95 Deville 4.9L... Dual exhaust?
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 95 Deville 4.9L... Dual exhaust? in Past Cadillac Vehicle Discussion; Okay, I have been wanting to get some more power out of this car since I bought it... but never ...
  1. #1
    dommi.b is offline Cadillac Owners Member
    Automobile(s): 1995 Deville Base 4.9L
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    95 Deville 4.9L... Dual exhaust?

    Okay, I have been wanting to get some more power out of this car since I bought it... but never have been too sure on where I wanted too start. Now I know I want to start with the exhaust system, but I'm concerned that if I just start cutting off catalytic converters and throwing on a whole new pipe for the duel exhaust if I'm actually going to lose power/or cause some sort of problem because certain cars need the back pressure to function properly... So some advice or opinions on what I should do would be much appreciated. Thanks. :3

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    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    Unfortunately, a freer flowing exhaust system won't get you much more than 1 or 2 extra HP at best. It'll sound nice, but that's about it.

    There aren't any performance upgrades available for these cars, 4.X or Northstar. Many of us would like some bolt on power, but it just doesn't exist.

    The cheapest way to add power to a base '95 Deville, is to sell it and buy a Concours.

  4. #3
    drewsdeville is offline Cadillac Owners Master
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    Re: 95 Deville 4.9L... Dual exhaust?

    The weakest link, by far, is the small valve heads. If you can't get the engine to breathe, the exhaust is moot.

    That said, when it comes to an engine with little/no aftermarket support, you have two options - get to know your local machinist very well and make it breathe naturally, or jam the air down it's throat with some forced induction.

    The 4.9 has been turbocharged a number of times, especially within the Fiero community. They've netted some ok results for (relatively) little cash. You might want to head over there for some tips.

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    basscatt's Avatar
    basscatt is offline Cadillac Owners 10000+ Posts
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    Re: 95 Deville 4.9L... Dual exhaust?



    you have simply chosen the wrong car to try to modify -
    there simply isn't any aftermarket support -
    and without spending tons of money -
    the only way to get any decent increase in power is to add NITROUS -
    but that will destroy the engine and trans very quickly -

    enjoy your '95 Deville for what it IS -
    and don't blame it for what it IS NOT -

  6. #5
    dommi.b is offline Cadillac Owners Member
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    Re: 95 Deville 4.9L... Dual exhaust?

    Well darn... and here I was all excited to make this old guy finally powerful enough to beat my buddies turbo-diesel Pick-up... Guess not!! Thank's for the info guys.

  7. #6
    SSickLS2 is offline Cadillac Owners Fanatic
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    Re: 95 Deville 4.9L... Dual exhaust?

    Quote Originally Posted by drewsdeville View Post
    The weakest link, by far, is the small valve heads. If you can't get the engine to breathe, the exhaust is moot.

    That said, when it comes to an engine with little/no aftermarket support, you have two options - get to know your local machinist very well and make it breathe naturally, or jam the air down it's throat with some forced induction.

    The 4.9 has been turbocharged a number of times, especially within the Fiero community. They've netted some ok results for (relatively) little cash. You might want to head over there for some tips.
    VERY well put! OP, here is your answer.

  8. #7
    Darth Mobius is offline Cadillac Owners Member
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    Re: 95 Deville 4.9L... Dual exhaust?

    GM makes a motor called the LS4, it will be expensive, but it is a front wheel drive motor/tranny combo, and it will fit in the engine bay with motor-mount modification. I am also looking into this for my car, far into the future.

    If you really want to improve the car for racing, internet research is your best friend. That is how I found the LS4. Also, next year GM is launching a new line of motors that look to be vastly superior in terms of engine power and efficiency. I would also suggest looking into it when they announce the new platform, as there probably will be a front-front layout car in the mix. If not, there is always the LS4.

    I also looked into a custom dual-exhaust setup, but because of the way the fuel tank is situated, you won't get a true-dual exhaust setup, so a little wider single pipe and a magnaflow can will make it sound beefier while at the same time not costing you $800 or so. (Prices may vary by location, but the shop here wanted $850 for a cat-back dual with high flow cat.)

  9. #8
    MoistCabbage's Avatar
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    Bolting an engine in is the easy part, getting it to work with all of the vehicles systems is the hard part. Your current PCM certainly isn't going to control a different engine/transmission combo.

    A freer flowing exhaust system will sound nice, but won't give you more than a few extra HP at WOT, at redline.

  10. #9
    VEGASELDO91 is offline Cadillac Owners Fanatic
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    Re: 95 Deville 4.9L... Dual exhaust?

    I've been thinking about having dual outlets installed on my Sedan Deville, but want to keep the quiet sound this time around. I had them on the Eldorado with a 80 series muffler (i think) and it sounded nice IMO. Being I look at this car as a big luxury cruiser, I think the dual outlets will look nice, but prefer to keep the muffler quiet this time around! Don't get me wrong I've watched a youtube vid or two of Devilles with upgraded mufflers and dual outlets and liked it very much! I got compliments on how cool the Eldo sounded frequently, I just think the sound was better for that car. Good luck with your plans, I really hope you find what you are looking for, it would really be cool!!

  11. #10
    Darth Mobius is offline Cadillac Owners Member
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    Re: 95 Deville 4.9L... Dual exhaust?

    You want to add 50 horsepower in an hour? http://www.performancechipsdirect.com/Cadillac/DeVille/

    Chip your car!

    Sorry I forgot about that, but my friend found that website about a year ago, and I had forgotten I had bookmarked it.



    Dommi B, I owe you huge, by the way. Looking at the installation for that chip I just posted a link for, I saw what an IAT was, and where it was located, and realized that when I got my friend to put the new motor in, he NEVER INSTALLED MINE! I think you just fixed my freaking idle problem.

  12. #11
    MoistCabbage's Avatar
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    All those "performance" chips do is alter the signal from the IAT, making the PCM "think" the intake charge is colder than it actually is. As a result, the air/fuel mixture is richened, causing idle/drivability problems, and DECREASING fuel economy and performance.

    Don't you think that if it were possible to add 50 HP, with a simple fuel ratio change, that GM would have done it from the factory....?

  13. #12
    basscatt's Avatar
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    Re: 95 Deville 4.9L... Dual exhaust?

    I totally agree with MC about the performance chips -
    they simply don't work -
    and the ONLY way those companies get away with advertising is the "fine print"

    UP TO are the 2 magic words that allow these guys to stay in business -

    UP TO a 4 MPG increase - and UP TO a 50 HP increase -

    if you get LESS THAN a 4 MPG INCREASE - the advertising is true -
    in fact - you WILL get LESS MPG - because of the nature of the chip -
    the chip simply tells the computer the air going into the motor is really cold -
    so the computer adjusts for a richer air/fuel mixture - which burns MORE fuel -

    and if you get LESS than a 50 HP INCREASE - the advertising is true -
    here too - you will NOT get ANY increase in HP -

    use your common sense when it comes to any of this stuff -
    don't you think Cadillac would KILL for the ability to legally advertise
    30 MPG highway rather than 26 -

    and 325HP rather than 275HP on the "Y" motor cars -
    and 350HP rather than 300HP on the "9" motor cars -

    and be able to do this all for a few cents worth of resistors -
    OF COURSE THEY WOULD - IF THEY COULD -

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