Tuner post discussion - Exhaust
 

As some of you may know, I come from the land of turbocharged 4cyl boxer engines. WRX's and STI's came out of the factory with decent amount of power(227hp/300hp) but they were severely limited in terms of power by 2 catalytic converters, one in the exhaust system and another in the uppipe. This leads me to post this discussion post here about the w204, knowing that there are a decent amount of cat's in our cars too. Simply removing those cats and having a straight uppipe and turbo-back exhaust system on Impreza's net such great horsepower. I went from a 15.1(very high humidity here) second quarter miles to a 14.2 with just a removal of cats and a very good flowing exhaust system without a change of boost levels, and that was my very first mod way back then.

Now I was looking at the potential of our 3.5L and 3.0L engines and I've thought that having 268 hp out of a 3.5L may be decent, but those engines may have huge potential.
I know my engine isn't totally new but I'm throwing it out there for those with C300's and to my best knowledge, they are new engines.
Imagine how much different this will be if the C300's engines or even the C350's can be unlocked to yield very good power, enough to silence those 335i critics.

Has anyone tried putting up a free flowing exhaust system which removes at least one catalytic converter to their w204's yet? I know Remus makes an axle back and I'd like to see their numbers out of it. I'm not particularly interested as much as a total cat-back or even a straight pipe.

Those who have or haven't, feel free to chime in.

I've like to also chime in that I remember reading that the C350's intake system is an AMG intake system. If so, does anyone know if the C300's intake system is the same?

Modest gains only.
 

The reason your Rex's and STi's got such good numbers is because they were forced induction engines. Like any turbo or supercharged engine, they have incredible amounts of back pressure and releasing much of that back pressure helped gain hosepower and torque, to a limit. Too big an exhaust would allow no back pressure to build and you want/need some. Had you really tuned your Rex, you'd have then also gotten a larger turbo and even replaed the fuel injectors to compensate for the leanness of too little fuel. Of course, you then also needed to remap the engine, which is why you bought a stage 2 chip. of course, you're messing with the flame fronts within the chambers at that point, and may not be getting totally efficient performance, but with a larger turbo, exhaust, test-pipe, chip and fuel injectors, you were making near 400 hp, so who cared with all that fun?

Well, the problem is that the merc just don't got no forced induction motor. Nope. Its only a normally aspirated engine. So, any gains would be modest at best if all you did was an exhaust. I have no idea on numbers, but I'd guess exhaust at cat-back would get you 5hp, 2or3 at the wheel. So maybe a cat delete or hi-flo cat would help, but again 5hp, 2 or 3 at wheel. Its not until you start uncorking the engine that you get any decent gains. This would involve something as reasonably easy as a new exhuast header - either full equal length race header, or street header. But, at that point you're voiding your warranty, and the gains still ain't great. Now, screwing with the cams would start to get you somewhere, especially with a header, test-pipe, and exhaust. But now the thing ain't smooth and doesn't really sound like a merc any longer. You've pimped or riced it out to a certain degree, why not just have bought a camaro and done that?

So, this isn't to say it won't work, and some gains could be had, and I'm likely to add some tune to it, but don't expect much at all until you do something drastic. The best bang for your buck with a NA engine is to make a forced induction engine. Yep, slap a turbo or supercharger on it if anyone makes a kit. I think kleeman does, for like $10K. Problem is mercedes people just aren't into tuning too much I'm learning. But then again, if I were still into it I'd be buying a subaru spec.B rather than haggling with salesmen over the price of a new merc.

Good luck, and if you get anywhere, let us know.

Curt

Gains from resonators removal are highly overrated, hence why we mainly manufacture axle-back exhausts, there are some exceptions.

Remus AT has not yet released dyno numbers on the C350.

Clean-N-Green is the trend these days, don't be surprised if many enthusiast oppose the idea of removing the cats.

-Ryan

Ironic you mentioned it. The "had I done blah blah" is a bit insulting. Please don't make like I don't know what I'm talking about. The point of my thread was simply to inquire about gains on the motors off the w204 on a simple BOLT ON mod. My MY02 GDA was a stage4 machine with a VF30 and AP 740cc injectors, Cobb Access Port w/ road tune. 12.87 @ 108mph. Don't get me started, I've rebuilt many EJ205's before.

Now back on topic: Too high of a backpressure is of no concern, we're not talking about a 3-inch diameter piping here. I'm concerned about the potential of the engine without any mods and an exhaust mod wouldn't be considered any type of serious mod for an enthusiast. Would I consider that rice? No, that's power.

Remus: Keep us updated. Like I've said, any type of numbers would be nice.

I don't think that may be the case for many. If you live in California then yes. We all bought a 3.0L/3.5L V6 for a reason; this isn't a Honda Insight forum. Here in Hawaii, there is no smog-check requirements.

I dont want to give the wrong impression; but I wouldn't mind going a little less green for +30hp.

my car tuning place here in montreal ( www.ultracar.com)
told me that they have a chip for the c350's
that gives you about a 20-25 hp gain and like 20 of torque.
and the chip is not readable/recognizable by the dealership computers
so it does not void the warranty. I'll call him later today to find out who makes it! i would get it but its 2500$.
maybe ill get it next year!

I removed the rear mufflers from my C350. I installed staight pipes and the reinstalled the original tips. The sound is very good. It is, however, not nearly as loud as my 335i, which also has the rear mufflers removed. Without a dyno it is difficult to definitively determine the hp increase. However, from my general knowledge I suspect that there is about a 5 hp increase. There is still sufficient backpressure so that low end torque is not diminished.

As a reminder, it is illegal to remove the cats.


TEAShea
from Nebraska

Could you post a sound clip of your engine? Did the idle rpm sound changed? How about some pics? Do you think you have a slower 0-60 now? Sorry if i'm asking for too much, but I'm really interested in konwing more about this mod... I kinda miss the sound of my FX45.

vcruiser , I just picked up my obsidian black C300 MANUAL last week.....looking to upgrade wheels next spring. are the wheel packages at Ultracar in Montreal good quality ? the prices on their winter wheel packages look very good

congrats on that. not too sure about the wheel packages. depends what you want tho. I'm ordering my 360 forged carbon fiber wheels from Toyzauto art (www.toyzautoart.com) in montreal. but ultracar has the best prices for the stuff they do. where u located in canada?

Modified cars
 

I heard just last week at my dealer that MB is going to be taking a hard approach to modified cars with the strong possibility of warranty cancellation.

It highly depends on which modifications.
Engine modifications? Yes those will most likely void the warranty.
Bolt-on mufflers? Yea right.

I'm looking to get the quad AMG exhaust. Anyone know where I can get them from?

I'm in for the quad exhaust!!!

Toronto

We offer a dual, if you want a quad, you'll most likely have to cut out the bumper, you can use our universal exhaust if you're looking for a quad instead of a dual.

LMK if you'd be interested in selling your amg 18's next spring. Mine came w/ the stock staggered prosperina 17's which I'm fitting w/ snows this week.