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Exhaust relief questions...

jtellor

jtellor

Member
first of all im aware that by doing this it will prolly be just a sound preference..but i wanted to know if it was safe or if it will actually hurt horespower..also ive read some threads that say that it will increase the prop slipage..if this is the case im not sure if i will do it because with a heavy load or pulling my prop has a tendency to blowout already...
i found only one example from talon on s and f...if anyone has any other pics please post them...because i really want to do this..but only if its safe
 
Noise Don't Make Horsepower

J, a previous owner of my 200 removed the can liner and drilled holes in the lower part of the can (exhaust housing) I ran it this way for a year befor I noticed the hairline cracks running from the holes to the mid plate. Sure it sounded cool and probably gained a whole 1.5 mph, but I have to tell you it wasn't a picnic replacing the can. Would I do it again, yes if I were racing but for a ski/pleasure boat never. I did prove you can replace the can without pulling the powerhead, was it fun No !!!!

Doug in Tampa:cheers:
 
Thats how the early 2.5s were each side has 4 half inch holes located at the bottom of the mid section.I would think reliefing the exhaust wouldn't help to much inless your running your RPMS up to the mid 6s and better.
They sound great but it does get bothersome times too! heres a ltitle video of mine idling I guess I should off spun it up a little!

http://www.youtube.com/watch?v=aybVOld3_0g
 
thank you both for ur pics and vids..they are very helpful..im probably going to go the route you went legend...mostly because i like the spot of the holes...it seems like a much stronger place to put them..and like enticer said they have a tendency to crack if they are in the back or sides...or so ive been told...
Is your exhaust coming out above the water legend?? because i want mine out of the water even at idle...
anyone else with pics??? i'd like to look at all options before i do this thanks:bigthumb:
 
Depending how high your motor is you can have it out of the water at idle. My motors about 1-2 inchs below the pad and I can cruise around or idle and have the holes above water but also trim it down a bit and silence it :thumb:
I talked to a teacher from Merc school about exhaust relief mods and this was the way he told me to do it, and then I followed Talon2.5's thread on S&F for the dimensions

Heres another pic of one. This is the bass mid from factory
2005_280-brandnew.png


Heres another option for drilling without risking the structural integrity. Doesnt sound as good IMO and you wont hear it until on plane
IMG_6460.jpg
 
IMO

I would NOT drill holes in the lower unit like in that last pic!! Thats a permanent deal and lowers arent cheap!! If you want to go the cheap route you should drill the holes in the can and remove the liner. As someone mentioned you can remove the can without pulling the powerhead. Not hard to do. On mine i have an offshore mid with a 260 tuner and a 1 piece adapter that is drystacked!! You cant get any louder than that setup. And relieving your exhaust wont hurt performance. Depending on how many holes u drill, u might be able to run an over the hub prop and jack that motor up!!:cheers:
 
i drilled my lower, and tapped the holes with 1/2" pipe thread, thinkin' i could put some plugs in and quiet it down if needed, but it aint loud at all, just when im takin off and slowin down it gets real loud, right now i got my propshaft just above the pad and it is not as load as i though it would be..ill probaly just plug 'em back off cause of all the exhast is leaving black chit all over the top of the a/v plate

this pic kind sucks but you can see it.. actually the only reason i took it is because i blasted a log the day before and you can see the marks in the paint/primer..

P5250238.png
 
Performed the mod to my lower unit just as described by Talon over on S&F. No problems and great sound. I also saved the piece I cut out, drilled and taped to be able to install it as a cover to cap the sound if needed.
 
Mr. Buss said:
this pic kind sucks but you can see it.. actually the only reason i took it is because i blasted a log the day before and you can see the marks in the paint/primer..

P5250238.png
Click to expand...

You know.......How long has that lower been in primer? I believe black spray paint is only .97 cents at Home Depot:poke: Haha....I had to....some people's kids.
 
:thumb: Thank you all again..for the pics and help...i def gonna do this and probably do it the way livelengend did it... seems to be a bit stronger...and as for getting the sound at idle...sounds like a good excuse to buy a jack plate and jack that baby up!!:banana: And it'll prolly be better if it is under water anyways cause im sure there will be times i dont want it to be that loud..
I almost forgot...i saw one of you posted that there is a way to remove the can without removing the power head?? also wouldnt there be a bunch of shavings and stuff i would need to clean out anyways and by not removing the powerhead i would think you couldnt get it that clean..??
 
here ya go

4vjz7r.jpg
 
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