The force required to push a car through the air at a maintained speed is always the same, the engine power output will be the same regardless of gearing.

This output is generated by the burning of fuel and is a direct result of such. The only thing that is going to influence the efficiency of this is the ignition timing, and airfuels. These are fairly well controlled. Rolling the engine 500-1000 rpm lower isnt going to do anything for you except for maybe slow the air down and reduce the efficiencies built into the motor.

As for driveabiltiy work, I did a bit of tinking and logging with my old Nissan, they run a hot wire maf so it is very easy to measure air volume. Coupled with a wideband, TP logging and a speedo, you can see the efficiency change between 4th and 5th gear at 60mph. It doesnt really change a thing.

 

Friction differential is going to be pretty minimal, like I said in my other post. If anything, dropping RPM's is going to reduce air speed through the intake manifold and head to a point where it is going to reduce atomization etc. There is a reason these motors make hp up top. I would trust that honda geared these vehicles the way they did for a reason.

If OP wanted to do an accurate test of this theory. Make a 100 mile trip @ 40mph in 4th gear, then again in 6th gear and compare the fuel economy change.

 

internal friction in the engine goes up exponentially with RPM, and it absolutely will be more efficient at 3500 RPMs that at 4500 RPMs. My fuel economy dropped 4 MPG on the highway when I installed 4.77 gears in my '02, and my fuel economy in my '08 AP2 is better than my '02 was with any gearing.

 

Internal friction is negligible in this situation. We arent talking about dropping the rpm from 6-3, we're talking 4-3, if even that. Folding your mirrors in would probably have more of an influence over MPG than dropping the revs, and again, we dont know that this will actually do anything because there is a trade off in fluid dynamics when you drop the revs.

Your 08' has better technology so it will definately getter better mileage.

Unless you calibrate your speedo when you change gearing and you were running under the exact same circumstances for both tests, 4 mpg is hard to measure. You might have been driving 5mph slower, been in colder air, had less air in your tires etc.

 

I did calibrate my speedo after installing the gears, and I did measure the drop in MPG in the most accurate way possible. I made a 16 hour round trip on the interstate with stock gears, and got 30 MPG, then made the same trip 6 months later with 4.77s and averaged 26 MPG.

Every person on S2KI that has experience with aftermarket gears will agree that their highway mileage went down. The fact that you disagree just means that you don't have any actual experience with what you're talking about.

 

BTW, the technological improvements in the '08 AP2 do not make it more efficient on the highway.

 

I don't want to beat a but the two examples I posted are new 2011 vehicles(with a V6) and they go down the freeway at very low rpm's unless you think 1500@60 mph is "not" low rpm . They do that to meet the new Fed. gas mileage requirements and I can show you that most car manufacturers do this to meet the new reg's on gas mileage. I don't know of another car(mine is a '06 S2k) that cruises down the freeway at 74 mph@50% of it's rpm limit(well maybe the Smart Car). The theoretical top speed of the 2011 V6 Mustang is about 260 mph, I just want to increase the theoretical top speed of my S to around 170 in 6th so it would cruise down the road at a lower rpm. I like the first 5 gears in the S but 6th could be higher for me and that is the magic word "me". I would never try to talk you or anybody else into doing to their car what I would do to my car. That is what this and all forums are for or should be for.

ROD

 

These are higher displacement engines with torque, if you reduced the gears on a 2K, it would likely bog with any acceleration @ 70mph and your fuel efficiency would go out the window. 6th gear is already gutless, go ahead and get some custom gears made so you can lower it, Im sure you know better than Honda.

I had a mid 90's civic VX, it had extremely long gears and would rev down the highway at 2000rpm, it got 50mpg but it also did nothing when you pressed the gas. If you think modifying 6th would somehow improve your driving experience and yield better gas mileage I think you're dreaming.

 

You are an idiot for not under standing what we some of us saying,

the point is this, drive your car around in never going into 6th gear. according to what you guys are saying you will get better gas milage this way since it will be easier to accelerate. your retarded. Second who accelerates in 6th gear. noone, you down shift to accel. maybe you guys need to learn how to drive a manual again.


The fact is I will NEVER acclerate through 6th gear. I could care less how fast i can accelerate in 6th as i will ALWAYS down shift to go faster. So drive your cars around in 5th gear, and see what kind of gas milage your getting, then drive your car aound using 6th gear. again record your milage. i can garuntee that there will be a difference and it will be higher while using 6th gear. NOw what if we had a 7 speed, can we all agree that it would be higher than 6th. would that increase MPGs? most likely, so there fore why dont we replace the 6th gear with the ratio of 7th. since the gap between 5 and 6th is not really an issue inless your constantly racing over 100 mph and need to power shift 5th. I wont be as i would probibly end up in jail for reckless driving.

 

Did 2 different people write these 2 paragraphs? You don't even understand your own experience with higher gearing, even though you actually typed it?!? Do you not realize that the higher gearing in your Civic VX was the REASON why it got 50 MPG? Do you not understand that the LOW gearing of the S2000 is why it is one of the few 2800 lbs 4 cylinder cars that can't get 30 MPG?

I consistantly got over 31 MPG in my '94 Lincoln Mark VIII, but I never got over 30 in my '02 S2000. The EPA ratings even show the Mark VIII having equivalent MPG's for city AND highway! Is that what you would expect from a 1994 US built V8 boat compared to a "high tech" 2000+ light weight 4 cylinder import?

Pull your head out of your ass! The OP is wanting to improve 6th gear CRUISING, not accelleration! Anyone who wants to have "power" for accelleration in 6th gear is just dumb!