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I have heard of people relieving the exhaust just above the cavitation plate on an outboard motor. My question is, is there any significant gain in doing this other than making the motor louder for bragging rights? Where and how are they exactly releiving the exhaust? Are they drilling holes into the midsection above the cavitation plate?
BTW:
I know I'm full of questions guys but I'm new to all this High Performance Boat stuff and I'm trying to learn all that I can.
Thanks again:
Jason
Jason,
I am from washington, and probably have seen you on the Tar River, (I am the guy with the blue Hydrostream and long ponytail that is always riding wheelies).
If you ask Raceman, he will say it makes no differance, (mabey on take off), I notice better midrange accelleration, and if I plug the holes, I notice a slight loss on top.
What does your boat look like?
What motor and size?
Waterwings,
I have probally seen you some time or another on the tar river. I haven't there in probally a year because my parents bought a place in Swansboro on the intercoastal waterway. The boat I have is a 17' Red and White Sunbird with a 115 Evinrude off the back. The boat is an older 1985 style. Where did you drill your holes at and how big did you drill them? Also how many holes on each side of the lower unit did you drill? Did it make the motor louder once you got up on plane?
Thanks:
Jason
I not far from both of yall.Lets swap props or stories some time.I have a blue with yellow checker board on the rear of my 85 action marine.Its actually a modified version of the hydrostream ventura.By the way i just bought a laser II 26 p prop for the boat .Iam building a mod 200 2.4. Is this a decent prop for it?
Does anybody have any pics that they can post so I can see exactly how it is done? I don't know what size to drill the holes and how many on each side do I drill?
Thanks:
Jason
I have used 1-1/2" hole saw on the rear of the mid, one hole on each side, at the bottom of the mid, I also removed the mid and drilled 5, 1/2" holes each side (on the inside so that they can't be seen)
I have seen it done many ways in different places, even in the center middle of the sides of the mid, even in the lower unit, but most are in the lower rear of the mid, (these are on mercs)
Sorry, I don't have any pics.
Hydro1, I run a 26 Trophy 4 blade that I like, it runs 88.3
I also run a 28 inline chopper for speed runs, it runs 94.1
But the Trophy is the best of my all around props, I did run a 25 Marage, but after running the 4 blade, I wouldn't go back to the 3 blade.
Waterwings,
When you say at the rear of the mid, one hole on each side are you talking about drilling them so if you were standing beside the boat looking at the side of the motor that the holes would be close to the boat where you could see them or would they be on the backside of the mid? Hopefully that question was not too confusing. LOL
Thanks:
Jason
At the very rear of the mid, pointing straight back on a merc.
I can't see in my mind how a evinrude is shaped at the rear, but a merc is kinda flat at the lower back of the mid.
Enough room for two 1-1/2" holes.
Here is one way to drill the mid.
i have a 19' baja with a 1994 200 johnson venom and i was wondering what prop i need i know i need alot more prop because im only doing 50 and i am gettting 6300rpm opened up trim up (no jackplate yet!;) ) i m runnin a 15x17 ss but i need more alot more i need to drop the rpm down to about 5500 or so ok thanks for your help boys
heres mine drain plugs will fit it if you want it quiet again.
Use Bob's Outboard Exhaust Housing.
c/6
Hooty
Check out the metal fabracation section. I have some pictures of a exhaust snout that I made with a couple of 1-1/2"x4" holes.
Tom
Here's Bob's setup. Requires one 2" hole through inner and outer exhaust housings.
http://home.comcast.net/~jehart1/wsb...6/site1055.jpg
c/6
Hooty