munis

Guys, there is a general consensus that downpipes for this car looses power. It has been seen multiple times on the dyno previously that using the same tune (tuning file contains the same boost curve), minus the tuner shutting off the CEL, the car made around 10hp less with downpipes, which is ofcourse counter intuitive.

Now I have some guesses why this happens. I know the car keeps track of exhaust manifold pressure/ flow, so when it experiences a flow that is beyond the calibration limits, the ECU might cut some timing reducing the power.

Now EC has gone past this problem as they are making more power now using downpipes and same boost curve (we can check boost curve of an EC tune using an OBD dongle, so we know the boost curve looks the same). So obviously they have figured out how to get past this issue, but for competitive reasons they kind of would not share how they did it, obviously.

What I am asking is, may be one of the guys here knows what can be manipulated to get past this issue? It was hinted that it can be done manipulating the wastegate valve position.

RichardCranium3

Ohnlee caym hear too say "loses" not "looses"

munis

Thanks! The downpipes are making power now that you corrected me, haha!

RichardCranium3

Yep, I knew that would fix it.

sean1.8t

It's possible, yes. Especially when no adjustments to the tune is made. Happens all the time when N/A cars put exhausts on their cars but don't tune for it and end up losing power. But you really shouldn't lose top end power, should just affect low end torque.

Are there any back to back dyno's when they added changes to account for downpipes?

munis

What I am interested in is what do they do when you say they have to tune for it? Like what parameters are changed? There is only so much you can do. Boost, fuel and timing.

DameMD

^^^This.... Which is why I haven't installed my downpipes yet as I am waiting for BMS to allow access to other parameters/functions of the Jb4. If downpipes are anything like headers, for my G37S coupe and sedan I had to retune once headers were installed because I definitely felt the loss of low-end torque. I keep telling people that I don't think downpipes on our car are just plug and play. You may be loosing power because the ECU is trying to adapt for the extra air flow. You will get the noise and sound form the DP but you may be running to rich or lean if you don't make any tune adjustments for them. I do 90% mostly city driving and I definitely do not want to lose my low-end torque.

303_AMG

DameMD

Nobody really knows the answer to this. Eurocharged so far has been the only company that did a before and after dyno of DP on the same car with same tune not adjusted for DPs and some members stated that car lost power. Not sure if it was just that car or if this happens with every car that gets downpipes installed. We are still waiting for someone to do a before and after dyno of downpipes with no tune. So far it hasn't happened. This may all be speculation ..... just my .02