see what you said is exactly what the mechanic said, except a little different with the ecu part. He said when the car is in 6th at 2k rpm, and you floor the gas the ecu wont allow any more fuel then the engine is requiring to maintain that speed. so even though your flooring the gas, the throttle body is still not opening all the way because it is computer controlled therefore limiting the amount of air/fuel coming in.


and who the hell called you dawg? lol

 

That doesn't sound right.

 

You're not kidding.

Each cylinder gets charged and fired once every 2 revolutions regardless of the load on the engine at the time. The volume of air is fixed by the displacement, and there's obviously a lower limit on the A/F ratio even in an engine braking, downhill or idle situation, not to mention a 6th gear cruise. All other factors being equal, 60mph in 6th gear at 2,000 rpm will burn less fuel than 60mph in 3rd at 4,700 rpm. For the same reason, an engine idling at 700 rpm in neutral will burn less fuel than an engine revving at a constant to 2,000 rpm in neutral. It has nothing at all to do with "acceleration potential" or "doing work".

 

Crap I can't find where I read this but I could swear I read that the Navi is using the vacuum reading to calculate the real-time MPG display....

 

+1^^ LOL

 

Running engine at lower rpm (i.e high gear) will almost always yield better better milage. That assumes that one doesn't run at such low rpm that the engine grunt, and knock to generate enough torque.

The trade off is high efficiency on a G35 (in high gear) that perform like a nissan sentra vs decent efficiency on a G35 that performs LIKE A SPORT CAR.

At a certain speed, the amount of POWER TO THE WHEEL needed to overcome air resistance and road friction is the same regardless of what gear, or RPM the engine is at. However, how much fuel the engine uses deliver that power to the wheel differ greatly at low rpm vs at high rpm.

At high rpm and in LOWER gear, a larger portion of power is taken to overcome engine friction power (negative power). In addiction, a combustion (gas) engine always give better efficiency yield when more time is allowed for more gasoline to burn completely (gasoline reaction rate), i.e at low rpm.

Try driving in low gear for a whole tank of gas, then you'll see the low milage.

How could the nav calculate milage accurately ?????????????

Don't trust the nav to give accurate milage.

 

Yeah we are saying the same thing, I think.

hehe jackygor said "thanks dawg"... had a highschool flashback.

 

I'm about done here... but it does so by getting a data feed from the ECU. SO, quite easily, it watches the vacuum. Driving in lower gears is hard to be efficient because it's easier to accelerate faster and thus use more fuel... higher gears/lower rpms "smooth" out your acceleration.

 

Idle is below 1500rpm and thus will be fed fuel to avoid stalling. All the things you said are true if you are not consider the momentum of a 3500lb vehicle traveling at a certain speed with the wheels interlocked to the engine flywheel. W/ the engine receiving no fuel the car will still take some time to stop, and all that energy makes it easier on the engine to maintain speed or gently accelerate.

The things you said are obviously true if you are sitting still in neutral. I'm done arguing tho... believe what you want

 

Whatever. I wasn't talking to you at all, let alone arguing with you. Haesvelg commented on the fact that one (how to pick just one?) of your statements
was questionable, and I was agreeing with him. The last three posts in a row are yours, so it's an argument of one (and you don't seem to be winning).

But don't let reality get in your way. You seem to have a good imagination when it comes to internal combustion, so... good luck with that.

 

oh man, now i m just confused

 

another way to squeeze the most mpg's is to use cruise control...

you manually doing 75 vs cruise control doing 75...

cruise control will get more mpg's

 

Not in my case. But I allowed my speed to vary depending on the incline.

 

++1

 

the high way i drive to go bak home has 75 mph speed limit.
i tried going cruise control all the way home on 75 mph
Next time I tried doin 85 mph and my mpg gallon was better around going 85-87 mph on freeway.

I might be wrong though..or was just imaginaing.