Need help with pipe length

[Kevin Sheren]

I need a starting piont for pipe length on an AA45 in my sport 40.

Thanks in advance for your help.

Kein

 

[Samuel Hagan JR]

I run 10 5/8th to 10 3/4.

 

[57fairlane500]

Kevin, what hull are you running and what prop are you trying to pull? What fuel?

Short answer, both answers above will get you in the ballpark.

Long answer, we need more info......Wait, that wasn't longer, hmmmm. :huh:

 

[Dasboatman]

Which pipe you intend to run, and boat weight less fuel would be most helpful also - - - in addition to line items posted above by Kelly. CHEERS !!! Bob

 

[Bert Dygert]

Kevin,

Start your set-up at 10 inches with the AA 45 pipe. You may end up around 9 3/4 for a sport boat. Your starting prop should be a x450 three blade. The hull is a GP-400 from ML Boatworks. The weight will be around 8 1/2 pounds.

Bert Dygert

 

[Randy Rapedius]

Hey Kevin.

I would start at 10 3/4 and then work your way in. You will find the sweet spot.

Randy

 

[SayMikey]

Id start with a x447x3 rev the motor its a Mac clone. Also if its a new boat knock the shine off all ride surfaces

 

[Kevin Sheren]

Thanks guys for your help. Bert It's almost done and the new 20 to.

Kevin

 

[Bert Dygert]

Kevin,

Which sport 20 hull GP-310 or GP-330? 20 Motor is AA, CMB or Mac?

Bert

 

[FloridaScaleBoater]

I need a starting piont for pipe length on an AA45 in my sport 40.

Thanks in advance for your help.

Kein

Kevin;

Just a "little bit" of my experience with the AA45.

Are you running the Ramped/angled up engine, or the flat intake.

I'm told by Al, the flat intake has a little better low end torque.

I am running the flat intake in my new sport 40.

I had the AA/parabolic clone pipe, and I just couldn't make the engine run the way I wanted it to,, Had SCREAMING top end, but no low end I like/need for milling I was running that pipe at 10-3/8" and moved it out to 10-1/2". No change.

Talking with Jerry Crowther, he said he had played with an AA45 with AA pipe, with no success, told me he got the best all around performance with a Mac's exhaust 7.5cc marine pipe.

Strapped one in my boat, and all is well at 10-3/8" a slightly cut down in diameter X450/3 prop

Still working on props for this hull/setup

 

[Duck899]

I ran an AA45 with the flat intake for 3 years in a Mutt sport 40. I ran the Macs products 10cc aero unmuffled pipe with an aftermuffler as per instructions with the Mutt hull. 65% nitro with a 1455/2 pitched at 3.3". The pipe was set at 10.5" from center of engine to first high part on the pipe. I found that I could get it down to 10.125" without loss of low end to get the boat launched. Altitude I ran at was 2200' to 3200' so seal level will show better performance. Engine had awesome rpm while still maintaining great low end low speed performance without being peaky. I won alot of races and a few championships.

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