250XS Question for JimmyB

[John Richied]

Bill, on some prop calculators you have to add 1” of prop pitch if it’s a cupped style prop such as a Chopper or Lighting ET. The prop calculator I use is from Pally Performance Products. It’s a cool download you don’t have to be on-line to use. Trust me you are about 7% slip.

And I think you CAN out run Lou, top speed…but in a drag race you will be wanting your mommy. Remember he can’t drive a piece of plywood with an outboard strapped to it and we know you can… :mrgreen: :mrgreen: :mrgreen:

 

[badbait]

I was just wondering why your figures were different. Maybe we should say were adding an inch or were not adding anything for cup. I for one have never understood why your numbers were different from mine. As far as racing Lou. It doesn't really have to be a race. we can just put a GPS in the boat and go out and make a few runs and see what the numbers are. That way nobody is staying on the gas when he thinks he should be backing off. I just want to see the best pass from both of us because of a few calls I've had from guys that are thinking of putting on more power and want to know how the 250 compares with the 280. I just thought this might be the best and most believeable way to compare them.

 

[froggy]

Mr. Bill,

You are running at 4.1% slip---that's unbelievable! You must be running light. The "theoretical" top speed at 5750 RPM / 30 Pitch prop / 1.62 gears is 100.83mph (this is with no slip). You are running 97.7 mph. Therefore 97.7/100.83 = 95.90% efficient or 4.1% non-efficient (slip).

Sorry John, that's the facts.

froggy

 

[jimmyb]

guys, please remember that prop pitch numbers are often an "average" pitch of the prop (pitch often changes depending on where you measure it on the blade) and often prop pitch is determined more by how a prop runs instead of the exact measured pitch. So, dont get hung up on slip numbers and running super low %. The prop calculator is simply a tool to describe how a prop will act. Dont get into arguement over prop pitch and how it might impossible for someone to run the numbers...

What Bill is doing is correct. He is using the prop pitch formula to better set up his boat. By playing with setback and motor height (while running the same test prop), he is figuring out how his boat runs. He is not worrying about getting a certain slip %, he is simply comparing the slip numbers of how his boat ran before and after the changes.

 

[John Richied]

Froggy what prop calculator are you using?

I hear ya Jimmy, if its faster on the GPS... it works!

 

[2fast4mom]

Bill I will run your 03 against mine with the JSRE 280 at the delta or later in September if the delta doesn't work. We can do 1/4 mile, 1/2 mile, all at Empire Cut it's a perfect speedway.

 

[John Richied]

Badbait… YOUR UP!

 

[badbait]

Lou that's sounds great I'll be there on the 6th ready to rock and roll. There seems to be some interest in just how these heavy motors run on a 2003. I'm looking forward to you driving my boat and seeing what you think. I have changed the setup 6 times since I installed the 250XS. There's not a whole lot of information out there on set-up for a 500 plus pound motor so its been trial and error. I have now changed the setback 4 times and am at 5.5 inches currently and running a manual plate. I just got this thing back together and had to build another skid plate for this new manual plate. Hope to be able to test tomorrow. What I'm seeing so far is big improvements in handleing and no loss of speed.

 

[John Richied]

Sounds like some great information for the guys running and setting up to run the 250XS Mercs.

Maybe you can even help Jimmy get his slug out of the hole faster? hehehe

Lets Drag Baby!

So are you guys going to drag the

 

[badbait]

John in drag racing you need a good prop, which I don't have at this time. Maybe Lou has one I could borrow. either a 26 ET or his 29 Hoss. Mine seems to come out of the hole pretty good with the 30 ET but it would be no match for Lou's 24 Hoss on that high reving JSRE motor. Yes I would like to run him both 1/4 and 1/2 mile to just see where I am. I'd also like to run top end numbers just to see how far apart we are.

 

[XB21er]

Bill,

I'll see you guys there- hopefully Lou can make it. We'll be there with the 21 and your motors twin(they are one serial # apart) fully loaded pluggin along.

Craig

 

[John Richied]

John in drag racing you need a good prop, which I don't have at this time. Maybe Lou has one I could borrow. either a 26 ET or his 29 Hoss. Mine seems to come out of the hole pretty good with the 30 ET but it would be no match for Lou's 24 Hoss on that high reving JSRE motor. Yes I would like to run him both 1/4 and 1/2 mile to just see where I am. I'd also like to run top end numbers just to see how far apart we are.

If it can't drag.... SELL IT! :wink:

 

[badbait]

Lou, I almost forgot I have my trolling motor on so you need to run yours. This will give some real life numbers.

Craig, which motel are you staying at?

Badbait

 

[XB21er]

La Quinta Inn, Stockton

my cell # 661-714-8934