Mechnologist

Can somebody tell me what type of outdrive lower was used on the Bravo 1 X that came on the Checkmate ZT 260 with a 496HO originally?
Low water pickup (LWP)?
Dual water pickup (DWP)?
Side water pickup (SWP)?

thanks

CAB

Had an 03 with HO and a bravo 1. It had dual water pickups

Mechnologist

Thanks. That helps.
I don't want to use the wrong lower and starve the sea water pump of water with this hull....

I bought the hull with no drive train. So I am doing some detective work....

I'm considering a -2" IMCO shorty also.

I have a new custom 565CI 620+HP engine, a Bravo HP transom assembly, a Bravo XR upper 1.5 ratio and a 28p 4 blade Bravo I prop...
I'm hoping to be in the low 80's at least.

noyzee

dual water, and i dont think this hull would like a 2" shorty. maybe a 1" and thats a big maybe. the way the bottom is and the little pad i think you will be blowing out the prop real bad with a shorty on the zt hull.
could be wrong but i dont want to make the big $$ trial

CAB

i have a 2 in shorty on mine with a 7 in set back and i have no problems. Put a 1 in spacer in and slowed it down 5 mph.

CAB

originally I had a 588 ci with 635 hp. Ran 79 with stock bravo 1 26 pitch prop on a 1.36 XR with 2 in. shorty.

Mechnologist

Thanks. That helps my calculations. always good to learn from those who have gone down the same road before you.

To make sure we are working off the same factory setup. Since after talking to the factory I found Checkmate made some boats differently.
My X - Dimension is 17"
This is how I measured as per the Checkmate factory:
Mine is 8" from keel line (holding a straight edge up to extend the line) up to the bottom of transom plate casting (not including the Mercathode if you have one). Then add 9" which is the distance from bottom of transom casting up to the crankshaft centerline.

When you say your "set back" is 7" do you mean that you have an extension box?

When you say you added a 1" spacer and it slowed you down 5mph, what top speed was that approximately? I know you have gone through a few HP increases over time)

The reason I ask is that I have learned that the Crescent Leading Edge (CLE) shaped bullet nose Bravo lowers like IMCO or Speedmaster only seem to help your top speed around 90MPH and up.

And the CLE shape which has more surface area and surface tension actually will slow you down if your top speed is below the low 80's.

The mid 80MPH range is a gray area as to whether the CLE helps or not.

By going to the 2" shorty did it slow you down much launching out of the whole? Enough to be a problem? I know that's a trade off with the shorty.

Did you have a 496 Originally in that hull?
It seems they built different stringers and engine mounts for 525HP motors.

So My dilemma is that shortening my lower seems like it will help my top end a few MPH but unless I up my HP I may loose a few MPH from the CLE bullet shape...
Currently my engine builder said my engine is 620HP and 600 torque. So judging by your numbers I may only be at 80MPH (If I'm lucky)
Although my engine builder says I might be able to tune it to get a bit more HP.

I need to buy an XR strength lower no matter what since I only have a standard Bravo 1 SWP lower now... (I have a Billet Marine XR upper)

The good thing with a shorty is that i can always space it back longer if I don't like it...

CAB

Speed difference was after the M3 was added. Ran 95 with 28 maximus without spacer and 90 with it. I have a mercury ITS so it is an extension box. Have zero problems getting on plane with shortie. The boat was originally an HO boat with bravo 1 drive. New power and xr shortie was added at the same time so not sure about speed with shortie. It has been a long project but it all seems to have come together nicely.