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Author Topic:   Dry exhaust on 48 SPL?
Island Bwoy 420 posted 08-18-2003 11:30 AM ET (US)   Profile for Island Bwoy 420   Send Email to Island Bwoy 420  
This question is for anyone who has done it but maybe Sal might know. I want to make my 48 SPL Rude growl. I haven't seen one on an engine except for some friends in the bahamas had a Johnson 225 VRO 89' with a dry exhaust and it sounded bad. Anyone got any suggestions to make this motor loud as hell??
Bigshot posted 08-18-2003 12:21 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Drill a hole(1"?) above the anticavitation plate into the exhaust chamber. Not sure about outboards but without backpressure it may run like crap or burn a piston.
captbone posted 08-18-2003 03:50 PM ET (US)     Profile for captbone  Send Email to captbone     
The only thing it will hurt will be your ears and you will gain almost nothing from it. Also you may have a terrible time getting on a plane due to the fact that the gas will not let the prop slip any more.
Gene in NC posted 08-19-2003 01:45 AM ET (US)     Profile for Gene in NC  Send Email to Gene in NC     
Heard some bass boats really bellowing last w/e. My son said that some of the guys take the baffles out.
Island Bwoy 420 posted 08-19-2003 12:19 PM ET (US)     Profile for Island Bwoy 420  Send Email to Island Bwoy 420     
Gene in NC, or anyone, how would you go about taking the baffles out? I just need to find a way to make my engine make some noise without messing it up.
Bigshot posted 08-19-2003 01:33 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Dirt bikes have baffles...outboards do not. If she is loud on muffs, no muffler. The reason why it is quiet is the exhaust is under water. To make it loud you must get the exhaust above the water which involves cutting a hole above the water in the exhaust chamber.
captbone posted 08-19-2003 04:20 PM ET (US)     Profile for captbone  Send Email to captbone     
I agree with bigshot, all it needs is a hole drilled in the mid section to sound loud, but this will destroy resale!
Sal DiMercurio posted 08-19-2003 10:59 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Theres more to it then just drilling a hole because theres water jackets that shouldn't be bothered.
I think theres a special minifold that fits on it.
The racing engine exhaust comes out right under the power head about 4 inches down the leg.
I wouldn't drill anything until I found out exactly how to do it, because you may end up spending a ton buying a new to replaced a drilled out that shouldn't have been drilled in the first place.
brisboats posted 08-20-2003 10:58 AM ET (US)     Profile for brisboats  Send Email to brisboats     
When you do determine just where you want to drill. That motor is relieved on each side of the exhaust housing above the cavitation plate. Drill a hole that you can refit with an expandable plug like the plumbers use. This will give you the option of plugging the holes and silencing the mayhem that you will create wherever you use this motor. As mentioned above you will experience very little to no gains by simply relieving the exhaust. This one modification alone is like attaching a playing card with a clothespin to you bike wheel. Its fun for a day or two but you will most likely soon outgrow/tire of it and it really didn't make the bike any faster. If you want to get a modest performance/noise gain, experiment with the exhaust tuner under the powerhead.

Good Luck

Gep posted 08-20-2003 11:09 AM ET (US)     Profile for Gep  Send Email to Gep     
Island bwoy,
I was just wondering. Why would you want to make it louder?
I always am looking for ways to make mine quieter.


jameso posted 08-20-2003 11:26 AM ET (US)     Profile for jameso  Send Email to jameso     
Forget the exhaust, install an extra battery, larger alternator and about a 300 Watt RMS stereo. Play a lot of rap music real load, this will be just as obnoxious as the loud exhaust.
I' be listening for you.
Island Bwoy 420 posted 08-21-2003 07:46 PM ET (US)     Profile for Island Bwoy 420  Send Email to Island Bwoy 420     
First of all jameso I already have a 250 watt amp and 4 clarion 6 1/2's for the 13 that I plan to blast reggae from. Second I dont like the idea of drilling anything. I was looking more for something like a racing exhaust or a performance part that would make it scream, that could also be removed. If nothing else I would like to get more information on how to tune the exhaust. If anyone has any ideas or knows how to get more out of this 48 spl evinrude please post or email me. To me mid 40's in my 13 sourpuss just isn't fast enough ;-) Already getting a jack plate and plan on tweakin the wieght setup. Like I always say this crazy islandbwoy is only going to be 17 once, and even if I flip it that what a kill switch is for! Thanks for everyones input. Now gimme more!


captbone posted 08-22-2003 09:37 AM ET (US)     Profile for captbone  Send Email to captbone     
Bobs performance marine makes snouts like on the 20inch V8 evinrude to retro fit on v6 and merc, yamahas. I dont know if they make them that small but it looks great and they have the removable plugs that make it louder.
Perry posted 08-22-2003 01:09 PM ET (US)     Profile for Perry  Send Email to Perry     
To improve perfromance and make a 2 stroke sound more crisp, you need to put on expansion chambers. My Yamaha RD350 street bike has them and it screems. I have never seen them put on an outboard though.
brisboats posted 08-22-2003 01:23 PM ET (US)     Profile for brisboats  Send Email to brisboats     
Fact is you'll probably get better gains from proper steup, engine height, weight balance, the right propellor, etc. than one simple bolt on motor modification.

You cannot simply bolt on one thing and make a 2 cylinder OMC scream, except for perhaps a nitrous kit and you will scream when the powerhead melts in a short period of time. But, you can bore it, put in bigger and higher compression pistons, shave and cc the heads, match the exhaust tuner to the powerhead, change the reeds, rejet or find bigger bore carbs, bump the timing, put on a nose cone and low water pickup, port it, or just put a 60hp decal on the cowl.

Its the old adage, "speed cost money, how fast would you like to go?". An outboard like any engine is a system designed by engineers to operate for a long period of time under normal operating conditions. Once you begin to change any of the systems you need to make additional modifications amongst the others. The more you change the more the longevity of the motor is compromised. You can spend a lot of money and time to find out that the engineers that designed the motor really did know what they were doing in the first place.

I would spend the time right know sorting out the setup and then if you just need more speed sell the 48 and perhaps get a OMC 3 cylinder. That would be more cost effective than wringing out the two banger. If you simply must build a hot 48hp and are committed to spend the money I can put you in touch with a guy that races 2 cylinder OMC's. His first advice to you will be along the lines of "you better buy a couple of extra powerheads, because we will be needing the parts".


Island Bwoy 420 posted 08-22-2003 08:23 PM ET (US)     Profile for Island Bwoy 420  Send Email to Island Bwoy 420     
I want to thank everyone for entertaining my idea and since I'm already running on a jack plate I figure I might just tweak with props and tune it to get max performance. I guess I dont need to break 50 mph in a 13' ft'er anyway. But remember if you in the palm beach area listen for the reggae blasting from a seafoam green whaler!

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