. Lastly, labbing the prop ( I hear Brett at BBlades has a template for this hull and power) might get you 1-2 mph. The exhaust will be my first and likely only mod, maybe the Whipple stage 1 too.
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Last edited by pondrunner; 07-01-2015 at 11:31 AM.
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It's a $1000 per MPH to 75.
$2000 per MPH to 80.
$5000 per MPH after 80.
Seriously, I've noticed something about the MPI Merc small blocks. I have a Chaparral with 5L MPI. It runs the same top end with a 19 or a 23. Holeshot is all that changes, but the computer seems to "adjust" for the props. I think alot could be done with programming on that motor.
$2000 per MPH to 80.
$5000 per MPH after 80.
Seriously, I've noticed something about the MPI Merc small blocks. I have a Chaparral with 5L MPI. It runs the same top end with a 19 or a 23. Holeshot is all that changes, but the computer seems to "adjust" for the props. I think alot could be done with programming on that motor.
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the imco gear cases you can get for under $2000 a piece swap everything but the vertical shafts and you are good to go. I would recommend adding the back half of hydraulic steering minimum if you do not already have it. which you would want to do either way with increasing horsepower
it. I think I read somewhere it takes 15 hp per 1 mph to up to 70mph?
imco lowers CAN increase up to 5 mph . the props will need to be changed to a for blade as well
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Back to OP. A good prop shop that will work with you can easily get you a couple of miles an hour. Just how and where the prop is cupped for bow or stern lift, etc. can make a big difference for little $$$ It's why racers cover their props.
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2000 Scarab twin 350 Mag MPI with 23* Mirage Plus Props.
Just looking for a couple MPH on the top end, that is all. Any ideas.
I posted something about a programmer a friend sent me a link to in the boat on a budget section. Looked like BS but figured hey why not at least ask.
Not looking to tear down the engine or anything. Some sort of tuning maybe, or full roller rockers, ect, just basic bolt on stuff. What works on these boats to get just a little gain?
Just looking for a couple MPH on the top end, that is all. Any ideas.
I posted something about a programmer a friend sent me a link to in the boat on a budget section. Looked like BS but figured hey why not at least ask.
Not looking to tear down the engine or anything. Some sort of tuning maybe, or full roller rockers, ect, just basic bolt on stuff. What works on these boats to get just a little gain?
I believe the best bang for the buck will be shorties. Measure your prop shaft height. Mine is 7 3/8 deep and bet yours is the same. yes I'm taking a chance, but No one can give me good reason not to or have personal first hand experience or know of anyone who has tried it. Labbed props will cost about 400-850 a piece, maybe more, depending if you use yours or buy new. Rebuilt 350MPI 300hp to 383's 400hp tuned and dyno by Full Throttle Marine. I have MEFI 3 and did have to be retuned. In short I gained 5mph using same 23p mirage plus props because I could turn an extra 300-400RPM. Went from 68mph to 73mph in real good conditions. can tell you more if you like
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HZ, I've done a lot of changes to mine. The majority not by choice. I have no regrets of the direction I went. I have learned a lot and have lots of information. My next step is -3 Imco's. ,,,,,
I believe the best bang for the buck will be shorties. Measure your prop shaft height. Mine is 7 3/8 deep and bet yours is the same. yes I'm taking a chance, but No one can give me good reason not to or have personal first hand experience or know of anyone who has tried it. Labbed props will cost about 400-850 a piece, maybe more, depending if you use yours or buy new. Rebuilt 350MPI 300hp to 383's 400hp tuned and dyno by Full Throttle Marine. I have MEFI 3 and did have to be retuned. In short I gained 5mph using same 23p mirage plus props because I could turn an extra 300-400RPM. Went from 68mph to 73mph in real good conditions. can tell you more if you like
I believe the best bang for the buck will be shorties. Measure your prop shaft height. Mine is 7 3/8 deep and bet yours is the same. yes I'm taking a chance, but No one can give me good reason not to or have personal first hand experience or know of anyone who has tried it. Labbed props will cost about 400-850 a piece, maybe more, depending if you use yours or buy new. Rebuilt 350MPI 300hp to 383's 400hp tuned and dyno by Full Throttle Marine. I have MEFI 3 and did have to be retuned. In short I gained 5mph using same 23p mirage plus props because I could turn an extra 300-400RPM. Went from 68mph to 73mph in real good conditions. can tell you more if you like