[badblack550xi]

Looks like Down pipes will give you lose of power because the ECU cannot be coded for down pipes... so unless you want more sound at current moment you will lose power.

__________________________________________________ _______________________________


A couple of weeks ago *********** published Dynojet results from BMS (Burger Tuning) showing the baseline difference between an N63 V8 in a 550i and the updated N63TU V8 rated at 45 more horsepower in a 2014 550i. The N63TU showed less power than the N63 V8 even though BMW rated it at 45 less horsepower. The caveat is that the 2014 550i had aftermarket catless downpipes and those seemed to be causing a power loss.

BMS did further testing on a 2014 550i that had the stock exhaust pieces in place and the results below 4500 rpm were about the same. Above this RPM though the car without downpipes showed more power. The power once tuned however is about the same between the two.

Here is a Dynojet graph comparing a 2011 N63 based 550i and a 2014 N63TU based 550i both with stock downpipes. The N63TU shows a smoother torque curve and a good amount more torque especially from 2700 to 4500 rpm:



Here are the N63TU tuned values on the 550i with the stock downpipes (transmission shifting issues prevented dyno measurements before 4000 rpm from being picked up:



Here is the tuned N63TU with aftermarket downpipes from before showing slightly more torque although slightly less peak horsepower than the car without aftermarket downpipes:



What is the explanation? BMS states the factory ECU is reducing boost in both stock and tuned form above 5000 rpm. Why? That is anyone's guess. BMW seems to have designed to the ECU to reduce its boost target in that RPM range. It is going to take further tuning to eliminate this and at that point aftermarket downpipes should show gains but as of right now the ECU is reducing boost stock, tuned, downpipes, etc.


source ***********.

[Mike@N54Tuning.com]

I think this only applies to the n63tu engine?

Mike

[badblack550xi]

Originally Posted by Mike@N54Tuning.com

I think this only applies to the n63tu engine?

Mike

id say both i did not see any large gains with my catted down pipes besides the sound and a little better 1/4 time nothing segnificant... id say all people need is Stage 1 BMS or stage 2 BMS and keep everything else stock unless they are after sound.

[alextremo]

I agree, have been holding off since another member posted before and after dyno showing loss of HP and TQ a couple years back.

The only ones showing gains sith downpipes installed are AA, on their dyno.

[combatbmw]

Yes this is my car with catless.
My car is with Evolution racewerks who built the catless downpipes. They will be putting it on the dyno for more testing this week. Untuned. Because tuned and untuned my car was losing boost and power.

They really think the car is spooling too fast causing ecu to freak out.

At this point. I'm going to keep her he down pipes.. Power loss or not. I can't feel the difference.. Sound is too amazing

And wait for a tune that takes care of this. Because there is no way in hell a car should lose power with bigger downpipes and No cats.

I'll keep you guys posted on dyno numbers.

We are doing catted stock dyno runs and catless this week.

[badblack550xi]

Originally Posted by combatbmw

Yes this is my car with catless.
My car is with Evolution racewerks who built the catless downpipes. They will be putting it on the dyno for more testing this week. Untuned. Because tuned and untuned my car was losing boost and power.

They really think the car is spooling too fast causing ecu to freak out.

At this point. I'm going to keep her he down pipes.. Power loss or not. I can't feel the difference.. Sound is too amazing

And wait for a tune that takes care of this. Because there is no way in hell a car should lose power with bigger downpipes and No cats.

I'll keep you guys posted on dyno numbers.

We are doing catted stock dyno runs and catless this week.

You might need a custom Tune that can tweak your editions.

[gragi]

I just had my catted DP installed AR brand and combined with the AFE Scorcher I am positive I can feel the difference. Car is fast, very fast actually. I did a comparison(test drive) last week between a 2014 335i stock and mine, I am telling you night and day. I like mine and I don't think there is any loss of power here. (No Dyno).

[scott135i]

Originally Posted by gragi

I just had my catted DP installed AR brand and combined with the AFE Scorcher I am positive I can feel the difference. Car is fast, very fast actually. I did a comparison(test drive) last week between a 2014 335i stock and mine, I am telling you night and day. I like mine and I don't think there is any loss of power here. (No Dyno).

He (BBlack) is talking about downpipes on a 550 not a 535...

But anyhow, now that he has full exhaust he will probably say they're worth the money for sound alone.

[combatbmw]

Yes I've confirmed catless dps making car run .75 - 1 points Richer the areas car losses power around 5500 rpms car with catless downpipes around 14af. Stock car near 13.0.

The end. Hope Terry makes a stage 2 that should fix the issue

[shoek]

So the conclusion is still that catted downpipes on a 550 doesn't help anything but the sound? Does it reduce turbo lag?

I noticed @badblack550xi was talking about going from catted to catless DP's. So there must be some advantage to them?

[badblack550xi]

Originally Posted by shoek

So the conclusion is still that catted downpipes on a 550 doesn't help anything but the sound? Does it reduce turbo lag?

I noticed @badblack550xi was talking about going from catted to catless DP's. So there must be some advantage to them?

After my car adopted to the catted down pipes my 1/4 got faster and my trap by 1MPH... but i am not going in to a very high boost settings for which i will need catless down pipes...

[shoek]

Originally Posted by badblack550xi

After my car adopted to the catted down pipes my 1/4 got faster and my trap by 1MPH... but i am not going in to a very high boost settings for which i will need catless down pipes...

OK, good to know. Do you attribute that just to the standard BMW engine management or did things improve when you went to BMS stage 2 beta?

[E60orBust]

Just to clarify, when you guys refer to catted, you mean comparing stock, catted DPs to aftermarket catless downpipes.

You are not referring to aftermarket catted downpipes and aftermarket catless downpipes?

[badblack550xi]

Originally Posted by E60orBust

Just to clarify, when you guys refer to catted, you mean comparing stock, catted DPs to aftermarket catless downpipes.

You are not referring to aftermarket catted downpipes and aftermarket catless downpipes?

stock to after market...