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  1. #1
    Cavan
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    Pros and Cons of Performance Exhaust

    I have been thinking of putting a custom exhaust on my car, and wonder what the implications will be. I am having a bigger pipe coming all the way from the Header leading up to a muffler\tip. I know that this will give me at least 15 more horses and a better sound, but what else? (gas mileage, does breathing of free flow help engine to last longer, work better?) But what are the cons of doing this. Someone told me that it makes the engine run hotter and you have to replace valves every 10,000 miles (74 tii). Any truth to this, I would just like to know the basic cons.
    please help me out, I would appreciate it, this board is great with tec help and I thank you guys for helping people like me out.
    cavan
    [email protected]


  2. #2
    Jeremiah
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    Re: Pros and Cons of Performance Exhaust

    : I have been thinking of putting a custom exhaust on my car, and wonder what the implications will be. I am having a bigger pipe coming all the way from the Header leading up to a muffler\tip. I know that this will give me at least 15 more horses and a better sound, but what else? (gas mileage, does breathing of free flow help engine to last longer, work better?) But what are the cons of doing this. Someone told me that it makes the engine run hotter and you have to replace valves every 10,000 miles (74 tii). Any truth to this, I would just like to know the basic cons.
    : please help me out, I would appreciate it, this board is great with tec help and I thank you guys for helping people like me out.
    : cavan
    : [email protected]


    I would say that you will be lucky to get a full 15 horses out of just that mod alone. With many exceptions I am sure, the general rule is that improving the flow on either end gives you better power, mostly top and mid end. However the two parts to this generality are the intake and the exhaust. Improving on the intake side decreases gas milage (usually), improving the exhaust increases(better). Some engines are slightly under fed and might peak fuel efficiency with more intake flow, most do better with more exhaust flow. But, I would say the 2002 is good with either on the intake, though dual carbs will show worse milage that a single. I would also say that without headwork and the later large valves etc, you should be carefull with the exhaust, you may get undesirable results(all top end gain, losing the rest). Finally, it is known that your valves are brought to higher temperatures and can become burnt whick leads to brittleness and damaged seating thus not sealing like they should.
    You should put in stainless or titanium exhaust valves when ever you plan to replace or rework your head, this will bullet proof your engine from fatigue due to that performance mod. Or just buy new valves everytime so often ( I do not know the milage, depends on the fuel, driving, etc.)
    Jeremiah/70'02/Fl student


  3. #3
    Dave Endersbee
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    Re: Pros and Cons of Performance Exhaust

    : I have been thinking of putting a custom exhaust on my car, and wonder what the implications will be. I am having a bigger pipe coming all the way from the Header leading up to a muffler\tip. I know that this will give me at least 15 more horses and a better sound, but what else?

    Cavan -

    While exhausts are a good mod, I don't think you'd ever see 15 hp, unless you were running a Supra Turbo through a Meineke system!

    Back when I used to read Sport Compact Car, I thought that exhausts were a magical secret for getting hp. To a minor degree, they are. But they aren't making any power, just letting the engine breathe a little easier. And like Jeremiah said, you have a trade-off - more flow=less backpressure, which means less low-end grunt (where I like it) but more high end power.

    I think you would be hard pressed to find 15 anywhere in a decent '02 engine. I mean, perhaps you'd get that out of a more aggressive cam, but then you'd probably have to do the carbs, too.

    Anyway, good luck, and let us know what you end up doing.

    -Dave
    '76 2002, waiting for brake linkage


  4. #4
    BigDog
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    Re: Pros and Cons of Performance Exhaust

    Cavan,
    I've allways been in favor of reducing back-pressure to increase the performance, and life of an engine. 15hp, I wish, but aside from that here's a couple of gotcha's that come along with the territory.

    #1)Some "performance" exhaust systems can cause valve damage, as you have read...
    #2)Some aftermarket exhaust products tend not to last very long, esp. headers which are notorious for cracking after time. Especially with large changes in temp, and it's getting cold around here at night!
    #3)Noisy exhaust is an invitation for a visit by Johnny law. I even got pulled over in Bellevue for honking at someone! This to me is one of the larger issues. Used to have super-trap on a car, and damned if the cops weren't following me all over like I was a donut truck.

