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Thread: HotPipes Exhaust Header from Speedlab

  1. #11
    Still Plays With Cars Loren's Avatar
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    Quote Originally Posted by IchabodCrane View Post
    Is it worth 6 or 7 hp if you're taking a significant hit in economy?
    Yes, even if I took a "significant" hit in fuel economy, it's totally worth it to me. I bought the car to autocross because it's very lightweight. Great fuel economy is a side benefit, not a requirement.

    But, it's not going to cause a reduction in fuel economy UNLESS it causes me to change my driving style. If I continue to semi-hypermile in my daily driving, I'll continue to get nearly the same MPG, and possibly better.

    A properly designed header and exhaust IMPROVES the efficiency of the engine. Why doesn't the factory do it that way? Because they're working to a budget, they're making the exhaust as cheaply and simply as they can. Because they're watching the weight, they want the car to be as light as it can be. And because they have to meet certain emissions requirements, which is why the car has two catalytic convertors, and the first one is VERY close to the combustion chambers (which prevents proper exhaust manifold design) so that it "lights off" as early as possible on a cold start.

    In short, I'm redesigning the exhaust to a different price point and to a different set of compromises.



  2. #12
    Moderator Eggman's Avatar
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    Quote Originally Posted by IchabodCrane View Post
    Is it worth 6 or 7 hp if you're taking a significant hit in economy?
    For racing, the answer is yes. Fuel efficiency is not the object.

    Quote Originally Posted by Loren View Post
    A properly designed header and exhaust IMPROVES the efficiency of the engine. Why doesn't the factory do it that way? Because they're working to a budget, they're making the exhaust as cheaply and simply as they can. Because they're watching the weight, they want the car to be as light as it can be.
    All good points. There are manufacturers using headers (Chrysler era AMC 4.0 I-6 comes to mind). Mitsubishi isn't saving any weight using a cast-iron exhaust manifold though.

    Still, it'll be cool to see how yours turns out.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.6 mpg (Imp)


  3. #13
    Still Plays With Cars Loren's Avatar
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    Quote Originally Posted by Eggman View Post
    Mitsubishi isn't saving any weight using a cast-iron exhaust manifold though.
    I believe the Mirage manifold is actually made of stamped steel pieces welded together. But, a lot of times they'll make a manifold from cast iron just because it's SO much cheaper to make them that way rather than by fabricating individual tubes.

    It's all about priorities. Performance. Reliability. Fuel economy. Cost. All have to be balanced to what the car's intended market is. The bean counters always win.



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