Johnson motor with exhaust bypass

[wagemaker]

I saw this at the Grand Rapids Boat Show. The owner was not around to ask about it. Were these factory or aftermarket?

Any other info would be appreciated.

Dale

[adam1961]

That is an aftermarket unit, and only the second one that I have ever seen.
I have been looking for one for a long time, without any luck!
Adam

[wiscoboater]

When you see an exhaust like that, or the long pipes seen on the racing motors used on hydros, are they separated inside the exhaust cover Isolating each cylinder? or is this open inside the exhaust cover both pipes getting exhaust from both cylinders?. I have seen some of these setups for Mercs on feebay and they are always big bucks. I would love to try and make one some cold winter day in my basement shop.

[bill-russell]

The set that I have on a 150 hp 4 cyl. Chrysler factory race engine are separated into pairs of cyls. With two stacks. Hope this helps. Bill

[vintin]

If there were a tuned exhaust system it would be really awesome!

[jw-in-dixie]

quote wannabe outboard guy:

When you see an exhaust like that, or the long pipes seen on the racing motors used on hydros, are they separated inside the exhaust cover Isolating each cylinder? or is this open inside the exhaust cover both pipes getting exhaust from both cylinders?. I have seen some of these setups for Mercs on feebay and they are always big bucks. I would love to try and make one some cold winter day in my basement shop.

They can be either way. a real racing motor usually has aluminum blocks in the exhaust chamber to separate the flow from each cylinder. Most of the "look good" setups don’t have the blocks, in my experience.

If you try to make a set, think of chrome sink drain pipes, or tub grab bars. Both have 90 degree turns, saving you that struggle. It could be done by modifying the exhaust cover plate to accept this type of pipe. Not easy, but doable. 😉

I notice the pictured motor has a cable-operated open/shut valve, for quiet or noisy operation. 😎

Cheers, JW in Dixie

[elgin2]

Have you got any pictures of that set-up?

quote BillRussell:

The set that I have on a 150 hp 4 cyl. Chrysler factory race engine are separated into pairs of cyls. With two stacks. Hope this helps. Bill

[Mumbles]

quote BillRussell:

The set that I have on a 150 hp 4 cyl. Chrysler factory race engine are separated into pairs of cyls. With two stacks. Hope this helps. Bill

Like this one? This particular 150 belongs to a club member in Vancouver.

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[bill-russell]

What I have looks exactly like that,with a racing lower unit on a 15 inch tower. I have owned it since about 1979 ,I have ran it on a boat a few times,but it is obnoxiously loud. Bill

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