AFTER MARKET EXHAUST or NOT?

[2prop]

Hey guy's i need some imput and thought's, my boat has twin 350 mags. with stock Merc. exhaust , will i see an increace in low end , and see an increase in top end ,with an after market exhaust system, and what do you suggest, any help will be greatfully apprecated.

[boatnam2]

no you will not dont waste your money.

[Tinkerboater]

It all depends if you want to do anything else to the motors. Do you have through transom exhaust? The motors will breath better and you will loose some transom weight. You will gain some speed but not worth the $ if your not planing to do anything else to the motors. Do the transom exhaust first.

[2prop]

thanks for your reply's , it has tru hull exhaust, sounds like i would be wasteing my money.

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]

[kab]

Racing Ray- What engine package are you running? I have a 502 efi with whipple. Dustin recommends powerflows. I was planning on making the purchase but maybe not.

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]

[Tinkerboater]

It would increase your cruise speed only if it increased your torque (and) you installed a higher pitch prop ( cruise rpm before = x mph is same rpm-speed after headers)

[boatnam2]

i think on a hp 500 and above you would see good results.but the guy who bought my 21ft ultra 350 mag put on powerflows and seen no gain.

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]

[Maverick]

Friend of mine, had the same experience with some Stainless Marine exhaust. Next, however, he did head work and enlarged the carb jets, and saw BIG GAINS.
Seems like stock is ok with stock. If you want more just doing one end of the motor or the other isn't going to change with equation much without changing fuel in, head work AND exhaust.
Just another boater, who hasn't cut loose with the bills for new exhaust....
Originally posted by boatnam2:
i think on a hp 500 and above you would see good results.but the guy who bought my 21ft ultra 350 mag put on powerflows and seen no gain.

[Tinkerboater]

Unless you change your prop to a bigger pitch your speed will be the same at any given cruise rpm. What will change by adding more torque will be your top speed not your cruise speed. Increasing torque will alow the motor to turn the original prop to a higher rpm = more speed. But at say 3000 rpm with a given prop increasing torque without increasing the rpm (cruise speed) you will not gain any speed. I used to turn 23 mirage at 3500 rpm at 47mph I increased my hp from 385 to about 600 and changed my props to 26 bravo 4 blades. I now cruise at 53 mph at 3500 rpm. More torque alows me to turn the bigger prop. but without changing the prop I still would have been going 47 at 3500 rpm.

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]

[Tinkerboater]

RR Your forgiven - we all make mistakes. You sound like you know what you are talking about I just wanted to make sure no one else got mixed up. Thanks

[Racing Ray]

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[This message has been edited by Racing Ray (edited March 12, 2002).]