Blownbillybob

I have a 21 eliminator mini day with a 80 series SP drive prop shaft is -6" below bottom WAY to deep !!!!!!! Picked up a 105 drive and going to raise it 3 inches should pick up 10 mph!! Had JTM do a custom noise cone and it picked up 10mph at the height its at now with blown 468 about 650hp
Found a 107 lower and started making a new nose cone for it to throw on my 105 upper.

Can't wait to pull out the saw!!!!

Blownbillybob

Stern Powr lower legs are hydrodynamicly inefficient they become a water anchor over 70 mph ?? IF to low !! That's why they were none to be surface drives

From what he is saying ur boat likes prop in water ! Stern Powr legs like to be on top of water!!!!!!!!

See the problem

ezrizer

I'm not sure I subscribe to the theory that narrow boats have to have deep drives. Having personally raised a Stern Powr twice on a narrow boat I can tell you that the boat did became more prone to prop torque (if thats what it's called) as the prop (and engine) were moved higher. However the boat did go faster and other measures were taken to combat the boat leaning to one side. In the end the performance and reliability were acceptable by my standards.

Now, after blowing all that hot wind I will say that if 60 mph were my target I would just scrounge up a Bravo and be done. It would only take about 400 hp to make that boat go 60+ and a bravo works fine in that range, even 70+ mph with 500 hp would be fine. North of 600 hp and now the Stern Powr mounted up with the right prop is a worth while consideration.

madmanmarine

I really need someone to show/tell me how to post pics of progress. I have a crap load of photos of how it's going. Want to share but can't. Stern is patched in and drive hole is cut out. Just got done welding up the new engine beds and the dash is all glasses and ready to be smoothed out. Came out awesome. Totally modernized the look of the interior. So if someone can help me out with photos or wants to post them for me that would be great but I can't seem to get ahold of mike anytime I want to send him pics to post. Thanks guys. Ian

madmanmarine

The engine is stock now but I do have another one. (Same thing ). That will be built for turbos. Just haven't had the time to get it to the machine shop.
I ended up going with 17.5 X dim. Which puts the cav plate at -4.5 and the prop shaft at 5.5" below the bottom of the delta pad. That is 1 1/2" above where it was on the old boat. We'll see.

ezrizer

When you reply to a message look at the tool bar across the top of the message window and select the third icon from the right, it should be a square with a tree in the center. From there load your pics.

Blownbillybob

I was at 6" below bottom with a blown 468 6psi boost the boat hit a wall at about 66 mph till JTM did my nose cone without touching anything on the motor 76 mph first pass got it up to 80 with some tweaking all on Cali pump gas????

I'm tryin to raise my out drive 3 " this winter JTM say +10 mph jus doing that. ??

I hope ur not to deep????

outonsafari

iTrader: (4)

so the drive is 22 1/2 inches shaft to shaft, propshaft is at 5 1/2 inches

the (cav plate at -4.5 is screwing me up), in your first post you mentioned something similar (when i put it together it was 3" positive) it's gotta be some misinterpretation

i grew up calling the notch in the transom a step (because it looks like one) and the steps on a hull air slots or ventilators and vacuum breaks (because thats what they are and do) i think !

i read on oso this past week that your drive uses 19 spline #3 speedmaster type props, i think they use to run those deep, (5-6- inches)

you need a subscription to post photos, then you need to set your camera to etch a sketch otherwise the file will exceed the 25 pixidoodles and you wont be able to put them on here, it took me 7 years and 2 months to figure that out

so join up and get some pictures posted

ezrizer

BillyBob,

I'm curious, what does the nose cone look like? post a pic of the lower unit.

Blownbillybob

Prop shaft to bottom of cav plate is 10"
2 different length uppers not sure which he has .book say 25" shaft 2 shaft???
-4.5 I jus cav plate above bottom of boat that have a formula in the owners manual? U can see it on line

Will try and post a pic??????