Scale Setup

[sport hydro]

Here's the spec's

Dumas Circus Circus wood kit race ready weighing in at just under15 lbs., painted as the 1988 Miller High Life.

New CMB 67 Green Head

Andy Brown AB67 Parabolic pipe

Octura X457/ 2blade

The boat runs stable and I'm told fast enough for race conditions. The thing that concerns me is the motor does not sound like its getting full rpm's out of it. The pipe is at 10 3/4" from the center of the plug to the start of the fatest part of the pipe. The center of the strut is 1/8" below the rear shoe's and 0 angle to the bottom. I tried a Y557/ 2blade and a Prather 250/ 2blade but both seemed to be slower.

I am wondering if the pipe is too short or not right for that motor/ boat combination.

 

[Mike McKnight]

Here's the spec's

Dumas Circus Circus wood kit race ready weighing in at just under15 lbs., painted as the 1988 Miller High Life.

New CMB 67 Green Head

Andy Brown AB67 Parabolic pipe

Octura X457/ 2blade

The boat runs stable and I'm told fast enough for race conditions. The thing that concerns me is the motor does not sound like its getting full rpm's out of it. The pipe is at 10 3/4" from the center of the plug to the start of the fatest part of the pipe. The center of the strut is 1/8" below the rear shoe's and 0 angle to the bottom. I tried a Y557/ 2blade and a Prather 250/ 2blade but both seemed to be slower.

I am wondering if the pipe is too short or not right for that motor/ boat combination.

I never got the AB Parabolic to run well in scale. It didn't have the torque to swing scale props. That's the reason you slowed down with bigger props. Those pipes seemed to be better suited for the riggers and could dial up high RPMs because more of the prop was swinging free. Here it's under the boat with more weight on it. The AB 67 Black pipe worked better for scales. Length might be a tad short too but I ran Muck pipes and 10 7/8 is the shortest I ever ran with a heavier boat. The AB 67 Black pipe and the CMB Fat Pipe I ran at 11 1/2.

 

[glenng]

Here's the spec's

Dumas Circus Circus wood kit race ready weighing in at just under15 lbs., painted as the 1988 Miller High Life.

New CMB 67 Green Head

Andy Brown AB67 Parabolic pipe

Octura X457/ 2blade

The boat runs stable and I'm told fast enough for race conditions. The thing that concerns me is the motor does not sound like its getting full rpm's out of it. The pipe is at 10 3/4" from the center of the plug to the start of the fatest part of the pipe. The center of the strut is 1/8" below the rear shoe's and 0 angle to the bottom. I tried a Y557/ 2blade and a Prather 250/ 2blade but both seemed to be slower.

I am wondering if the pipe is too short or not right for that motor/ boat combination.

I never got the AB Parabolic to run well in scale. It didn't have the torque to swing scale props. That's the reason you slowed down with bigger props. Those pipes seemed to be better suited for the riggers and could dial up high RPMs because more of the prop was swinging free. Here it's under the boat with more weight on it. The AB 67 Black pipe worked better for scales. Length might be a tad short too but I ran Muck pipes and 10 7/8 is the shortest I ever ran with a heavier boat. The AB 67 Black pipe and the CMB Fat Pipe I ran at 11 1/2.

I agree with Mike on the pipes/length. Try a X457/3 or X455/3 if you have them.

Glenn

 

[Hydro Junkie]

Definately go longer on the pipe, especially if the engine is new. Not so sure if the parabolic is a bad choise or not as I'd need to see a picture of it. I know the Brandts use a pipe that has a diverging cone that goes into a converging cone that goes into a cylinder and then a stinger and their boats flat out fly, as demonstrated by multiple high points championships. I'll have to see if I can find mine and get a picture posted as I have the same set up going into my 108 Muck hull

 

[Duck899]

Here's the spec's

Dumas Circus Circus wood kit race ready weighing in at just under15 lbs., painted as the 1988 Miller High Life.

New CMB 67 Green Head

Andy Brown AB67 Parabolic pipe

Octura X457/ 2blade

The boat runs stable and I'm told fast enough for race conditions. The thing that concerns me is the motor does not sound like its getting full rpm's out of it. The pipe is at 10 3/4" from the center of the plug to the start of the fatest part of the pipe. The center of the strut is 1/8" below the rear shoe's and 0 angle to the bottom. I tried a Y557/ 2blade and a Prather 250/ 2blade but both seemed to be slower.

