PIPE for 3 HOLER

[Hunter 93-N]

Has anyone tried or had success with a pipe on a 3 Hole OMC ? My late father started on a project a few years ago , but we never finished the manifold end.. I'd be entertained to continue with it if anyone thinks its worth a try. I vaguely remember reading that John Runne tried something on a FEH back in the day ?

[dwhitford]

Hunter, the 3-cylinder 2-cycle engine presents a unique opportunity for exhaust tuning quite compactly because the exhaust pulse from one cylinder helps scavenge the exhaust (and also the intake) from another cylinder. I don't understand this well, but I know it works because of the 120º rotational timing of the firing impulses among the cylinders. The 3-cylinder Crescent outboards from Sweden use tuned megs in their driveshaft housings, and 3-cylinder Saab two-cycle car engines of the 1960s did as well. I think your dad was wasting his time with that exhaust chamber. You'd need such a tuned chamber for each cylinder to work, and that would be far too unwieldy on your boat.

Better you do some internet research on your exhaust situation: find out what Johnrude did on Stingers, for example. I'm sure that someone on this forum can better advise you. -- dave

[rumleyfips]

When Crescents were the fast C engine, people tried megapones and chambers on them. The factory setup was better. I like the story that the Crescent was designed with a pencil and a papkin while drinking beer.

[dwhitford]

What's a ''papkin'', John?

[rumleyfips]

It's either a paper napkin or a typo Dave.

[dwhitford]

Typo, John. That's what I thought. You're excused this time, but maybe you should proof- read what you send out what the world will see later . :<))

[DiGia54D]

Hunter, Lopez on the west coast that had a crap load of records in FE ( had a post last year trying to sell everything )had sold a 3 holer with tunes pipes to Kevin Fitzgerald. I do know there is a couple of sets of those pipes kicking around. Maybe shoot Kevin an email...he may know who has some.

[SPW]

Hunter: Have tried chambers on 850 MOD 3 cylinder engines many times. Have tried both 3 into 1 and 3 individual pipes. Both designs work though the 3 into 1 works best should you desire to pull the pipe. Looper engines really perform best with expansion chambers.
john sharp 8H

[1100-one]

Wayne you are correct that's Mike Lopez. Now in Texas. Hunter get a hold of Steve Benson in Wash area. He built the snail pipe exhaust that Lopez had. It was Steve that did that years,ago prior to selling to Mike.

[fitsracing]

Gun I have 3 sets of Benson pipes for the OMC, if interested let me know

[joejohn44]

i cleaned Lopez out. I have 2 sets of chambers and plan to run them this year. have not yet tested....stay tuned

[matthias]

Hey Gun. If that is the pipe Jaws made, it is for a two cylinder.

[Hunter 93-N]

yes, thats the one.. Thanks. !

[modifiedoutboard]

Inland Jet Made a 900ZXI Triple pipe that worked well...………….
Presently working on Design for Yamaha Triple based on their pipe INLAND JET ZXI CHZMBERS.jpg

[John Schubert]

Hunter, the 3-cylinder 2-cycle engine presents a unique opportunity for exhaust tuning quite compactly because the exhaust pulse from one cylinder helps scavenge the exhaust (and also the intake) from another cylinder. I don't understand this well, but I know it works because of the 120º rotational timing of the firing impulses among the cylinders. The 3-cylinder Crescent outboards from Sweden use tuned megs in their driveshaft housings, and 3-cylinder Saab two-cycle car engines of the 1960s did as well. I think your dad was wasting his time with that exhaust chamber. You'd need such a tuned chamber for each cylinder to work, and that would be far too unwieldy on your boat.

Better you do some internet research on your exhaust situation: find out what Johnrude did on Stingers, for example. I'm sure that someone on this forum can better advise you. -- dave

Dave is correct. I doubt if there is any pipe system that would improve upon hole the 3 cylinder naturally is tuned. Perhaps playing with tuners inside the tower, but nothing else. Charlie Strang's first engineering project at OMC was to design that 3 cylinder system. Ed Runne's system also was a good one based on the naturally tuned 3 cylinders. While Merc was running stackers on their 6's when we were having the tunnel wars they figured it out also with their down stackers first with the cow bell at the bottom then in to the housing. They did have to change their cranks & firing order but it worked.

[hoss20h]

Hey Hunter I have two omc three cylinder block they have the three plate exhaust system if you need them give me a call
804-928-8952 thanks Gary Pond

[mercguy]

Hunter, I have a 3 pipe expansion chamber motor in the works right now....

[M Miner]

Polaris snowmobile had a 3 hole tuned pipe , if it was me I would find a way to try it.

[bh/]

...My late father started on a project a few years ago.. ,

Gun; -this was one system of his that I really liked;
-loud, ...but fast..??
He loved to play with those pipes

-also , a pic of the pipe that John R used on his 2cyl FEH,
the 'Hovercraft '.