At the dealer I used to work at, people would rev engines to redline as soon as they started them. I cringed every time. I hope to gawd nobody will have done that to the FR-S I buy.

Playing around with a gearing spreadsheet and eye-balling a couple of the dyno screens I noticed a couple things about the dip/flat-spot. First thing, is in performance all-out redline shifting, it has basically no effect. The rpm drop from the upshifts at 7400+ rpm always (well almost, 2nd starts just a wee bit from the flat area) put the next gear's rpm in the upper super-flat torque area. I calculated the following;
1-2 @ ~4500
2-3 @ ~5200
3-4 @ ~5800
4-5 @ ~6100
5-6 @ ~5700

@ 4500 rpm the dip is starting its rise and is probably ~90%+ of peak. So shifting at redline we will probably (based on the dyno graph accuracy) ALWAYS have at LEAST 90% (95%?) of max torque AVAILABLE ALL THE TIME.

The second thing is what the dip may be like while putting around town. Given the curve, based on feeling the torque taper down for the dip it may encourage short shifting at ~ 3600 rpm which puts the next gear just on the other side of the low rpm peak (which looks very close to the 151 total peak). So it will probably feel pretty strong even taking it easy. Maybe a minimum of 80% of peak available in this operating range.

Only places I could see the dip being noticed are on the highway and trying to accelerate from cruising to passing without downshifting, and light aggressive (no wheelspin) launch in first gear only (like taking off gently then punching it).

Lastly with the power, torque and rev limit shifted up ~ 800 rpm, plus a ~5% torque increase in the upper range (5k+), and a 4.3:1 rear end (Mk3 NA Supra, if the guts are interchangeable), this car would run with an out-going model GenCoupe V6. This may be just headers, intake, exhaust and a re-flash. But would probably kill the nice putting around town effect.

Other thoughts? Corrections?

ive done the calculations and for a 86 to have the same power to weight as a 3.7 v6 mustang you would need 200 whp prob 205-210 to be at the v6 gencoupe power to weight

intake, headers, exhaust should add the 20 whp you would need to be that fast in a straight line, but we would leave them around the corners with out a doubt

When I head from the review about this dip, and then it got confirmed by the dyno graph, I made excactly the same interpretation as you. And in fact the dip does not hurt unless you drive the car as if it was turbocharged. When I drive normally in my car which has a similar torque curve, with the dip but still less flat, I shift between 2.5-3.5K, I the car pulls quite well. When I do a spirited driving, the I use the range between 4.5-6.5K. The GT86 will be far better.

It's not only about power to weight, but also wheel torque to weight and shift points which has to do with where in the rev range torque is made, gearing multiplication, how much rpm you have available and wheel size.

yup :D im just saying that its close enough, the 86 is geared a bit better for torque, weight also helps the 86 aswell

the mustang and gc has a larger contact patch when it comes to tires

ill do my mods and put it up against my friends 3.7 andd see how things compare


im just speaking theoretically ofc

Not to resurrect an old thread, but I thought it'd be interesting to compare the COBB dyno to the January 2012 screencap.

To recap, Spaceywilly and Ryephile plotted curves based on the Jan 2012 screencap, but the plots showed peak power and torque coming at earlier RPMs than the official numbers, and much lower tranny losses than one could reasonably expect (only 3.5%). It seemed too good to be true, and there was speculation about the hard-to-read scale. WingsofWar plotted a hypothetical curve with a different scale.

Earlier in this thread, old greg and I had plotted wheel torque for the original crude curve from the .jp website, and then I later plotted against both interpretations of the screencap.

Now a video has surfaced showing results from a COBB dyno run of a stock BRZ. My initial reaction was "Oh, only 164 whp... that's a bit low." Then I looked more closely and realized its shape is close to the original interpretation of the Jan 2012 screencap. Output is lower, but it still seems too good to be true. If COBB's dyno run is representative of a typical BRZ:

• Peak torque is at 4500 and 5800 RPM (official spec is 6600 RPM)
• Peak power is at 6200 RPM (official spec is 7000 RPM)
• Peak power is a tad low due to the 6200 RPM dropoff
• The FA20 is underrated below 6200 RPM (since it shows a tranny loss of only 6%)

COBB's dyno stopped at 6800 RPM; here's a plot assuming it continues to drop at the same rate until 7400:

https://lh4.googleusercontent.com/-4...+dyno+COBB.png

Wheel torque for 6MT with 4.1DR (using a tire dia of 24.3"... it might be as low as 23.9" or as high as 24.6"):

https://lh5.googleusercontent.com/-U...eel+torque.png

Estimated Acceleration vs 2004 WRX:

https://lh3.googleusercontent.com/-S...celeration.png

Something seems amiss because the 2004 WRX's traction advantage shouldn't be enough to overcome a deficit this large (going by MT's BRZ test, the 2004 WRX hits 0-60 and the 1/4 in less time, but the BRZ traps at a higher speed).

Of course, I'm comparing cars run on different dynos with different conditions (and perhaps COBB's BRZ had an especially strong engine or the WRX from that dyno was on the weak side).

Estimated Acceleration vs 2009 WRX:

https://lh3.googleusercontent.com/-E...celeration.png

Estimated Acceleration vs GTI:

https://lh4.googleusercontent.com/-e...celeration.png

:clap:

Quality stuff good sir. Now if we could just work that terrible dip out of the curve we would be in business.

Interesting thing about the 'too good to be true' numbers is that someone said that Cobb uses a Mustang dyno which is one of the 'heart-break' dynos. Very curious what an inertial one like Dynojet will read.

Here's my revised torque at tire plot based off the InsideLine dyno, where RPM scale is easily readable. My assumptions are using 844 rev/mile for tire rolling size.

Just saw this thread. Great job Deslock and Ryephile, very useful data there. Looks like optimal shiftpoints for the BRZ are: Redline in 1st and 2nd; Few hundred RPM short of redline in 3rd-5th.

Observation for AT ?
 

Originally Posted by old greg http://www.ft86club.com/forums/third...s/viewpost.gif
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?

Real world RPM curve
 

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.

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.

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.

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

More Ponies please
 

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! :burnrubber: