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

[dzalj1]

hey, i will put some pictures of my gearbox and that exhaust snout, but as soon as i get back fom work tommrow i will get some better ones and post them, but for now enjoy lol. the pictures of my gearbox is with the low water pick up instaled, and the z brackets are the stainless steel mounts because i have shortened my midsection to 15 inch and i am using the normal 20inch trim bracket so i made up the mounts. stainless solids on the bottom and stainless and rubber on the top for flexing.

[dzalj1]

some more

[dzalj1]

some more

[dzalj1]

last three,

[dzalj1]

when i get bak from work i will put some pictures of my v4 and v6 tuners cut down. please let me know if any one wants any detailed pictures, or if any one wants to know what has been done to my johnrude just let me know and i will giva you all the info u need.

[terry taylor]

HI. Looking forward to more pics. also very methodical motor mounts. Do you have any powerhead mods. or tricks . Steering setup very interesting thanks.

[dzalj1]

hi, i wont be able to get pictures of the tuner for a while because ive droped my phone today as we were testing a s3000 mercury today and my phone got nocked over the boat. but i will try everything to get those pictures up. i can give u every single powerhead modification i done to my engine as a backyard mechanic and with only with a limit of tools, my little v4 is doing 7700rpm. i done all the port work, the boring, the gringing, the shortening of the midsection, doing the mounts, lowwater pick up every little thing on my engine is not bought it was manufactured by me and built by me.. my whole engine is completly modified. if you want i can explain with you or any one here, how i done every modificaton to my power head i can think of. i had to do everything my self because i had only a small amount of funds available and i wanted to have the fastest crossflows around, and now i do. but for this i would need to post some more detailed pictures of my engine and show you guys what i have done so far., but any way let me know what ever you need , tips, tricks etc, and i will get back to you
thank you dzalj1

[trimmed out]

its an 85 175 lower unit and looks like you know your stuff i will print the pics and take them to my mech. and see if hes able to pull that off hes a full blooded merc man he used to work at lake x in south fl but he works on my old work horse for me but thanks for the pics

[dzalj1]

hi trimmed out i sent u a pm, no worries about the pictures, as soon as i find a new fone i will post some more detailed pictures. thanks for the message.