now this is interesting my bravo 32 4blades are not lab nor are my hyromotive 31 5 blades are you running standard length xr drives

yes they are standard length but I have nose cones on the drives I run 54 mph at 3500 rpm and boat comes on plane with ease

we are not to far apart at 3500 I am running 55 mph did you run the boat with props that were not lab props and if you did how much difference did it make. I just feel like I have the hull and the hp I should be able to see 100 plus mph and if shorties and boxes are the answer along with a pair of hearings I am willing to do it. That being said I am not an engineer and if I do all this work and spend all this money and do not get the results I am looking for I will not be a happy camper . Do you know any buddy who has put the extension boxes on a 38 avs hull and if so would he do it again. thanks for the info I really appreciate it And yes I know if you want your boat to go faster just buy a faster boat

no never tried boat without lab did try with the 5 blade and it went slower than the bravo 4 everyone that puts shorties on boats all seam to be faster by 2 to 4 mph my motors dynoed at 804 with 790 ft of torque boat ran 96 at its best before I dialed them back to a safe setting this is in fresh water also

Any new info?
 

I'm curious if anyone never made the mods spoken of. Inown a 1999 38 avs with 700's. Best has been 85 with 30 Maximus and 86 with 32 bravos
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Its not that hard to install an extension box once everything is out of the boat. If you are going with shorties then you can use a neutral box and use the original bolt holes. ( I raised mine 1 1/8 inches so I had to redo everything. Already running -3 IMCO shorties.) You just bolt the box on,then bolt the transom assemble to the box,then install the engine,check the alignment and install the drive. It really wasn't that hard.
The herd part was cleaning up all of the hoses. I ran my hydraulic hoses through the box. Less holes in the transom. Trim cable also.

You sure you have 700 HP? What is your prop slip?

86.9 sounds about right, around 650 for 85. not much difference from 650 to 700, 1.9 gain is probably it, maybe another couple mph gain in 3' choppy water getting hull out of water more. 38avs seems to be around 17% prop slip with bravo 4 blade. 32 pitch 4 blade 5200 17% slip 87mph, 88 with 16% slip. U are right there.

Did you ever get yours going with the new mills? How's it run now

Pretty sure