Boat1

The XR uppers are all the same gear count / ratio. The XR final ratio is all determined by the lower gear count. The standard Bravo and the XZ have different gear counts / ratio in the upper, but the lower is all the same. Hope this helps.

CB-BLR

I disagree with the statement regarding V-bottom boats. On my single engined v-hull (which does over 100 mph), I picked up over 3 mph going from a 1.5 gear ratio to a 1.35. The props around 28 are the most efficient(lower slip %) as to slip when comparing them to their larger pitched bretheren. Also, as a prop increases in pitch, the blade is more parralel to the water, causing more transom lift. (ie the smaller pitched props tend to carry the bow easier with less trim.)

Just my documented observations on a couple of near and over 100 mph v-bottom boats.

Chris

tcelano

Agreed. I had more typical rigs in mind. Over 100 mph, you are in a different league and are playing with a lot more power. What are you running?

CB-BLR

Whipple stage X upgrade on a 600sci motor.

540 cu/inch (Callies crank)
Heads ported by Chapman racing
Whipple proprietary cam
4.0 Whipple Supercharger with MOAC innercooler

1067 hp at 6200 rpm

A far cry from my 600sci...which made 589 hp stock.

Chris

tcelano

That's a pretty trick rig. Did you buy it down here in Portland? I was guessing you had to be over 1000 hp to get that kind of speed.

What are you doing for a drive?

Never mind- you can't see avatars and descriptions when you are replying...

UrbanDisturbance

I didn't know you could get 1000+ HP out of a 540? That's amazing! I have Dart Block 502's (509). Are your engines reliable? What Gas?

CB-BLR

I guess it is all a matter of perspective...Teague gets 1200 hp out of a 565 spinning 6000 rpm...1335 hp out of a 565 spinning 7200 rpm...both on pump gas... my motor producing 1067 hp at 6200 rpm...doesn't seem all that remarkable.

I believe that Mercury's 1200 hp motor is 557 cu/inches...which is the same bore as mine...but with a 1/8 inch longer stroke.

Dustin has pulled over 1800 horsepower from a 582 on race gas.

My motor was rated at 1067 horsepower on 91 octane on Dustin's Dyno, and I get 92 octane fuel here in Washington.

The motor was built by Dustin Whipple...he is a friend of mine.

Chris

paintman

holllly crap thats is NICE sure beats chit outta my 535 hp......frig me n i upgraged from 400 hp

CB-BLR

I originally bought my boat from Tim of OCM with a Merc 600sci in it...It has since gone thru a few motor modifications

Chris

tcelano

Cool,

I live about five blocks from Tim. If you ever bring your boat down to the Columbia and go roaring past St. Helens, let me know, and I'll listen for it. Maybe that will help motivate me to finish my rig instead of working all the time.

P.S. Sorry Paintman, this has degenerated way off topic...