King Tut's Stock Dyno Experience

[King Tut]

Last weekend myself and Irb Digital went to the local dyno to put down some numbers. My E92 is bone stock and his car just has the Active Autowerke exhaust. I made 3 images. The first is the uncorrected plot and the second is the SAE corrected plot to show the differences the dyno can show based on how you have it configured. I also added an image of my stock car plotted against Irb's modified car. You can see that the 3 hp difference is pretty much maintained across the RPM range. I was really hoping he would hit at least 350 hp with the AA exhaust. I also added my and Irb's dyno videos our buddy shot.

[C17MooseDriver]

Not much gain with the AA exhaust. Manufacturer claims 15+ hp and 7+ftlbs of torque.

[Sticky]

Originally Posted by C17MooseDriver

Not much gain with the AA exhaust. Manufacturer claims 15+ hp and 7+ftlbs of torque.

You have to have a baseline from the same car to really make that statement.

[MrHarris]

What does IRB's car have in it?

[TonyTone]

M's look great!!!!

[mixja]

It is just me or is that AFR curve whacked - 15:1 at 5300RPM and higher below 5300RPM??

[Cab5er]

Whats the correction factor? How does this translate to the crank? Did BMW underate the M3's numbers?

[Irb Digital]

Originally Posted by Sticky

You have to have a baseline from the same car to really make that statement.

+1. No 2 engines are the same. Not to mention, I saw a difference of 7whp between my 3 runs. So its really hard to tell if (A) the exhaust made any difference at all (B) the exhaust is making more than 4whp on a motor that is less powerful than tut's, since there's no baseline to dispute that or (C) our motors put out identical stock numbers, and the exhaust is truly making 4whp

Originally Posted by MrHarris

What does IRB's car have in it?

I just have the Active Autowerke exhaust

Originally Posted by mixja

It is just me or is that AFR curve whacked - 15:1 at 5300RPM and higher below 5300RPM??

We had to use the tail pipe sniffing method, which isn't the most reliable. I couldn't get my A/F because the operator didn't want to clamp it too tight onto my tips. He was afraid it might damage them, and the car kept blowing the sensor out of the pipe.

Originally Posted by Cab5er

Whats the correction factor? How does this translate to the crank? Did BMW underate the M3's numbers?

SAE correction factor. It was a nice cool day, which resulted in almost 20whp I guess you could do the math. Both cars put 340-345whp down, and stock they are rated at 414. At 340whp, thats a 18% loss. A loose rule of thumb is 15% 2wd, 20% awd. I'm sure you can throw a +/- 5% in there with that loose rule of thumb. At 18%, I'd say its about right, but nothing close to under-rated.

[King Tut]

Originally Posted by Sticky

You have to have a baseline from the same car to really make that statement.

Yeah and after seeing the numbers our 2 cars put down from first to last run I can see how a manufacturer could do 10 pulls take the worst stock pull and 10 exhaust pulls and take the best exhuast pull and then base their numbers off that. I personally don't feel that the AA exhaust is good for 15+ hp though.

[King Tut]

Originally Posted by mixja

It is just me or is that AFR curve whacked - 15:1 at 5300RPM and higher below 5300RPM??

For some reason the probe in my exhuast tip had issues catching up so all that data is bad. The probe was also blown out of Irb Digital's tip each run.