avalanche prop pondering

Anyone have experience with different props on an avalanche. i have the 350 mpi. has GREAT pull out of the water, but my rpms are running high and can't get it past 42 when cruising to the next spot. any help would be great, thanks guys... (kevin any thoughts?)

Sorry to say With that engine it probably will never go much past the low to mid 40's I have barefooted behind the Avalanche and The best speed I got was about 42. A change of prop at best might get you another couple miles per hour.
Email Acme and see if they have any ideas Bill Weeks bweeks@acmemarine.com

Monte-

I have an 03 Avalanche with some 3-blade prop on it... I run about 3000lbs of ballast and it pops onto plane without any problem (5 seconds max), yet it will top out at around 51 also. When I go out next, I'll grab the info on the prop and let you know.

(oh, I talked to my dealer about this, and they said another key determinant of top-end speed is if the boat was properly broken-in... Apparently, the Merc engines can gain up to 50hp if broken in right!)

Hmm I can make my boat go 50 to however if I check it on the GPS not so much 50 has the mid 40's

Top speed at the boat test was 43.1

http://www.waterskimag.com/boat_inspector/index.html?manufacture=2&boat=1

This is kind of outside the scope of this thread. I just calibrated my PP last week with a GPS. Yesterday I saw 47 mph at 5350RPM. (Malibu VLX 340HP 4 Blade Prop, 1 passenger and 250lbs fixed ballast)

Well I would have 2 comments
Malibus tend to be faster than Centurions by a couple MPH.
Second the only way to know how fast your are going is to go wot in a straight line in both directions with the GPS in hand.
IF you calibrate the pp at 20 or 22 mph that does not mean that they are accurate at WOT since the speedos are not linear in their accuracy.

(Message edited by krbaugh on June 25, 2006)

ugh... GPS will show true ground speed, and the a calibrated paddle wheel speedo will indicate ground speed +/- river current. I calibrated the GPS in a very small stagnant lake with tests both directions. I ran many tests and calculations for over an hour. I calibrated at 25 MPH, 35 MPH and 40 MPH. The multiple tests were to determine if the on-board system was linear. In contrast to your statement, I found that indeed the PP reported a linear reading. The PP would report as accurately at 25MPH as it would at 40MPH. However, when calibrated at 25MPH, the Malibu speedo head unit showed a -2MPH variation at 40MPH. Conversely, if calibrated at 40MPH, the Malibu unit reported +2MPH at 25MPH.

ugh ok your right this is outside the scope of the thread. I Don't remember talking about a river. Of course you would have to take into account any current. The same way you do if you check speed through a slalom course. I must say I have never spent an hour calibrating a paddle wheel system. I assumed paddle wheel systems where not back linear. Back in the day I spent a lot of time as a driver at barefoot tournaments when we calibrated the old pito speedos they where not linear in any way. I should not have assumed that the paddle wheel systems where not linear without testing that theory myself. You know what they say about assuming...... So assuming you are right then I was wrong about the linear part. Not that it has much to do with the tread

I think my prop says it's a 13x11.5 3 blade, it came stock. should i switch to a 4 blade to lower my rpms? i have another 3 blade laying around, it is off a 2003 avalanche. i haven't gotten a chance to see the pitch on that particular unit yet, we had poor weather this weekend in CT.

The 13x11.5 is a acme 525. The 2003 came with a 515 13x12. You will be much better off staying with a 3 blade and the 13x11.5 will give good performance. But why do you need too even go faster than 45ish? Its a wakeboarding boat not a speed boat and a few MPH will not make that much differance just suck more gas.

oh, of course i understand about speed/wake. i would like to not have to run the rpms so high. my rpms are screaming at 5 for me to go 41-43 on a glassy day. i got that 2003 to go 47, (now i suppose b'c i didn't use gps, it may have not been correct, but it felt faster in the 03 than my 05. I was just hoping someone would have some good info about props suggested for my boat.

Your 05 has a 3 blade?
In 05 they switched over to gear reduction V drives so they could spin bigger props. They
also switched to 4 blade props.
You could go to a bigger prop that would do 2 things less Rpms and less hole shot.
They prop them so they run around 5k at WOT and also give you a good whole shot.
Bill Weeks bweeks@acmemarine.com is a great guy and will be glade to give you advice. He will want to know what the number is on your prop and the RPMs at WOT

(Message edited by krbaugh on June 25, 2006)