10-23-2014, 07:31 AM
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#11 (permalink)
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A True Z Fanatic
Join Date: Dec 2010
Location: Houston
Posts: 14,532
Drives: '10 G37 6MT
Rep Power: 2465058
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Quote:
Originally Posted by dragonbreath
I found this article regarding a 3 inch vs 3.5 inch exhaust.
3-Inch Vs. 3.5-inch Exhaust Test - Tech - Modified Magazine
I thought about maybe having a custom 3.5 inch made after reading that. I have a single 3 inch, and I seem to be getting some lower numbers compared to the other guys with dual exhausts. At 11 psi, I am getting 509hp when dyno'd in 4th gear. Anyway, do you have any input Sasha? Or anyone else? I wont be doing this anytime soon as I have spent waaay too much money on the car this year lol. Needless to say I have a lot of rear end kissing to do with the wife lol. |
I'll start with I'm no expert but a couple things to note. First off, of course you are going to get some gains by adding exit diameter cuz you are decreasing the friction loses. The 3" and 3.5" in the article you linked are not like for like comparisons. They don't list what type of muffler was original on it with the 3". Also you can see that the newly fabricated 3.5" is more of a straight shot with less bends in it. More bends equals more friction. Although they don't address it, I'd bet they lost torque going to the larger exhaust.
I wouldn't get carried away with the fact that you 'only' made 509whp. Your numbers aren't much different than any of the other cars running a BP kit. For ex: jlo made 52Xish whp at 11.5.psi, that's about spot on where you are for a 11psi max and he's running a FI exhaust.
And then you thrown in all dynos are different and all tuners tune differently with different goals.
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