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  1. #1
    Join Date
    Mar 2021
    Posts
    7

    Default Indmar Raptor 440 Catalytic Converter Delete

    Hello everyone,

    I am curious if anyone has done or heard of removing both cats from an Indmar Raptor. I have a 2015 SE450 that I have been looking to maximize my fuel economy on, as it loves to guzzle some gas while surfing. I researched the cooling/exhaust system on the raptors and realized it is possible to unclamp each cat from the manifold and y-pipe fairly easily, then of course unbolt both 02 sensors and it is free to work on. Since the catalytic converters are not water jacketed they can be cut from both sections of exhaust and replaced with stainless exhaust pipe. The pre cat 02 sensor would remain in it's factory location allowing for the ECU to properly adjust/manage fuel, while the second 02 sensor which checks exhaust contents post cat would be replaced by an 02 sensor simulator to keep any codes from being thrown. I would also like to throw in I have already removed the baffle in the exhaust while installing a fresh air exhaust to deaden exhaust noise while surfing. Does anyone think this would be worth it in the end? My only thought is that even if it does not improve gas consumption that much, at least I am removing the possibility of my catalytic converters going bad down the road.

  2. #2
    Join Date
    Mar 2022
    Posts
    7

    Default

    I would be interested to see some dyno readings before and after that modification. Maybe some truck enthusiasts have done similar.

    Sent from my SM-G781V using Tapatalk

  3. #3
    Join Date
    Apr 2012
    Location
    Lake Wylie NC Area
    Posts
    439

    Default

    Is there some data that the converter is a source of increased fuel consumption?
    Michael
    Mikes Liquid Audio

  4. #4
    Join Date
    Jul 2007
    Location
    Flowery Branch Georgia
    Posts
    2,740

    Default

    You will get worse fuel economy if you do that . The new boats are computer controlled and will not respond well to missing parts. The fact is you have a huge boat and add tons of weight to make a surf wake there is no way to push that much boat through the water without feeding it with lots of gas. My advice is to buy a comp and learn to ski .

  5. #5
    Join Date
    Mar 2021
    Posts
    7

    Default

    Quote Originally Posted by michael hunter View Post
    You will get worse fuel economy if you do that . The new boats are computer controlled and will not respond well to missing parts. The fact is you have a huge boat and add tons of weight to make a surf wake there is no way to push that much boat through the water without feeding it with lots of gas. My advice is to buy a comp and learn to ski .
    I would very curious how the boat would respond, whether it would need to be retuned to completely take advantage of the modification. However I would think with easier removal of exhaust gas from the combustion cycle it would allow the engine to allocate less work to moving the exhaust gas through the catalytic converters. And yes Michael I understand moving a boat full of water to throw a wave will burn a lot of gas, but the point here is to optimize fuel consumption. And do not worry I am not only a surfer, got a old 1995 watercraft I slalom ski/trick ski behind.

  6. #6
    Join Date
    Mar 2021
    Posts
    7

    Default

    Fundamentally restricting exhaust gas will cause the engine to work harder, by eliminating this restriction the engine becomes more efficient. The real question here would be how much more efficient the engine would become, as well as if the engine would need a re-tune to optimize a cat delete.

  7. #7
    Join Date
    Apr 2012
    Location
    Lake Wylie NC Area
    Posts
    439

    Default

    Quote Originally Posted by michael hunter View Post
    You will get worse fuel economy if you do that . The new boats are computer controlled and will not respond well to missing parts. The fact is you have a huge boat and add tons of weight to make a surf wake there is no way to push that much boat through the water without feeding it with lots of gas. My advice is to buy a comp and learn to ski .
    The post-converter O2 sensor would be the only ECM input that would be effected by removing the cats. They are easy to cheat because the post-cat voltage signal from an efficient cat is mid range and very little fluctuation.
    Michael
    Mikes Liquid Audio

  8. #8
    Join Date
    Mar 2021
    Posts
    7

    Default

    This was my thought, my only concern is if the engine would become lean from the engine being originally tuned with the back pressure from the cats. But then when the cats are removed it will allow for better fuel burning meaning a need for more fuel. However, with the pre cat 02 sensor reading how well the combustion cycle is burning, it may recognize this lean condition and compensate by adding more fuel. This more becomes a question for an experienced tuner.

  9. #9
    Join Date
    Mar 2021
    Posts
    7

    Default

    Also another thought to this modification, it may result in a decrease of exhaust noise in the "cabin" of the boat, as the catalytic converters are located directly behind the surf seat, and definitely result in additional noise compared to a straight pipe, as the filter material in a cat would cause a disturbance in exhaust flow resulting in vibration.

  10. #10
    Join Date
    Dec 2015
    Location
    Lake Nottely, Blairsville, GA
    Posts
    1,226

    Default

    Quote Originally Posted by michael hunter View Post
    My advice is to buy a comp and learn to ski .
    lol, this cracked me up.

    You never fail to humor me Mr. Hunter.

    1983 Supra Rider aka Mischief IV
    1983 Supra Beast
    1985 Supra Rider
    1986 Supra Sunsport Skier
    1987 Supra Marauder
    1991 Supra Comp ts6m
    2012 Supra Sunsport 242

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