The FRS torque curve
 

How do the engine characteristics of the FRS/BRZ manifest themselves in the dayly driver situation?

Most have seen the information that has been posted regarding the torque curves for the FRS/BRZ. I saw an interesting article in Car & Driver today regarding a test drive of the BRZ in France. What caught my eye was the comment about the noticeable dip(~120 vs. ~150) in the torque curve between 2800 and 4800 rpm(C&D), (3200-4800 rpm according to the Edmunds torque curve). Comment was made about how a 3-2(if I remember correctly) downshift from 6000 rpm put you right in the middle of the dip and resulted in a sluggish response! The other comment was that, operating above 6000 rpm on the 2nd flat part of the torque curve delivered more acceptable performance, but at the expense of fuel economy, more like city than anywhere close to highway fuel consumption.

Now mind you a Boxster has a similar but smaller torque dip.

It makes me wonder what one might be trading in engine performance for the handling benefits of the FRS/BRZ? Example: The Scion TC with 160 ft-lb at 4000 rpm vs. 120 is almost 36% more torque to propel agreeably a heavier weight(but only by 10%) for the TC!

For those switching from a TC(as an example) to an FRS, I would not expect similar perception of engine performance?

I have driven an FRS, but unfortuately not long enough to really assess this observation.

Just wondering if anyone else has made any observations or has any thoughts on this observation?

Is this a track car first and a "potentially" lukewarm in the engine department dayly driver 2nd?

:popcorn:

You mention not noticing the dip, Im not surprised. I suspect you will really have to look for it or isolate the experience to make it anything concerning. The car already has meager TQ figures, so downshifting will solve the issue in less than a second.

I only went around the block, which isn't really enough time to even get used to the shifting characteristics.

http://blogs.insideline.com/straight...477-118670.jpg

http://img178.imageshack.us/img178/1...iontct2zd9.jpg

ohh yeah and the tc has a horrible tq drop off...

173 whp = 200 bhp = 14.5% loss

143 wtq = 165.32 tq

200 hp and 165tq vs 2ar-fe 180hp and 173 tq

2700 lbs car vs 3100 lbs car

tc
First Gear Ratio (:1): 3.54
Second Gear Ratio (:1): 2.05
Third Gear Ratio (:1): 1.38
Fourth Gear Ratio (:1): 1.03
Fifth Gear Ratio (:1): 0.88
Sixth Gear Ratio (:1): 0.73
Reverse Ratio (:1): 3.56
Clutch Size: N/A
Final Drive Axle Ratio (:1): 4.06

frs
http://kaizenfactor.files.wordpress....t261.jpg?w=640

4.1 final drive

the frs will def be faster

in first gear the frs puts down around 2458 lbft of tq
in first gear the TC puts down around 2486 lbft of tq

frs weighs 400lbs less, puts down 28lbft/tq less to the ground and get better real world gas mileage, plus its rwd :D


sorry i got bored and wanted to research and do maths...

I have commented in my review of FR-S, but I'll keep it simple for ya.

You won't feel the dip. Only way I kinda, maybe, prob, I think, felt it was 2 ppl in the car max AC. Even w that it was a big question in my head.

I didn't do around the block, but did full course meal. City, freeway, figure 8, autox, & track... Give or take about 5~6 hrs in the car.

The tC2 is not a willing performer. It's not "rev-happy" and has very poor throttle response. It's not all about the numbers.

this

i know its not about numbers, but i like math, but i dont like putting numbers on the frs/brz/gt86

A downshift from 6000 rpm would put you right in the middle of a dip in your engine block which, I'll admit, probably would have an adverse effect on response. ;)

VVT/or variable lift?...? direct injection also comes in at certain engine speeds, i believe it cuts off in the midrange

I understand the concern (as it is a big dip), but unless I'm missing something, all of this speculation is based off of ONE dyno (by Inside Line) on ONE FR-S. For those of you who have tuned cars before or even compared dyno graphs, it's very possible for two different examples of the same car to dyno differently even under the same conditions. So other FR-Ss (and BRZs) may not dyno with that kind of a flat spot. And considering how new this car is, this might be an early production hiccup that Toyota/Scion/Subaru might cure with a factory re-tune to smooth it out.

But seeing how both the hp and torque curves have dips in the same rpm range (and the hp curve is practically a rotated version of the torque curve, if you look at it), it might be specific to that one car and not necessarily the exact output that they had intended. They did mention that they wanted the punch to hit as low and as immediate as possible, but I don't think that they inteded a random 20 lb-ft drop from 3300-4600 rpm on an otherwise flat torque curve (for an NA 2.0-liter four-cylinder).

no its multiple graphs

http://blogs.insideline.com/straight...477-118670.jpg
http://www.ft86club.com/forums/attac...7&d=1328422528
http://photos-e.ak.fbcdn.net/hphotos...41539534_n.jpg

plus other na Subaru's do this, Porsche's, its related to the boxer design... and the angles of the exhaust headers as they leave the engine.. has partially to do with harmonics and a various assortment of other things...

^ Thanks for the update. I wasn't sure if it was common, but I had only seen it on that one Inside Line dyno.

Since it sounds like you're familiar with that, you mentioned it has to do with the boxer design... what about it causes it? And why can't it be remedied from the factory (or why isn't it)?

