What type of power gains are you seeing in x166 GL550 by deleting the mid resonator and adding a xpipe?

 

Do not add an X pipe to a turbocharged vehicle, just don't. You will lose power.

 

Correct, you want the least amount of restriction. You can remove the resonator and add straight pipes instead. I used Supersprint's mid-pipes.

 

I think an 'H' pipe is what your looking for, its for pressure equalization and not flow merge like an X Pipe.
I ran an X pipe on my truck that had an N/A LS1 383 and a 4" stoke, LT headers, 3" X Pipe, 3" dual in/dual out muffler. The truck made 394HP & 375TQ without the X pipe, I installed the X and it made 412HP & 419TQ. Good numbers for a Daily

Chad

 

X pipe is for scavenging on a NA engine. There is no scavenging on a turbocharged engine. You want the air in a turbocharged engine to get out of the way as fast as you can with the least resistance.

 

I couldn't agree more, the X pipe does more scavenging than the H pipe. The H Pipe does more equalization of cylinder banks so you don't have that have that raspy crackle that you hear from an old pickup with Glasspack's. When I was in high school that was the shizzle, rack'em off we said as we put in first gear and drove by the Principals office at 20mph and then let off the gas!! Man the noise it made crackin and fartin and an occasional flame coming out the back under the bumper!! Good times right there!

I've read a hundred articles on performance forums from Subaru, Toyota, GM, Ford and Porsche. All of which are running Single and Twin Turbos on the street (not the track) and they use either X or H pipes in their exhaust set ups. The difference being sound produced at the tail pipe with the HP & TQ numbers varying only slightly. On those cars making in excess of 700RWHP the X or the H were mostly picked by or decided on by which one fit the best on the car. When they visited the track most had cutouts and re-tuned the car for optimal exhaust flow, even then the performance numbers lost were marginal, 15-25 HP lost when going back and forth between the strip and the street exhaust setups.

Exhaust tubing with mandrel bends help dramatically in achieving those "exhaust" performance characteristics. Look under your car, mine (my wife's) has mandrel bends all the way to the tips. Quite impressive since its a factory exhaust. Bravo Mercedes, bravo indeed. Every Chevy truck I've ever owned has had crush bent tubing, including my Camaro SS. The only GM product with mandrel bends are on the Vette's and I think they didn't start that until the C5's.

Now let's talk about removing the resonator which is in essence, a noise cancelation box. I haven't cut one open to see how they are constructed but my guess would be like most, a perforated pipe going thru some sort of sound deadening glass packing. Most likely a chamber where exhaust gasses enter, are mixed and spit out like what you see below;


Removing the resonator and running straight pipes will most like make the car louder and the performance gains WILL NOT be noticeable in the seat, but might be in the ears. From what I have read from guys with cars making damm good HP, either X or H works for the street. Installing one or the other will still make the car run better than the resonator and the sound will be a beefier sound without giving any drone inside the car. Just a low tone rumble that sounds great at idle and will raise the eyebrows of the cars next to you when you hit the go pedal!!

It's a Luxury car, or at least that what I say they are. Beautiful, comfortable, fast, luxurious and total eye candy. Plus its an SUV, in my opinion this is not the platform to install twin 76mm turbos, ported heads & intake, stroke crank, big lumpy cam, turbo headers, gigantic intercooler and try to make low 9's on the strip. But hey, not saying you can't, but you have to put in an 8 point cage after you make your first 9 second pass. They will ask you to leave or park the car until safety measures are taken!

Like I said in my earlier post, I had an X pipe on an N/A engine and it sounded great. But from what I've read the H pipe is a better fit for my GL450 from a sound standpoint. I can have the car tuned to squeeze as much HP & TQ out of it as possible on a dyno after I do the H pipe install. After the install and tune I can gain (from what OE Tuning has told me and sent dyno numbers to me) a HP gain of anywhere from 75 to 100 in stock configuration. Could I add an H pipe for a few extra ponies? I bet I could and my wife wouldn't know anything different about her car.

That's a WIN/WIN for my house!!

Chad

 

Xpipe or Hpipe on a turbocharged engine is for sound only. You don't need either one on a turbocharged engine. Anything that slows the exhaust velocity and flow will cost you hp. Again, don't do an xpipe on a turbocharged engine if you are looking for better performance. It won't do a thing for HP and may cause you to lose power.

 

Another look at the inside of a Resonator off of a 2015 Mudstayne (ok, Mustang) GT500. Found it on a Mudstayne forum and it shows exactly what I tried explaining earlier, the two in/two out exhaust tubes in a resonator. The perforations in the tubing acts as pressure equalization between the cylinder heads, just like an H or X does only not as efficient. You can see they removed most of the sound deadening material inside the chamber, most likely it was fiberglass from the strings I see.



My guess is that's what's on my GL450 or something very much like it. The shape & internals maybe different but for the most part this what we have in the GL and most likely in other Mercedes as well. Remove the resonator and add the X or the H and I think you will be happy with the results. When I get a chance to remove the resonator off the wife's car I will cut it open to see what's inside.

Chad

 

Do you have a P/N for these mid-pipes or a website where you got them?
Thanks!

Chad

 

Hello all I did the resonator delete straight pipe. It sound good and spools up quick.

 

Got a sound clip?

Chad

 

Will up load when I get somewhere with a good signal.

 

From our GL with catless DPs, no res, straight pipe, and with elec cutouts.

 

Nice work, sounds good.

 

Sounds Great!

Chad