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  1. #1
    Join Date
    Jan 2008
    Location
    sydney australia
    Posts
    4

    Default 8.1 Litre exhaust pipe size

    Hi there,Could somebody tell me what diameter exhaust I should run.I have 2 -4"pipes coming out of the risers in to a Y piece what diameter from there Thanks Rex.

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,531

    Default Re: 8.1 Litre exhaust pipe size

    You'll have to measure the existing Y pipe if you plan to reuse it.

    The Crusader Installation manual will give you minimum acceptable sized exhaust pipe.

    When our 454's were redone, we 'upgraded' the riser outlets to 4" ID and custom made Y pipes with 5" ID outlets.

    I'd expect the 8.1 to be happiest with dual 4" ID 's straight out the transom. I'm sure it will be quite functional with a 5" ID outlet Y pipe.

  3. #3
    Join Date
    Jan 2008
    Location
    sydney australia
    Posts
    4

    Default Re: 8.1 Litre exhaust pipe size

    Thanks MakomarkI was thinking that way myself untill I spoke t a guy that makes fibreglass mufflers,he suggested 6".I don't really don't want to go that big I think it will defeat the purpose of making it run quieter.The installation manual gives no information on collector diameter thats my dilemma,I dont want to do anything to void my warranty.Need advise thanks.

  4. #4
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,531

    Default Re: 8.1 Litre exhaust pipe size

    As far as your warranty goes, Id think the big item would be to have documentation of the backpressure in the exhaust. As long as you don't exceed their specified max pressure, you should be golden there.

    As far as the 6" pipe goes, I'd suspect you won't have enough vertical clearance to install 6" outlets in the preferred manner (lack of clearance under the deck). It won't hurt performance any. The other concern is with that much 'extra' area, there really won't be much pressure to "push" the exhaust out....only an issue if you spend a lot of time at idle.

  5. #5
    Join Date
    Jan 2008
    Location
    sydney australia
    Posts
    4

    Default Re: 8.1 Litre exhaust pipe size

    Thanks Makomark I think I will go 5" I will be able to get the angles right and get the noise down.

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