Adustable pipe length coupling design ?...aka,slippy pipe

[yamaha74]

I've heard of people making a coupling to adjust pipe length while the engine is running, to help with more bottom/top end power. Refered to as a "slippy pipe", by a few people. Anybody seen designs for an adjustable coupling ?

 

[steve wood]

I've heard of people making a coupling to adjust pipe length while the engine is running, to help with more bottom/top end power. Refered to as a "slippy pipe", by a few people. Anybody seen designs for an adjustable coupling ?

seen them about 25 years ago. they all seemed to bind up. never seen any one use them with any success

 

[lohring]

Jim Wilson has run a very successful 7.5 mono with an adjustable length pipe for years.

Lohring Miller

 

[jetpack]

 

[SayMikey]

Blast from the past Winner Circle Products Harry Byrne used to make and run them I never saw an advantage. With todays carbs i dont see the need

 

[Duck899]

Just something else that will go wrong......there's an old saying.....(keep it simple stupid), KISS... and it seems to work just fine.....

 

[John Kubitz]

Just something else that will go wrong......there's an old saying.....(keep it simple stupid), KISS... and it seems to work just fine.....

One of the problems that people i had seen had with this unit was keeping it together while running. The vibration would shake the screws out.

 

[yamaha74]

...did anybody notice an improvement in running an adjustable coupling, versus not running one ?

 

[ids987]

...did anybody notice an improvement in running an adjustable coupling, versus not running one ?

Here's an article I found some time back. Can't say I've ever got around to trying it myself.

It's linked from the Prestwich Models website as well.

http://home.intekom.com/modelboats/boat/tunepip.html

 

[waltr]

There is only one person that I know that takes advantage of a sliding pipe with great success.

Ernie Lafluer uses it on his OBs.

There aren't too many people out there that are as talented as Ernie. He runs 5 channels in all and that also includes power trim.

I have enough to do with 3 channels

 

[Terry Keeley]

...did anybody notice an improvement in running an adjustable coupling, versus not running one ?

I ran one on my K&B 7.5 SAW boat in the mid 90's, worked well with some mods, we welded it to the header and installed silicone O rings.

It moved the pipe in 1/2" when the throttle was pushed from 3/4 to full.

I might try this again (or water injection) on my SAW boat once I get the stock horsepower to the track. :lol:

 

[LarryConrad]

There is only one person that I know that takes advantage of a sliding pipe with great success.Ernie Lafluer uses it on his OBs.

There aren't too many people out there that are as talented as Ernie. He runs 5 channels in all and that also includes power trim.

I have enough to do with 3 channels

I asked Ernie about his 5 channel set up one time, and he told me he adjusts the pipe, and needle to dial in the boat for heat racing. During a heat race he uses power trim on the motor along with steering and throttle. When at an event like the Internats he can re adjust his pipe to optimize his set up in the timed events. He has one many US-1 titles, so his system works well for him.