87 242 thru-hull exhaust options
 

I have a 1987 242 with the 454. I want to add thru-hull exhaust :D . What are my options for this boat? I know that when it came from the factory it went through to bolt on fiberglass swim platform. Is the factory set up still available. Does anyone know a salvage place that I might be able to find the set up? Is there any aftemarket kits? Thanks for any help you can give.
Brian

Re: 87 242 thru-hull exhaust options
 

Are you saying that the Silent Thunder platform is not on your boat? Did not come with it? If you don't have the platform, it will be very difficult to find one. Matter of much searching. Guys here on this board are your best bet.

Re: 87 242 thru-hull exhaust options
 

Yes , I do not have the silent thunder platform-it does not have the cut outs. I think I need to swap out the whole platform, if I can find one...that is the problem

Re: 87 242 thru-hull exhaust options
 

So, you've basically got straight through hull exhaust with some sort of aftermarket platform?? Got tips? Any pics?

Re: 87 242 thru-hull exhaust options
 

No, I have no thru-hull, it goes through the drive now. I want to add thru hull, but do not know how to make it work with a non-silent thunder swim platform

Re: 87 242 thru-hull exhaust options
 

Ohhhhhh, now I understand!

Believe it or not, the Silent Thunder Exhaust platform was actually an option, at least back in the '80s it was. Almost all Formulas were ordered with it. Obviously, yours is one that was not ordered that way.

So, as I stated above, finding a Silent Thunder platform is probably not an option. It's relatively simple to run your exhaust through the transom though. The hardest part is to figure the height. Silent Thunder exhaust holes were cut quite high on the transom, you could go a bit lower than that. Once you locate the holes its just a matter of doing a nice job cutting the holes. That will be a bit tricky as the transom is pretty thick. Then you either run straight tips or mufflers (cha-ching for the mufflers). Buy some marine exhaust hose and run it from the manifold risers to the tips. Stuff is very stiff, you won't be able to bend it into place.

You'll also have to block off the old exhaust outlet on the inside of the drive. There is a Mercruiser blank flange and gasket for this purpose, but I think you have to pull the engine to install it (not sure on that).

Hope all that helps some, there are others here that can direct you more better than me. Good luck. :cool:

Re: 87 242 thru-hull exhaust options
 

Thanks for all of the info. I would like to get the whole platform. If I went through the hull with tips I think I would have to go through the platform up high, but then the exhaust would dump over the platform and possibly discolor it? Or I could go below the platform in the middle, but that would be awfully close to the waterline. Theblank plate would be nice but I do not want to pull the motor out again! Thanks again.

Re: 87 242 thru-hull exhaust options
 

If you go with through-hulls, you'll have to blank off the through-prop setup or your gonna sink the boat.

Re: 87 242 thru-hull exhaust options
 

good point!

Re: 87 242 thru-hull exhaust options
 

Welcome to board

The first thing you may want to do is pull the platform off and see if you run the exhaust thru it like the factory did. It will require a little cutting to do it like factory IF the inside is the same, my guess it would be close.

Thirdbird has a good idea run it straight under the platform or thru the platform.

Look through some of the old threads I have on on 242 exhaust a little to much work :D Remember you will get no performance benifit from this but it will sound nice :D

good luck

mark

Re: 87 242 thru-hull exhaust options
 

loud is good! :evilb: Thanks for the info. I will take a look at your old threads. I love the way it sounds when I run it on the trailer with the ears on the drive. I want it to sound that way in the water!

Re: 87 242 thru-hull exhaust options
 

My platform had a little rumble before,I kicked it up a little :D www.putfile.com/masi242

Re: 87 242 thru-hull exhaust options
 

How does the thu platform exhaust work? Is there pipes inside the platform or does the exhaust just go through the platform itself? If it just goes through the platform doesn't the platform fill up with water? I thought I read of guys drilling holes in the platform to help the exhaust get out faster?
Can someone clear this up for me. Also how does the exhaust hook up from the risers to to the platform? Could someone take a picture of theirs and post them if possible. I am trying to figure out what I am up against in trying this conversion. I found a platform from one of the members. I am trying to figure out what else I will need to make this work. I am Ok with a stock setup, I am not doing it for performance, I just want to hear it!
thanks for all of the help

