Lets talk about tunning and the C250
On the Stage2 being unable to add more boost we experimented with higher advance and leaner AFR targets, but dyno gains were also minimal.
The platform seems generally very limited at least at this point in time. We'll continue looking at things but no immediate plans to offer anything other than the Stage1 + intake we currently offer for it.
https://mbworld.org/forums/c-class-c...ld-thread.html
New here and just picked up a c250 coupe on a killer deal.
Seems the most apparent limitations are an 1) undersized turbo, 2)the Direct Injection style system, and 3) being able to program the ECU.
Some thoughts:
As to the turbo it should be relatively easy to have its compressor or turbine worked for more capacaty and more efficient flow. If not just a bigger turbo.
GDI is a new puzzle and from my limited reading seems to be more of a challange to increase its flow than normal port injection system. At some point the more HP we ask of it the lower the rpm limit will be unless it can be worked around with larger GDI injectors (probably hard to source), a higher pressure fuel pump (again probably difficult to source), or additional piggy back injectors (even fuel distribution might be a challenge). I guess it is possable MB left us some head room here but from looking at what has been done with other GDI MB's there probably only about 15% more fuel potental.
As to the ECU if someone can not crack it, it might be worth looking at setting up a Unichip piggy back system. This worked well for the newer MiniCooper Turbo's. I first saw this used on a Porsche 993 twin turbo. It is very programable and adaptable around the stock ECU. Added function is possable including driving addational injectors.
Of course all the normal turbo tuning tricks apply.
If that does not work, check out the Unichip piggy back system. It is really a solid solution if needed.
I think the most significant issue is increasing fuel substantially even if we have control over the ECU.
Direct-Injection is a different animal and just does not seem to have the head room for much of an increase. I think it can only take on fuel for about a couple of hundred degrees of crank rotation. Compared to Port-Injection where it can fill the intake tract with fuel for up to 720 deg of rotation. There just is not the aftermarket for DI injectors or higher pressure fuel pumps.
Some of the other GDI performance cars have both DI and PI which would be much better for getting more fuel as we can swap the port injectors.
This is probably the largest issue to overcome on these cars if we want to make real HP.
But I am not an expert on this.
The Best of Mercedes & AMG
Read some of you posts and you sound like you are on a great track! Also looked up the A45 you note and found the following quote:
350 hp and 332 lb-ft of torque. Code-named M133, the AMG engine is a modified version of the unit fitted to the A250 Sport, but apart from the 1991-cc displacement and the cylinder block, almost every part is new. There are now two radiators instead of one, the intercooler and the variable-vane turbocharger are larger, and the reengineered exhaust boasts four chrome tips as well as an optional full-volume mode. Although the numbers aren't yet final, the AMG car is expected to accelerate to 62 mph in 4.6 seconds, and the electronically limited top speed of 155 mph can be stretched to 175 mph with an optional performance package.
Read more: http://www.automobilemag.com/reviews...#ixzz2DinnWXXw
He was looking at making a replacement for the factory wastegate as he said it lets all of the pressure out and is pretty wasteful. I'm not too familiar with the technical terms, this is my first FI vehicle, but it definitely has opened my eyes to the 4-cylinder alternatives.
EDIT: After reading above it seems he has stopped trying to make an aftermakert wastegate. It seems we will indeed have to wait for the A45 parts to become available, or until the CLA 45 ///AMG is released here in the U.S. to get some quality parts.
Last edited by jctevere; Nov 30, 2012 at 04:21 PM.
It sounds like the pressure increase in the exhaust manifold before the turbo is getting very high relitive to boost.
To get boost so early they may have put a very small and restrictive hot side on the turbo.
If so forcing the WG may not be a good idea.
It would be a good (and basic) idea for someone to put a tap off the exhaust manifold before the turbo hot side and a tap after the turbo hot side but before the cat to see what kind of pressures are being achieved at different boost levels.
We might be missing something very basic here.
If pressure is high before the turbo but not after we need a bigger hot side. If it is more so high after the turbo we need a sport cat and exhaust.
I could be wrong.
Last edited by 00ML Keith; Dec 19, 2012 at 08:11 PM.
Here is a quote of what I was thinking about:
" Boost And Drive Pressures
... another important aspect of turbocharging is drive pressure. Drive pressure is the amount of force (in pounds per square inch) that is being used to spin the turbocharger. A drive-to-boost pressure ratio of 1:1 is ideal, although in reality, drive pressure is usually a bit higher than boost pressure. If a situation occurs where drive pressure far exceeds boost pressure (say, 35 psi boost, 65 psi drive pressure) then you might be looking at trouble..."
cheers! Mike
I suspect there is a lot of potental left in this little motor but it is probably going to take a sport turbo /cat / intercooler, plus injectors & higher pressure direct injection pump.
I guess my search around the net has shown several tunes, with only one or two having been utilized by board members:
*BMS JB+
*Carlsson
*Brabus PowerXtra
*Power-bit
*Kleeman
*Tuning-Box
etc.....
With the exception of Terry, whose presence is extremely appreciated and felt across the board, no other manufacturer has listed any dyno figures for their product. There are variations in many of these products as well. RADO is developing some parts for our cars, but there is no price/performance numbers regarding the ECU tune at this time.
Do any of you have experiences with a 250 tunes/piggybacks outside of JB+? Is anyone familiar with a complete ECU reflash of the 250? I would love to see this thread continue. We probably have a good 1.5 model years (at most) before W205/C205 comes out and our engines become a stop-gap afterthought.
Do any of you have experiences with a 250 tunes/piggybacks outside of JB+? Is anyone familiar with a complete ECU reflash of the 250? I would love to see this thread continue. We probably have a good 1.5 model years (at most) before W205/C205 comes out and our engines become a stop-gap afterthought.



