BagMan
Active member
Absolutely right. Not to mention avoiding detonation/meltdown.
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missing speed and handling
- Thread starter nickhedstrom
- Start date
Absolutely right. Not to mention avoiding detonation/meltdown.
denis leblanc
Member
I would start with the 24p its up to you and you can always sell it. the person you are buying the prop from would he be willing to let you try it? I am running a 25p 3b Tempest Plus that I had to get modified to be able to run 6100rpm to get 88mph
denis leblanc
Member
Nick Chapleau is still 10 hrs. away from me
denis leblanc
Member
denis leblanc
Member
Nick !! this may sound stupid but your boat may have a hook in the "v" area it happen to me before on on of my J-Craft. if your boat is stored on the trailer that does not support it properly for a good period of time in the cold or in the heat fiberglass has a tendency to shift a bit to check that is put the boat on the trailer and from the back of transom put a 6ft. straight edge at the "v"and there should not be a gap check it also on each side of all the stringer v up to the edge of the boat. If the boat has a hook the bow will never lift and chine walk like crazy
Mark
Well-known member
It is easy to get frustrated trying to turn the Starflite/Starliner into something it was never meant to be... a rocketship. These boats have a stepped hull and a V shaped pad instead of flat. A step will, and is designed to, draw the bow down at speed. Typically this design works best for bigger go-fasts that will never 'fly' on pad. You can feel it happen on a Starflite at around 40 MPH. In our attempt to go faster we add more power and more setback and try to lift the step out of the water. You can also feel (and hear - aerating stops) that happen somewhere over 60 MPH. The 300 hp V8 Johnson back in the 80's did a good job of this because of the shear weight and horsepower of the beast. But we are really fighting against the way the hull was designed. Nose cones and super high engine heights are all counter productive.
In the 1990's Checkmate redesigned the hull with a flat pad and no step, which of course is the Pulsare. They must have realized the Starflite was too small to need a stepped hull. It rides very differently and horsepower for horsepower a Starflite will never keep up with a Pulsare. On the other hand they will arguably do better in the slop.
My feeling is that we should set these boats up to make the best of their design features. A heavy motor, moderate setback, and a 4 blade prop will lift the bow enough to avoid resistance from the step and ride high... but never really fly on pad. Depending on the horsepower it should be good for 65-80 MPH. Play with the setup, get the max out of it and ENJOY. To compare speeds to a Pulsare will do nothing but leave you frustrated.
In the 1990's Checkmate redesigned the hull with a flat pad and no step, which of course is the Pulsare. They must have realized the Starflite was too small to need a stepped hull. It rides very differently and horsepower for horsepower a Starflite will never keep up with a Pulsare. On the other hand they will arguably do better in the slop.
My feeling is that we should set these boats up to make the best of their design features. A heavy motor, moderate setback, and a 4 blade prop will lift the bow enough to avoid resistance from the step and ride high... but never really fly on pad. Depending on the horsepower it should be good for 65-80 MPH. Play with the setup, get the max out of it and ENJOY. To compare speeds to a Pulsare will do nothing but leave you frustrated.
Mark
Well-known member
He hasn't been around since the fall. He never did give speed numbers with the pad but said it ran smoother. http://checkmate-boats.com/forums/showthread.php?t=21274
denis leblanc
Member
Mark you are so right again !! you know your stuff , and I mention in a post before back in the days we put v8 300hp Jonhson with lots of set back and ran fine because of the weight and thorque of those engines and was able to get the bow up. These starflite were never made to to be the fastess boat on the lake they look mean and ran 75mph we were all happy> I am going to do some home work and find out the weight of those v8 engines and compare it to the new 300XS Optimax and 250XS Optimax and compare the thorque difference and I will come back with the fax result
nickhedstrom
Member
Ok guys get this, tried 25P 4B Trophy Plus stock prop today and got the same speed and the same RPMs as my other prop (70mph at 5300-5400). The other prop was a Hydromotive 27P 4B worked and labbed. The chime walk improved very little. Noticed less chime the higher the motor (1 1/2 to 2" below the vee. One thing i noticed is that the hub on the Trophy is smaller than the lower unit so it doesnt look streamed line from lower unit to prop, (where the to meet). Could this cause a problem? Plus the higher the rooster tail the faster the boat went. I wonder if i got a problem with the motor not able to get rpms out of it. The motor only has bout 35hrs on it but i suppose a plug could have fouled out. It has some vibration at bout 1200rpms and sounds a little funny idleing. Could these motors still push a boat on plane and to 70mph on 5 cylinders? (08 250xs)
nickhedstrom
Member
BTW the new prop was run for 1 hour and the inside of the new prop was very black inside when we pulled it out of the water. Or is this normal?
denis leblanc
Member
Nick Yes this could be normal because at this time of the year the water is colder than the summer and the computer sends more fuel and the motor could run rich (black hub & black plugs) and the type of oil is important for the injection system but if you have this black soup in the hub in the summer time you have to take it to the dealer to callibrate the computer sometime these engines are set on the rich side because of the waranty. Do a speed run next time and when at full throttle shut it of in gear do not bring to neutral cause it will not have same reading keep the control at full and when you come to a stop pull all the plugs out and they should be light brown if they are not take it to the dealer because a engine that runs rich all the time is not good for the piston rings the grooves will get soupy and the rings can start sticking and you lose compression and power
Mark
Well-known member
The hub is probably black because you are lugging the motor. The computer tells it to increase the oil. You still have too much prop for 1.62 gears. And no you would not get to 70 mph on 5 cylinders.
