Discussion: Did the 2015 Subaru WRX get nudered because of numbers?
 

Disclaimer: This may be sort of long, but I think you will find it an interesting read.

I will admit, when I am interested in something I over-search, over-think, and over-justabouteverything. So needless to say when I am thinking of trading in my 30,000 mile FR-S 6AT for something that feels brand new again, I spend a lot of time researching. But in doing so, I find out some interesting details that I think need discussion.

Inevitably in my search for a replacement car I looked at new takes on the FR-S. The Monogram Series with all its "premium" features and the RS 1.0 Series in it's striking Yuzu yellow paint with expensive TRD parts are both very attractive. I know the twins are excellent at handling and love how it cuts through twisty roads. I also know the twins are just a tad bit lacking in the straight away. Which led me to at least look into the newly stiffened up WRX.

I looked at the STI and compared it to the base WRX. With the STI and it's grandfathered 2.5l engine, you get full boost high in the RPM range. This translates to a rush of power close to redline. With the base WRX and it's newer 2.0l engine, you get full boost at a much more usable RPM range. This translates to a smoother acceleration in more of the RPM range.

As you probably know, the new WRX carries the newer FA20 DIT engine. Being essentially the same engine in the twins (with a turbo, lower compression ratio, and Subaru-only injection system) I was happy to see our engine was good enough to be mated to a WRX. While diving into the engine I took a quick look at the specifications on Subaru's website.

THE FA20 DIT IS TUNED FOR 87 OCTANE! What the?! I almost jumped out of my seat when I saw this. I could not imagine giving the FA20 87 octane.
Back to my over-thinking, I wondered why Subaru would tune the WRX for the lowest available gas. It says "recommended 91 octane" next to the required 87, but then again who runs the "recommended 93 octane" in our cars? I remember reading that lower compression ratios can allow for lower quality gas, but it just seems so odd in my head to grab the 87 nozzle and put it into an FA series engine.

0-60 times are one of the most looked at numbers when enthusiasts compare cars. Although we twin drivers generally feel different and prefer handling over acceleration, the acceleration is still a big part of the overall car's image. I watched a few Youtube videos to get a realistic feel of how fast the new WRX's accelerate.

The STI video came first because I knew without a doubt the time would be faster, which it was. Different sources provide different numbers, but the general consensus has the STI around 5 seconds and the regular WRX 1/10th of a second behind. This made me begin to wonder if their was more behind the low octane requirement.

What do you think? With the new WRX's and STi's 0-60 times being so close, does the base WRX's 87 octane requirement seem suspicious? If Subaru had required 91 for the WRX like the STI, would these two models have the same 0-60 figures and potentially lower sales of the sportier brother?

- FRSFrank

I want to hear what you think! Please keep the discussion respectful.

Neutered?

Its hard to market a car like wrx with s premium fuel required sticker. Its easy to put that on sports or luxury cars because the owners most likely dont care about that. Dont overthink it

I get what you are saying. But I also think the WRX falls into the sports category. Especially with this 2015 series because they have completely eliminated the Impreza name which it has carried since 2004. Now, the Impreza is an Impreza. And a WRX is either a WRX or a WRX STI.

Think of it like a BRZ. If you could buy a BRZ or a BRZ STI tS and the BRZ ran on 87 while the STI tS ran on 91, wouldn't you feel like the potential was artificially limited because of the sportier versions existence?

- FRSFrank

When its -20f to -40f in alaska, my WRX literally feels like it has over 300hp!

Performance and economy numbers are run on the best fuel a car is tuned for, not the worst. It's not so difficult to tune the WRX to run 87 as the edu controls not just timing but boost as well, there's less headroom (floorroom?) to do the same in an FRS/BRZ due to the high static compression ratio.

Too add a few details:

As far as I know, the new WRX & WRX STI are sold only in North America and Australia. In Europe only the WRX STI is for sale, no WRX, and in Japan, neither the new WRX, nor the new WRX STI are sold.

This means, in Europe and Japan, only WRX STI (in Japan the old one) are sold with EJ25. North America and Australia exclusively have the FA20 Turbo.

Here again the engines, and where they are sold:
FB16, FB20, FB25: EU, NA/AU, JP
FA20: EU, NA/AU, JP
FB16 Turbo: JP
FA20 Turbo: JP (300 PS), NA/AU (268 PS)
EJ20: JP (old STI)
EJ25: EU, NA/AU, JP (old STI)
EZ36: NA/AU

I would guess Subaru would switch to 1.6 and 2.0 Turbo engines only. If they kept EJ25 for the STI, maybe it is because the FA20 Turbo is not enough good for an STI, an EJ25 replacement could come later.

:laughabove::laughabove::laughabove::laughabove:

Another thing to consider is the STI takes 2 shifts to hit 60mph while the WRX only needs one.

I think the previous gen WRX was actually faster to 60 than the STI because of this.

If they were that concerned about the numbers, they really should have just adjusted the gear ratios on the STI instead of "neutering" the WRX.

Don't sweat the 87, any turbo car can run 87 by limiting boost.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

Also, neither the WRX or STI get full boost to redline. Boost in both dies off about 1000 rpm before redline, so you've only got about a 1k rpm power band, which is more precisely the midband.

And, really, 30k miles and you want to replace the car? It's still fairly young at that mileage.

New wrx uses a 6 sped which actually requires shifting to 3rd gear.



