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Old 08-21-2008, 07:05 PM   #1
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Default accelleration / 1800SR3 / 2006 / 4.3 MPI / 220 HP /

I have a Maxum SR 1800 SR 3, Mercruiser 4.3 MPI / 220 HP. Orginal propeller is 14.25x 24 / aluminium. The boat is absolutely not water ski suited. Now I have a Piranha prop 14x 24 / 4 blades. Acceleration is much better and 0-30mph is reaching in about 12 seconds. RPM 4800/topspeed 52 mph is OK. Mono skiing ist still not possible. Boat does not get out of the water, even with the 4 blades prop. I wish an acceleration of 0-30 mph in 7 to 8 seconds. I had for 20 years a Glastron SV184 crestflight / Mercrusier 165 HP and starting mono skiing was definitly much better. I am not spoilt of the power of a 8 cylinders. Do you have any recommendation? Which prop? Do I need an other Maxum? Greetings from Switzerland.
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Old 08-21-2008, 07:26 PM   #2
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welcome to the zoo...are you sure about the WOT rpm??...4800 is at the hi end of the range for that engine....so..I'm kinda questioning the tach accuracy...
the other item is with a 24" pitch prop...the engine should be pretty much loaded up...
you should check with your local prop shop...but when I had my 2455..it had the 5.0lter engine /drive with a 15.5x19 prop...I could reach wot but only do about 42 mph..realizing that your running a whole lot smaller boat...I'd say...switch to a 3 blade...Stainless steel...15x21 inch prop...that will hopefully keep your rpm's the same....but give a bit better hole shot...might loose about a few mph on the top end....
or see if the SS 15.5x19 will fit.....sometimes a prop shop will let you try a few props and keep the one your happy with..return the ones that don't work....

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Old 08-21-2008, 08:03 PM   #3
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If you want to ski try a 19" or 21" pitch Hi five. Should make a big difference to hole shot, might have to be careful not to over rev with the 19". TBH I would have said that you are over propped ATM although your WOT rpm suggests otherwise a lower pitch 3 blade stainless in a 19" or 20" with plenty of cupping might be good compromise, vent holes may also help.
The boat with that motor should be fine for sking with the right prop.
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Old 08-21-2008, 08:29 PM   #4
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I entered your information into the Piranha Prop web page and this is what it said:

Evaluation of Your Current Prop:
WOT RPM:

Your motor is running in the correct RPM range!

Your current prop has the characteristics of a "Power Prop". Your RPM is in the higher end of the rpm range which results in performance favoring acceleration over top speed. This is a good choice for watersports or vessels that are some what underpowered.


Application Considerations:

With the information you've supplied, your prop is slipping a noticeable amount. This suggests a different choice in props is in order.

Since you're using a 4-blade Piranha prop, double-check to make sure you removed your stock thrustwasher if instructed to in your directions. For more information about this issue Click Here

You've indicated you are interested in finding a well suited propeller for low end power and towing capability. This would work well for skiing or if you have a heavy boat, but it may likely reduce your top speed and fuel economy. Your performance will be best for this use when you prop your boat to get as close to 4664 RPM as possible.


Something does not seem right to me. Like Overfinch said, it seems like your overproped. But, your RPMs at WOT suggest otherwise. Did you remove the thrustwasher befor installing the new pro?

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Old 08-21-2008, 09:46 PM   #5
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I swear there is something wrong with the European 1800's. Yet another story of a Euro 1800 that can't get out of it's own way.

I have the 190hp version with a STOCK 23p prop and I can pull grown men out of the water with little effort. 30mph comes in under 5 seconds and I'm on plane right after I nail the throttle. All that with PASSENGERS!

Are they installing governors on those boats without telling anyone? That's the only thing I can think of. You do have any passengers sitting in the bow, right?

weird.
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Old 08-21-2008, 10:24 PM   #6
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14 x 23" is way over propped... not surprised you can't get out a mono skier out the hole with it! Piranha are wrong, that setup is for high speed, not low down grunt in the least bit... I'd send that prop back and get a refund considering they supplied you duff info. I've run 1800SR's with that engine setup, and one with the 4.3 carb so am familiar with the best props to run on these boats. Interestingly the 1900 is a faster boat given the same HP....

Try a 13.5/13 x 21" High Five - that'll suit the boat far better. You'll drop to about 45mph (At the moment you are geting the MAX speed out of the hull.. they don't go much more than 55 without handling in a very 'interesting' manner
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Old 08-22-2008, 12:03 AM   #7
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Quote:
14 x 23" is way over propped... not surprised you can't get out a mono skier out the hole with it! Piranha are wrong, that setup is for high speed, not low down grunt in the least bit... I'd send that prop back and get a refund considering they supplied you duff info. I've run 1800SR's with that engine setup, and one with the 4.3 carb so am familiar with the best props to run on these boats. Interestingly the 1900 is a faster boat given the same HP....

Try a 13.5/13 x 21" High Five - that'll suit the boat far better. You'll drop to about 45mph (At the moment you are geting the MAX speed out of the hull.. they don't go much more than 55 without handling in a very 'interesting' manner
This sounds like great advise and I think you are right. But, how do you account for his 4800RPMs at WOT? Won't the revs climb dangerously high with a 13X21"?
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Old 08-22-2008, 12:25 AM   #8
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I'm thinkin his tach is not set right...or is misreading the revs on the engine..


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Old 08-22-2008, 01:50 AM   #9
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Quote:
Originally Posted by tglee
Quote:
14 x 23" is way over propped... not surprised you can't get out a mono skier out the hole with it! Piranha are wrong, that setup is for high speed, not low down grunt in the least bit... I'd send that prop back and get a refund considering they supplied you duff info. I've run 1800SR's with that engine setup, and one with the 4.3 carb so am familiar with the best props to run on these boats. Interestingly the 1900 is a faster boat given the same HP....

Try a 13.5/13 x 21" High Five - that'll suit the boat far better. You'll drop to about 45mph (At the moment you are geting the MAX speed out of the hull.. they don't go much more than 55 without handling in a very 'interesting' manner
This sounds like great advise and I think you are right. But, how do you account for his 4800RPMs at WOT? Won't the revs climb dangerously high with a 13X21"?
My owners manual says not to rev past 4400rpm. 4800rpm is grenade time.
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Old 08-22-2008, 01:59 AM   #10
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I thought being an mpi the revs would be limited anyway by the ECU?
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