Interesting. I thought they were cutouts that you could un-cap and bypass the second mufflers. Backpressure tubes makes some sense though.
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04-25-2009, 11:40 AM | #16 (permalink) |
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Interesting. I thought they were cutouts that you could un-cap and bypass the second mufflers. Backpressure tubes makes some sense though.
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04-26-2009, 03:23 AM | #18 (permalink) | |
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Correct me if im wrong here, but wouldn't narrowing the piping to increase exhaust velocity be more effective than adding "backpressure" tubes. |
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04-26-2009, 09:00 AM | #19 (permalink) | |
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04-26-2009, 01:46 PM | #21 (permalink) | |
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Thanks for the pic post as I wonder whether the 5Zigen does not have a similar setup when viewed underneath with the extra cans atop the actual mufflers? Can you please fly your private jet to Japan and find the answer for me? Inquisitive minds want to know. (Now watch AK smoke me on finding this out first.)
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04-26-2009, 03:57 PM | #23 (permalink) |
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A side note on HKS. I believe in the most recent Grassroots Motorsports Magazine they tested several exhausts for the 335i and the HKS exhaust was their pick.
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04-26-2009, 04:48 PM | #24 (permalink) |
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I believe those extra canisters on the HKS are for sound reduction and avoidance of drone.
"Backpressure tubes"? Forget what you've heard, but backpressure is a bad thing and kills power. Initialgemini had it right, as exhaust velocity is key. The key is to match pipe diameter to give the greatest exhaust velocity with the least amount of backpressure and of course matching to your power band. A narrow pipe will have greater velocity at low RPMs while a wider pipe will flow better at high RPMs so a well-designed exhaust will take this into account and should have a correct balance. Last edited by sensi09; 04-26-2009 at 04:51 PM. |
04-26-2009, 06:28 PM | #25 (permalink) |
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There's no need for separate piping if all you're looking to do is reduce sound -- that's what in-line resonators are for. Now, I want to be clear here. I am not vouching for the effectiveness of using separate piping for backpressure, I'm just explaining what the intent behind the design is. Personally, I think they're gimmicky. But believe what you want to believe. It doesn't make an ounce of difference to me.
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04-26-2009, 07:30 PM | #26 (permalink) | |
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04-26-2009, 11:16 PM | #27 (permalink) |
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From the marketing of the HKS hi-power exhaust, these extra canisters are for sound reduction and tuning. In this regard, they are similar to resonators. Search for "dead chambers" for more info on this.
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04-27-2009, 08:26 AM | #28 (permalink) |
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Hmm...well that makes the design even worse, IMO. Extra piping = extra weight. If the right sound can't be achieved with the normal in-line resonators and mufflers, that's just not good. Just my 2 cents.
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04-27-2009, 01:21 PM | #29 (permalink) |
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With regards to the SACLAM unit, it looks to me as though the HUGE resonators up front are what cures the drone, and the extra piping out back prevents the loss of backpressure.
Now, the HKS unit shown above looks like it serves both purposes by incorporating a "dead-end" with a resonator attached to it. Also, backpressure isn't bad if its used correctly. For N/A applications, you need backpressure to prevent the loss of torque in free flowing exhausts. If you have too much though, then you will lose power. Think of it as a glass of red wine a day. In moderation, its actually good for you, but in excess its not. Horsepower and torque are both important IMO, and not just horsepower.
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04-27-2009, 01:36 PM | #30 (permalink) |
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Hard data is what really would convince one way or the other...............where's the comparitive dyno chart, that and the weight numbers?
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