Ian,

I'm not sure where you saw that our headers lose any power vs stock ones in the midrange. Here are dyno sheets published on our site. They show the actual power gained/lost with our headers added to our mufflers/cats vs stock headers with our muffler/cats. As you can see, there is no negative power (loss) across the entire powerband. Granted, at ~3000 rpms, gains/losses are zero, but everywhere else is a gain:




Here is a graph of the gains/losses with our muffler/cats vs stock muffler/cats (no headers in either test). Notice the couple hp loss at ~3000 rpms that does not exist with our headers (above):



Now, when you compare these two sheets, you are correct in your assessment that gains with our headers are in the upper rpm region, but to set the record straight, we do not see any losses when adding our headers.

Our development encompassed using different primary diameters and lengths, and the configuration we are now using produced the best overall results. We were not interested in releasing any of the versions that produced power gains at other areas of the curve but also lost significant power at other areas. None of them produced an acceptable trade off our opinion.

Let me know if you have any further questions.

 

Hi Todd

Thank you for the response. It was this quote, lifted directly from the 'Dyno Graphs' section of your website that led me to believe there are losses associated with your headers:

"Swapping in AWE Tuning mufflers, Hi-Flow cat sections, and merge collector headers for the stock muffler and cat sections results in another substantial gain in power. Gains at the power peaks were 33.7 wheel hp and 26.8 wheel torque. Using a 1.16 correction factor, this results in a total gain of ~39.1 crank hp and 31.1 crank tq for the AWE Tuning 997S Exhaust System vs stock. While the addition of the AWE Tuning headers results is a slight loss of torque vs our mufflers and cats with the stock headers, the gain of 6.3 wheel hp (7.3 crank hp) adds a big bump in power at the sweet spot of this engine!"

Hence my questions regarding header designs that increase torque compared to the standard header, rather than just increasing top-end power at the expense of low-end torque.

Regards

Ian

 

Goes to show that I must be getting senile with age.

But it also goes to show how peak power numbers do not tell the whole story. Examining our own dyno sheets shows that I was obviously referring to ~5whtq loss at peak when mentioning on our site the slight loss of torque when adding our headers.

Yet when I just made that last post above, I was glancing at the graphed power curve differences, which shows the entire story and not just the peak power numbers. Those graphs really show that any losses in torque are quickly overshadowed by the tremendous gains found in the rest of the area under the curve.

Nevertheless, my previous post's statement about our development still stands. As with all our exhaust products, we test many variations in house on our chassis dyno, and our current header configuration is based on what we were able to achieve overall when considering area under the curves. We believe this trade off is worth it.