Noise suppression

[dave roach]

Steve

I was drinking a bud light from a alum bottle today and the size of the can would make a nice muffler over the pipe.

Than you could put the stinger off center and past the end of the stinger on the pipe that way it is 180 for the ext to get out.

Dave

 

[brad nichols]

Like an Irwin pipe.

Brad

 

[rctinman]

The pipe worked well, readings between 79-82 DB.

Thanks,

Steve Ball

 

[Terry Keeley]

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

 

[rctinman]

Terry, that's where I got the idea, LOL I always liked that pipe, it worked well on the K&B 7.5 motors, and was very quiet.

There's a Harry Gerhart muffler clamped and JB welded on the stinger, inside, then the can is JB welded on.

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

 

[Terry Keeley]

Terry, that's where I got the idea, LOL I always liked that pipe, it worked well on the K&B 7.5 motors, and was very quiet.

There's a Harry Gerhart muffler clamped and JB welded on the stinger, inside, then the can is JB welded on.

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

So like triple muffled? Any issues with heat/back pressure?

 

[rctinman]

Terry, that's where I got the idea, LOL I always liked that pipe, it worked well on the K&B 7.5 motors, and was very quiet.

There's a Harry Gerhart muffler clamped and JB welded on the stinger, inside, then the can is JB welded on.

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

So like triple muffled? Any issues with heat/back pressure?

None, that I can tell. Ran with the same plug all day.

 

[Ray Sametz]

Terry, that's where I got the idea, LOL I always liked that pipe, it worked well on the K&B 7.5 motors, and was very quiet.

There's a Harry Gerhart muffler clamped and JB welded on the stinger, inside, then the can is JB welded on.

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

So like triple muffled? Any issues with heat/back pressure?

None, that I can tell. Ran with the same plug all day.

Wow, that's a blast from the past. Harry Gerhart made some great mufflers.Cloak it in a Crown Royal bag to keep it secret.

 

[Rick Reisinger]

It was awesome > I have never seen a rigger run so fast that Quiet ...

I was extremely impressed .........

 

[julianconde]

Terry, that's where I got the idea, LOL I always liked that pipe, it worked well on the K&B 7.5 motors, and was very quiet.

There's a Harry Gerhart muffler clamped and JB welded on the stinger, inside, then the can is JB welded on.

Nice job, reminds me of the old K&B 7.5 pipe.

JB weld? Aluminum solder? Tig?

So like triple muffled? Any issues with heat/back pressure?

None, that I can tell. Ran with the same plug all day.

Wow, that's a blast from the past. Harry Gerhart made some great mufflers.Cloak it in a Crown Royal bag to keep it secret.

I run those Harry after mufflers on my twins and F mono last time I remember you told me my F mono was too dam loud lol or you did not have enough crown that day ;-)

 

[XtremeRcBoats]

Doug, In the Netherlands we have the same noise rules and at the WC's. When I went in 2010 and 2012 to the Naviga WC's I didn't change my setup. I've only concentrated on the pipe noise and not on carb noise.

If you are concerned about carb noise, as an option you could perhaps add some foam to the inside of the cowl, see also this recent topic:

http://www.intlwaters.com/index.php?showtopic=69792

For my 45 I've got 2 designs as muffler section, see pictures below. On my 21 I've used a muffler as described which turns it 180 degrees.

Currently I don't have time to race, so I don't compete in August. My wife is pregnant and we are expecting our daughter end of July. Hopefully I have some time to visit the races. Maybe I see you there. What classes are you running?

 

[Doug Sick]

I have tried to past a picture of my latest muffler but I can't seem to get past some security issues.

My latest version is made of PVC electrical conduit. The original was made from 6061 which seemed to add a high pitch ring to the sound. Most pipes are made of soft aluminum which does not radiate as much sound. The plastic is muffer has an aluminum core tube that clamps on to the .45 AA muffled pipe stinger. The inner tube is partly blocked diverting exhaust through holes into the outer PVC sleeve which is in turn packed with SS scrubbing pad. The sound came down to the 82 db level. I diverted my water outlet into the exhaust stream which further dropped it under 80.

To deaden the intake area, the cowl is lined with ethafoam padding material and the cowl is isolated from the hull with the same material. The number plate (IMBRA requirement) is installed next to engine compartment which blocks direct noise from the engine. During the last test, it was hard to distinguish between the boat and the wind noise blowing past the sound meter.

I will be running one boat, an Eagle with an AA 45.

It will be a great experience to be at a race with representatives from over 30 countries.

 

[Ray Sametz]

Doug pic

 

[XtremeRcBoats]

Looks good Doug. Hopefully I can make it and see you there. Have a safe journey.

 

[Doug Sick]

Thanks Ray for finding my picture. I was able to get it on to my gallery but I was not sure if anyone could see it.

 

[Charles Perdue]

When i was running engines on the Dyno, I played with reducing the carb noise some. I found that when I used the pleated fabric RC car filters (similar to a K&N filter) and mounted a semi-circular deflector around about one-half of the filter, spaced about 1/4 inch away, this helped a lot. When I positioned this deflector between the filter and myself, the carb noise almost went away. I made deflectors from small plastic cups or plastic film cannisters. In a boat hull, I think that if you positioned the deflector above the filter, that would be where it is the most effective.

It is amazing just how loud the carb noise at full throttle, caused from the airflow through carb, really is when you are within several feet of the engine. I was trying to listen for pinging and/or detonation when running under a load.

Charles

 

[XtremeRcBoats]

Charles, do you have a picture of this?

 

[Charles Perdue]

Charles, do you have a picture of this?

Sorry, I did not take any photos......

This was several years ago....