I am wondering if the pipe is too short or not right for that motor/ boat combination.

What elevation? What nitro percentage?

Pipe is too short in any case.

11 3/8" to 12"

X-455/3, X457/3, X460/2, 1460,1462, 1465, prather 245-255

An X455/3 will be easy to set up with the pipe at 11 1/2".

 

[Duck899]

Definately go longer on the pipe, especially if the engine is new. Not so sure if the parabolic is a bad choise or not as I'd need to see a picture of it. I know the Brandts use a pipe that has a diverging cone that goes into a converging cone that goes into a cylinder and then a stinger and their boats flat out fly, as demonstrated by multiple high points championships. I'll have to see if I can find mine and get a picture posted as I have the same set up going into my 108 Muck hull

Most of those guys use Muck pipes with add on mufflers which are hard to find now but the AB silver or black pipe works good too....

 

[sport hydro]

Thanks for the replies.

I am running on 45% Red Max fuel at 400 ft. elevation.

I do have an OPS 67 tuned pipe with add on muffler I could try.

I'll also lengthen the pipe out to 11 1/4" and try a X457/ 3 blade.

 

[Mike McKnight]

Thanks for the replies.

I am running on 45% Red Max fuel at 400 ft. elevation.

I do have an OPS 67 tuned pipe with add on muffler I could try.

I'll also lengthen the pipe out to 11 1/4" and try a X457/ 3 blade.

That's about the same as I am here. I run a Muck 6511 in my Circus and my son's Miller. He can run a little shorter than I do since his boat is lighter and I have his at 11 1/4 and he has good throttle control. He can slow to a troll and punch it. I run a modified x460 on his boat. Mine I have at 11 3/4. Any shorter and it won't come back on if I come off the pipe in the mill. I run a 457 heavily modified three blade on that boat and it has hit the 60's a few times with good air. Best thing though is that it handles well in turns with the three blade. All of my boats run 60% nitro. I have run these pipes as long as 12 1/2 in elevation or low air quality. Remember it's a heavier boat so it will need pipe volume to give you some torque.

 

[glenng]

Thanks for the replies.

I am running on 45% Red Max fuel at 400 ft. elevation.

I do have an OPS 67 tuned pipe with add on muffler I could try.

I'll also lengthen the pipe out to 11 1/4" and try a X457/ 3 blade.

That's about the same as I am here. I run a Muck 6511 in my Circus and my son's Miller. He can run a little shorter than I do since his boat is lighter and I have his at 11 1/4 and he has good throttle control. He can slow to a troll and punch it. I run a modified x460 on his boat. Mine I have at 11 3/4. Any shorter and it won't come back on if I come off the pipe in the mill. I run a 457 heavily modified three blade on that boat and it has hit the 60's a few times with good air. Best thing though is that it handles well in turns with the three blade. All of my boats run 60% nitro. I have run these pipes as long as 12 1/2 in elevation or low air quality. Remember it's a heavier boat so it will need pipe volume to give you some torque.

Noticed that about the three blade props also. Seems to hold the boat up better in the corners(almost appears to pick up speed in the turns). Are you willing to share any info as to the mods on the 457?

Glenn

 

[Mike McKnight]

Well I don't wanna tell all that I had done to it but what I will tell you is that if you take a 457/3 and cut it down to a 455 diameter that will be a really good all around prop on a lot of boats. You will lose a little in the straights because of the extra drag of swinging another lobe on the prop. That being said it can give you some exceptional handling in the turns because that extra lobe is giving you more bite at slower speeds. I don't know about you but I've won more heats by holding turns than I have in the straights. Trust me I'm no prop guru I'm just giving you what I have experienced with scales and when I ran big boats.

 

[bsmtboy2]

I agree with the others, move the pipe out to 11 3/8 and run it. I run with a modified x457 as well and you can reach 60mph or better. If you go with a x460 cut down and hub relieved, she will get really close to 65. Move your pipe out in 1/4 in increments until your happy.