Comparing Boxer Outputs

[SUBE555]

I'm just showing some comparison of FACTORY numbers to perhaps make a better assumption on some of the potential differences we'll see in the opcoming models. All models compared are current unless otherwise noted. Some conversions to look at: 1Nm = .73692 Lb-Ft 1Kg-m = 7.23301 Ft-Lb 1kW = 1.34102 HP [b]JDM Legacy 3.0R[/b] [img]http://www.subaru.co.jp/legacy/b4_30r/05/imgs/01/p2.gif[/img] Torque @ 2000rpm = ~191Ft-Lb Peak Torque = ~224Ft-Lb @ 4200rpm Peak HP = ~247hp @ 6600rpm [b]JDM Forester STi w/ 2.5L (It's not just a rumor)[/b] [img]http://www.subaru.co.jp/forester/stiversion/01/imgs/top.jpg[/img] [img]http://www.subaru.co.jp/forester/stiversion/02/01/imgs/p1.gif[/img] Torque @ 2000rpm = ~199Ft-Lb Peak Torque = ~278Ft-Lb @ 3600rpm Peak HP = ~261hp @ 5600rpm [quote]Originally posted by Trey: [QB] Dyno Graphs as promised. [img]http://www.cobbtuning.com/forester/images/forxt-dyno.jpg[/img] There are two runs shows, with Torque and HP graphed for each. From top to bottom here are what the lines represent: BLUE = Torque w/ catback BROWN = Stock Torque GREEN = HP w/ catback PURPLE = Stock HP Keep in mind all these numbers represent power measured at the wheels. We use a Mustangdyne Chassis Dyno. Manufacturer Claimed Power Figures are at the engine, and do not account for drivetrain loses. [b]THE TEST[/b] Our Stock Forester XT was dyno'd with 3000 miles on the odometer. We use 91 octane fuel, and are at ~4000 ft altitude here in SLC. The test conditions were very dry (~20% humidity) and cool (70 degrees F). SAE corrections were used. 3 runs were made in each configuration with a pause between runs to allow the fluid temps to stabilize. The average run of each group was used for the comparison. The two tests took place on the same day, within 20 minutes of eachother. The stock exhaust was dyno'd first, followed by our Cat-back. All runs were made in THIRD GEAR. A final FOURTH gear run was made for our own uses to determine the error caused by torque multiplication of 3rd gear. [b]RESULTS[/b] Our STOCK XT produced a PEAK HP figure of 192.4 HP @ 5200 RPM on its average run. The PEAK TORQUE figure was 221.1 ft-lbs @ 4000 RPM. With our Cat-Back, the PEAK HP figure was 195.3 HP @ 4800 RPM on its average run. The PEAK TORQUE figure was 224.8 ft-lbs @ 4000 RPM. This represented a PEAK HP gain of +2.9 HP and a PEAK TORQUE gain of +3.6 ft-lbs measured at the wheels. Measured every 10 RPM from 2000 to 6600 RPM, the AVERAGE HP gain was 3.88HP and the AVERAGE TORQUE gain was 4.65 ft-lbs. The HIGHEST OVERALL Gain came at 4400 RPM with +8.07 HP and +9.53 ft-lbs TORQUE. [b]IMPRESSIONS[/b] Overall, the Forester XT performs better than SUBARU's claimed power output. Subaru claims the XT produces 210HP @ 5600 RPM and 235 ft-lbs @ 3600 RPM. Perhaps due to altitude, our XT produced its peak torque slightly later and its peak HP slightly earlier. Nonetheless, the overall power was impressive. We did run the XT in 3rd gear, which gives it a slightly skewed (higher) result due to the torque multiplication over the gear and final drive. While we normally test the WRX in 3rd gear, its 3.90 final drive does not multiply torque to the wheels as much as the XT's 4.44 final drive does. This all means that if you had two identical engines producing identical power, the one with the higher torque multiplication will show to make slightly more power on the chassis dyno. All that being said, our XT definitely made more power than we'd expect given Subaru's claims...regardless of the drivetrain differences. Based on our experiences running Subaru's on our particular dyno, coupled with some experiements when running our XT to calculate the difference in torque multiplication due to the final drive gear ratio, I'd estimate the actual PEAK flywheel power output of the XT to be in the neighborhood of 235-240 HP and 260-265 ft-lbs Torque. Roughly 10% more than what Subaru is claiming. We'll be dyno testing the other XT once we get it broken in to compare the results. Hope this info is helpful, Trey @ COBB Tuning [/QB][/quote] More info to come when I can find chp or converted maps...

[gurpman]

Pretty dramatic how much flatter the 3.0's torque curve is compared to the 2.5T. If the USDM Outback engines have similar shaped curves, I bet the 3.0 will have quite a bit more torque and power than the 2.5T under 2500 RPM. I'm guessing that while the turbo will be faster at 0-60, the 3.0 will be as fast or faster at 5-60. What do you think?

