If it were possible to have a lower revving 6th gear, would this car get better highway mileage? Like, if we were cruising at 2K rpms, wouldn't we be in the 3*mpg range? If you needed to accelerate you could just downshift to 5th like most probably do anyway. I don't know if that's too big a jump in gearing though and if it would shock the system.

Personally, I don't care about the gas mileage, but this would give people better range if they routinely take long trips. I just got 19.33mpg and I thought it was well worth all the enjoyment of driving this car. I was more interested in what specifically causes a small displacement engine to be less efficient as my h22a4 was and now this f20c. It seems to me like revs would be it.

 

What you call inefficient is only so in one way, fuel economy, Our engines are EXTREMELY efficient at making power for a NA 4 cyl.

 

im extremely happy with the possible fuel efficiency of this engine.

 

Definitely, I'm just talking about miles per gallon here. I wanted to pin down what makes it 26mpg highway or whatever it's supposed to be. I'm thinking the 11:1 compression doesn't really make it less efficient from a fuel standpoint, right? Edit: If anything, the compression should be making it more efficient. Which means that if you geared it differently, this engine would be more efficient than a 2.0L in an econobox, right?

 

this has been discussed endlessly. i suggest you search. i'm really surprised this hasn't flamed out already...

 

There are plenty of gas mileage threads, but I don't see where the specific reasons for it are discussed. The actual, mechanical reasons. That's what I'm interested in. This isn't whining about how my sports car burns gasoline, this is me wanting to know specifically how this car works instead of assuming the engine is filled with gremlins who blow pixie dust into the cylinders.

Thanks for the helpful info though, pal.

 

Looking at other sites, it looks like revs do have everything to do with it. As such, the question becomes, "would it be possible to make 6th gear tall enough to make a significant gas mileage difference in our transmissions?"

Like take rob's thread where he was trying to increase range with a fuel cell or something for when he runs from the feds. Wouldn't it also be possible to have a really tall 6th gear and get the same effect as adding a lot more gallons of capacity to the tank? At some point the gear just won't fit in there or the jump between 5th and 6th will be too great. I'm kind of wondering how many teeth you could realistically add and what the difference would be. I know Honda made something like 4-6 taller in AP2s, but how many teeth is it, and how many more could you add to 6th?

 

Top down with speeds of 75-85 the car gets into the high 20s highway MPG. Top up and at 65-75 my AP2 will top 30 highway MPG. I'm good with it.

 

I get ~28mpg when it's all highway.

You might have some underlying issues causing your poor gas mileage.

 

Few things...

Look at a S2k dyno graph. See what RPM's peak tq is? That's why this car doesn't get the gas mileage of an econobox. The further RPM away you are from peak tq while cruising, the worse your gas mileage will be given a constant speed. The motor isn't neccesarily working harder, its just not as efficient. Hence the reason why 6th gear is higher in an AP1 than an AP2...when the tq curve shifted left with the step up to 2.2, the sweet spot for fuel economy also moved with it, hence revised gearing.

Want to see how much better your gas mileage will be if you cruised 6th gear at 2k RPM? Get on the hwy and try it. Here's a hint: the car doesn't move lol

I think I'm halfway right here.