Thanos

I have heard that aftermarket exhaust yields no HP gain with our C6's. Whats the skinny with Corsa's ad(pg 47) Corvette Quartley summer 2006....More Torque & HP , especially below 4000 rpm, 22% Increase in flow over stock with valve open; 171% increase in flow over stock with valve closed. Whats the deal, does aftermarket exhaust yield any HP gains, or is this just false advertising???

jimman

Got nothing with before and after dyno pulls, only sound. With headers different story.

tjfontaine

For sound only mainly - little to no HP gain .... if you want more of a growl AND want HP /Torque gains leave the stock exhaust on and go LT headers.

fredgpowell

No Gain just 1000 for better sound. Get some long tubes

Whiterock1

Headers do add hp, but I wouldn't dismiss freer flowing (i.e., lower restriction in exhaust path) from the cat back too quickly. I work with a PhD in mechanical engineering--Porsche 911 driver, but nobody's perfect...and he said the layout of the B&B Bullets will certainly increase hp--more so the higher you go in the rpm band. Even the best flowing muffler is still significantly more restrictive than a resonator only design, B&B, SLP Loudmouth, etc. And with the sound attenuation of the stock muffler--why we all seem to complain about it...there is little doubt (in his mind) that a meaningful (10-20+hp) increase is available to the 6000rpm max hp curve of the C6. The max hp may well move up to 6150-6300, but with a decently flowing induction--I used my K&N Aircharger as a reference, even if not the absolute best out there, still far better than stock, the airpump that is an internal combustion engine must improve its efficiency with better outflow. More efficient is measured by more available hp. I know this has been argued ad nauseum--here and on the LS1 forum, I might add, but I had the same opinion before I bought the Loudmouths for my WS6 in 2000 by our chief mechanical engineer at the company I worked for then. And he was a WS6 driver too, so wanted the best for his 1999 T/A. He chose the Loudmouth and headers for the max improvement. However, he felt the Loudmouth alone was worth 10 hp over the already free flowing 2000 WS6 system. For what it's worth, but I spent $1200 on the induction and exhaust to not only improve sound--my primary goal, but get an expected 15-20 hp at the rear wheels higher in the rpm band. I believe that I will.

k0bun

That's all fine and dandy but it's basically all hypothesis and theory. Yes that's where engineering starts but in the real world testing cat-backs are producing little to none in the hp department. Now this is true on a stock vehicle. Obviously the more power you make the more of a restriction the stock exhaust can become. But I don't believe most are coming anywhere near the limit of the stock exhaust. The only stock cars that I've seen make gains with a cat-back are FI cars. Turbos mostly. But most vehicles aren't pushing in enough air where the stock exhaust is holding them back. Don't go by dyno numbers from the manufacturer. Most of you know that a dyno can change up to 5-10 hp from one run to the other on the same car. Get it for looks and sound but just don't expect a sudden increase in power.

timd38

Dyno doesn't lie, but different dynos will give different results.

I put a MagnaFlow 15884 on my car and am very happy and would do it again. I just like the sound.

Cookee

I think the data supports that Hill and other smart PE`s put together a very well designed exhaust system that balances flows and backpressure without drone to deliver max hp and torgue.

Sinister Evil

WERD!! Registered PE(CA) here...lol....no gain with exhaust(B&B bullets) saw a nice gain with LG LT's.

bunk22

Like Jim with his dyno runs, I did back to back track runs and gained nothing with a cat-back. Gained .3 and 3 mph in the 1/8th from long-tubes though

jschindler

Yeah, nobody believes a cat back exhaust adds horsepower until you post your 1/4 mile times on the forum. Then people say "yeah, but you have Bullets on your car". Trust me, I've had people tell me this!

Maybesomeday312

What kind of gains can be expected from longtube headers?

CBB

I don't think its false advertising.

There was an article in "Vette" magazine October (Oct 2005) issue of Vette magazine had B&B Bullets on a stock C6 making 10.9 more horsepower & 21.5 more ft/lbs of torque vs the same exact car dynoed bone stock and on the same dyno, same day.

So yes it is indeed possible.

Bullets are pretty much a straight through design with not much of a muffler at all but a resonator. Its darn near a straight pipe. The only reason why Bullets are not on my own car is that they are too loud.

With people getting all these codes and emissions concerns associated with long tube headers, I would personally do Bullets as opposed to headers if I were going to do anything. If I got the 11 RWHP/21.5 ft/lbs RWTQ then great. If I got somewhat less than that then that would be cool too.

bunk22

Again, I gained .3 and 3 mph in the 1/8th mile. I'm guessing maybe 25rwhp and 15rwtq...peak.

Whiterock1

My ME friend says dynos are not real world, and that is beyond debate. Static state is not the same as underway on a car (parasite and induced drag, areas of negative or high pressure, active cooling/intake, heat throwoff, lift, cross winds, etc.) anymore than a wind tunnel is an absolute aeorbatic predictor--or dogfight, if you prefer, for a fighter. And dyno runs, with no relative wind and poor cooling effects, are rarely repeatable, which at least wind tunnels are. 1/4 mile times, as we all know, also can vary under seemingly identical conditions by .3 easily. Change temp, barometric pressure, altitude, et al and they scatter diagram all over the place. Bottom line: nobody can conclusively say, one way or the other, what affect if any an exhaust change makes. My bottom line was simple: sound. I believe there will be a hp bump as a nice side effect--both from the Aircharger and Bullets. However, ultimately I will get what I want for $1200 and that's all right with me. For the cost vs. gain from headers, I'm not interested. To each his own...

jschindler

I agree with some of what you say, but not all of it. A dyno is the best way to compare different variables. Certainly, the dyno has to be the same, and the operator has to set it up properly. This is not magic as long as they are not trying to cook the numbers. I've had cars dyno'd on the same dyno months apart and in different weather conditions, and the numbers were identical.

Sure, they can't take into account outside conditions, but that doesn't mean a comparison of a stock car to a modified car is not an accurate measurement of the difference.