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View Full Version : Correct RPM/Prop for a 1989 Prostar190 with Powerslot


bonk78
07-10-2012, 01:34 PM
Hey all you experts. Question for you. I purchased a 1989 Prostar 190 with the 351 and powerslot transmission. It came with the factory 14 x 18 nibral prop. Top RPM is only 3800. Is this normal? It will do 45mph at this speed. It has pretty good pulling power. I have pulled three slalom skiers at once.

I was given a deal on a stainless steal prop with the factory measurements and it does the same thing. Has some more pick up but won't rev past 3800. Any thoughts? If I can get more rpm and more take off with a different prop I think I should do that. Althought I could just hot rod the engine to get enough power to pull to 4500 which woudl be fun as well. :)

TRBenj
07-10-2012, 01:42 PM
$5 says your tach is off... your performance sounds normal but your RPM #'s dont.

pram
07-10-2012, 02:12 PM
that would be a sucker bet I am thinking

pull your dash and see if there is an adjustment on the back of the tach

cptskier15
07-19-2012, 09:23 AM
There is no adjustment on back of these tachs... We have oppositte problem. 5600 rpm 34MPH OJ 13x13 but thats not even at 3/4 throttle. Just a little worried to open it up to WOT as do not know what Revs we are actually doing.

EJ OJPROP
07-19-2012, 09:52 AM
There is no adjustment on back of these tachs... We have oppositte problem. 5600 rpm 34MPH OJ 13x13 but thats not even at 3/4 throttle. Just a little worried to open it up to WOT as do not know what Revs we are actually doing.

1:1 transmission or Powerslot?

tockit
07-19-2012, 11:49 AM
that would be a sucker bet I am thinking

pull your dash and see if there is an adjustment on the back of the tachMy 1989 190 has an adjustment screw on the back. Pretty sure its the original VDO.

d2jp
07-19-2012, 05:54 PM
Hey all you experts. Question for you. I purchased a 1989 Prostar 190 with the 351 and powerslot transmission. It came with the factory 14 x 18 nibral prop. Top RPM is only 3800. Is this normal? It will do 45mph at this speed. It has pretty good pulling power. I have pulled three slalom skiers at once.

I was given a deal on a stainless steal prop with the factory measurements and it does the same thing. Has some more pick up but won't rev past 3800. Any thoughts? If I can get more rpm and more take off with a different prop I think I should do that. Althought I could just hot rod the engine to get enough power to pull to 4500 which woudl be fun as well. :)

I have the exact same boat. My original VDO tach does not work, and there IS a position switch on the back for the # of cylinders, plus a knob which seems to control how responsive the tach is...but - regardless of the settings, mine is stuck at 2Krpm's.

I believe the engine RPM on these boats is also the approximate MPH. So, at 45MPH, you're somewhere close to 4500RPM.

Prop RPM however is not the same, due to the powerslot.

Others more knowledgeable will probably chime in.....

cptskier15
07-24-2012, 06:58 PM
Hi eh, it's a power slot.

cptskier15
07-24-2012, 06:59 PM
Prop is 14x18 powerslot. Had to pop back under boat to check!!