Evo headers on and new dyno---480rwhp - The Unofficial BMW M5 Messageboard (m5board.com)

cjm6 · 26th February 2008, 21:26

Got my car back today with the headers on. It is much louder but I think it sounds even better now than with just the AA exhaust. My mods are in my sig. The shop has a video of the dyno and Ill try and get them to send it to me today. How much rwtq have others seen when adding headers? 7 seems low but it is most likely because of backpressure. I dont have cats and its 3" tubing all the way. Evosport guys, is that what caused the dip in tq from 3500-4500rpms? What kind of gains could I expect to see from switching over to your exhaust w/ high flow cats?

bonehead · 26th February 2008, 21:44

Congrats, CJ. Good solid numbers. What kind of dyno? Does the AA exhaust delete the secondary cats?

Here are my numbers.
http://www.m5board.com/vbulletin/sho...65&postcount=1

6speed · 26th February 2008, 21:55

Great numbers but something is wrong as your HP and Torque numbers should cross at 5250 rpms.

Cheers ///

cjm6 · 26th February 2008, 21:57

Yeah it deletes the secondary cats. Very similar mods and numbers...the cat delete prob gave me the few extra hp and took away the tq. Do the SAE correction factors take temp into account?

cjm6 · 26th February 2008, 23:10

Yeah it seems like the torque curve is just out of place although the numbers seems to be right. My last dyno looks more correct and is the before run thats on the new printout. Should look like this one.

Quote:

Originally Posted by 6speed

Great numbers but something is wrong as your HP and Torque numbers should cross at 5250 rpms.

Cheers ///

extassy · 26th February 2008, 23:13

Same result I had when I ran straight pipe... I lost about 30 lbs/ft torque around 3500 rpm... The car feels weird at WOT as if it was choking... and then back to the power band... All I did was put the secondary cats back on (replacing section 1) and the gained back the torque... Although I lost about 6 HP on the peak HP...

cjm6 · 26th February 2008, 23:23

Quote:

Originally Posted by extassy

Same result I had when I ran straight pipe... I lost about 30 lbs/ft torque around 3500 rpm... The car feels weird at WOT as if it was choking... and then back to the power band... All I did was put the secondary cats back on (replacing section 1) and the gained back the torque... Although I lost about 6 HP on the peak HP...

Yeah I feel like the car doesnt have the throttle response it used to. How did it effect the sound when you put the stock cats back on? I am def. interested in seeing the results from evo's high flow cats.

extassy · 26th February 2008, 23:53

Quote:

Originally Posted by cjm6

Yeah I feel like the car doesnt have the throttle response it used to. How did it effect the sound when you put the stock cats back on? I am def. interested in seeing the results from evo's high flow cats.

Yes... most people I talked to had attribute the lost of torque from lack of back pressure. I actually like the way the car drive better without the dipped in torque... I rather sacrifice the 6hp for the 30 lbs/ft of torque.

I actually have the shop weld the stock cats into the Meisterschaft section 1... The sound is significantly subdued... the rasp especially had been reduced significantly.

DY1103 · 27th February 2008, 00:34

post up the video pleases!!! thanks

cjm6 · 27th February 2008, 00:50

Quote:

Originally Posted by extassy

Yes... most people I talked to had attribute the lost of torque from lack of back pressure. I actually like the way the car drive better without the dipped in torque... I rather sacrifice the 6hp for the 30 lbs/ft of torque.

I actually have the shop weld the stock cats into the Meisterschaft section 1... The sound is significantly subdued... the rasp especially had been reduced significantly.

I actually like how the car felt better before the headers but Im sure replacing the cats will fix it. it just feels sluggish now in first and second and I dont feel it pickup until the very top of 3rd and then a lot in 4th.

Mike@ESSTuning · 27th February 2008, 00:56

Something wrong with the dyno... HP/TQ will always cross at 5252 RPM.

Nice numbers though.

extassy · 27th February 2008, 01:00

Quote:

Originally Posted by cjm6

I actually like how the car felt better before the headers but Im sure replacing the cats will fix it. it just feels sluggish now in first and second and I dont feel it pickup until the very top of 3rd and then a lot in 4th.

Yep... that's exactly how I felt... now it is a total beast... I am very happy with the headers... replacing the the sec. cats will fix it.