So as you may know, I have had the turbo-back downpipes on my car going on a year now and promised a "after" dyno. Well things got hectic, out of country trips, work, family, etc etc, never got around to it.

Anyway last month I finally did it and the results were......

Let me start with this.
The car felt strong as hell up top post install! I also installed a pedal box and wheelspin galore in 2nd sometimes half way through 3rd gear (remember I am RWD).
Sometime in Nov, I sent the car to dealer A for a 40k mile service where they drained and refilled my radiator fluid, etc etc.
The weather got much colder and I noticed the car wasn't much stronger in the colder weather. Fast forward I made it to the dyno and the results were disappointing. In fact it barely made the tune only numbers....but lost a whopping 130rwtq in the midrange!!!

My mind started spinning. Took it to dealer B for a checkup (where I bought the car and the Renntech tune, I would use them but they are really far), I got a long long lecture on how MB will void my CPO if the downpipes remained on the car. We wondered if my turbo was going bad or something else happening. To test that, I had to get the stock pipes back on.
So off to the local speed shop and had the stock downpipe and bridge reinstalled. And plugged in my OBD scanner for some datalogs (yes in hindsight I should have done this first, it's been hectic and I haven't had time to play with the car much). That's when I saw it. After about 15-20mins of driving, my IATs were around 170-180 degrees and holding. Will shoot up to 190 and then come back down after a WOT pull. Now note, I have the full AMS cooling setup with a secondary pump and fender gallon reservoir and split cooling (comes with the kit).

My reservoir tank under the hood was empty....

So plan was to refill and figure out where it is leaking from. Took almost 3 gallons over a course of 2-3 days to get it full again. Meanwhile, IATs have been holding steady at 90-110 now (same as it was when the setup was first installed). It has been over a month and no leaks.

Finally figured out what happened. Dealer A must have drained both the radiator and intercooler fluids on my 40k mile service back in Nov. They however, refilled it using whatever MB manual says they should and did not think to check and refill the now separated intercooler system. Whatever was left in the reservoir in the fender was all that was left cooling IATs.

The car is back strong as ever, however, I can tell it's not quite as strong at it was with the downpipe in place.

I will attach dyno sheets on next post and dissect that

 

HP curve with AFR



HP and Torque curve

 

Stock vs Renntech tune vs DP (with IATs over 180 degrees)

Interesting to note. Despite the ridiculous IAT, the DP outdid the Tuned only dyno between 5400-6000rpm

 

Wow, that's frustrating but the good news is you were able to quickly figure it out. Do you plan to reinstall the DPs?

 

I'm surprised you didn't feel the power difference? I guess it was good thing you went to the dyno to help find the problem , I'm glad you figured it out You should Dyno it now with the cats in , then again with the dps to compare numbers .

 

I felt a whole lot of power difference when the pipes were first installed. With time it felt normal again.
After the intercooler fluid was drained, I didn't really notice a drop in power initially (takes a couple of pulls to heat up and we just had a big drop in temperature along with rain-no WOT).

Now if you look at the dyno charts, I made the similar peak HP except at different RPM with just the tune vs DP with no intercooler fluid around 500rwhp @5800rpm DP vs 509rwhp @5000rpm tune only

I might dyno again just to see if I am making the same rwhp as before. But I will not reinstall the pipes, too much work and time to deal with it. I barely made it to dyno this last time, don't think I will follow through lol. Maybe over the summer when things calm down for me

 

Sucks you pulled the dps off. Torques difference is amazing with the Turboback DPs. Acceleration is effortless.

 

You guys are forgetting the best part of the cattless downpipes.


THE SOUND!!!

 

does turboback downpipes sound similar but just give more power vs catless dp setup?

 

i would think they are close. But my guess is the turbo back sounds even better

 

We installed the weistec turbo back pipes and the exhaust sound is pretty awesome. But the "other sound" is the turbo whistle. Much more noticeable when not being a total hooligan. Speaking only for the weistec turbo back system. Its is very refined when you are not deep into the throttle.

 

A lot of turbo noises with these turbo back DPs as well