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Thread: HP gain from no cat??

  1. #1
    Hybrid booster
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    HP gain from no cat??

    2.5 motor, 3" exhasut turbo back, no muffler, what kinda gain could i see removing the cat??

  2. #2
    turbo addict Turbo Mopar Contributor Anonymous_User's Avatar
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    Re: HP gain from no cat??

    If the cat is in decent shape, not plugged, you might see a little gain. If the cat is original, old, plugged, or just in sad shape, you might see a lot.

    Basically, it is hard to say.

  3. #3

    Re: HP gain from no cat??

    10 or so maybe more

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    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: HP gain from no cat??

    Quote Originally Posted by Anonymous_User View Post
    If the cat is in decent shape, not plugged, you might see a little gain. If the cat is original, old, plugged, or just in sad shape, you might see a lot.

    Basically, it is hard to say.
    Exactly! I've gained 216WHP one time on GLHS #991. The cat got so plugged up the car stopped running. Put a new cat on it and it ran great after that That car made 216WHP BTW, big #'s in the early 90's

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  5. #5
    turbo addict
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    Re: HP gain from no cat??

    from 0 to 216 is a pretty big gain! lol

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    Hot Certified Christians at TD! Turbo Mopar Staff Directconnection's Avatar
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    Re: HP gain from no cat??

    It all depends on what power output your engine is producing right now.

    Larry aka: 4cefed4 dynoed a before and after years ago, but I forget! I think it was 5-7whp going from stock to a catco, or catco to nothing...can't remember.

    I'd say 5whp on a 200whp car would be my best guess.
    Quote Originally Posted by 22mopar
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  7. #7
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    Re: HP gain from no cat??

    ok, i dont think its plugged but my experience with cats so far been when they get older they just become hollowed out anyway after so many thousands of miles, my luck theyll go to pull it and its empty on the inside anyway, although its not real loud like id think it would be but it also has a resonator in line so that may be quiting it down a lil

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    Buy my stuff!!!!!!!!!!! :O) Turbo Mopar Vendor turbovanman²'s Avatar
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    Re: HP gain from no cat??

    5-20+ whp, depending on setup, cat size etc. Really hard to say. That cat looks old so it could be loose or tired, bang on the case, if it rattles, its done. Leave the resonator, vans need them otherwise they drone badly, especially with an auto.
    Last edited by turbovanman²; 09-20-2008 at 05:16 PM.
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    Hot Certified Christians at TD! Turbo Mopar Staff Directconnection's Avatar
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    Re: HP gain from no cat??

    If the cat breaks up, it will plug itself as the pieces will lodge themselves iside, or worse...downstream at the muffler.
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

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    Re: HP gain from no cat??

    On the dyno... Gained 11whp and 22 ft lbs on the dyno opening the cutout in front of the Catco 3" cat to a dise exit exhaust. Car was making 290 unplugged.
    Ken Adler....
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    Hot Certified Christians at TD! Turbo Mopar Staff Directconnection's Avatar
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    Re: HP gain from no cat??

    most likely 50% was due to the piping and muffler loss, other half to the cat?
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

    Steve

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    See me ride out of the sunset... Turbo Mopar Staff BadAssPerformance's Avatar
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    Re: HP gain from no cat??

    My shadow runs the same mph with open 2.25" DP or full cat-less 3" with Dynomax race magnum oval. I think a cat would slow it down.

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  13. #13
    ¿ Turbo Mopar Contributor oldgregg's Avatar
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    Re: HP gain from no cat??

    Pulling the cat off my 89 Daytona with a 2.5 gave me 3 psi more of boost which is about 20 HP given these cars typically average 7 Hp/1psi.

  14. #14
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    Re: HP gain from no cat??

    I seriously doubt that on my setup the cat is restricting anything. I drove around with the Exhaust off, and with it on and did not feel any difference between the two. Its a 3" turbo back with a carsound high flow cat.




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    Moderator Turbo Mopar Staff Vigo's Avatar
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    Re: HP gain from no cat??

    is that just a funny angle pic or is that turn tighter than 90*? if so, why?

  16. #16
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    Re: HP gain from no cat??

    Quote Originally Posted by Vigo View Post
    is that just a funny angle pic or is that turn tighter than 90*? if so, why?
    Its a 90, must be the angle of the pic. The exhaust runs right along where the stock goes, but just dumps out the side before the rear tire.

  17. #17
    Hybrid booster Turbo Mopar Contributor
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    Re: HP gain from no cat??

    I am running a 3" down to Hi flow catco butt welded to a flowmaster race muffler. I have not dynoed the car but just ran it at the track. It ran 8.04 at 86.8 mph. Monday I will be removing the cat and gutting it then running a 3" pipe through the middle and re welding it. Sound like a lot of trouble but I live in California so I need to look legal. I will be taking the car to the track thursday and will be reporting the ET change on the car.

  18. #18
    Hybrid booster Turbo Mopar Contributor
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    Re: HP gain from no cat??

    Okay cut off the car beat out the guts and installed a straight pipe through the cat. Reinstalled the cat in car. Went to the track tonight no other changes made to car. Last week I ran 86.8 at 8.04 after cat gutting I ran 7.7 at 91.4 so take that to the bank. Dont know the hp gain but what a mile per hour improvment.

  19. #19
    Hybrid booster Turbo Mopar Contributor
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    Re: HP gain from no cat??

    Oh as for racing the lil red Mazi well he was a no show. Something about family time

    AMOPARACER

  20. #20
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: HP gain from no cat??

    Soccer practise for the 7 year old (lead coach pulled another no show so yours truly had to pick up the slack again.) TaeKwaoDo class for the 5 year old, then after that, race like heck to get the princess to dance lessons in time, then after that I spent a few quality hours of time on the Rampage, Line X in the am The wifey had a business meeting so Dad had full time shuttle service going...

    BTW AMoparGazer, I think a 7.7x and 91 MPH deserves it's own thread and vids too. I was a bit more confident that I could MPH you when you were running 86... 91 is moving

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