Also...

The difference between 0-60 is more than 1/10th. The fastest I've seen the new sti get is 4.6 second while the fastest I've seen for the wrx was 5.3. So almost a full second difference.

91 octane would help but not enough to make up over half a second gap.

Regardless though, they're great cars and I've considered moving to one from the FRS but just can't. Only reason why is because I've already owned a wrx, and if I sell my FRS for something, it'll be to move up a step to something like an M3.

Car And Driver proved that you can hit 0-60 in two shifts and 0-60 time was 4.8 seconds or about the same as the last model. That said, we are talking about dumping clutches here and some violent launches.

But then again this is how most of the car mags hit these numbers.

As far as octane goes, I am pretty sure they recommend 91 minimum on the gas door of the car. While it would run on 87, the Ecu is likely to cut back on power and I would not recommend it.

You can skimp a bit on fuel quality when you have direct injection, less time for the fuel to heat up and pre-ignite.

Seriously I think 87 octane is more of a marketing move (as gas isn't cheap anymore) so it is more attractive to non car enthusiasts...who's going to put 91 in it anyway, right?

Seriously? Do you have a link to this review?

I'm not questioning you, but I'm genuinely interested to see how the rest of their test/review varies from other magazines. That's pretty cool though that it still is only one gear change for the wrx.

EDIT: nevermind, found it. Yeah they managed a 4.8 second run which is awesome.

Sure thing, no problem:
http://www.caranddriver.com/reviews/...al-test-review

Here are the stats from their test:

C/D TEST RESULTS:
Zero to 60 mph: 4.8 sec
Zero to 100 mph: 13.1 sec
Zero to 130 mph: 25.3 sec
Rolling start, 5-60 mph: 6.3 sec
Top gear, 30-50 mph: 12.1 sec
Top gear, 50-70 mph: 7.9 sec
Standing ¼-mile: 13.6 sec @ 102 mph
Top speed (gov ltd, mfr's claim): 144 mph
Braking, 70-0 mph: 160 ft
Roadholding, 300-ft-dia skidpad: 0.95 g

The WRX is very conservatively tuned. it would trump the stock STI with a reflash I am sure.

I am taking delivery on a 2015 WRX hopefully this Fri. While Road and Track did 14 consecutive clutch dumps from redline to attain the fastest 0-60 times on Subaru's engineers insistence, that only proves the transmission is tough.

Wait until Cobb get's their AP tunes up and going. Then we will see what it can do.

I decided on the WRX over the STI not due to price, but the fuel economy, more modern and less peaky engine. This will be my daily driver and likely never see a track, so it made sense. When you get the revs up high, the STI is clearly more powerful, but for daily driving the WRX should feel every bit as fast for most people. And aside from a not quite as tight steering gear, it feels just as tight in the handling dept with the new artificial torque vectoring which does the job of the mechanical LSD's. The Brembos are nice, but again only really useful in a track environment. I dont need to adjust the torque distribution to drive to and from work either.

In another lifetime I would have loved to go to lapping days regularly, but in reality I just don't see that happening. Plus, the wing is pure rice IMHO.

All the write ups say they did a good job of tightening up the handling compared to the previous generation WRX.

It looks that way. One tuner was able to achieve 50hp and 35ft lbs of torque on a tune alone (meaning stage one with no other bolt ons).

Love getting Nudered. Coed skinny dipping is the best!

I am pretty sure that the WRX & Foerster Run lower compression allowing them to run lower quality gas.

From cars101.com:

The twins have a what... 12.5:1 ratio?

12.1:1 i thought, but yes.

STi will always be faster and a better buy then the WRX. Funny how WRX owners always try to out class the STi, not happening. And this is coming from a WRX owner. EJ257 is not a bad engine, it has great power and tq even if it is from 2004. It has improve since its introduction 10 years ago. There is to much difference from the WRX and STi.

2015 WRX is a different car compared to the previous WRX in every way.
What exactly is different in the 2015 STI compared to the 2014?

So that generalization from perceptions past owners had doesn't really hold any weight.

Off the top of my head the differences between the 14 STI and 15 are:
- Much stiffer chassis
- More bracing
- Stiffer springs
- Larger sways
- Much tighter steering rack
- Torque vectoring
- Upgraded interior
- The changed the throttle mapping in the 15, and supposedly it is more responsive

I am sure there is more. I think the big change is going to be the handling and suspension. Subaru really focused on that with this car and it shows if you drive one. They feel very different from the previous car.

So the only reall difference between the WRX and the STI is the fa20 and the EJ25.... :p

No, I thought you were asking about the 14 STI and 15 STI.

15 Sti and 15 WRX (outside of engine) are pretty typical of previous years:
- Better gearbox in the STI that can most likely hold down more power
- Stiffer suspension
- 6 way adjustable center differential
- Brembo braks
- 18" wheels and wider/griper tires
- Tighter steering rack
- More standard amenties
etc, etc.

Actually the WRX has a higher compression ratio than the STI because it has a newer engine that doesn't suck. However 10.6 is still quite low, the typical 10.5-11 range port injected engine these days runs fine on 87 naturally aspirated, and this engine being direct injected should be able to run some decent amount of boost on 87 without knocking. You just don't get full power, obviously.

12.5

The comparison was the twins having to run 93 vs 87 like the wrx, not the wrx vs the sti.