Gernby

Thanks for the feedback guys!

Gernby

After repeating my drone-o-meter testing of the new midpipe I built last week with sound deadening, it turns out that my drone is about double what it was with the previous mid-pipe. I made more than 1 change, so I'll have to do some more testing to figure out what caused it.

On another note, I decided to post this video from my fastest run at an autocross this weekend. I wasn't going to post it here, since the sound recording is so poor (very distorted), but I wanted to show how awesome the torque curve is. After shifting into 2nd right after the starting gate, I stayed in 2nd for the whole rest of the run. I had plenty of torque whenever I needed it.

Note: The video performance is much better if you click the "Watch on YouTube" button.

[media]http://www.youtube.com/watch?v=e1SkANwk-Ao&hd=1[/media]

vooper

Greg, I didn't hear any drone on this whatsoever. The throttle response looked good! What were you using to capture video (did you use the iphone or a separate camera)? If it was a separate camera, did you use a program to overlay the HLT data onto the video or is this all through your iphone? Lastly, what are you using to get the OBD II data to HLT?

Thanks

iDomN8U

Greg, I have a question regarding your design.

By changing the diameter from 2.25" steped up to 5" back down to 2.5" will cause exhaust velocity to slow down. Which reduces the scavaging effect.

I understand from high school physics that sound waves that cross with equal but opposite amplitude will cancel each other out, which is one method to reducing sound. But I don't understand how increasing the diameter and then reducing it will help with low end torque.

This goes against your prinicple with test pipes vs exhaust diameter, the key being that it should be the same diameter from the header back to maximize HP/TQ.

Did I miss something?

award78

It would really be nice to see a better comparison of ASM 70mm tp/exhaust to Gernpipe. Or 3" berk headerback to Gernpipe.
...with all other variables the same, ie pwjdm intake.

Gernby

You wouldn't hear drone in that video, since I don't think I ever dropped all the way down to the drone RPM (about 3300 RPMs). I was using my iPhone 4 with Harry's Laptimer and a PLX Kiwi Wifi for OBDII.

Gernby

There are multiple types of scavenging, and only one of them has to do with the velocity of the exhaust gas. By the time the exhaust gas reaches the expansion chamber, the scavenging potential of the gas has already been deminished. The highly ordered individual pulses of gas have "flattened out", and the flow is almost static. The temperature has decreased by about 1000 degrees, which automatically decreases the velocity of the gas due to increased density.

However, there is still a tremendous amount of energy in the pressure waves that precede the exhaust gas pulses (at the speed of sound). Those pressure waves are usually converted into plugging pulses in conventional exhausts, which are the cause for the huge dip in torque at ~5K RPMs if VTEC is engaged with the OEM cat. However, the expantion chamber in my mid-pipe, replaces that plugging pulse with a scavenging pulse, which generates the large mid-range gains.

I feel a bit guilty for not correcting my conclusions from the TP / HFC tests and thread I did 18 months ago, but I couldn't afford to jeopardize my patent. The truth is that I was wrong back then. I haven't done any testing to see exactly which would be the best combination of diameters with "off the shelf" test pipes and exhausts, but I do know my assumptions were wrong at that time.

Gernby

If I had other production exhausts and intakes laying around, and time to test them, I would do that. However, I don't have any of those things. Even if I did have it, I'm sure that my results would be questioned anyway, since the tests wouldn't be "independent". I've already done more / better testing than I've seen from other manufacturers, but those are still being questioned.

Vitt

I take your results as legit since you seem to be your own worse critic at times anyway. But don't you have someone actually doing some independent tests on your system? In previous posts you asked for someone with a stock '06, and I read a post in the NA forum where you asked a tuner to test your system on a dyno. Is that in the works?

pmptx

I am testing the Gernpipe and have dyno time set up for this Friday.
My intention is to test the Gern pipe with the stock exhaust with the optimal tune the stock tune and the full stock exhaust with the stock tune.

So the hope is to get some results up this weekend or early next week. Whatever the dyno says, we should get a definitive answer.
As I have no stake in this process, that should be the independent results all are looking to receive.