blackbenzz

Alot of people have tried different things with exhausts. I'm wondering how much power people have gained from doing a custom exhaust from the headers back. Mine is stock from the secondary cats back except for an eisenmann race muffler and I am considering running bigger diameter pipes all the way back to the muffler with no cats and was wondering if/how much power it would gain. Any input? I know on turbo cars you can make huge gains by removing exhaust restrictions, whats the deal with the s/c cars? It has been discussed before but if anyone has dyno gains to back up the claims that would be nice. 1/4 mile traps even better Feel free to discuss opinions/theory as well but try and back it up with at least some factual data

Vadim @ FD

W208s are tough in clearance department. See if you can squeeze dual 2.75''.

That should be enough for close to 1000HP.

V12Godspeed

I am going with QTP cut outs and deleting primary cats....
In terms of gains don't know yet...

blackbenzz

^ You have a turbo car, it's a little different

Thanks for the advice Vadim . What do you think about dual 2.5" into a y-pipe and either 3 or 3.5" back to the muffler?

Edt: BlackonblackCLK has dual 3" all the way back so it will fit.

V12Godspeed

I know...for you it's all about the right back pressure...somehow I have seen a few E55's putting on the Cut outs...maybe it's just for sound...

alphanumeric

I have heard bad things about cutouts on the internet. +

I always thought it would be a good idea if they were placed right before the first cats to have nothing blocking, kinda like dragster style. It would be only for racing tho... against z06's and such

hooleyboy

I have custom exhaust on my C55 I chopped on the resonator and secondary cats and picked up 12whp and like 18wtq. Then only to go with a cat back custom exhaust and gained an extra 5whp. Then I replaced my Primary cats with Random technology 300cell hiflow cats (no CEL issues at all) and gained 5whp. I have all the dyno charts somewhere.

Random Tech talked me into these 300cell cats saying they flow the same as 100cell cats without the CEL issues.

BlackOnBlackCLK

You gained a total of 22whp? So in theory without the 300 cell cats you could gain an extra 5whp...

MRAMG1

Yeah blackbenzz, It IS the same for all FI motors. I have posted this MANY time int he past under other threads. Numerous companies have also backed this up like Vortech, KenneBell, etc. If you are forcing, aka pressurizing the intake track, you DO NOT want any back pressure, or need it. Check out their web sites for the full details my friend.

See yeah

PS: My KenneBell stang running 10 pounds of boost had JBA shorties, MAC box x pipe, flowmaster 40 eaxhaust, which when swapped from the stock cats dropped my 1/4 mile times by over .6 seconds. Nice gain. Yes I know it was a Ford, but an engine is an engine here guys.

blackbenzz

The electronic cutout motors are known to fail
Wow, nice gains!!! What diameter piping did you use?
Thanks for the info. Going over to the sites to read up now.

Vadim @ FD

If you can squeeze dual 3''. Do it.

prodigymb

look into DMH cutouts, they are very good. had it on my vw, they have a 4yr warranty on the entire thing too. i know several people that had DMH cutouts for 2+ years now without problems.

aleksandar1099

Thats very good! I know of people with QTP cutouts that fail every year with normal use....

prodigymb

QTP is garabage. period. a friend had it and it failed in 3 months and they refused warranty due to "improper installation". i had the dmh on my car for about 8 months and it worked great and sealed better than QTP.

here is a vid of my vw with cutout closed and my friend's (who had qtp and then went to dmh) cut out open
http://ca.youtube.com/watch?v=HcaWwJqq0m0

liquiddi

In my experience with cars in the past you actually lose a little HP and gain some torque with opening up the exhaust. I've never seen a HP gain with adding an exhaust. Granted, you add noise. That is the only reason I do it anyways

blackbenzz

Thanks
But I dont want any more torque Hooleyboy said he gained 22whp

marn

what prevents a E55 from having a 3 inch exhaust.

when we talk about clearance problems are you talking about the exhaust channel that runs under the car where a 3 inch pipe will not fit or hit.

blackbenzz

He was refrring to my car, a W208 CLK55. But dual 3" pipes has been done on a CLK55 and I think thats what I'm gonna do too. Dunno if I should go catless I dont want the stink

Vadim @ FD

Forced Induction cars are a lot less sensitive to exhaust tuning. Since they have pressure source on intake side, the function of exhaust simply becomes to evacuate combustion and reduce backpressure as much as possible.

E55Pilot

Sorry but that simply is not true. Since you have almost zero overlap on the cam you really need to work on the exhaust scavenging to help clean out the cylinders.

S5LorinserF1

i have a no secdonary cat with a 3 inch long pipe into my custom catback setup.

just installed the dmh cutouts. the best upgrade i have done so far.

MRAMG1

Sorry E55, but that is NOT true. ALL camshafts for AMG's HAVE overlap. Quite frankly ALL internal combustion engines 4 cycle engines have overlap. That is how you GET a good scavenging effect in the cylinder to begin with. You might want to read up a little bit on how a 4 cycle engine works my friend.

You are 100% correct on a NA engine requiring a properly tuned exhaust to help pull the spent gas out of the chamber, however ALL FI cars are really a different issue.

See yeah

MRAMG1

Dead on my friend +1

See yeah

jangy

Then why would we lose power with too little back pressure? There must be a tune to any air tube; in or out....

chiromikey

f/i or not, our cars DEFINITELY lose low end power without "some" back pressure...however, not to the extent of a n/a car. you can't just lump all f/i cars in the same category as turbo cars.