CMB .21 Seaducer pipe length?

[Keebibear]

I really have not had any time to run this year and havent ran my Seaducer since blowing the bottom out of my Mac last years final race.I had a modded CMB greenhead lying around I bought some time back and installed it in the Seaducer.Im interested in start pipe length( 8-8 1/2) neighborhood sound right?Im using a AB Parabolic now and have a older Cooper,3280 ops,Speedmaster(rossi) pipes.Any may work better than the AB?Thanks

 

[Dan Hydro]

I know for a fact that the OPS 3280 is doing pretty good on a CMB 21 LS greenhead, 21 Valvola, 21 Novarossi LS and a 21 Mac.

They are all set at 8 1/2"

Dan.

 

[redracer]

I am running a mac 21 same as the green heard i am using the ops pipe measured at 8 inches and the engine can take it shorter Robert

 

[shoboat]

Boaters,

7 1/2" to 8" is the place to be on a good running 21.

RPM is the reason that these pipes and motors rev up.

With a long pipe you will never get the speed that you

are looking for. Another big problem with being able to

run a short pipe length is the exhaust timing needs to stay

low around 178* for a good 21 motor. With high timmed

motors, you will never get that pipe to run short for great

RPM. One other issue with short pipe lengths, are the propellers

need to have the cup reduced so it can spin up easy,this is the

key to going fast fellas.

Have Fun Testing,

Mark Sholund