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Thread: Running a 2.5 instead of 2.2

  1. #1
    Mitsu booster
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    Running a 2.5 instead of 2.2

    Ok,title says it all.I know most guy's with the heavy cars like to run a 2.5 and us guys with the lighter cars typically run the 2.2's.I know the 2.5's have a good deal of torque.Is there any reason not to run a 2.5 in my 87 charger?I'm do for basically a complete rebuild and if you have seen my other post my head is trashed.But if i can get a complete 2.5 turbo to put in there for cheap is there any reason not too?

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Running a 2.5 instead of 2.2

    I don't see anything wrong with a 2.5. Although with a light car I would opt for a 2.2 personally.

  3. #3
    boostaholic
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    Re: Running a 2.5 instead of 2.2

    Wheel spin might be a factor with the light car and more torque if that matters.

  4. #4
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    I had a 2.5L in my GLH. Works great to 50mph, not so good after that. Power start dropping off after 3500rpm.

    Putting a 2.2L back in my GLH.
    Last edited by tryingbe; 04-02-2015 at 12:59 AM.

  5. #5
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by tryingbe View Post
    I had a 2.5L in my GLH. Works great to 60mph, no so good after that. Power start dropping off after 3500rpm.

    Putting a 2.2L back in my GLH.
    I put a 2.5 in a Horizon for a customer. Basically a stock engine with a G head and 50 trim T3/T4 .63 exhaust AR turbo. The engine would easily pull to 6K plus. Car ran 8.20's in the 1/8th on only 18 to 20psi!

  6. #6
    Mitsu booster
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    Re: Running a 2.5 instead of 2.2

    Well it looks like we have some good and bad.I might opt for the 2.5 for now.It does give me some decent parts to work with in the future when i do decide to build something a little more radical.

  7. #7
    boostaholic Turbo Mopar Contributor
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    Re: Running a 2.5 instead of 2.2

    I remember talking to a guy quite a few years ago at the Mopar Nationals who had done a 2.5TII conversion on a Rampage. It was a 5-speed truck. I assume he had an A-555 in it. He told me that 1st gear was basically useless unless he took off at an idle. The 2.5 was so torquey down low, all he did was turn rubber into billowing plumes of smoke... That could be fun, but very expensive...

    He did admit to me that if he had it to do all over again, he would have used a 2.2...

  8. #8
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    I can 2nd that story. We put a mostly stock 2.5 in an 85 laser which didn't weigh more than 100lbs than my GLHT did. At the drag strip on some of the stickest 225/50/15 street tires at the time (1999) you'd leave the line at 1100rpms. Anymore than that and it was instant wheel spin.

    Now the 2.5 in my 87 ShelbyZ was 3500 then 3grand with some mods, then 2850 with the 2 step rev limiter activated. Much better than the 4grand the 2.2 required in that car.

  9. #9
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by glhs875 View Post
    I put a 2.5 in a Horizon for a customer. Basically a stock engine with a G head and 50 trim T3/T4 .63 exhaust AR turbo. The engine would easily pull to 6K plus. Car ran 8.20's in the 1/8th on only 18 to 20psi!
    I've looked thru a lot of 2.2 and 2.5 dyno sheets. There are only a handful of people able to make a 2.5 breath up top. Most experienced what I had, which is great low end torque, power dies around 3500rpm.

  10. #10
    turbo addict boost geek's Avatar
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    Re: Running a 2.5 instead of 2.2

    i would love to try a built 2.5 shortbock on my car
    later Dick Westerhof

  11. #11
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Running a 2.5 instead of 2.2

    The stock 2.5 swirl in my Lebaron runs out of breath above 5k, I usually shift between 4500 and 5k.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  12. #12
    boostaholic Turbo Mopar Contributor
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by Force Fed Mopar View Post
    The stock 2.5 swirl in my Lebaron runs out of breath above 5k, I usually shift between 4500 and 5k.

    I'm going to have to get used to that on my Daytona. It's so much fun to rev the 2.2 in my Scamp to 7K... I'm going to have to rremember I can't do that with a 2.5...

  13. #13
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by tryingbe View Post
    I've looked thru a lot of 2.2 and 2.5 dyno sheets. There are only a handful of people able to make a 2.5 breath up top. Most experienced what I had, which is great low end torque, power dies around 3500rpm.
    I'm going to have to say that if a 2.5 has a power peak at only 3500RPM, something is wrong! Chrysler themselves had a higher peak power RPM rating for a 2.5 than that.

