exhaust questions

[trimmed out]

I have only seen it on mercs where there is some welding done to the exhaust something in that nature but its loud and sounds good to me. But what is that called and are there any hp gains from the exhaust flowing more freely instead thru the hub and last ? can it be done to a 85 johnson lower unit

[trimmed out]

guess nobody knows what that is called

[David]

sounds like a Bob's exhaust housing

http://www.bobsmachine.com/

You'll make noise, contribute to people wanting fast boats banned, and won't gain any speed.

[trimmed out]

I Was Just Wondering If There Would Be Any Horsepower Gain. I Know The Engine Is Tuned To That Exhaust System And Doing So Would Lean It Out Some But Thanks For The Reply And Clearing That Issue Up

[terry taylor]

hi. That in itself will not create a leaning out condition thanks.

[shawnjetton]

make it loud. i like all my boats loud, my airboat is the loudest. it just makes me beleive i have more power.

[jpickett]

I relieved the exhaust through the bottom of the mid section by drilling six holes on ethier side, as well as replaced the tuner. i rejetted my carbs. You have to remove the power head and lower unit to do this. Its loud and exhuast flows well on plane but but is quit and polite when need be. But your on the suwannee and no cares about noise. We dig it.

[jpickett]

Oh yeah its a Merc 2.5 200, not a OMC

[terry taylor]

I relieved the exhaust through the bottom of the mid section by drilling six holes on ethier side, as well as replaced the tuner. i rejetted my carbs. You have to remove the power head and lower unit to do this. Its loud and exhuast flows well on plane but but is quit and polite when need be. But your on the suwannee and no cares about noise. We dig it.

HI. What was the size you removed. And what size
did you replace them with thanks ?

[trimmed out]

i got my mech. working on it now and got a set of boyesn reeds on the way. but if im able to drill the holes like you did that will work for me.

[shawnjetton]

HI. What was the size you removed. And what size
did you replace them with thanks ?

drill 1/2" holes just like the 260 strait leg use to come from mercury. after u remove the exhaust bucket u can easilly drill from the inside. i have a 1/2" bit welded to a 12" rod to reach into the mid.

[jpickett]

Terry, let me check and about the jetting sizes and I will pm you with em.

[TD]

All the Bobs snouts that I have seen end up cracking around the welds. If I were to use one of these I would bolt it on and feather it in with Marine Tex or some other epoxy. Just my opinion.

[dzalj1]

hi,
if you want your johnson really loud you dont really have to take you midsection apart and cut the megafhone or tuner half way of. what year is your johnson? i use to have a stock johnson v4. it was the loudest engine anybody has every heard here. it was louder than the f1 mercury slider engines. if you dont believe me, every time i would take of from the ramp or somewhere, the poeple on board would have to cover there ears from how loud it was. the way i done it was i droped the gearbox, above the cavitation plate is a roughly 75mm gap to the top where the midsection comes flush to. in that gap where the exhaust flows from the power head through the propeller externally on each side i drilled 16 holes , 8 on each side, with each hole 10mm big, but then i had to drill them to 14mm just for fun. i also have a sorta home made bobs exhast snout. but this is way better. it only a a rectangler tubing. and moulded that into the midsection and gave it better flow on take of. i did feel a lot of lower end improvement and on top end it would just scream. i did not have to rejet the jets or do any mods to the engine. the other way of doing is to pull your mid section apart, and if your engine is fitted with a long exhaust snout from the sandwhich plate to the bottom of your mid, yopu can cut that also as short as you want. i cut mine right of to the top. if your engine has a megafone exhaust, you can cut that half way off to make it more louder on idle and more cracklier. if any one would like me to pst pictures of my whole modification's please let me know i have all the pics so dont be shy to ask

hope this helps dzalj1

[terry taylor]

HI. Please post pics. thanks