I have a 1997 35 Lightning with HP500s.
I recently went from stock 28 Mach props to 27 Hydromotives.
Although the Machs looked good, I really do not know their history IE. had work done to them and so on. With the Hydomotive 27 cleavers, I picked up 500 RPM and 4 MPH. I am making 5200 RPM and seeing 80MPH. the engines could probably use a freshening up so there are probably a couple more MPH in there but I just wanted to share this info.

Regards
Dan

is that on the GPS? that's a huge improvement just changing props, so the best your turned the machs was 4700 @ 76 ??? -you were away's from the sweet spot of the motors. Have your tried Bravo 1 props just for comparison sake??

I have the same boat with 525SC's. Absolute best I have seen was 82-83 mph. 80 mph is more the norm.

Use Bravo 1 28" pitch. Turn 5000 rpm or so.

Joel

joelHene, I have the same boat a 1997 35 with 525sc''s. Mine has 1.36 gears and ext boxes and 28p bravo's. the boat also runs 80 on gps any time but will run 82-84 on some days. I was woundering if you could check the X-dem on your boat and tell me what it is. I think mine could run faster with 1.50 and 30p props. I think the drives on mine are to deep inthe water. My drive height is 4" from the bottom of the boat to the center of the prop shaft. not from the notch but from the very bottom right in front of the prop shaft.

I will measure it for you. May take several days.

As you suspect, I have 1.5 gears. The props have never been blue printed. I took a few very minor dings out with a file...so they are not the absolute best pair of props...but very servicable.

Joel

BTW, how did the boat run before the boxes? Did you raise the x-dimension when installing the boxes? Your 525SC's have CMI headers I assume.

Joel

yes it does. these motors should run 5250rpm and I can only get 5000 out of mine . If you are only turning 5000 with 28 you might what to try a pair of labbed 28's to get your rpm up. if you get a chance just put a straight edge on the bottom of the boat and put it up to the bullet and measure from the top of your straight edge to the center of the bullet, with the drives straight. I have called fountain to ask what it should be and I must be on a long waiting list two month and no call back.

to answer your question on the boxes, I do not know the boxes were on when I got the boat. and the boxes are as high as they go and I think the drives are still to deep. I what to try shorties and five blades but the tree is not putting out money I think it is to dry.

I'm in the same boat, (no pun intended) mines a '99 HP 500's done up to 600 Hp (dyno) -turning labbed 28's @ 5200 82-83
GPS. I reallllly want to try shorties - this is why so I'm told I have not seen the speeds I was expecting.

I have a pair of new 27' Hydromotive's that are labbed and balanced. Approx. 6 hours of use that I pulled off my 98 35' fountain before I sold it. If anyone is interested $1000 for both. I have pics if anyone would like to see them. They are not the right prop for my new 35' fountain T/S and are sitting in the factory boxes. Thanks