[SUBE555]

Considering I so rarely operate below 2000rpm, a 2.5T would be a bunch faster in my book. Even driving around Chicago yesterday I was operating in the 2500+ (or well more than that on the highways) in a GC RS. Around town, I rarely run below 2500 because I want to get some place. Cruising, I might drop down to 2000, but once that turbo is on boil and quickly at that, bye-bye H6. That's just my particular driving style and how I use the car. I'll try to get the power maps & dyno charts up once I find more. I think we can all agree though either way you cut it, you're still getting a hell of a lot more power than the base 2.5L SOHC at any rpm.

[PPower]

very nice. 2.5T all the way. even though that is the f-xt tuned more for tq.

[SUBE555]

BTW, the person I talked to who some may have gotten the initial H6-2.5T impression about the H6 being faster. The word on the street is if you are interested at all about performance, the 2.5T is the ONLY way to go. The H6 will only suffice if you wish to have more cylinders.

[gtguy]

Careful not to read too much into those numbers of non-existent cars (as regards the USDM). We don't know the ECU, turbo or state of tune, and how those parameters relate to the Legacy 2.5T that we're getting. JDM cars, as we all know, have different states of tune, even with the 2.5 liter turbo motor in the JDM Forester STi. As it will be making less horsepower, I can almost guarantee that the USDM Legacy will have a very different state of tune. Oh, and it looks like a cat-back isn't worth the bother, eh? :lol: Kevin

[EJ20H-TT]

I think if they had reflashed the chip with the catback then u would get a much better gain

[SUBE555]

Kevin, those other ones were just an estimate, but note the EZ30 they have makes about 5Lb-Ft more than the one shown with about 3hp less than USDM listed specs. Do note the FXT with a nice write-up by Cobb gives a taste of the USDM FXT. I think even the current USDM FXT will be quicker than the EZ30. If you don't believe me, take it up with Paul. Perhaps he'll set you straight. :D

[SUBE555]

Bump for 3.75L guy. ;)

[apexjapan]

Hey, I've driven a Spec B GT with the STi cat-back! And I would agree, it is almost not worth the bother, especially in bang-for-buck. A good high flow panel air filter replacement would likely get you as much power gains for a vastly smaller percentage of cash. Tuning is getting harder and harder these days, the standard ecu's smarter and smarter and compensating better for changes to the system. It is having a dragging effect on the Japanese tuning scene, actually, there isn't *that* many good tuners in the market, and they are having problems keeping up with the ECU's. Ah, and to get back on track towards the current discussion. On paper, the 3.0 should be somewhat superior to even the 2.0GT's, but back to back, the 2.0 vs. the 3.0 with the same tranny (automatic 5-speed) was a different story than you would expect. The 2.0GT had more torque where you needed it - in the low to mid-range - while the 3.0 only gained a slight advantage once you spun past 5800rpm or so. But as gtguy stated, that comparison is for Japanese models, and the american versions may have different powerbands and feel. Still, I would be rather surprised if the USDM 2.5GT did not feel torquier than the 3.0 NA. It reminds me of Nissans 2.0 inline 4 turbo vs. their 2.0 inline 6 turbo (ie, silvia vs. skyline GT). The inline 6 was smoother and spun a bit higher, but the inline four was torquier and made more power. But to be honest, I did prefer the inline 6 in that instance, because it was just soo smooth in comparison... Cheers, Paul Hansen

[gtguy]

All I'm saying is until we get the cars, drive them, and see dyno plots for the USDM cars, be careful of any speculation or extrapolation based on other numbers. In that regard, I don't know how much "setting straight" is necessitated by a simple cautionary note. Kevin

[Dr. Zevil]

[quote name='gtguy']All I'm saying is until we get the cars, drive them, and see dyno plots for the USDM cars, be careful of any speculation or extrapolation based on other numbers. In that regard, I don't know how much "setting straight" is necessitated by a simple cautionary note. Kevin[/quote]C'mon kevin.. we have NOTHING else to talk about.. if you exclude drooling over Paul's car. :lol:

[SUBE555]

I just bumped it because I was asked if I had any more info on the Forester STi, and this contained a bit of info on it. Don't get so torn up guys.

[gtguy]

[quote name='SUBE555']I just bumped it because I was asked if I had any more info on the Forester STi, and this contained a bit of info on it. Don't get so torn up guys.[/quote] I don't think anyone is torn up, Sube. Speculative natterings aren't worth getting torn up about, if ya dig what I mean. Kevin

[SUBE555]

Kevin, I know we all went through the conversation in the past and someone wanted to see the factory charts with the Forester STi and the 3.0R, so I gave it a bump. Just seemed to open those old NA/Turbo wounds of drive it and tell. I agree, but someone just wanted a comparison to look at if you guys didn't notice the date gap and my note. ;)

[3.75L H6]

I can't find performance stats, accel, track times, etc. on the Forester STi anywhere.....ideas? thx. :D

[SUBE555]

Can always try Google. :)