<blockquote><font class="small">In reply to:</font><hr>

Stillen pulled 7.1 rwhp and 7.3 ft/lbs torque rather than the 8.1 rwhp you show. Didn't their ads claim 15 hp gain?

<hr></blockquote>And their ads may still be correct. Note that the 7.1 ( or 8.1 ) hp gain was at peak power rpm. What isn't shown is that at redline the engine may have made 15 more hp than stock. This is why so many aftermarket companies' claims have to be carefully examined. Their ad does not say a 15 hp gain in peak power. They are telling the truth if at any point on the rpm curve the engine made 15 more hp than it did stock stock at the same rpm.

 

For all of ya considering about NISMO, I have to mention that it WILL make your car more quieter than stock below 3000rpm. I was really suprized how quiet this muffler was.

Nuttin chillin in da holydae in

 

Fluid: Actually, their summer 2003 ad in SportZ magazine claims a 13 HP gain. What you suggest is just not possible looking at the Dyno curve on the day the shootout was run. After peak, HP decreases despite increases of RPM.

03G35c/C_Blue/Willow/5AT/Prem/Splash/ SteetPilot 2610/V1/SAT/XM/18" PermaStar rims w/NITTOs/Borla True Dual Exhaust/Gialla Grille/Z Intake/Dynamat Door Kit.

 

Hey, I was just respnding to the comment made by another poster suggested 15 hp. It doesn't really matter what the dyno readings you saw were ( anyone with much dyno experience knows that values can change day-to-day - and who knows what other mods Stillen may have had on their test G prior to installing the exhaust). The point of the post, which many (most?) readers don't seem to understand, is that aftermarket claims are not always what they seem to be. A 15 (13, 11, 9, whatever ) hp gain could be at any rpm, and is not always ( or even usually ) at the power peak. The aftermarket manufacturers WANT us to believe that their product increases the maximum power value, but often that isn't the case. Some products may actually decrease the maximum power, yet still give a total performance increase to the car. That last concept is apparently difficult for some to comprehend....

 

Fluid said: "Some products may actually decrease the maximum power, yet still give a total performance increase to the car. That last concept is apparently difficult for some to comprehend...."
No wonder. It sounds completely contradictory. How do you decrease power yet recieive an increase in performance???

03G35c/C_Blue/Willow/5AT/Prem/Splash/ SteetPilot 2610/V1/SAT/XM/18" PermaStar rims w/NITTOs/Borla True Dual Exhaust/Gialla Grille/Z Intake/Dynamat Door Kit.

 

No disrespect intended, but only amateurs rely on peak power values when analyzing an engine's performance. What matters - if maximizing acceleration is the goal - is the area under the power curve. The engine with the greatest usable area under that curve will have the best acceleration in the same vehicle. It is clearly possible to reduce the peak hp by 5 yet at the same time increase the hp at redline by 20. If the resulting area is greater, then the car will be faster even with less peak hp.

This fact is not that difficult to comprehend, and is one reason that two cars with the same peak hp can have markedly different performance - one has a greater area under the power curve.

A not-too-perfect analogy: a 4000# car has a 2.0 liter engine making 250 hp. An identical 4000# car has a 4.0 liter engine making 245 hp. Which one will have the best acceleration?
Hint: not the one with the highest horsepower.

 

that analogy is kind of misleading...

<font color=white>Pearl Ivory</font color=white> G35 Coupe 6MT Prem/SplashG/BSM, <font color=red>Injen CAI</font color=red>, <font color=red>Injen Super SES</font color=red>

 

Well, I did say it wasn't perfect. However, it isn't misleading at all to anyone who understands how power is made. The question was - how can an engine with less horsepower give higher performance. The 4.0 engine in the example will have a broader power curve and thus much more area under that curve....and that means more performance. The same principle applies to ALL engines.

This is still a good example of why it is foolish to rely only on a peak power value to evaluate an engine's performance. The entire usable power curve needs to be examined to learn the truth....that was my whole point. If all you're interested in is bragging rights, then we can sh*tcan track results and just race peak dyno values.... :^)

 

IMO... High across the board torque wins races, especially on the street. Peak horsepower numbers are for the novice's bragging rights.

 

Fluid: Thanks for the detailed explanation --- that's why these forums are so valuable.

03G35c/C_Blue/Willow/5AT/Prem/Splash/ SteetPilot 2610/V1/SAT/XM/18" PermaStar rims w/NITTOs/Borla True Dual Exhaust/Gialla Grille/Z Intake/Dynamat Door Kit.

 

I understand everyhting that has been said and it makes sense. Now, if I just went in and got a new exhaust, how would I know which one would provide me with the best performance? Is there a way to tell this? Help me understand. I do understand that lower hp can provide more performance, but how can I tell a difference between the exhausts in performance?

Ryan

03.5 Red w/ Willow G35 Coupe, Premium and Nav
Strictly stock for the time being.

 

That is always a problem, since many ( most? ) owners are more interested in the exhaust sound than they are in performance. Just a change in sound level or pitch can "fool" us into thinking the car is faster, while in reality it may be slower or the same.

The only way to know for certain is to either dyno the car before and after ( where differences of 2-4 hp can be meaningless ), or go to the track ( the problem there is conditions can change daily, ruining any comparison ). One of the Mustang magazines did a comparison dyno test of 20+ mufflers on one car in one day, and the result was virtually no statistical difference between any of them! Sound was the major differentiator.

Bottom line is tough to determine. Probably our best route is to ask as many different G owners which exhaust they use and why they like/don't like it. Even comparing track times is not too exact, due to different tracks, drivers, and the natural difference between different cars. Perhaps the non-performance guys have the right idea - go for the sound you like. Wish I could be more helpful!

 

Thanks for the summary niko. Have to say, I'm a bit disappointed with the Borla. Out of the current options, that was the one I was leaning towards.