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E90/E91/E92/E93 (2006 - 2013)
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Old 08-29-2011, 06:37 PM
BrooklynNY1015 BrooklynNY1015 is offline
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e90 Resonator delete hurts Low RPM torque?

From what i have read at club lexus, completing a resonator delete to make your exhaust note "better" (subjective) actually takes away some of the torque your car has at lower RPMs. Is this true for any of the e90 sedans?
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Old 08-29-2011, 06:51 PM
Squidget Squidget is offline
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I'm no mechanic, but I fail to see why that would happen.

Unless the delete somehow puts backpressure on the exhaust, but that would impact HP across the entire powerband, not just the low end. Right?
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Old 08-29-2011, 07:02 PM
David Williamso David Williamso is offline
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Actually if the exhaust system is too large for the engine you will reduce the low RPM torque but in normal street driving you will never notice it. It will just piss off everyone else with the noise
David
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Old 08-29-2011, 07:17 PM
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Zeichen311 Zeichen311 is offline
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Quote:
Originally Posted by Squidget View Post
Unless the delete somehow puts backpressure on the exhaust, but that would impact HP across the entire powerband, not just the low end. Right?
Backwards: As David said, if there is too little backpressure, the exhaust gases escape the cylinders more quickly when the exhaust valves open, slightly reducing the useful duration of the power stroke and thus the gross torque.
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Last edited by Zeichen311; 08-29-2011 at 07:19 PM.
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Old 08-29-2011, 08:57 PM
Squidget Squidget is offline
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Old 08-30-2011, 07:19 AM
boilers93 boilers93 is offline
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Originally Posted by Zeichen311 View Post
Backwards: As David said, if there is too little backpressure, the exhaust gases escape the cylinders more quickly when the exhaust valves open, slightly reducing the useful duration of the power stroke and thus the gross torque.
Yep, this would be my diagnosis. Turbo cars in particular are more efficient with a certain amount of back pressure. I could see how a resonator delete would diminish the backpressure to where the torque could be affected.
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Old 08-30-2011, 07:39 AM
33beto 33beto is offline
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I was thinking to replace the resonator with a dual in/single out Borla muffler, but i have yet to read anything regarding low end torque loss.
Doesnt the VANOS compensate for this?

Lou.
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Old 08-30-2011, 08:20 AM
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Mystic1 Mystic1 is online now
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I had a fairly modified supercharged vehicle, and others with the same vehicle that had replaced their stock exhaust with a free flowing cat-back system did indeed lose low end torque as proven on a dyno. When you lose back-pressure, the torque will decrease as previously stated. Now what engine dynamics are behind this, I have no idea, but it has been proven to be the case on other vehicles.
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