Yes I agree something like a 5-10 ft-lb drop would seem more reasonable. And the car tested in the C&D review, as may the torque curve car, may only have been an early prototype.

I did notice the car had a very responsive throttle!


I was just wondering if other new owners or those able to get extended test drives like ichitaka05 would be able to share their experience?

im pretty sure toyota knew there would be a dip right there from the get go, im pretty sure it was also considered when looking at DD gas mileage.

http://www.ft86club.com/forums/showt...200#post204200

this is the first 86 owner in the US and hes getting 27~30 mpgs with spirited driving and fast highway cruising speeds

from reading a lot of different threads I imagine the dip comes form a collection of these things:
1: header design due to boxer shape
2: harmonics
3: cam phasing
4: gas mileage(pretty sure the dip wouldnt look as bad if they didnt tune gas mileage into the equation)

some people say its the direct injection, but i disagree, when the car has the pedal to the ground, Direct Injection is always on
when we can get this car on a dyno and study timing, a/f ratios, duty cycles for port and direct injection, bench flow the heads, ect ect

we wont know for sure what this engine is capable of... but im excited for the first 10 years this car is out.... lots of dif mods, ill probably have 2-3 engines in my garage in 5 years just for tinkering :P

Thanks for the reply and also for the info. But on the topic of the dyno plot numbers possibly being due to intentions of better gas mileage, with a six-speed and its ratios, does anyone know at what rpms the car would be in when cruising at normal highway speeds (say, 60-80 mph)? And have any automatic FR-Ss been dyno'd yet? I'd assume that given that dip from ~3300 to ~4600 rpm, cruising speeds would put it at a bit below that unless you're going 80+ mph.

It will depend on what your expectations are.

For instance, even at the dip, the BRZ is putting down more torque than an RSX-S. I posted this graph on a different thread, but I think it helps put the dip into perspective:

http://farm9.staticflickr.com/8165/7...6e06d588_b.jpg

The BRZ makes more torque across the board, including at the dip, until 7000+ rpm. So if you think the RSX-S has adequate midrange torque for daily driving, then you'll think the BRZ is fine or even better (they're comparably geared).

If you haven't driven an RSX-S, you can substitute a comparable weight/torque car, like the 8th gen Civic Si, or NC Miata.

I'll also add, I drove an FR-S automatic during a 1st drive event. The dip in the torque curve was not really an issue, at least from what I could tell wringing out the car on a course in mainly 1st and 2nd gears.

It would be interesting to see the injection map to see when Direct & port are used?

i would say its tuned for better gas mileage when driving spiritedly, shifting at 4-5k on public roads, the first frs owner drove spiritedly up to 4k and got 29 mpgs :D
my current car is like that as well, during the 3-5k rpm range fuel duty cycles are lower than at 2.5k rpms(less fuel is going into the chamber at 4k rpms per revolution vs at 2k) this also has to do with resonance frequency of the metal, in my engine the metals vibrate the least from 3-5k rpms allowing just a bit less friction thus less fuel needed per cycle, there was a big write up about it back in 2007 when someone was doing research and trying to figure out how toyota was able to achieve that, its lost in the newcelica.org threads , i cant find it anymore...

I think overlaying this plot would better put things into perspective.

http://www.subaru.jp/legacy/dit/perf...ges/pict02.gif

That's the engine I want in my BRZ.

More insight here:

http://www.ft86club.com/forums/showthread.php?t=3583

Self explanatory, really.

You know you can't really calculate torque from two different dyno's right? IL dyno is notorious for reading high torque output. I would rather multiply first gear x final drive x 151 lb ft instead. I don't think the 2.5L TC-2 engine only makes 8 more lb ft with .5 more liters of engine. Maybe if it was 2.2 liters.

so you're THAT guy... if we all are getting those tq figures when we dyno, then the engine really is underrated we really do make 160 something tq at the crank

You only feel the dip when you are at WOT. Just driving around it's really like there isn't a dip there at all. That being said, if you want to accelerate fast downshift so you're over 4K and get over with the dip. There is more than sufficient torque at low rpm for quick city driving, and it's quite smooth power delivery too.

If it wasn't for DI, the dip would creep further down the RPM, it would be worst.

this video shows the torque dip and kinda shows how to get rid of it
[ame="https://www.youtube.com/watch?v=iM_QmVF2-fQ&index=1&list=PLHxU7q4gi5_sFJCSzL7x5zPsz4WxzuKgd "]Searching for Torque - Header & Exhaust - FR-S Long Term #4 - Everyday Driver - YouTube[/ame]

this thread is almost 4 years old, man

Although surprisingly most of the people posting to it are still active. I bet they know the way to fix it by now though.
Much funnier when somebody replies to a 4 year old post where none of the people have been active for 3 1/2 years.

We need a mod to move this post. It belongs in the engine and/or tuning forum

How do I deal with it? I have to plan passes better, downshift, run the revs up high and hope the other person isn't a **** and decide my passing is an invitation to race. My Genesis didn't have this problem because it was a torque monster. The power this car has feels more or less like my Tc used to. I don't remember any sort of torque dip, but it was similarly gutless. But the reduced weight and better suspension give the FRS a much more responsive feel.

Just keep the right RPM and right gear and you wont feel torque dip.
Otherwise, OFT, header, stage 2, E85 will helps you.