Headers Installation...

[WARP TEN]

Hi Schrade--I see you have a Power Effects exhaust. That was one of several I tried when I was testing exhaust systems in the mid to late 90s. Wrote a couple of articles on exhausts. I loved the sound and the fit and finish of the Power Effects but it has the most horrible resonance of all the systems I tested and there is no real solution to it short of fabricating Helmholtz resonators for it.

As I noted in another exhaust post today in general discussions, when I had my PE system on I had an acoustical engineer from Outboard Marine take the car for a day and test it. He instrumented it, provided graphs of the frequencies throughout the rev range, including the big spikes at 1800 and 3400 rpms, and calculations for the proper sized Helmholtz resonators for each of the two offending frequencies. (Those are what the stock and Corsa systems use to quell resonance). At the time I was in fairly constant communication with the guy who owned Power Effects. I liked the PE system so much otherwise I wanted to help him solve the resonance problem so I sent him all the info I got on how to incorporate the resonators and eliminate the problem. Unfortunately he was primarily a designer and had then just agreed to sell his company so he did not want to make any changes. To this day they sell the same system I tested back in the late 90s. I no longer seem to have the info on the resonance but I believe Jim Voter and Marc Haibeck may still have copies of the graphs and resonator calculations.

As has been noted before, after all my testing of systems I ended up with Corsa for the better part of 15 years on two cars due to lack of resonance and max power, until I finally went back to stock with cutouts.--Bob

[XfireZ51]

PE system always struck me as something a bit overthought and pretty heavy especially in the rear.

[Schrade]

EXCELLENT INFO MR B. PERFECTLY ANSWERS MY QUESTION ABOUT DRONE. KUDOS TO YOU SIR!

Even tho' there's not really a solution, short of buying more hardware - we'll see if any drone reduction can be had with additional wrap, and additional interior sound-damping material, such as Dyno-Mat, or something comparable here.

So think twice Kevin..................

Originally Posted by WARP TEN

Hi Schrade--I see you have a Power Effects exhaust. That was one of several I tried when I was testing exhaust systems in the mid to late 90s. Wrote a couple of articles on exhausts. I loved the sound and the fit and finish of the Power Effects but it has the most horrible resonance of all the systems I tested and there is no real solution to it short of fabricating Helmholtz resonators for it.

As I noted in another exhaust post today in general discussions, when I had my PE system on I had an acoustical engineer from Outboard Marine take the car for a day and test it. He instrumented it, provided graphs of the frequencies throughout the rev range, including the big spikes at 1800 and 3400 rpms, and calculations for the proper sized Helmholtz resonators for each of the two offending frequencies. (Those are what the stock and Corsa systems use to quell resonance). At the time I was in fairly constant communication with the guy who owned Power Effects. I liked the PE system so much otherwise I wanted to help him solve the resonance problem so I sent him all the info I got on how to incorporate the resonators and eliminate the problem. Unfortunately he was primarily a designer and had then just agreed to sell his company so he did not want to make any changes. To this day they sell the same system I tested back in the late 90s. I no longer seem to have the info on the resonance but I believe Jim Voter and Marc Haibeck may still have copies of the graphs and resonator calculations.

As has been noted before, after all my testing of systems I ended up with Corsa for the better part of 15 years on two cars due to lack of resonance and max power, until I finally went back to stock with cutouts.--Bob

[KILLSHOTS]

Since this is turning into more of an exhaust thread than a header thread, vis-a-vis the drone issue, I just gotta say: Corsa is unreal! Confirmed on my first highway drive today. ZERO drone at any RPM with a system that's basically straight pipes. Amazing, amazing system.

[efnfast]

Originally Posted by KILLSHOTS

Since this is turning into more of an exhaust thread than a header thread, vis-a-vis the drone issue, I just gotta say: Corsa is unreal! Confirmed on my first highway drive today. ZERO drone at any RPM with a system that's basically straight pipes. Amazing, amazing system.

My OBX, that is a copy of Corsa, also has no drone.

[Paul Workman]

Originally Posted by efnfast

My OBX, that is a copy of Corsa, also has no drone.

Not zackly a copy...

The "resonator" of the OBX uses perforated tubes - like a "glass pak" muffler might have, whereas the Corsa is a true (Helmholtz type) resonator. The difference being the Corsa utilizes an opening at the front of the chamber for sound waves to enter, then be reflected out of phase (thus cancelling) the low frequency sound waves. And too, IIRC, the Corsa mufflers too have a similar setup, but are affective in cancelling the higher frequency resonance (occurring around 3.4K rpm).

As far as performance goes, outside of noise reduction, Marc Haibeck and Pete do not appear to be of the same opinion on the matter. As I understand it, on the one hand, Marc H. is on record favoring the Corsa as part of his 510 hp upgrades, whereas Pete is of the opinion that what is essentially a modified 3" B&B type with a "Stainless Works" type X-pipe and flappers (for resonance abatement) is better. Both are successful at making power from the 5.7L LT5s (among others).

I followed the 3", X-pipe route, because it was cheaper and easy for a DIY'er to fab up, AND it seems to be a proven system (Pete's car, among others), And because too it preceded Marc's announcement regarding the findings he made with the Corsa. Also, the Corsa cancels the low frequency resonance, but does not address the high frequency notes, resulting in a "tinny" sound - at least to my ear: a personal thing.

I'm at 432 rwhp w/ stock TB and cams using what is essentially Pete/B&B approach (see signature). And, it drones. I can't wait to install the NPPs to address that issue!

Getting to this point has been a trial and error journey. And, in the end I can't say I saved a nickel or have realized performance over what might have been the cost of the Corsa. Performance trumps sound, IMO, and Pete's system seems to have both of what I like...EXCEPT that drone - the reason I'm interested in installing the NPPs (with Mike 100's control system) as soon as possible.

[XfireZ51]

Paul,

I'll have to give you a ride in mine and see what you think.

[Paul Workman]

Originally Posted by XfireZ51

Paul,

I'll have to give you a ride in mine and see what you think.

Love to!

I studied Mike's system, and was especially interested in his experience with mountains - leading to his active (electronic) control system vs. vacuum only. Soon I believe I will duplicate his system, or perhaps resort to a simple manual switch approach - haven't decided yet.

Note: Mike's article appears in the (members only) ZR1NetRegistry's New Letter.