BRZ / FR-S Boxer Engine Dyno Powerband revealed

[smbrm]

Originally Posted by old greg
Manual = Blue
Auto = Red
Purple = Manual 5th and Auto 4th

Attachment 4646
Attachment 4647

It looks like the car would benefit from a few more rpm up top, even without any mods.

When I look at this speed vs. rpm curve in attachment 4647, I wonder how often you would even use 6th gear in the automatic? Assuming you are maintaining the speed limit of 70 mph, you do not have much torque in 6th. So while you may be using the box more in the manual at low speeds, you will probably be using the paddles more at high speed in the automatic to manage hills on the highway? Just wondering if anyone else sees it this way?

[Dadhawk]

Originally Posted by smbrm

...When I look at this speed vs. rpm curve in attachment 4647, I wonder how often you would even use 6th gear in the automatic? Assuming you are maintaining the speed limit of 70 mph, you do not have much torque in 6th. So while you may be using the box more in the manual at low speeds, you will probably be using the paddles more at high speed in the automatic to manage hills on the highway? Just wondering if anyone else sees it this way?

I recently drove the AT through back roads of the mountains of North Carolina, and on the freeway through same said mountains. The AT had no issue maintaining speed in 6th gear from what I could tell, including grades that trucker warnings on them (6% or greater). This included on and off cruise control on the highways.

In the mountain roads I was enjoying myself so I had it either in Sport or Manual mode, never got into anything higher than 4th during that time. Regardless of the grade the FR-S had speed it left on the table because of my unwillingness to drive it faster. I was doing 25-35MPH marked curves and switchbacks at 45-60MPH the entire time.

I will say that when passing, the AT had to kick down to 5th gear. Sometimes I dropped it down to 4th or even 3rd gear at highway speeds to pass and stay in the upper torgue range. 3rd was never really necessary, just having some fun after finally getting through the break-in period.

Some more details in my Owner's Journal if you are interested. Hope that helps.

[smbrm]

Originally Posted by ZDan

At low engine speeds, the hydrodynamic wedge that supports the conrod bearings isn't as strong. Consider the film strength of the oil in the bearing gap with no relative motion. Weak. Applying full torque is a bad idea at low engine rpm...

At high rpm when inertial loads dominate, the high speed gives a MUCH stronger hydrodynamic wedge to support the conrod.

Agreed,

At low engine speeds it also depends on the temperature of the oil as the film thickness will be effected by viscosity as well as speed.

At higher rpm the shear loads on the oil are higher so there is more temporary viscosity loss in the oil(depending on its design) which can contribute to reduced film thickness particularly with higher loads.

Flow volume can be more important than oil pressure, in both cases as you need to keep feeding the wedge. So oil that is too thick at low speed can starve the bearing while oil that is too thin cannot provide the support.

Oil that is too thick at high speed can create too much oil drag and impact power and fuel economy.

It is a complex balancing act.

[smbrm]

Originally Posted by Dadhawk

I recently drove the AT through back roads of the mountains of North Carolina, and on the freeway through same said mountains. The AT had no issue maintaining speed in 6th gear from what I could tell, including grades that trucker warnings on them (6% or greater). This included on and off cruise control on the highways.

In the mountain roads I was enjoying myself so I had it either in Sport or Manual mode, never got into anything higher than 4th during that time. Regardless of the grade the FR-S had speed it left on the table because of my willingness to drive it faster. I was doing 25-35MPH marked curves and switchbacks at 45-60MPH the entire time.

I will say that when passing, the AT had to kick down to 5th gear. Sometimes I dropped it down to 4th or even 3rd gear at highway speeds to pass and stay in the upper torgue range. 3rd was never really necessary, just having some fun after finally getting through the break-in period.

Some more details in my Owner's Journal if you are interested. Hope that helps.

Thanks Dadhawk, that is indeed useful information. I was wondering about the response in this type of scenario. It sometimes hard to tell the response on the slopes of the torque curve. Was the transmission downshifting from 6th while in cruise control? How controlled was that, would it shift down sequentially or also jump gears eg. 6-4th?

Where will I find your owners journal?

cheers

[Dadhawk]

Originally Posted by smbrm

Thanks Dadhawk, that is indeed useful information. I was wondering about the response in this type of scenario. It sometimes hard to tell the response on the slopes of the torque curve. Was the transmission downshifting from 6th while in cruise control? How controlled was that, would it shift down sequentially or also jump gears eg. 6-4th?

Where will I find your owners journal?

cheers

Member's Journal section is on the main page, mine specifically starts here where I am tracking mileage, driving experiences, etc using the FR-S as a daily driver.

It did occasionally shift down to fifth while in cruise control on a particularly steep or long climb, but its an almost undetectable shift (very some, no jerk, etc). I have not experienced it jumping from 6th to 4th directly, although it may if you really stick your foot in it, I have not tried that. Anytime I was being that aggressive, I manually shifted using the paddles.

Bottom line is 6th gear is definitely a "cruising gear". I've posted photos of at speed in 6th car and its barely breaking 2K RPM. Either you or your computer will down shift if you want to gain speed.

[smbrm]

Originally Posted by Dadhawk

Member's Journal section is on the main page, mine specifically starts here where I am tracking mileage, driving experiences, etc using the FR-S as a daily driver.

It did occasionally shift down to fifth while in cruise control on a particularly steep or long climb, but its an almost undetectable shift (very some, no jerk, etc). I have not experienced it jumping from 6th to 4th directly, although it may if you really stick your foot in it, I have not tried that. Anytime I was being that aggressive, I manually shifted using the paddles.

Bottom line is 6th gear is definitely a "cruising gear". I've posted photos of at speed in 6th car and its barely breaking 2K RPM. Either you or your computer will down shift if you want to gain speed.

Yes, I would agree very much so. If you want MT 6th gear performance, just use AT 5th! Its almost the same!

[Tradewind]

This from Car and Driver

The BRZ’s 0-to-60-mph time of 6.3 seconds and 14.9-second quarter-mile

A Camry could almost hit that quartermile time

Time for mods )

[Jordo!]

Originally Posted by Tradewind

This from Car and Driver

The BRZ’s 0-to-60-mph time of 6.3 seconds and 14.9-second quarter-mile

A Camry could almost hit that quartermile time

Time for mods )

Yeahhhh.

Bring on the twincharger!