Another prop test.. getting better, but still not as good as my 280/ros

[Pachanga_rick]

*Back when I bough this cat I bolted up a Mercury 2.5/280. No Hydraulic jack plate, no tilt indicators just me running buy the seat of my pants. I ran over 110mph ..

The new engine is a 300xs with a hydraulic jack plate so I can adjust the motor on the fly.... I still cannot get close to the numbers I ran with the 280 :confused:

Test Set up:

- 31p Hydromotive Quad IV
- 14 5/8 dIA
- Race prep trailing edge
- Sharpened
- Four 1" Vent holes drilled.


Boat ran up to 5900-6000 rpm with a top speed of 102 mph, Also a large hop developed between 55-80mph that is not present on the small props (26p) . Boat does hop and pull right simultaneously most likely due to the large prop. Acceleration was not great.

But the testing never ends (except in the winter, testing ends for me in the winter)


https://www.youtube.com/watch?v=2DZFZRpL-SY

[kct11]

Looking for speed get your hands on 3 blade lab cleaver.

[Pachanga_rick]

Looking for speed get your hands on 3 blade lab cleaver.

I'm trying now. :)

[AZMIDLYF]

Pachanga, there is a member on here that has a Twister hull with a 300 running, I believe 126. His sign on is Adam McKeon and he might help with some tips.

[Pachanga_rick]

Pachanga, there is a member on here that has a Twister hull with a 300 running, I believe 126. His sign on is Adam McKeon and he might help with some tips.

Adam is running a pleasure boat hull. The tunnel is wider than mine and a lot lighter, maybe 800-1200lbs lighter. But I still think I should get a strong 110mph plus with this 300xs .. they are running 115mph plus in KILO runs overseas with the canopied twisters and argo's with 200xs ROS motors.

(picture of his and picture of mine)

419414 419413

[NICE PAIR]

*Back when I bough this cat I bolted up a Mercury 2.5/280. No Hydraulic jack plate, no tilt indicators just me running buy the seat of my pants. I ran over 110mph ..

The new engine is a 300xs with a hydraulic jack plate so I can adjust the motor on the fly.... I still cannot get close to the numbers I ran with the 280 :confused:

Test Set up:

- 31p Hydromotive Quad IV
- 14 5/8 dIA
- Race prep trailing edge
- Sharpened
- Four 1" Vent holes drilled.


Boat ran up to 5900-6000 rpm with a top speed of 102 mph, Also a large hop developed between 55-80mph that is not present on the small props (26p) . Boat does hop and pull right simultaneously most likely due to the large prop. Acceleration was not great.

But the testing never ends (except in the winter, testing ends for me in the winter)


https://www.youtube.com/watch?v=2DZFZRpL-SY

You are showing 5/6 % slip on the dream chart. Sounds like you need 34/35 pitch.

34 @ 60000, 5% slip = 113

35 @ 6000, 5% slip = 117

Give Dave Dewald a call.

[Pachanga_rick]

I'm not sure if she will spin a 34p, but I have a 35p 3 blade cleaver to test tomorrow.

[Whaaaaat]

*Back when I bough this cat I bolted up a Mercury 2.5/280. No Hydraulic jack plate, no tilt indicators just me running buy the seat of my pants. I ran over 110mph ..

The new engine is a 300xs with a hydraulic jack plate so I can adjust the motor on the fly.... I still cannot get close to the numbers I ran with the 280 :confused:

Test Set up:

- 31p Hydromotive Quad IV
- 14 5/8 dIA
- Race prep trailing edge
- Sharpened
- Four 1" Vent holes drilled.


Boat ran up to 5900-6000 rpm with a top speed of 102 mph, Also a large hop developed between 55-80mph that is not present on the small props (26p) . Boat does hop and pull right simultaneously most likely due to the large prop. Acceleration was not great.

But the testing never ends (except in the winter, testing ends for me in the winter)


https://www.youtube.com/watch?v=2DZFZRpL-SY

What are you using to get all the overlay data on the video? Especially the g force numbers. Can you overlay rpm as well. I like it.

[NICE PAIR]

I'm not sure if she will spin a 34p, but I have a 35p 3 blade cleaver to test tomorrow.

Do you know what your boat weighs?

If you have to you can raise the limiter to carry the smaller prop out farther.

31 x 1.62 x 6800 x 117mph @ 5% slip (dream wheel calcs)

your 280 had the gears and rpm capacity to run the numbers. Good Luck.

[Pachanga_rick]

I'm just going to have to build another 280 if I want those big numbers.. 103 was about it today.

[NICE PAIR]

I'm just going to have to build another 280 if I want those big numbers.. 103 was about it today.

The 3 blade slips too much.

35 x 1.62 x 6000 x 103 = 16% slip

35 x 1.62 x 6100 x 103 = 17% slip

you could also be bumping the soft limiter.

Can you borrow a decent 4 blade 34 ?

[Cervelo777]

I wouldn't give up yet. I am running a 2.5 liter, and I have a buddy that is whipping my ass with the 300xs.

[JPEROG]

Rick,

Is the tunnel shut down in the rear with a rubber flap? I know that the fast ones that I have seen have them.

Joe

[Pachanga_rick]

It had one, but was told by the previous owner that hull did not like it. Caused to much Stern lift at speed and the boats back end would come around with little notice above 80..

I'll pass on that
.lol