  14. #14
    Moderator Turbo Mopar Staff Vigo's Avatar
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    Re: Running a 2.5 instead of 2.2

    You feel torque but you don't feel power. It feels like power drops off at 3500 but it's really torque dropping. Peak power rpm is probably 4800-5200 rpm on most modded 2.5s. If power peaks at 4800 rpm you still wouldnt shift until 5200+ if you are trying to go as fast as possible. The only good/quick way to figure out ideal shift points is off a dyno sheet.

    Dont push the red button.You hear me?

  15. #15
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by Vigo View Post
    You feel torque but you don't feel power. It feels like power drops off at 3500 but it's really torque dropping. Peak power rpm is probably 4800-5200 rpm on most modded 2.5s. If power peaks at 4800 rpm you still wouldnt shift until 5200+ if you are trying to go as fast as possible. The only good/quick way to figure out ideal shift points is off a dyno sheet.
    Now that I can agree with on a bone stock 2.5.

  16. #16
    Hybrid booster
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    Re: Running a 2.5 instead of 2.2

    my input would be to ask a couple questions...what FD/trans? wheels/tires? road/track/both car? what other parts going on it? set up for tuning/logging (WB02)? if you're only running a 525, stop right there. a 2.5 will snap the spider gears in the diff and go boom first chance it gets, the case isn't designed for big power (> 175 ft-lbs.).

    I run a 2.5 setup in my 1st gen. G. mostly stock setup - head & short block are stock, .63 a/r + 3" SV, 3" exhaust including high flow cat. 3.87 a555 with 225/45/17's. if you do the calculations, that actually drops the effective FD down to 3.69. a small difference, but with a 2.5 mildly set up with a good tune, decent tires, and even a cheater diff setup (ideally a real limited slip), you can take advantage of the deep torque the 2.5 gives you - dumping clutch is not a necessity even from a dig. the commonly unmentioned component is traction. any FWD setup is going to need attention with the torque a 2.5 can dump out down low. with a lighter car you'll just have to better focus your set up around that (good rubber, etc.).

    the cal is the more important part...I went thru the experience of DIY way back when, but started with a MP II (L-body module). getting the right cal is an absolute priority if you go that way, know in advance what a difference it will make (there is no comparison between a mis-matched calibration and the right one on any setup). a good tune and good flow setup, the plateau at high RPM's is so much less noticeable, I don't consider it a factor - unless you constantly drive interstates, you'll have more power than road most of the time. more options out there now, just a factor in which way you go. in terms of what will give you the drop on the open road - 2.5, no question, for streetable power (torque).

  17. #17
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    Quote Originally Posted by glhs875 View Post
    I'm going to have to say that if a 2.5 has a power peak at only 3500RPM, something is wrong! Chrysler themselves had a higher peak power RPM rating for a 2.5 than that.
    This is what I mean.

    Typical 2.5 Dyno.


  18. #18
    Supporting Member II Turbo Mopar Contributor
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    Re: Running a 2.5 instead of 2.2

    3.50 gears and tall tires . . . .
    John Laing

    "The sole condition which is required in order to succeed in centralizing the supreme power in a democratic community, is to love equality, or to get men to believe you love it. Thus the science of despotism, which was once so complex is simplified, and reduced . . . . to a single principle."
    -- Alexis de Tocqueville

    "One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary."
    --Ayn Rand

    "To evolve, you don't need a Constitution. All you need is a legislature and a ballot box . . . . things will evolve as much as you want. All of these changes can come about democratically; you don't need a Constitution to do that and it's not the function of a Constitution to do that."
    -- Justice Antonin Scalia

  19. #19
    turbo addict
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    Re: Running a 2.5 instead of 2.2

    1st thing a 2.5 needs is to ditch the 1 piece and install PT lifters. It's a whole other animal after those 2 things.

  20. #20
    Supporting Member II Turbo Mopar Contributor
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    Re: Running a 2.5 instead of 2.2

    Yes ported big valve head and two piece manifold . . . . .
    John Laing

    "The sole condition which is required in order to succeed in centralizing the supreme power in a democratic community, is to love equality, or to get men to believe you love it. Thus the science of despotism, which was once so complex is simplified, and reduced . . . . to a single principle."
    -- Alexis de Tocqueville

    "One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary."
    --Ayn Rand

    "To evolve, you don't need a Constitution. All you need is a legislature and a ballot box . . . . things will evolve as much as you want. All of these changes can come about democratically; you don't need a Constitution to do that and it's not the function of a Constitution to do that."
    -- Justice Antonin Scalia

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