Re: 87 242 thru-hull exhaust options
 

The platform is designed to fill with water at low speed and muffle the exhaust. As you run it drains from holes in the bottom and becomes a big open chamber. When you open the holes up it either wont fill with water or drains quicker. The openings in the platform are more than enough to exit the exhaust. The exhaust hoeses basically attach to small stubby through hulls that dump into the platform. My platform is cut with 4-4" holes and will not hold water at all. My exhaust measures 108 dB on one engine, 113 on 2. You can find rubber caps to cap off your thru prop pipes, so pulling the engine wont be necessary. Home Depot has them in the plumbing section.

Re: 87 242 thru-hull exhaust options
 

OK, now if the platform is basically used as a big muffler, first question is that the hot exhaust does not melt/affect the fiberglass and second, could I just use the platform I have? I know it is hollow because there is 2 drain plugs that I remove when i take it out of the water. It looks exacly the same as the silent thunder one, is it? It seems like I could just cut holes in the platform I have now and install some sort of aftermarket tips where the factory ones would be. I have never actually heard a factory setup with 1 454. How does it sound...is it worth doing this.
Thanks for all of the info...this is great

Re: 87 242 thru-hull exhaust options
 

The exhaust kind of pooches up the glass inside some, but doesn't hurt anything since it is mixed with water. If you have a platform that looks like the ST one then you could just cut it for tips and punch the thru hulls in. Then cut a few holes in the bottom to let the water drain, the bigger the holes, the louder it will be.

Re: 87 242 thru-hull exhaust options
 

I think this is what i want to do...Can anyone get me close up picks of how the exhaust goes throught the transom, maybe if someone has their platform off I could get picks of where the pipes come through the transom from the factory. I think from what I have found here that all I have to do is cap the pipes that go down to the outdrive, and use rubber exhaust host from the risers to some sort of collar through the transom to the platform. How is the exhaust connected from the transom to the platform from the factory? All I have to do then is cut tips in the back of the platform on each side and it should work. The water cools the exhaust enough not to melt the platform/paint, and I should cut additional holes on each side on the bottom to let the water drain out fast when I get up on plane, so it get rid of the weight and it gets louder. Is this really as simple as it sounds or am I missing something? Thanks for any input you can give.

Re: 87 242 thru-hull exhaust options
 

Can you get us a picture of your platform? If so then I think that we can much better help you out.

Jon

Re: 87 242 thru-hull exhaust options
 

Ok here is pics of my platform. The boat has 1 454, so I would not need anything in the center. Does this look like the silent thunder platform, just without the holes?

Re: 87 242 thru-hull exhaust options
 

So what do you guys think? Can I just cut the holes in this platform? It looks the same too me.

Re: 87 242 thru-hull exhaust options
 

Looks just like my buddys 242LS but without the holes. Not sure if the baffles are inside or not. Won't make that much difference anyway :D

Re: 87 242 thru-hull exhaust options
 

No baffles would just mean it would be louder, right? :evilb:

Re: 87 242 thru-hull exhaust options
 

What can I use to go between the transom and the platform, and what can I use for tips out of the back of the platform? Does anyone know where I can get that kind of stuff. I also need some pictures in and out of how it passes thru so I can cut the holes in the right place if anyone has any.
Thanks for anything you guys can offer.

Re: 87 242 thru-hull exhaust options
 

Anyone have any pictures of a boat with a single 330 around so I can get an idea where I need to cut the holes...It seems like they just come out of the risers and just go straight back through the transom. Is there some sort of flanged coupler through the transom into the platform or is it just a raw hole with a pipe sticking through it?

Re: 87 242 thru-hull exhaust options
 

OK, now that we have pics of your platform, it is clear that you have one of the very few Formulas that ever got ordered without the Silent Thunder option.

But, that's no big problem. It's the same platform. All you need to do is cut holes for the tips in the transom as discussed above. If you do a search in this forum under "silent thunder", "exhaust", "thru-hull", etc, you're going to find many pics of platforms in various states of repair and disrepair. That should show you about where the transom holes should be located. Then you template those holes and transfer to the paltform.

