Just Dyno'ed my C55
MBWorld Fanatic!
Joined: Feb 2006
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LET C32 2002
man there is some dirt on this post...i dont proclaim to know it all but let me add some insight here...
dynos can be set up and configured however the operator wants. you input a number of variables and from that comes the calculation that takes into account the rollers. its not about "awd vs 2wd dynos" its about what type of dyno it is and how its set up.
furthermore, backpressure is not some power robbing thief, it is a component of a proper design...removing exhaust backpressure isnt like removing a stain, the more you get out the better off you are, thats not how it works. there is a proper amount of backpressure needed to make optimal power. a car manufacturer will walk the balance between performance and exhaust noise and implement a system in between. could there be benefits to removing a resonator, sure, but to say it hands down makes a difference or doesnt will depend on the application. removing a muffler or resonator does not always result in power gains. in fact for a lot of cars, you'll gain 1-2whp up top for 300 rpm and lose 8-12 ft/lbs 3000 rpm in the midrange. IE, no likey.
dynos can be set up and configured however the operator wants. you input a number of variables and from that comes the calculation that takes into account the rollers. its not about "awd vs 2wd dynos" its about what type of dyno it is and how its set up.
furthermore, backpressure is not some power robbing thief, it is a component of a proper design...removing exhaust backpressure isnt like removing a stain, the more you get out the better off you are, thats not how it works. there is a proper amount of backpressure needed to make optimal power. a car manufacturer will walk the balance between performance and exhaust noise and implement a system in between. could there be benefits to removing a resonator, sure, but to say it hands down makes a difference or doesnt will depend on the application. removing a muffler or resonator does not always result in power gains. in fact for a lot of cars, you'll gain 1-2whp up top for 300 rpm and lose 8-12 ft/lbs 3000 rpm in the midrange. IE, no likey.
MBWorld Fanatic!
Joined: Feb 2006
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LET C32 2002
I agree with you on the dyno. Its all up to the operator of the dyno, even when strapping down it can make a difference. About the rwhp those # seem correct. The resonator is a straight pipe with some muffling thing around the inside but does not obstruct the pipe and just quites down the exhuast so there is no (back pressure) to lose. If interested in seeing the inside of it i can post some pics. The headers on this car can get you about 12-16 rwhp & torque so i don't understand why is there so much concern about (back pressure) without some real dyno's to prove you really do lose (hp) or (tq). Btw i have done plenty of dyno runs to see what works and what doesn't and by far the exhuast is the way to go on a C55 i don't know about the rest this is what i have tested. As a matter a fact i don,t even have the primary cats nor the resonator and the car gives me plenty of power with no losses. Hope this helps.
To my understanding All the big guns(C32/C55) here have pretty much done there exhaust over...usually removing the resonator and two cats and replacing their other cats with hiflow ones
MBWorld Fanatic!
Joined: Feb 2006
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LET C32 2002
Your just flat out wrong. I've dyno'd my car about 30 plus times on a dyno-jet with resonator on and off and secondary cats on and off. With the res off it made NO difference, however on one run though it showed a 1.5hp gain, but that means nothing. With the secondary cats off I actually gained 8hp and 12tq, but I put them back on after awhile because I didn't like the sound it made.
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Joined: Jul 2005
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From: Chicago, IL
02 996 Turbo, 05 CLK55 AMG
+1...
Your just flat out wrong. I've dyno'd my car about 30 plus times on a dyno-jet with resonator on and off and secondary cats on and off. With the res off it made NO difference, however on one run though it showed a 1.5hp gain, but that means nothing. With the secondary cats off I actually gained 8hp and 12tq, but I put them back on after awhile because I didn't like the sound it made.
Super Member
Joined: Sep 2007
Posts: 784
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From: Miami
Bicycle
Vic the only way to tune is threw the Diag. port if the car is taken to shop and they have a laptop, saw it when done to mine by Renntech. Other than that you have to remove the ecu and ship it to the tuner.
Senior Member
Joined: Feb 2007
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From: Peoria, Arizona
RENNtech C32 AMG
I have no secondary cat's and no res. From what I, and about 8 other exhaust shops around PHX all said the same thing about the stock cats being hi-flow already. many of the shops showed me some hi-flow (Random Tech, Magnaflow, Pace Setter) cats, and they all looked like the stock one. Most of them all said to not even bother with swapping them out and stated that the stock ones were built better than the others too. After chopping the secondaries out, the sound was a lot better, power might have felt a little better, but that could have just been the "sounds faster" deal. Now driving under a bridge, I gas it, and it sounds like a race car, lol
Senior Member
Joined: Feb 2007
Posts: 383
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From: Peoria, Arizona
RENNtech C32 AMG
I cant say for the V8 motor, but from hearing only the res-free version on a C55, It would be enough to keep me very happy!
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Joined: Dec 2007
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From: Corona, CA
03 g35 coupe...........02 c32 Sold
I think people still have the impression that modern engines are like the ones in the 80's where the cat would eat up a lot of the engines power. Thats why a lot of tuners in the past saw getting rid of the cat as a way for getting free power with huge gains.
The automakers have had over 30yrs to design there engines with the cat in mind and have been able to incorporate it into there designs. For NA engines they used the backpressure from the cat and reasonator to add to low and mid end torque.
Most people just pay attention to peak hp and not the torque curve. I would rather give up some peak hp to have a flatter torque curve.
Anyways, i just wanted people to be aware of it. I didn't think it would cause such as huge argument, i said my peace and lets just leave it at that.
