I'm not trying to make a case either way. I just bring this up to stimulate some thoughtful disussion. So, to keep this as productive as possible, please debate the technology not someones post.

What measurable effects doAir Kits such as the K&N system have?
What measurable effects aftermarket engine control computers have?

I think the engineering facts are:
1. Fuel injected engines need calm cool air to produce their maximum horsepower.
2. Automobile manufacturers include in their designs quieting techniques to the air intake.
3. Automobile manufacturers are required to meet federal CAFE standards andtherefore they design in as much HP and fuel efficiency as they can.

Question: If these aftermarket air kits and ECU's did such wonderful things, whyhasn't HUMMER put them on?

 

Test conducted on airflow show that aftermarket CIA's flow more air than stock but also show that stock air filters will and do flow much more air than a stock engine can pull. Tests also show performance air filters do not filter as well as stock filters.So IMHO waste of money with stock engine.The increased noise probably gives more of an impression of increased performance than anything. Dyno reports done by those selling the CIA’s show horsepower increases but at max engine RPM’s not where I run my engine. Would like to see dyno results from independent party.And yes I have used them in the past but have never felt they were worth the money. I know everyone that has one will dissagree with me but that is OK. If you like them and want one get one.
As for tunes and tuners have used those and have seen some improvements. But the tuning has to be done to give the changes you want and need to be useful. Tuning for max horsepower will help a drag racer more than a casual off roader. I think off road low end torque will benefit more than horsepower at max RPM. But just my opinion your mileage may vary.

 

FICTION!!!!

 

This may help answer questions on air filters.


http://www.duramax-diesel.com/spicer/index.htm

 

Remember, it's not the peak HP but the area under the RPM-HP curveplotted on a graph.
I have owned several high performance cars over the years, and I really could never detect the 10 HP increases promised by cat-back exhausts, or the 7HP increases promised by high-flow air filters (numbers based on the cars I owned). In fact, with the Mustang GT I had, hooking up smoothly at launch had far more of an affect on acceleration than any mods I added.
At the drag strip I believe torque influences ETs while HP influences trap speed.
Anyway, I don't intend to drag race our H3 any time soon. ;o)

 

There is a limit of performance and production costs that the manufacturer has to balance. If you want something that has had every inch of every element performing its job to the max of its intended purpose, get a Bugatti Veyron or similar car. But even on that car, the manufacturer loses money for each production because of the high costs.
As to determining the cost vs return, you have to remember that for the 5-10hp are-engineered intakecan produce, a human in decent shapecan produce about 1.5 horsepower.Having a base team of engineersre-engineer and testa component for amonth during production can cost up to $20,000-$30,000 just to evaluate the component. So if you want to consider how much power something is going to add, screw horsepower, think about people power. To squeeze out 5 ponies, the result will be the same as having about 3 of your buddies pushing your truck when thereare already 147 otherpeople pushing.

 

Well that's a new take on it.

 

The biggest restrictions in stock intakes are silencers that are put in by the manufacturerto reduceNVH. These don't so much affect HP as they do throttle response.

The main performance increase you see fromaftermarket PCMs is with the shifting of the automatic transmission. While a firm shifting transmission will last longer than the mushy stock one, buyers don't want to spill the Starbucks.

Manufactures must consider NVH, longevity, EPA etc... aftermarket, not so much.