Post by
Tony407 »
https://forums.nicoclub.com/tony407-u34190.html
Sat Mar 17, 2007 3:52 am
Well, I've been doing some reading here and there and I've come to some conclusions.
First of all, with every 10 degrees Farenheit difference in air emperature, you gain or lose about 1% of the engine's horsepower. At 325 HP, with a 10 degree gain in temperature, you'd lose about 3 HP. Considering my 3 tests were all within 6 degrees of one another, I can rule this out as a significant variable.
Second of all, if you have a restrictive exhaust and replace it with a less restrictive one, then you'll get more power. If the exhaust on your car is already free-flowing, then changing it won't help at all. The opposite is just as true: If you add a more restrictive exhaust, you'll get less power. Ideally, you'd want an exhaust system that's as free-flowing as not having an exhaust system at all. Same thing with an intake.
The whole idea of a cold air intake is that it reduces the temperature of the air sucked in by the engine. Assuming the air is actually cooler, then you should be seing HP gains consistent with the 1% HP gain with every 10 degree loss in temperature. Now I can't tell you what the air intake temperature is on our OEM intake systems vs. the intake temperature is on an Injen (although it'd be nice to do some tests, which is what Injen should have hopefully done before they produced these for consumer use.) But if you consider the fact that my runs have shown a DECREASE in HP as well as run times and speeds after I added my intake, then the Injen intake must be more restrictive than the OEM one (or) the air temperature it sends into the engine must be hotter. Or a combination of both? But I suspect that it's more likely to be an air restriction issue than a temperature issue, since the air filter element sits down so low in the engine compartment. Who knows. Without testing the air intake temperature and making some comparisons, we really don't know for sure.
Anyone disagree? Anyone have any better ideas?
Bottom line is this: I've done 3 sets of runs under virtually identical conditions. I had some excellent gains when I added the Element exhaust. Then when I added the Injen intake, those gains were gone and I was seeing pretty the same results I had with stock parts. I've therefore concluded our cars' exhaust systems are restrictive enough to see some decent gains with an aftermarket system but our intakes are a different story. Evidently, the OEM intake systems on our engines are very well designed. My advice to everyone is that if you want an intake for some performance gains - don't get one. If you want an intake for some nicer sights or sounds under the hood - get one. I am definitely happy with my Injen when it comes to the way it sounds at WOT!! And it looks good, too.
And anyone can theorize all they want. Unless they can show me how they've come up with some different numbers using an equal or better testing method than I did, it's just a theory.
I'm eventually going to pull the intake off and do another set of runs. I "should" get similar results to the 2nd set of runs I got with just the exhaust. If that's the case, I'll have an intake for sale. I love the way it sounds and looks, but if I can get decent gains with only my exhaust, then off it comes...
Tony