As for the short tips Formula used, email or call their Tech Line and ask what they used. They may still have some kickin around.

The tips that go on the outside of the board can be found because several guys here have removed their paltforms and may let the tips go.

As for any plumbing inside the platform, none. You don't need any piping inside. All Formula used was baffles and lots of guys (like me :cool: ) just cut them out anyway.

You'll need a new set of gaskets for the newly minted Silent Thunder Platform you will have created, MagicFloat can get those for you.

Presto!! Bolt it back on and you'll be rumbling away!! :D

Re: 87 242 thru-hull exhaust options
 

Cool, I cant wait to be loud!! Does anyone have a set(2) of tips that they would like to part with?

Re: 87 242 thru-hull exhaust options
 

You can get exhaust tips from many diffrent people on this site, what I had on mine were tips that were 4 inch and they stuck out about 1 inch from the transom.

Here is a pic of my platform when I had it off this spring to do a little work. The holes you see are about 8 inches around so when you fit the platform back to the transom the 1 inch tip sticks inside the box.

I would start by putting tips on and blocking off the exhaust that goes to thru the hub, than you will have a better idea where you holes shoud go.


Hope this helps

mark

Re: 87 242 thru-hull exhaust options
 

From the info I have gathered... I need short stubby tips to hook up to hoses from the risers and stick out into the platform. I then need a set of square factory tips to cut into the back of the platform. I also need rubber pipe caps to cap the old exhaust down to the drive. I am thinking that if I can come up with brass valves and a tees, I can sort of make my own silent choice set up. I don't know why I would want it quiet again, but I think it would work. Do I need to worry about any type of flap or check valve with the silent thunder type set up to keep water from getting into the motor :( . Also can anyone recommend a place to get the exhaust hoses,tips,etc. The local boat store will most likely be a rip-off.
thanks all, this site is great!

Re: 87 242 thru-hull exhaust options
 

Mark, do you think you could send me some pics of your engine compartment when you get a chance. I want to see how the exhaust runs from the risers out the back of the boat.
Thank you,
Brian

Re: 87 242 thru-hull exhaust options
 

Brian, I hope this pic works to show you, the exhaust hose runs straight out the back. If you go to cpperformance or eddie marine you will find the exhaust tips you are looking for. If you wanted something diffrent you could run the exhaust out to the side of the boat with diffrent tips that would be flush, and not have to remove the platform, just a thought. You will get a very nice sound out of that :drink:

Re: 87 242 thru-hull exhaust options
 

Here is one tip from eddie marine, I believe $59 each with no flapper inside. If you go with this one ask if they can cut the tip to 1' that should be just enough to go inside the platform. You might want to find the rectangle tip for the outside of the platform, for the most part it`s only cosmetic unless your using a flapper

Re: 87 242 thru-hull exhaust options
 

Thanks for the pics and info, this is great stuff! I see they make those tips with and without flappers. Would I want flappers so I don't have any chance of hydrolock or is there a negative side to having flappers?

Re: 87 242 thru-hull exhaust options
 

I don`t believe you would need flappers, personal choice.

Re: 87 242 thru-hull exhaust options
 

You could have a couple of problems you will need to sorth out before drilling holes. You need to check the height of your risers to make sure you have enough fall to stop water incursion at an idle. Also you need to check your water line under the platform to decide if you need internal flappers or simple backup flappers will work. As a master mech. for 15 years i have done this on several older Formulas like the 272LS and the 242Ls twins and singles. There are several ways to make your boat louder but not all are fesible both in price and application. If you would like to talk about this you can send me your phone number and I will try and help you with some options. Since going into sales and with the new models that have came out since then. We have put custom Corsa kits on boats like the 280SS and 330SS. Want to talk Formulas dropme a line at [email protected] I been with a Formula dealer since 1979 and last year we were the largest dealer in the world!

Re: 87 242 thru-hull exhaust options
 

That sounds great, I'll shoot you an email
Thanks

Hello. I know this is an old post, I am curious if you were ever able to complete your thru hole transformation. I am in the same "boat" 1987 formula f223ss 350 mag swim platform, and no thru platform exhaust. any help would be great