Do I need q blow out ring?

[Cervelo777]

I run an Allison xb03, 15" offshore mid, drystacked JSRE 260. Best speed so far is 99mph. I purchased a sportmaster that had the blowoit ring ground off on the bottom half, the skeg was cut back and had a welded on torquetab. I ran it on a sand bar and lost about 1/2 to 3/4 of inch of length. It seemed to become unstable at the 99 mph mark. So I purched an new sportmaster. It ran 10 mph slower on the first test run. I want to grind the blow out ring. What say you?

[Will hedrick]

The only reason you would need the blowout ring is to improve holeshot.the torque tab is most important In that it prevents crabbing. 10 mph slower? Did any of the gearcase #'s change?

[capteliminator]

I picked up a XB02 this year and it has a 15" 280 on it with a stock sporty with blow out ring intact. I am still learning to drive it but i have had it to 102 mph and there is still plenty left. My opinion is its not the blow out ring.

[Cervelo777]

Update: I raised the motor 1/8", and installed a Mazco RE3 I just got back from the prop guy and it ran 98 mph, so now I am only down 1 mph from the previous sportmaster with the blow out ring removed on the bottom half. Guess I will have to put the 28ET back on and see if I can bust the trips.

Is there anyone out there that will tell me that I need the blow out ring at or above 100mph? I notice the new sportmaster for the 300R does not have a blow out ring?

[David L]

I've got an XB2003 and have run all sorts of motors and gearcases: 1995 225 Promax / 1996 2.5 SS 260 / 2.5 Drag / and currently a 225X.

I've never heard of anyone playing with the blow-out ring on the SM case. Sure sounds risky and this baot is not foregiving (at all !!) when it comes to "what happens" when it blows-out. I'm sure you now this.

I'd focuss on the setup first as your rig should run 100 easy with a stock SM.

Is the lip on the pad stock? If it has been removed some then most Allison guys have to increaase motor hieght way up, 1/2 inch or more to get speeds back. You probbaly already know all this.

Guess you know this also but the Prosport becomes weird at 103 and up. During one of the rallies, Darris said this was due to aerodynamics of the boat specifiaclly the console dome.

[Cervelo777]

I've got an XB2003 and have run all sorts of motors and gearcases: 1995 225 Promax / 1996 2.5 SS 260 / 2.5 Drag / and currently a 225X.

I've never heard of anyone playing with the blow-out ring on the SM case. Sure sounds risky and this baot is not foregiving (at all !!) when it comes to "what happens" when it blows-out. I'm sure you now this.

I'd focuss on the setup first as your rig should run 100 easy with a stock SM.

Is the lip on the pad stock? If it has been removed some then most Allison guys have to increaase motor hieght way up, 1/2 inch or more to get speeds back. You probbaly already know all this.

Guess you know this also but the Prosport becomes weird at 103 and up. During one of the rallies, Darris said this was due to aerodynamics of the boat specifiaclly the console dome.

David,

Thanks for your very logical response. I am just getting frustrated trying to do the 100 mph thing and looking for every little piece of knowledge. I plan to raise it another 1/8th of an inch and pray that it doesn't come around..... I guess that's the fun part right?

[David L]

Well, first off, don’t be frustrated! Just enjoy the experience of playing with the setup and the observed results. Heck, you're already pretty close to where this boat should run with this type of power.

How long have you owned this rig?

Do you know the status of the pad (stock or shaved)?

You know the health of the motor - Leak Down?

What was the motor height when you hit 98 with the Mazco RE?

Does your new SM has a stock skeg? Search this site as there a couple mods to cut the profile to reduce surface area.

But NEVER NEVER EVER weld anything on the skeg!!!

It was a blessing that you trashed the other SM with the welded skeg as at some time, IT would have broken off like all the other SMs with welded tamers. It happened to my SM once that had the “Allison” mod welded tamer. Happened about 70 MPH and luckily nothing happened as far doing a violent hook which this boat is known to do. I was real lucky as the previous run was spot on 100.

We all have our fav top end wheel for the Prosport. The Mazco RE has always been my best top end wheel for mine.

[pappa pete]

Lots of gofast mods for the sporty, grinding lower half of blowout ring is one, putting a leading edge of a wing shape on front of skeg,leave flat side on left side, fill in left side water pickup ,radius the back of lwpu, just do a google search on sportmaster mods. It all comes up, good luck on you speed quest