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      10-17-2009, 09:04 PM   #1
krnnerdboy
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muffler delete myth...

Hey guys, just thought I'd post in the performance section as well regarding the muffler delete and the loss of HP in question.

As a disclaimer I'm not sure if the muffler delete loses any HP but it definitely doesn't lose any acceleration!

details can be found here...
http://www.zpost.com/forums/showthread.php?t=310055

I tested on 2 different nights to make sure that the DME would have enough time to compensate.

night 1
66* ambient temp and humidity was relatively low. I have been driving on my muffler delete for over 500 miles.

with my muffler delete I hit a trap speed of 85 consistently in the 1/8

night 2
71* ambient temp and higher humidity than night 1, but not much...it's so cal I had been driving on the oem mufflers for one week and also over 500 miles.

oem mufflers hit a trap speed of 83 mph.

reflection...
I hit a 60' time of 2.001 on both mufflers. This shows the consistency and that the wheel spin off the line was equal. The launch would have the most effect on the trap. (the more spin,slower 60', the higher the mph). The track situation for OEM muffs was less ideal than Muffler Delete, so I wouldn't conclude that the OEM's are slower but that at least the MD's are not slower.

So all you cheap or loud sound loving M drivers get your muff deletes on I get nothing but compliments from passerbys, but then again this isn't my daily driver
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      10-18-2009, 10:44 PM   #2
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Pictures of the underside with the delete?

Here is my stock underside... which did you remove the resonators or the cans in the back?


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      10-19-2009, 04:43 PM   #3
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just the can back...I've only heard horror stories from removing anything else w/o a tune

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      10-19-2009, 05:14 PM   #4
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That's interesting...

Plugging those numbers into the typical drag race calculator:

http://www.eldemoniorojo.com/calculator.htm

With muffler: 265 HP @ wheel

Without muffler (assuming ~50 lbs weight removal): 268 @ wheel

Well within statistical error range. In fact, the car weighing less sans muffler probably, by OP's account, the conditions on the launch with the muffler was ever so slightly WORSE. I guess we can safely say that the presence of the muffler makes very little statistical change in HP output (at max HP).

Which is safe to say that any muffler only exhaust making any real appreciable HP are pretty much false claims.
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      10-19-2009, 07:26 PM   #5
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Quote:
Originally Posted by The HACK View Post
That's interesting...

Plugging those numbers into the typical drag race calculator:

http://www.eldemoniorojo.com/calculator.htm

With muffler: 265 HP @ wheel

Without muffler (assuming ~50 lbs weight removal): 268 @ wheel

Well within statistical error range. In fact, the car weighing less sans muffler probably, by OP's account, the conditions on the launch with the muffler was ever so slightly WORSE. I guess we can safely say that the presence of the muffler makes very little statistical change in HP output (at max HP).

Which is safe to say that any muffler only exhaust making any real appreciable HP are pretty much false claims.
I don't think there is any manufacturer that claims major hp gains w/ exhaust mods...but there are claims to intake mods and the car seems more receptive to them.
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      10-21-2009, 09:02 PM   #6
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Quote:
Originally Posted by The HACK View Post
That's interesting...

Plugging those numbers into the typical drag race calculator:

http://www.eldemoniorojo.com/calculator.htm

With muffler: 265 HP @ wheel

Without muffler (assuming ~50 lbs weight removal): 268 @ wheel

Well within statistical error range. In fact, the car weighing less sans muffler probably, by OP's account, the conditions on the launch with the muffler was ever so slightly WORSE. I guess we can safely say that the presence of the muffler makes very little statistical change in HP output (at max HP).

Which is safe to say that any muffler only exhaust making any real appreciable HP are pretty much false claims.
Welcome to the world of NA cars.

Not sure I follow the logic of calculating power from weight loss. Esp. since I take it you aren't including the range of driver weight into the mix.
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      10-23-2009, 03:16 PM   #7
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Quote:
Originally Posted by krnnerdboy View Post
just the can back...I've only heard horror stories from removing anything else w/o a tune

Better picture of your setup? Do you have a video of how it sounds?
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      11-14-2009, 08:01 PM   #8
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can we please see a pic of your muffler delete please!!!!
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      11-14-2009, 08:49 PM   #9
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here is a crappy video...it sounds much better than this



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      11-21-2009, 05:29 PM   #10
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not to thread hijack, but man your car is frickin HOT.
<--- very jealous
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      01-08-2010, 03:41 PM   #11
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Hard to tell from video. How is the resonance while cruising?
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      01-08-2010, 04:39 PM   #12
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Quote:
Originally Posted by James_E85M View Post
Hard to tell from video. How is the resonance while cruising?
no droning when the top is down only when it's up
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      02-06-2010, 07:20 AM   #13
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Can you post images of your muffler delete implementation? What is the pipe diameter? What tips are you using? How did you suspend the straight pipe section and the tips? Was it a rigid connection to the stock mounting points or are you using some kind of hanger solution? I am thinking about welding my own muffler delete setup together for fun and some examples would be useful. Also, this is a long shot, but do you know how many decibels this set up registers at WOT from a road side sensor that is about 50 feet away? In other words, would I be black flagged at Lime Rock Park (I think their cutoff is at 89 db). Thanks.
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      03-08-2010, 05:47 PM   #14
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Quote:
Originally Posted by fitchesbass View Post
Welcome to the world of NA cars.

Not sure I follow the logic of calculating power from weight loss. Esp. since I take it you aren't including the range of driver weight into the mix.
If you follow the link I posted, it's a drag racing calculator that determines HP based on the weight of your car and your trap speed. So if you plug in the numbers of several different runs done in similar conditions you can get a general sense of how your modifications potentially affects your HP rating at the wheels.

While it's not exact science, it does show that based on the original numbers OP posted, there's very little difference in terms of horse power generated with or without muffler. The end result needs to be calculated with the weight loss in mind to get the more accurate reading since your trap speed is almost a direct correlation to weight of the car and power at the wheels.

I may have worded it wrong.
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      03-12-2010, 07:55 PM   #15
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good info, thanks
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