The Trophy is a small hub prop and is meant to fit like that. It allows some of the exhaust to vent over the hub during holeshot to get you going quicker. At speed the water covers the gap and it has no effect after that.
Because you are still over-propped you are having to trim the crap out of it to get your rpm up. But you now are seeing 9% slip which is good. You just need to get the right pitch prop. I would still try (not buy) a 23p Trophy. You might need even less from what you are seeing with the 25. If you can get a 23 to spin 6000 rpm at 9% slip you would get 74 mph.
For a frame of reference my 250 Etec has a 1.85 gear ratio and I can turn 26 Trophy to 6000 RPM for 73 MPH. Do the math as to what prop you need with the 1.62 gears before you waste any more money.
http://www.go-fast.com/Prop_Slip_Calculator.htm
The Trophy is a small hub prop and is meant to fit like that. It allows some of the exhaust to vent over the hub during holeshot to get you going quicker. At speed the water covers the gap and it has no effect after that.
Because you are still over-propped you are having to trim the crap out of it to get your rpm up. But you now are seeing 9% slip which is good. You just need to get the right pitch prop. I would still try (not buy) a 23p Trophy. You might need even less from what you are seeing with the 25. If you can get a 23 to spin 6000 rpm at 9% slip you would get 74 mph.
For a frame of reference my 250 Etec has a 1.85 gear ratio and I can turn 26 Trophy to 6000 RPM for 73 MPH. Do the math as to what prop you need with the 1.62 gears before you waste any more money.
http://www.go-fast.com/Prop_Slip_Calculator.htm
denis leblanc
Member
Yes it will get it on plane and 70mph but this is probably why you are only getting 5300rpm with the new prop. for the prop not lining up with lower unit yes it is choking the motor a bit for you to run that prop you will have to get it to a prop shop and get them to drill vent holes in the prop and there is a proper place to drill to keep the prop balanced. And yes you could of fouled a plug that is normal it can happen any time especially when the water is very cold and your engine runs rich
denis leblanc
Member
Ok this is how a prop works ex. a 25p prop does 25in. for each rotation, a 27p will do 27in./rotation so rule of thumb if you can run a 27p @6000rpm you will get more mph 2 reasons : 1 the prop travels more and : 2 the more it travels it lifts the bow more and you do not have to trim as much and more bite more speed. So you ran the new prop today and got the same rpm & mph this is normal cause the prop is smaller and puts less load on engine and you were able to trim up a bit more and got the bow up a bit and got same mph. Just imagine if you can get that 27p prop to run @ 6000rpm you will be in the mid 80mph but the chances are slim with that prop and your boat so again like I say start with a low prop toget rpms and you will be surprise you may get more bow lift and mph and keep the rpm up
I love boating so much that I could talk all night
Nick do not quit try every thing this is how you acquire your experiance and you share with freinds
I love boating so much that I could talk all night
Nick do not quit try every thing this is how you acquire your experiance and you share with freinds
denis leblanc
Member
nickhedstrom
Member
This doesnt make sense though, i go from a 27P to a 25P which should be at least 500rpm, and the 27P is a 15" diameter and the 25P is a 13 3/4" diameter so i should gain rpms there too but i stayed the same (5300). This motor with 1.62 LU and 25P 4 blade should be all day 5800rpm no questions asked.
nickhedstrom
Member
Or more, Y dont they post or stamp on the outside of the motor what the ratio is like they did on I/O. 1.5, 1.62, 1.75 ect. From other boats simalar im missing 10mph plain and simple. All my speeds are true GPS handheld. BTW the air temp was 85 today and water temp was 60 but i know they got stats in them and if they read water temp they would run rich all the time. Dont they have a sensor in them to tell the computer thats its too rich or too lean like a O2 sensor on a car?
nickhedstrom
Member
Before i got this 250xs i had a 95 200xri efi with 6" less set back and a wrong prop on it and i still got 65mph GPS all day long. Didnt matter to much on engine height and trimmed it pretty good. This is crazy!!!!!
Mark
Well-known member
If you have 1.62 gears your LU should have a nose cone and be silver. Although I am not an expert on Mercs.
Yes it is strange that the 25 and 27 are both turning the same revs. Not sure you are missing 10 mph though. Don't forget most everybody lies.
I had a 200xri on mine as well and saw about the same... 65ish. I figured I would get a lot more with the 250. But 74 is it so far. Kalugs22 is seeing 76 with the same motor as you.
Sometimes propping a new motor can be a pain. It is possible your motor is not running right, but I think you would be able to tell by how it sounds coming up to speed. Like I said before I would try every prop I could beg, borrow or steal until you figure out what your combo likes.
Yes it is strange that the 25 and 27 are both turning the same revs. Not sure you are missing 10 mph though. Don't forget most everybody lies.
I had a 200xri on mine as well and saw about the same... 65ish. I figured I would get a lot more with the 250. But 74 is it so far. Kalugs22 is seeing 76 with the same motor as you.
Sometimes propping a new motor can be a pain. It is possible your motor is not running right, but I think you would be able to tell by how it sounds coming up to speed. Like I said before I would try every prop I could beg, borrow or steal until you figure out what your combo likes.