Custom Exaust Info

[Hydroguy8234]

I have a hydroplane that has very little room for a tuned pipe. I was wondering if I could use a straight pipe to run the exaust to the end of the boat and then put a muffler on the end of it. I don't race I just run my boats for fun so loosing a few RPM's is ok. As long as it dosn't make the boat stall, run lean, or hard to tune. Tell me what you think! Thanks!

 

[MikeP]

Hey,

You will need to consider where to get pressure for your fuel tank, I had an airplane once with a straight pipe and it was common to put a pressure fitting close to the engine, we tapped a fitting right into the header flange and ran it to the vent of the fuel tank. I think you will loose more than a few rpms without a tuned pipe but you shouldn't have any problems.

-MikeP

 

[_laxmasta2039]

Hydroguy,

if really high performance isn't an issue, then as long as you've got a place for a pressure fitting and no kinks, leaks, or blockups then you can do anything you want!

get some aluminum piping and be creative....i've only seen this on a mono but i cant think why it wouldn't work on a hydro: put one big pipe straight down the center 'till several inches from the transom, then solder 3 or 4 little stinger pipes coming off of it, kind of like headers on a street car. hit them with a hammer on the ends to form a wide, flat opening [be sure there's no kinking] and have them come out right above the bottom of the transom [under water] kind of like trim tabs except fatter....water cooling, sweet looks, and serious muffling all in one-presto!

[the boat i know of that has this system probably hasn't touched water for >15 years, my friend who owned it told me it was a state-of-the-art racing setup when he made it!! ]

Joe

 

[Hydroguy8234]

What about back pressure? Is there a great importance in having it? I had a prather with a inboard 3.5cc and once in a while the exaust header came loose. The boat ether died or wouldn't hit full throttle when this happened.

As for the boat I'm working on... I plan to use one of thoes mufflers for quieting down a tuned tipe. I don't know what they are called. It's the type that just connects to the back of a tuned pipe. Do you see any problems with this?

My only alternative is to use a tuned pipe and place it between the radio box and top cowl. It fits but it touches both surfaces. The radio box cover is made out of wood not plexiglass, but I still think that heat would be a problem.

 

[EatMyShortsRacing]

There are mufflers that almost work like tuned pipes.. Think they were called magic mufflers. Still get good performance and they were a lot smaller than a tuned pipe...

 

[_laxmasta2039]

hydroguy,

car pipes are much shorter but fatter if something like that would work.....

also, what size is the engine? if it's 3.5cc here's a great way to make your own cheap but efficient pipe muffler [just up the sizes for larger engines] :

cut a piece of brass tubing with a slightly wider dia. then the end of your tuned pipe [so you can attach it w/ a hose clamp] and drill some holes in it .[around 10-12 holes the size of BB] cut a hole that it's fits through snugly on one end of a film canister [glue the top on]

and then glue the film canister to the brass pipe so a little bit is sticking out on the end and it is pressed snugly onto the other end of the canister. clamp it on to muffle, and take it back off when it gets too dirty or you dont want a muffler!!

come to think of it I found that in an RCBM article on OB's, so chances are Jerry Dunlap wrote it........i dont know if he checks in the General forum much so you could PM him about it or ask on the OB forum too if my directions arnt good enough.

Joe

 

[Hydroguy8234]

Thanks for all the good ideas! I have a tuned pipe for the engine, but I would have to make a taller cover for it to fit. Thanks to you guys I'm going to make two covers. A larger one to fit the tuned pipe, and the short one and try some of your ideas. I really like to look of the shorter cover so hopefully it works!