Join Date: Jan 2015
Vehicle: SLK55 AMG R171 (2007)
Other Toys: Corvette C6 Z06
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Intake/exhaust mods on my SLK55 R171
Before we begin, couple of notes:
a) I do not know the performance gains of these mods and I have no intention to dyno my car. All I do know is that it sounds absolutely great, revs faster and accelerates noticeably quicker than stock as well as several Ferrari 360s!
b) Sorry, no photos available
c) use this information at your own risk
To summarize, my intake/exhaust mods are:
1) BMC airfilters
2) Modded stock airbox
3) Modded MAF
4) Modded elbow between MAF & throttle body
5) Ported & polished throttle body
6) Renntech short headers
7) Supersprint X-Pipe.
In addition I have Eurocharged ECU tune.
I believe mods 1, 6 & 7 are well covered in other threads or forums, so I'll concentrate here on 2-5.
Please note that I did mods 2-5 during winter storage period so I can't say how any of these mods would impact independently.
So here we go:
2) MODDED STOCK AIRBOX
Removing baffles inside the box. Metal screen at the MAF connection left as-is to leave debris protection.
Better air flow - especially the lower part after the filters seems to be obstructive.
There are good threads about air box removal, not covered here..
After removal, I used pliers to remove most of the baffles and used Dremel tool to finalize rough edges.
Easy job, took like 30 mins including careful cleaning.
Can't really say as I have not tested this mod alone. Might do some good in the overall setup.
It's interesting that the Black Series box looks to have exactly the same shape as the stock one.
The information I've gathered says the BS box contains sports air filters (brand/type unknown) and has no metal screen. It's also worth noting that the Renntech box is noticeable higher than stock/BS box without baffles and gains ~10 hp.
3) MODDED MAF
Removing metallic fine mesh
Better air flow. This metallic mesh is there to stop possible debris, but taking into account that there are air filters, air box screen and the plastic MAF screen, I felt safe to remove it. I've done this to my previous SLK as well and it worked fine for years.
Removal of airbox & MAF not covered here, good existing material in this forum,.
As you take the MAF off, you can see the metallic mesh under the plastic screen that guides the airflow to the sensor.
I removed the metallic mesh carefully with long nose pliers. Leave the plastic screen alone as it is needed to smoothen the airflow for the sensor! It is also a good time good to clean your sensor with CRC MAF cleaner etc. Easy job, 30 mins.
Based on different sources, this mod can result to 1-2% power increase on higher rpm. In my SLK230 I could feel somewhat quicker revs when I did this mod only.
It's interesting that the Black Series MAF sensor is in carbon shell, I've found no details if/how it really differs from stock.
4) MODDED ELBOW BETWEEN MAF & THROTTLE BODY
Smoothening edges within the elbow and removing restrictions
Yes, better airflow...
Instruction to remove airbox, MAF & elbow can be found elsewhere. Once off, I used sand paper and Dremel tool to smoothen all edges on the inside of the elbow. The inner bend right from MAF seemed restrictive so I opened the area a bit. I also sharpened the edges of the two air guides inside the elbow (from approx. 3 to 1 mm). I polished the touched areas carefully with Dremel tool and felt tip bit (be careful or the plastic melts).
This was a bit difficult and fiddly job, took like two hours.
Can't really say as I have not tested this mod alone. Might do some good in the overall setup, especially as there were many edges and obvious restriction areas in a 90 deg bend.
5) PORTED & POLISHED THROTTLE BODY
Removing edge inside of the connection area between throttle body (TB) and the elbow and polishing the area. Cleaning the throttle actuator area of any gunk.
You guessed it, better air flow!
Instructions to remove air box, MAF, elbow and TB not covered here.
After careful masking of TB areas not to be touched, I used various Dremel bits to carefully grind the inside surface of the connection between TB and the elbow so that no edge could be felt between them. I used Dremel with felt tip bit and some car wax to get "mirror" finish, surface. My throttle body had some gunk, so I cleaned it with normal brake cleaner. As there was a small molding imperfection (5 x 1-2 mm) on the intake manifold side, I used fine (500 grit) sand paper to smoothen it too.
Overall, took 1.5-2 hrs of work, not too difficult.
Note: If you remove TB, buy a new gasket between it and the intake manifold!