    Just my $.02. I'd definitely do "something" over stock, especially a tii exhaust manifold, but be careful on how loud you go!

    --------------------
    BigDog
    PSR BMW ACA / BMW CCA
    '76 2002 SoapDish (Tii manifold, bosal, ansa)
    '88 325
    '95 Ram2500 (Needs to be visited by Borla)


  5. #5
    milton
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    Re: Pros and Cons of Performance Exhaust

    Cavan,

    I run the setup advocated by both Ireland and TEP. It consists of a turbo tube in place of the center resonator, and a Dynomax rear muffler connected by custom bent piping to TEPs header. The header is very, very low. And, if I didn't have height adjustable suspension, I would probably replace it with a Stahl or Supersprint header.

    I've had several exhaust systems on my tii. The first was of unknown origin and came with my car. It was replaced when I got tired of chasing rattles. Second iteration was to have a custom pipe fabricated to exit by way of a supertrapp. This looked cool, but sounded like I was being followed by a Jet plane flying about 5 feet over the car. So, I installed a center resonator which made the exhaust note very cool. But, I still set off every car alarm within 500 yards of my car. The sound when driving under and underpass was unbeatable - can we say F1 boys and girls . But, still too loud 8^(. So, tried ANSA - this was junk (actually JUNK). The center resonator let go after 1.5 days of driving producing the most obnoxious resonation I've ever heard, and the power loss was immediately noticeable. I junked it quickly in favor of the TEP/Ireland recommended system.

    I've been entirely pleased with this system. I am blessed with a good performance exhaust installer in town, and they did a very good job of bending pipe and fabricating hangers for the system.

    Regarding power gains to be had. If you are moving from ANSA, 15hp is almost guaranteed according to my arse dyno. In fairness, this was the ANSA regular stuff - they do have higher end products which may be adequate.

    Regarding valves, I've put lots of miles on my car with the present exhaust system. I haven't had any problems. I do adjust my exhaust valves to the loose end of the spectrum - .010, versus .008 for the intake side. This is per recommendations in a tii register article. When checked hot, they read consistently all the way around. So, this does indicate that the exhaust valve heat cycle is more extreme.

    If I was going to do another exhaust system, I'd use either turbo or tii exhaust parts from BMW. In the end, the cost of the TEP system plus installation was comparable to the cost of the BMW system.

    Hope this helps.


    Milton

    : I have been thinking of putting a custom exhaust on my car, and wonder what the implications will be. I am having a bigger pipe coming all the way from the Header leading up to a muffler\tip. I know that this will give me at least 15 more horses and a better sound, but what else? (gas mileage, does breathing of free flow help engine to last longer, work better?) But what are the cons of doing this. Someone told me that it makes the engine run hotter and you have to replace valves every 10,000 miles (74 tii). Any truth to this, I would just like to know the basic cons.
    : please help me out, I would appreciate it, this board is great with tec help and I thank you guys for helping people like me out.
    : cavan
    : [email protected]


  6. #6
    Keith W. Allen
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    Re: Pros and Cons of Performance Exhaust

    Although I no longer own a 2002 (now into P cars, but that's another story...:-), I still think the '02 was the best thing going since sliced bread. That car will always have a special place in my heart. Anyway though, I digress. As for what exhaust to use, I can say from personal experience that the Tii exhaust manifold is the best route, supplemented by factory components throughout the rest of the system. I switched exhaust systems on my 2002 more than I care to mention, trying so hard to find the right "combination" (using Ansa, Stahl, Supersprint, etc.), and I ultimately found the factory performance set up to work best and to be the most durable (hands down); and to think it was there all the time, right in front of my eyes, but I didn't know how good I had it. The grass is not always greener on the other side of the fence. Believe me. When I had the aftermarket headers, they broke, and I'm not talking about after any length of time either,...and, yes, they were installed properly by a BWW enthusiast shop in my area. My point is this, and I also have learned this from experimenting with parts for the P car, BMW, Porsche, Mercedes Benz, etc. (all of the marques), spend a huge, and I mean huge, amount of money researching and developing their products, so you can bet your bottom dollar that if they put an exhaust on the car, it's about as good as it gets (from a practical standpoint). Stick with it and be happy!

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