Does increasing your cars horsepower increase your cars gas mileage (through intake and exhaust means), assuming nothing else changes.

I know this is probably a noobish question, but I tried Googling this and found nothing.

 

It depends on whta mods you do.

If you wee to install a Short Ram or CAI with a GOOD filter (Fujita, AEM, Injen, K&N, etc) you will get better milge as your car will get "cleaner" air. Cleaner in the sence it will be smoother an dless turbulant.

The same with exhaust. I personally gained a few PG and a few HP/TQ when I swapped my D16y7 exhaust over to a d16y8 exhaust. (Granted there were other problems but that is another story)

Either way I/H/E is about letting the engine breathe better. If you can do that, it will make more HP and have better combustion, ergo also increasing your mileage.

 

Keep in mind that horsepower is gained by adding air and fuel. The more power you make, the more air the engine needs and the more fuel it's going to have to use to create the proper air/fuel ratios needed for combustion. More fuel being used means worse fuel economy.

With bolt-ons like intakes, headers, exhausts, etc, the difference in fuel economy would be negligible though.

 

OK, My muffler and possibly the rest of my exhaust needs to be changed anyway, just wondering if it would help any in that arena.

Thanks for the info

 

Generally speaking - no, but you can increase gas mileage by changing gears (numerically lower gear ratio) or buying lower rolling resistance tires and lighter parts - like wheels and a stainless steel exhaust. Still, it is very difficult to gain fuel mileage without changing your driving habits.