Official BRZ MPG Numbers. Big Gear Ratio Differences?

[Lonewolf]

Originally Posted by serialk11r

Manual transmission has same ratios as the S15 Sylvia (6th gear is 0.767), auto has same ratios as IS250 or something (evenly spaced, starts at ~3.6-7 or something, 6th gear is 0.582, 4th is 1.000), both are 4.100 final drive in the US. Markets with the stripper model have a 3.727 open diff option. The 6th gear in the manual transmission revs 30% higher than the 6th gear in the auto, which a lot of people are kinda upset about.

It's been posted at least 20 times already...it came out with the BRZ specs/options brochure in December/January ish. You seem like you usually post good stuff, I was hoping you'd find it in a search.

I saw some numbers thrown around like that...but I didn't know if they had been confirmed for the US market and if the same numbers also applied to the FRS...

That is exactly the type of info that I was looking for...thank you :happy0180:

[dhpinoy]

Originally Posted by 7thgear

for fucks sake, did you not bother to read the technical discussion posts right above you?

like i said, "dumb person". I barely understood (understand now, but I dont get the diagrams). I'm still goin to school

[serialk11r]

Okay, it's like this. An automatic transmission these days controls the engine and gearbox together, so the gearbox can shift up very early and operate the engine more efficiently in the EPA test, where a car is required to accelerate at a predetermined rate at any given time. The manual transmission however is to be kept in the same gear until some speed, which could be much less efficient. Thus an automatic wins out in the EPA test, while in the real world normal drivers can do just as well with a manual transmission typically speaking.

Basically what it comes down to is, a manual transmission's fuel economy depends more on the driver. The computer is not necessarily "better" at shifting the gears for you (aside from the fact that it shifts faster), since the way it's programmed is a compromise.

[Jeff Lange]

Auto and manual have the same final drive ratios (4.10:1).

Jeff

[Allch Chcar]

Originally Posted by Jeff Lange

Auto and manual have the same final drive ratios (4.10:1).

Jeff

Negative. They have the same axle gears, 4.1. The Final drive is taller in the automatic. 3.14 for the manual vs 2.39 for the automatic. (Approximately based on the previously posted numbers, I don't have them memorized.)

I don't know about the typical driver but ecomodders and hypermilers tend to do better with the manual, despite the gearing disadvantage. For MPG, control is huge. Which is also why the autos get better scores on the EPA cycle.

Thanks for the writeup arghx7. It didn't interest me but hopefully that helped a couple of the guys understand it better.

[serialk11r]

Um Allch Chcar, I thought final drive typically refers to axle ratio?

[dsgerbc]

Originally Posted by serialk11r

Um Allch Chcar, I thought final drive typically refers to axle ratio?

He probably means "tranny ratio in 6th X rear diff ratio". I have heard people refer to that as "final drive ratio", although usually I'd associate it with rear diff ratio.

[Jeff Lange]

Common terminology refers to Final Drive Ratio as the Axle Ratio, it applies to all gears.

Effective 6th gear is what you are referring to, as that multiplies transmission/axle ratio.

Jeff

[Allch Chcar]

Originally Posted by Jeff Lange

Common terminology refers to Final Drive Ratio as the Axle Ratio, it applies to all gears.

Effective 6th gear is what you are referring to, as that multiplies transmission/axle ratio.

Jeff

Yep, that's right.

I misspoke. Must have been an off day. <.> *derp*

[serialk11r]

Well well well, Pekingduck has finally got us some real numbers to play with!

He said he averaged 29.5mpg on a mostly highway at 85-90mph (holy shit) trip, and 39mpg on a mostly highway 70mpg trip. Put through the ecomodder calculator, these points basically match the 1NZ-FXE's equivalent load BSFC points, and considering that his car is brand new and will probably pick up a few percent higher efficiency as he drives it, I think this is reason to celebrate Going off the 1NZ, 65mph should give 42mpgish, but it could be even better than that :O

The real interesting thing will be to see how this engine behaves under very low load, but I feel like they're never going to release a BSFC map

I think a 6th gear right in between the manual and auto 6th gears would be worth trying, with 15% longer 6th gear and looking at the same range of points that apparently approximately match the 1NZ-FXE, we can expect the difference to close to within 7% at the engine, 6% minus AT parasitic load 46mpg 65mph cruise anyone?

[Ryephile]

Very interesting indeed. Hopefully his numbers are typical, and the EPA estimates are very pessimistic [as I was hoping].

[Nibby1]

Anybody ever try or using an aftermarket throttle accelerator module?

[DarkPira7e]

[churchx]

Originally Posted by Nibby1

Anybody ever try or using an aftermarket throttle accelerator module?

You shouldn't. If you want more performance, see some ecu tuning solution (eg. OFT or Ecutek) (and throttle pedal mapping even stock is not too linear to open throttle much more in initial travel. Not sure it's worth to make it even less linear and further rob throttle fine control by those .. "modules").