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Thread: 2.5 Inch Exhaust Upgrade

  1. #1
    Mitsu booster
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    2.5 Inch Exhaust Upgrade

    1987 Chrysler New Yorker, T-1 motor. Would like to upgrade to a 2.5 inch exhaust. I am curious if it's just a bolt on upgrade or if I have to do something to my turbo to make it fit? FWD has exhaust systems, but I never see my car listed. It's an E series I think. Basically just a luxury K car.

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: 2.5 Inch Exhaust Upgrade

    Welcome to the site!

    There will probably be some tweaking necessary for any exhaust kit you want to put on it, but it should be no problem for a good shop. Your turbo has a tiny 2.25" swing valve, but I believe the 2.5" DP should go in there well enough. I think you will notice a decent gain with the mod.

  3. #3
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    Re: 2.5 Inch Exhaust Upgrade

    Went full T2 and 3" exhaust on my old 87 Yorker. Fun car at 14.5psi. Ran low 14's. 11" brakes and a Shelby suspension from a Daytona. Too bad the snowplow guy backed into it. I used the kit from TU, It worked ok, but we believe his instructions are wrong. I had a bunch of cuts to do to mine to get it over the axle. We did it a different way on a friends car and only had to make 1 cut and then it bolted right in. Both 3" systems. A friend got a 2.5" cat back kit from FWD for his 91 Lebaron. I trimmed a bit off one end of a pipe and it slipped together like butter.

  4. #4
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    Re: 2.5 Inch Exhaust Upgrade

    Quote Originally Posted by cordes View Post
    Welcome to the site!

    There will probably be some tweaking necessary for any exhaust kit you want to put on it, but it should be no problem for a good shop. Your turbo has a tiny 2.25" swing valve, but I believe the 2.5" DP should go in there well enough. I think you will notice a decent gain with the mod.
    I'm still a little confused. You say the swing valve is 2.25, how will that accommodate a 2.5 down pipe or will it? I'm not so much worried about the rest of the system, as I have a friend with a pipe bender in his welding shop. I'm concerned with fitting a 2.5 down pipe to my turbo. I know that in 88, they went to a 2.5 inch system. Do I need to look for a later turbo, or can I make this work with the one I have. This is a daily driver that I would like to get another 30-40 hp out of.
    Thanks.

  5. #5
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: 2.5 Inch Exhaust Upgrade

    A 3" DP fits a 2.5" SV pretty well. I've done that myself. I've never tried to put a 2.5" DP in a 2.25" SV, but I'm sure it would work just fine. A better option would be to find a 2.5" or even 3" DP and put it on your current turbo. That generally requires removing the head though, so that's a much bigger job.

    If you're looking for that much of an increase in HP, and you are pulling the head, you might want to consider a TII conversion. It would pretty much guarantee that you reach your goals right out of the box with factory parts and reliability.

  6. #6
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    Re: 2.5 Inch Exhaust Upgrade

    Quote Originally Posted by elmor353 View Post
    I'm still a little confused. You say the swing valve is 2.25, how will that accommodate a 2.5 down pipe or will it? I'm not so much worried about the rest of the system, as I have a friend with a pipe bender in his welding shop. I'm concerned with fitting a 2.5 down pipe to my turbo. I know that in 88, they went to a 2.5 inch system. Do I need to look for a later turbo, or can I make this work with the one I have. This is a daily driver that I would like to get another 30-40 hp out of.
    Thanks.
    The hole in the Swingvalve where the exhaust bolts up is only 2.25" in dia. But it's flanged enough that a 2.5" downpipe should fit. Since the bolt pattern is close you might have to open up the holes to get the bolts in though. In 88 The exhaust was still 2.25" but they moved the bolt holes out which most of us call a wide flange. Presumably to get the bolts in and out easier. In 89 They opened it up to 2.5" through hole with the same bolt pattern as the 88.

    If you want 30-40hp going to a full T2 conversion is your best bet. I left mine an Auto, threw on an 87 2 piece intake, factory rad/ic setup, converted the stock turbo and dropped in an 87 T2 LM. I modified the LM to run 14.5psi of ECU control, and turned off the overboost setting. It'd hit 14.5 and just hold it there as well as a manual boost controller since the turbo was stock on the stock 87 T1 exhaust. It was such a sleeper. This is basically the way they came in Mexico. The 11" brakes and big pre-91 Shelby sway bars allowed it to stop on a dime and turn corners pretty good too. It cornered harder than you could stay on the couch like seats.

  7. #7
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    Re: 2.5 Inch Exhaust Upgrade

    Sorry late to this thread. About 7-8 years ago, I put on a Spirit 2.5" exhaust kit from FWDP on my 1985 New Yorker. It did not fit well. Had to cut and weld like 7-8 places going over the trailing axle and around the fuel tank. FWDP does not have a kit designed for the NY'er. Thought the Spirit would be closest. Not sure about TU's fitment in a NY'er?
    Fast forward to last year. The aluminized coated mild steel kit rusted out badly. Not wanting to go through this again, I bought a series of 304 stainless 90's, 45's, and couple 15-30° bends. That is one thing I'll never have to deal with again on this car. Should have done it in stainless the first time. Another approach to dealing with the 2.5 pipe & donut going into a 2.25" swingvalve, would be to cut your 2.25" donut flange off and swag or bump the pipe out 2-3" past the donut. That way the donut and the swingvalve match and the donut doesn't get chewed up by the swingvalve over time. Best approach obviously would be to change swingvalve out to a 2.5" one, but that isn't always a viable option for everyone.
    Todd

  8. #8
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    Re: 2.5 Inch Exhaust Upgrade

    I was under the impression and just by looking up there that they'd all be the same. What's different? The rear of my 87 ShelbyZ looked identical to my 87 Yorker.

  9. #9
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    Re: 2.5 Inch Exhaust Upgrade

    Todd’s suggestion - cut your 2.25” downpipe a couple inches below the swingvalve and weld onto it your new 2.5” downpipe is the simplest way to go
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