True Honesty

[thebeepster]

OK guys, I'm looking for an honest discussion here.

I have an '07 C6 w/ just over 4000 miles. So far I've added LT headers, new wires, 160 deg t.s., K&N filters, and a dyno tune. I have to tell you that I see very little difference (if any) in performance since I took delivery (bone stock) last Sept. I do not track the car so I have no times, etc. to compare. I only know that the car dynoed @ 343rwhp/341rwtq after all of the above. I think this is sad for a car that is marketed @ 400HP new (plus the above mods).

This causes me to wonder how much snake oil is being sold out there. How much of these "gains" that everyone writes about are real and how many are just illusion??

I'm not looking to point the finger or start controversy, just an honest discussion:banghead:

 

[Nytro]

Interesting. I don't think your going to see any gains from wires, thermostat, and filters. As far as the headers go, from all the info I have seen there doesn't appear to be much of a HP gain there either unless you used high flow or no cats and changed the mufflers. I think the main question here should be what were your numbers before you did the mods to the car, especially the headers and the tune. I would think that a tuner would run a baseline to be able to compare the before and after numbers.

 

[thebeepster]

The baseline before the tune was 326rwhp. So the net gain from the tune was +16rwhp, not bad! I'm just saying a baseline for the car w/ the above mods seems to be amazingly weak. I would expect a gain of at least 10hp from the headers, so I guess that means that it would have baselined at about 316hp bone stock???? Truly disappointing I'd say for a $60M+ car that is supposed to deliver 400hp/400tq from the factory...

 

[Mark Dalton]

The baseline before the tune was 326rwhp. So the net gain from the tune was +16rwhp, not bad! I'm just saying a baseline for the car w/ the above mods seems to be amazingly weak. I would expect a gain of at least 10hp from the headers, so I guess that means that it would have baselined at about 316hp bone stock???? Truly disappointing I'd say for a $60M+ car that is supposed to deliver 400hp/400tq from the factory...

326 before the tune does sound a bit low. You're going to lose hp through the drive train, anywhere from 15%-20%, depending on the tranny but I would have expected your baseline to be more in the 330-340 rwhp range. My '02 ZO6 is rated at 405 hp and dynoed, bone stock, at 345 rwhp. That's exactly 60 hp, or a 15% loss. Of course, there are a lot of variables in dynoing. Humidity, altitude, even the dyno's themselves will give different numbers.:shrug01:

 

[chris308]

you'll lose more through an automatic as well.

 

[CHASZ51]

Just headers should give you a 20hp gain. With the mods you have done it should be around 370RWHP. Maybe the tune is off?

 

[THOR]

Hey Ted, You know I like your car!!! The way I understand these cars is to think of air flow throughout the system. Any restrictions to air entering or leaving the engine wil restrict performance. You have headers which is in the middle of your air flow system but you have restrictions with the stock air intake and exhaust. I think the headers will give you your biggest bump of the 3 components and you might find a better bump and feel in your performance with a better CAI system. The exhaust will help a little more but I personally think it's more throttle notes than anything uless you take the muffler off totally and run a straight pipe. Then it's too LOUD! Talk to John at Auto XTC and pick his corvette brain.
This is my humble .02 worth. ENJOY THE RIDE:wavey:
PS: Any bigger gains you want could be acheived by changing the rear gears through DTE and switch to a 3.15 gear. The torgue will go significantly up but the gas mileage will go down. Mark

 

[Rich Z]

Just headers should give you a 20hp gain. With the mods you have done it should be around 370RWHP. Maybe the tune is off?

That sounds about right. Greg at AntiVenom did a pull on the dyno with my C5Z before installing the STS turbos and it logged in at 368rwhp. That was with LPM pro headers, X-pipe, and after market airfilter. The Ti Z06 mufflers are already pretty good at passing air, so that does help.

But you have to look at it as a system. It does little good if ALL of the components don't work together to improve airflow. That is IN and OUT of the engine. Any one part being a restriction affects the output as a whole.

 

[98 softtail]

I agree with all of the above, for the modest modifications you have done you are in the ballpark for HP increase. The K&N will allow more airflow and the Plugwires may produce a better spark, and the headers will move the exhaust more freely, but if the exhaust gets restricted again at the cats or in the mufflers at the end, very little power is achieved to the wheels. It would stand to reason that since you had headers installed, hi-flow cats, a comparable X-pipe and performance exhaust should follow...if you get my flow. Air in - Exhaust out.

Joe B.

 

[thebeepster]

Thanx for the responses! I think I really learned something here, and that is: You can't piecemeal mods! I added the headers (w/ hi-flo cats) because they were only a few $ more than adding a catback system. My rationale was that the headers should provide not only the improved sound, but also provide a 10-15 hp gain (unlike the catback which by itself produces zip). I guess what I really didn't think about was that in order to achieve the full benefit from the headers/cats you must also add the CAI, catback, and a tune (another $2000 or so). Now, what was originally a $1600 mod has turned into a $3500-4000 mod! I mated the headers/cats to the stock exhaust because I did not want LOUD or DRONE. So in order to achieve any benefit at all, I must think in terms of $4000 and a LOUD car. Hell, I wish I'd left it alone...Rant, Rant. I guess these are the trade offs. Thanx for all the comments!:banghead:

 

[THOR]

Hey Ted, Check out Corsa Touring or SPORT. The only difference I hear is when you step on it, the Sport will be louder and meatier but with a more european sound and not the muscle car sound like the B&B, etc. Also, no drone on the Corsa products due to their inherent design. I'm not sure you will see a noticeble difference in your giddy-up. According to John and Larry at Auto XTC, it also takes about 20-30 starts before you will see a difference in performance (CAI, headers, exhuast, etc.) This is due to the onboard computer chips adapting to the new hardware. I think I got this right but please check with our mutual friends about this. Best of luck. Mark:wavey:

 

[AdvAutoBob]

It's posts like this one that reinforces my statement to prospective clients that dyno numbers in and of themselves are not the "end all be all" that most forum guys think they are. Dynamometers (chassis and engine) are simply tools, nothing more, and are subject to error and/or manipulation.

This being said, have you tried a different shop, or spoken with other clients of this shop? Perhaps it's simply a calibration/operator issue and you might be chasing ghosts...

Hope you get it sorted out...