Looper V6 exhaust

[phatmanmike]

how can i port my midesction/ exhaust housing on a 1991 omc 3.0L<br /><br />on my merc v6, it had 4 large holes on each side just at the bottom where it met the lower unit, but they were underneath a lil fin. my omc has no fins....<br /><br />can i just cut a set of holes on each side of the lower portion of the exhaust housing, or is there a better way?<br /><br />here are 2( bad) pics....<br /><br />do either of these look like they would work?<br /><br />or should i just do this:<br /> bobs machine exhaust housing <br /><br />

<br /><br />OR<br /><br />

 

[Mod3]

Re: Looper V6 exhaust

Moving to Johnson/Evinrude questions.

 

[phatmanmike]

Re: Looper V6 exhaust

is mod 3 new?

 

[Dhadley]

Re: Looper V6 exhaust

No. He had 3 other posts.<br /><br />What in the world are you try to do with the holes?

 

[phatmanmike]

Re: Looper V6 exhaust

just crazy ideas im having. i want to port thr exhaust like my merc v6 had, so that the exhaust exits though the air instead of the water. dry stacking is a similar term i believe.

 

[Dhadley]

Re: Looper V6 exhaust

Open exhaust and dry stacking are two different things.<br /><br />Do you just want noise and dont care about performance?

 

[Dhadley]

Re: Looper V6 exhaust

Heres what we found -- just drilling those holes in the side like that does nothing for performance but it does let noise out. In fact if the motor is set up below 6000 rpm and not dry stacked it may hurt performance slightly.<br /><br />If youre looking to relieve backpressure you can open the exhaust but not there. Youre close though. Look down inside the lower unit from the top, as if your looking down the exhaust path. You'll see the exhaust passage gets very narrow as it goes into the lower unit. Thats called the envelope. Thats where you do the cutting. The cut is actually verticle not horizontal. If you remove that metal the exhaust opens up quite a bit. The middle will flow down and out just as before but the outside of the exhaust can now blow right out of the case and on top of the AV plate.<br /><br />However, if you dont dry stack the exhaust not much will happen. To take full advantage of the open exhaust you have to dump the water before it goes into the exhaust passage in the midsection.<br /><br />Even if you dry stack it and open the exhaust not much is going to happen (except irratate the heck out of folks) unless you start to turn some pretty good r's. Once over 6500 or so youll start to see it. About 7000 it really starts to help.<br /><br />At 6700 and below the stock passages are pretty good.<br /><br />Now, Bob is a pretty good friend but I gotta tell ya -- that exhaust snout is about the ugliest thing ever stuck on an outboard.

 

[phatmanmike]

Re: Looper V6 exhaust

thanks, ill leave it as is.

 

[Dhadley]

Re: Looper V6 exhaust

Did you get the prop figured out?

 

[phatmanmike]

Re: Looper V6 exhaust

its a 27 p x 14 1/2 custom prop by gene remco. thats what i was thinking it was. <br /><br />its a nice one , heres a pic, and by the way, it fits nicely on my big omc looper <br /><br /><br />

 

[Dhadley]

Re: Looper V6 exhaust

What boat are you putting this on?

 

[phatmanmike]

Re: Looper V6 exhaust

1984 sportcraft center console fishing machine!<br /><br />motor has a sea drive unit, and i picked up a standard 25 inch midsection with trim til today. i will swap over my powerhead and lowerunit soon.<br /><br />the boat is 20 feet long, and 7'6" wide and has a 12 inch pad at the bottom of the " V "<br /><br />im swapping the sea drive unit out, and putting in a 10" fixed height jack plate and a 6" adjustable jack plate, giving me a total of 16 inches of setback, and 6 inches of total up/down movement.<br /><br />i plan on placing the anti-cav plate 3 inches above the keel ,and then doing all my adjustments from there with the jack plate.<br /><br />when i had the sea drive still hooked up, i used a 20p 4 blade stainless prop, and could get 52 mph at just under 6000, about 5900 if i trimed out all the way. but the anti-cav plate was even with the keel at that time.<br /><br />ima gonna toy around with the remco 27p, just for zhits and giggles, to see what it does.<br /><br />who knows, we'll see.<br /><br />i will be using this one , on the transom:<br /><br />

<br /><br />and one similar to this, but aluminum color, and 1/2 thick instead of 3/8 thick, bolted between that and the motor:<br /><br />

 

[phatmanmike]

Re: Looper V6 exhaust

dhadley, what do you think of my new setup. work, wont work, what?

 

[Dhadley]

Re: Looper V6 exhaust

It should work fine. All your dimensions are an excellent starting point. If you get that 27 to hook up & spin it should be an interesting ride!