formula2?2

A friend of the family had a 272 SR1. He cut 4.5 inche holes into the bottom of the swim platform. I thought it was to make it louder but, read on one thread that someone did this to his 292 to help let out more exhaust to help out his engines. Does anyone know if it makes a noise difference as well. Does it work on 242LS as well? Also does anyone have pics of modified baffles without taking off the swim platform?

Ted G

My 311 has 4" holes in the platform bottom. 2 in the center and 1 on each end. It is much louder than stock- 108 dB on one engine 113 with both running. The holes allow all the water to drain so there is very little silencing.

Formula Outlaw

I cut big rectangular holes in the bottom of my silent thunder, as large as possible approximately 6 x 9 inches or something like that.

Then I dropped the entire platform when I swapped out my exhaust to EMI Thunder aluminum units with Stainless Marine Superflapper Tips.

Treads

I cut 3-1/4" holes in the bottom of the box, 2 holes directly in line with each exhaust outlet. Didn't go into the box and remove the baffles, felt it wasn't necessary with double sets of holes. As insptech said, it allows all the water to drain out when your running, increases the noise level (didn't measure) both at idle and at cruise. Also allows the engine to breathe a little easier. I also just put EMI Thunder.

rlv1017

could some one maybe take a few pics to get an idea what,where and how much. i too would like to "thunder" it up a little. but cant go too crazy because of the sound police.
Thanks for the help

Formula Outlaw

You can open up the bottom of the box, bigger circular holes, big honkin' rectangular holes like I did, and the bottom of the box doesn't really completely clear the water until about 35mph or a little more. On mine as it was on plane and gaining speed, all of a sudden it got considerably louder, that's when the box was completely out of the water. It also tends to act a a big "center plane" when coming up on plane. I noticed a big difference when I removed my box.

So as long as your going slow or idling, you could remove about all of the bottom of the box and the sound police ain't gonna know....

rlv1017

did you guys cut the holes in the bottom of the port and starboard sides. or under the flat part tucked up where the exhaust enters the box initially?(above the drive.)i already have the little factory holes under the port and starboard side. is that the right area? i would like it to sound better idling too. it sounds a little toilet bowlish idling . hell, maybe ill do what rambuncious did and run pipes right through it! that'll fix it

Treads

In the bottom of the port and starboard sides, just in front of the rectangular factory exhaust ports. You shaould also have a similar section in the center of the platform as well. Drill the holes in line with the existing exhaust ports.

rlv1017

thanks again. time to break out the holes saw, and maybe the sawzall!

Waterfoul

Actually "rambunctious " here

before you cut big hoes in your show surface of yoru swim platform , I have two other options

1)

remove or cut out the baffle plates that are about 5" from teh square tips. I did this with a very long saw zall blade, through the square tip openings. start at teh bottom ( 1" gap exists, cut up, over, and down, like a dog house hole.

this makes it louder, but still muffled


2) plumb from the thru hull flangess to the square tips with marine exhaust hose and some stainless elbows
( takes some fabricating , but sounds awesome now)
search my posts to find info and pics


Rambunctious