accelleration / 1800SR3 / 2006 / 4.3 MPI / 220 HP /

[swisslake]

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.

[seapuppy]

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....

SP

[Overfinch]

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.

[tglee]

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?

[racer2c]

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.

[Brit Rider]

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

[tglee]

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"?

[seapuppy]

I'm thinkin his tach is not set right...or is misreading the revs on the engine..


SP

[racer2c]

Originally Posted by tglee

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.

[Gazjen]

I thought being an mpi the revs would be limited anyway by the ECU?

[seapuppy]

OOOOOOH!!!!...I missed the mpi part ...the engine will go right to the rev limiter and according to the mercruiser folks...they like to to run hi...so...his prop is probably ok but if he's having a heck of a problem with pulling a skier..then yeah..he could keep the same diameter prop but go down a couple of inches in pitch and still be ok....

my boat has 20" pitch on the b3 drive...it will spin right up to the rev limiter...i asked about that and they told me that they want this engine to run a bit hi...so..I cruise at 4000-4200 rpm....it will spin right up to the rev limiter of 5280......the rev limiter will stop the engine from over revving....

SP

[tglee]

......the rev limiter will stop the engine from over revving....

You guys have all this fancy high tech stuff! Maybe I need to buy a boat that was built during this century .

[Gazjen]

So he's not getting to max RPM because its higher for the MPI isn't it?

So it's got to be over propped

I've just brought one of these: http://propulse.jetshop.se/

Cant really comment on it yet because I've not had my boat in the water since but it's a variable pitch prop so you can experiment

[davidula]

I have a "european" 1800 SR3, i live in south of france, but i can easily pull out a skier like me, 90 kgs !
I precise it is the 190 horse power with standard propeller 23'.
I can pull out 2 wakeboarders at the same time.
My top speed is 52/54mph, at 4700/4800 rpm
Hope this helps

[tglee]

So he's not getting to max RPM because its higher for the MPI isn't it?

It is 4400-4800 for the MPI. Check out the specs here: http://www.mercurymarine.com/engines...4-3l_specs.php

[Brit Rider]

Mine actually revs to well over 5,000RPM before it begins beeping furiously at me

Also, contrary to what was previously stated, standard prop if a 3 blade 14 x 23" ally. not 24 pitch...

[swisslake]

Hey friends. Thank you for your comments. To specify: Mercrusier marine recommends for the 220 MPI an optimal rev range of 4440 – 4800rpm. The boat was originally delivered with a 14.25x21 / 3-blade propeller instead of a standard 24� propeller as it was noticed in the Maxum quality control paper! WOT was 5300 rpm/ 53 mph (no rev limiter, only acoustical siren from 5000 rpm), boat suffered of excessive cavitations and ventilation. So a 21� prop is definitely not the right thing! Mercruiser customer service recommended me to change to a 25“ Revolution 4 blade. To get a maximum whole shot Piranha calculator recommended a 4x24 / 4 blade which I bought and installed by a Maxum dealer. Whole shot and acceleration is definitely better but by far not acceptable. WOT 4800/ 52 mph. A good mono skier with 180 lbs / 80 kg does not get out of water with one driver and one passenger (each 160 lbs) on board and 10 gallons in the tank. If the boat is plane (it takes time… ) it is running as a thunder. I believe, that another propeller is not changing very much. What is the problem: Hull Design? Special European 1800 Models? What are your experiences with your 1800SR3 / 220 HP MPI? Which propeller? NB: Mercruiser 190 HP has another torque and another gear ratio! :roll:

[Overfinch]

Something is not right, my best guess is that the tachometer is out or you have a different drive ratio than is normal for that boat. It is also possible that the engine is not providing bottom end torque for some reason, is it missing, overfueling? It must be ok at the top end as you are getting good speed.
It is a fact however, that if you prop the boat down to a 19 20 or 21 you WILL get out of the hole faster assuming other things are equal, power weight etc...
Alternatively fit a blower, N02 system, or a small block V8 or for best performance all three. If you go down this route you may need to uprate the drive...........
On a more serious note get hold of a cheap ali prop in a 19 or 21 and try it.

[Brit Rider]

Originally Posted by Overfinch

On a more serious note get hold of a cheap ali prop in a 19 or 21 and try it.

Totally agree. Though sounds like you are going through the pain of fitting loads of different props which are incorrect (whoever used a 23+" prop on one of these boats for skiing?!?! ). If you'd just try the props that are proven to work (High five 19"-23") I get the feeling you'll be fine.. and if not then its an engine/drive problem.

[Argonaut]

OK .. actually bothered to look at the gauges yesterday.

I have an 1800 SR3 (2007) with 4.3L carb engine .... it absolutely can be used for monosking.

I changed standard 23" prop out for High 5 21" ..... this gave far better acceleration without too much losing top end (as it's a cupped blade)

This runs at 4500 WOT and makes 46mph .... would probably go a few mph higher if I had flat water and could trim out (those figures are fully trimmed in)

The biggest issues was that although it had holeshot, it had awful bow rise ... I fitted SMART TABS, and that cured the problem with slight improvement in acceleration,m and definite improvement in straight line tracking, esp against a beam sea.