2.5 vs. 3 inch debate (again)..

[Paul Workman]

Provided w/o comment due to so many variables (unaccounted for in the video). BUT! Interesting, none the less...

Enjoy!

https://www.youtube.com/watch?v=_PVXvHkr-Vs

P.

[efnfast]

Anybody here dyno with and without cutouts?

[WARP TEN]

Originally Posted by efnfast

Anybody here dyno with and without cutouts?

Marc has done this, although not with mine. I think on Gunny's but not sure. I recall we considered the stock mufflers (which I had on the '95 with cutouts) to be the biggest bottlenecks costing about 20-25 HP, so I would imagine that the gain on mine with cutouts open would have been close to that. Looks like in their video that the 2-1/2" system with muffler cost about 20 HP. Another note: they said the 3" system as configured weighed 80 pounds, the 2-1/2" system weighed 72 pounds. The (admittedly a bit shorter) Corsa Stainless system weighed 64 pounds when I weighed mine about 10 years ago. --Bob

[Gunny]

Yes to dyno question - short answer: 12-13 HP gain when open

#2957 has SW headers, no cats, and '96 LT4 exhaust with QTP cutouts installed a couple of inches before the muffler inlets. In the fall of 2015 Marc ported (as much as possible) the top end and also eliminated the secondaries which really woke up the Z. The LT4 exhaust is 2.75" and supposed to be the most free flowing OEM exhaust from the C4 era plus it has a balance pipe behind the resonator.

I wasn't sure what to expect but was hoping for 20+ HP increase with the cutouts open. I suspect (but have no tests to support the theory) that the earliest OEM exhausts might well show an increase of 20+ HP and that later exhausts, especially coupled with headers, porting, etc. are already approaching the apex of efficiency.

Since the QTP electric cutouts can be open, closed, or anywhere in between I find them to be an effective solution for "tuning" my exhaust to a pleasing sound level without drone. For obvious reasons the cutouts are best left closed when I'm leaving my house (wife, neighbors, small children) and then opened up to suit me. With the cutouts totally open the sound is, well, totally awesome. In a large parking garage it's possible to set off a dozen or more car alarms with this setup - at least that's what I've heard.

FYI - I've had the following systems on my '90 over the past 15 years: OEM (both '90 & '95), Borla (both the 2.5 and the 2.75 challenger), Corsa, and finally the modified LT4 w/QTP cutouts which I like best of all. An interesting side note is that I actually prefer the sound from my stock C5 ZO6 (titanium exhaust) - and apparently the gains from changing the ZO6 OEM exhaust to 3rd party are very minimal. Don't know how they did it but the exhaust is very pleasing (even tame sounding) until you get above 3K RPM and then it becomes very aggressive sounding, still with absolutely no drone. Works for me.

[efnfast]

12 more hp. Hmmm. I'm goona start breakin' stuff.

[DRM500RUBYZR-1]

Glad to see that my "butt-dyno" remains perfectly calibrated.
I too have had more systems on and off the car than I care to think about.
One thing however was always ABUNDANTLY CLEAR.
My 3 inch B&B, particularly with no mufflers, made a huge difference in the cars power over the Borla's that it originally had, the Corsa, and the stock system that was put back on for NCRS.
There was simply no comparison.
I am now going on 4 years with a new B&B Fusion still sitting in the box in the garage. The current setup just sounds TOO good to mess with.
Even better, when the car had " test pipes" on instead of the cats, I would routinely get 18-24 inch flames out the back to accompany the off throttle bark.
Marty

[Vette73]

I drove a C-5 Z06 a few months back with a B&B cat back....Super super loud for me..How is the sound on your B&B system with no mufflers?

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[DRM500RUBYZR-1]

Originally Posted by Vette73

I drove a C-5 Z06 a few months back with a B&B cat back....Super super loud for me..How is the sound on your B&B system with no mufflers?

Sent from my LG-TP260 using ZR-1 Net Registry mobile app

What?
Did you say something?
I can't hear you.............................

Loud?
Not at idle.
Drone?
Hell, yeah, but livable.
We called it "right" back when I was a kid, no one knew about drone.
Sound good?
Y E S !

The longest I drive it now is two and a half hours to Carlisle, and no problem.
Six hours to Lake George..................... my son needed Tylenol, but he was still smiling.
Marty

[Vette73]

Originally Posted by DRM500RUBYZR-1

What?
Did you say something?
I can't hear you.............................

Loud?
Not at idle.
Drone?
Hell, yeah, but livable.
We called it "right" back when I was a kid, no one knew about drone.
Sound good?
Y E S !

The longest I drive it now is two and a half hours to Carlisle, and no problem.
Six hours to Lake George..................... my son needed Tylenol, but he was still smiling.
Marty

I hear ya......I mean, well sort of...Lol...

Sent from my LG-TP260 using ZR-1 Net Registry mobile app