Increased MPG or HP anyone????

[07WYarisRS]

FWIW if you know how a transmission works AUTO or MANUAL a gear ratio CAN NOT CHANGE ON ITS OWN. RPM MUST be the same. Ron is 100% correct
Adding any component to the intake or exhaust CAN NOT lower or raise your gear ratio or cruise speed RPM. It's impossible.
If you say it can please by all means explain this mechanical phenomenon to us

Man I love it when people that have no idea how fuel injection or carburetion works post in threads like these. Gives me something to laugh at and makes my day.

As for more HP = less MPG
Yes, usually

An engine is basically a big air pump the more air you let in and out the bigger the combustion. BUT in order to maintain reliability the fuel injection system will always maintain a PROPER fuel/air mixture (stoich) 14.7:1
That's 14.7 parts oxygen to 1 part fuel
That's what oxygen sensors are for. They read the mixture levels and send the info back to the ECU so it can correct the fuel trims and injector timing to maintain the 14:1 mixture.
Regardless if you lower the air temps or even force air in via a turbo or supercharger the STOCK ECU can alter the fuel injection over a WIDE range to maintain the proper fuel mixture. If the car is run higher or lower then this fuel mixture it will cause serious engine problems. And NO matter what you do as far as bolt on the ECU and FI system and the dozens of sensors on this car will maintain the perfect fuel mixture.
If you add more air or colder air it MUST ADD MORE FUEL.
Saying the EFI will not add extra fuel for more oxygen is just silly. That means nobody here can drive their car from here to Florida then up into the high mountains of Colorado with out serious tuning issues? Give me phuckin break. The ECU and EFI system will compensate for air temps, humidity, intake air volume and YES altitude. It has to compensate otherwise you car would run like ass.

If you allow more air into the engine buy either changing the intake or exhaust or both the engine MUST add more fuel. If it does not you run lean and even a little bit lean will cause DETONATION, PRE-IGNITION, and both will destroy your engine. Most engines also use a knock sensor that listens for any signs of detonation or pre-ignition and will alter the ignition timing to compensate (none of which adds power but infact greatly reduces it to prevent engine damage)


The reason people don't often see a MPG difference is because under normal driving conditions or at cruise speed there is no HP gain
Look at the latest dyno results posted in the WR secret weapon short ram intake thread.
There is no noticeable HP gain until after 4500 rpm. The intake or exhaust don't do a damn thing before that rpm range and as long as you drive in this rpm range your mileage will remain the same.
At 2000-3500 there is no big gain BUT drive in the power curve 4500rpm + and you will see a loss of MPG because with more air, there is a need for more fuel.

Anyone that says they feel a difference in power 1hp at normal cruise speeds is completely full of shit.

That's why colder weather/air temps make every FI engine harder on fuel. Colder air temps mean more dense air = more oxygen and more oxygen means the car must inject more fuel to maintain the proper fuel/air ratio (stoich)

Plain and simple
Colder the air temp = more oxygen= more fuel (to maintain stoich) = more hp
More air volume = more oxygen = more fuel (to maintain stoich) = more HP