JuxtaGT Posted November 1, 2005 Share Posted November 1, 2005 30 hp for an exhaust on a NA car like the subaru is total BS, try <10. Just made an attempt to write a summary on the subiesport article about modding the '05 2.5RS, but hit the back button right as I finished, stupid multi-button mouse. Will try again later, this time in Word first! Link to comment Share on other sites More sharing options...
Xantium Posted November 1, 2005 Share Posted November 1, 2005 I think there are some considerable gains to be had if you go full exhuast (including headers). Everyone who looks at my car (mostly becuase at first they think its a gt) says the exhuast piping looks way too small for a 2.5 liter. And i remember someone else saying that becuase we dont have a turbo to spool its best to "open up the headers". I think ion is still working on an exhuast and if cobb can make AP for us that would be great --there has to be a gain through 93 octane. Link to comment Share on other sites More sharing options...
JuxtaGT Posted November 1, 2005 Share Posted November 1, 2005 I agree. But "considerable gains" is a relative term. On a NA car, it is very important that the entire system flow well: intake, headers, and exhaust. This plus engine management would net around 20 hp. Which doesn't sound like much, but looking at a the dyno curve for a car with these mods would show that it is making a lot more power accross the entire rpm range, and thus a MUCH faster car despite "only" gaining 20 on the top end. Link to comment Share on other sites More sharing options...
Xantium Posted November 1, 2005 Share Posted November 1, 2005 Yes i forgot about that... it feels like we have a really narrow power band.. around 3500-4500. Are there any 2.5i dyno graphs (or even impreza rs dyno graphs)? Link to comment Share on other sites More sharing options...
JuxtaGT Posted November 2, 2005 Share Posted November 2, 2005 Ok, this is a short summary of the article that appeared in the October Subiesport magazine. This is for a 2005 Impreza 2.5RS. But, as I found, the base horsepower for the 2.5RS in only 3 lower than the 2.5i Legacy, so this ought to be pretty darn close. You should check out the article in full if you can, as I'm sure it does a better job of explaining the hows and whys. To see the real difference being made on most of these mods, you need to see the dyno graph. Mod 1: Headers. $948 Tech Works Engineering (TWE) "Super Stock" equal length headers. Basically, there are two types of headers, un-equal length, and equal length. Power potential is higher for the equal length headers, but you will give up the Subaru "boxer rumble" sound. If you really want to make the rest of your power upgrades count, this seems to be the best place to start. By itself, a header does not do much, but makes a big difference once you start to open up the rest of the system. Note, the article does not print the bone-stock power levels of this car. Baseline HP with headers: 113.19 whp 132 wtq Mod 2: Intake. $190 Weapon R "Secret Weapon" short-ram intake. Worth almost 4 hp, and 2 ft/lbs. of torque, also extended the time above 130 ft/lb. of torque by about 800 rpm. They also note that with ECU tuning later on, that the intake was good for almost 7 hp, though they doubt most buyers would get an ECU for just headers and intake. Headers + intake: 117.2 whp 133.8 wtq Mod 3: Exhaust. $429+$495 Random Tech high-flow cat and TWE muffler. With the foundation laid down for an open system, completing it with a full 2.25 inch system really made a difference across the board. Plus, now the car sounds the part! Headers + intake + exhaust: 127.1 whp 146 wtq Mod 4: ECU $459. Rallitek PerfectPower piggyback ECU ($$$ + for tune, dyno time, or not if you get an off-the-shelf map). The problem with our cars is that closed loop fueling (anything below 4500 rpm) is very hard to adjust. Anything above 4500, though, is open game. Though not much in the way or top end gains is made by adding the ECU, the peaks and valleys of the power curve have been smoothed out, and a little more area under the curve is created. Again, this is one where you need to see the dynoplot to really see what is going on here. (I wonder if Cobb or someone else will start offering other options like full ECU replacements that will allow closed loop fueling adjustments..) Headers + intake + exhaust + piggyback: 129.1 whp 146 wtq - no change (all runs done with 93 octane once PP was added) Mod 5: Cams + Light Weight Pulley. $499 + $135 Cobb "Spicy" camshafts and pulley. Ok, likely if you are putting in camshafts, you are pretty serious about making power for your NA engine. Note that the cams are $899 without the core exchange. So, you can't "undo" this mod without your old cams, not that you would. Also, engine dis-assembly should be left to the professions, so you should factor in a fair amount of labor for this upgrade. The character of the car is now very different, the idle is a bit "bumpy," and gives the impression the car is about to die. A CE light came on during this upgrade as well, though they think the high-flow cat might have something to do with that. This is another power gain that doesn't sound very good when you just look at peak hp numbers. Though peak is only up 5hp with the cams, it is up 25hp at 6000 rpm over previous upgrades, and 40 hp over stock. The entire power spectrum of the car has been totally changed, much more area under the curve. Headers + intake + exhaust + piggyback + cams + LW pulley: 132.5 whp 146.4 wtq Total cost of upgrade parts: $3,196 for 20hp gain 14.4 ft/lbs (+$2k in labor) What would they do next? Port and polish the heads for better low end response. Stand alone ECU to increase redline among other things. Light weight flywheel. So, is 200 whp possible? Yes, but you are probably better off looking at adding a turbo to your car, on an engine swap. Link to comment Share on other sites More sharing options...
GeorgeB Posted November 2, 2005 Share Posted November 2, 2005 5200$ for 20hp :-/ that is one expensive horse tks for posting this Link to comment Share on other sites More sharing options...
JuxtaGT Posted November 4, 2005 Share Posted November 4, 2005 Don't see it as "only" a 20hp gain, you have to see the dyno plot to understand that this is totally different power curve. Where the stock car peaks around 5k rpm and falls off, the car with upgrades keeps pulling all the way to redline at 6k. This is about 40+hp gain at redline over stock, 25 hp gain without the cams at redline. Much, much faster car now. Link to comment Share on other sites More sharing options...
Garandman Posted November 26, 2005 Share Posted November 26, 2005 Had a Subaru service manage say that just an exhaust upgrade would yield 30 HP improvement. Bogus? No, the decal adds 30 hp..... A fellow at work used to work at a BMW parts and tuner outfit. He says most aftermarket tips decrease power. Decals still give best bang for the buck.... Who Dares Wins スバル Link to comment Share on other sites More sharing options...
stanjk3 Posted November 27, 2005 Share Posted November 27, 2005 5200$ for 20hp :-/ that is one expensive horse tks for posting this Just wondering, wouldn't it be cheaper to just drop in a 3.0H6?? Shouldn't be that hard to do considering there are 3.0R versions in other parts of the world. Though I imagine the aftermarket for that engine is very limited here in the US. Friends don't let friends drink cheap beer. Link to comment Share on other sites More sharing options...
GeorgeB Posted December 2, 2005 Share Posted December 2, 2005 i think it would be cheaper just to buy the whole car with a 3.0R inside from the factory my next car ( in 4-5 years or so:-/) will pbb be a legacy 3.0R (maybe a wagon) Link to comment Share on other sites More sharing options...
Drakuun Posted December 2, 2005 Share Posted December 2, 2005 Have you guys seen the price you'd pay for a real horse, just one.. Upwards of 1200 for a domestic breed, upwards of 10,000 for show and race breeds.. 5200 for 20HP doesn't really sound that bad /joke Link to comment Share on other sites More sharing options...
fazzster Posted December 3, 2005 Share Posted December 3, 2005 on a 05-06' 2.5i, any tips tricks and suggestions. This is what I did......I guess I am around 180 hp up from 168hp.....I ended up not going with the cat back because it was too loud and did not make a noticable power gain. The intake, header and hi-flow cat are making good power...... http://www.xcceleration.com/imp-gallery-05-leg.25.na.htm Link to comment Share on other sites More sharing options...
stanjk3 Posted December 3, 2005 Share Posted December 3, 2005 i think it would be cheaper just to buy the whole car with a 3.0R inside from the factory my next car ( in 4-5 years or so:-/) will pbb be a legacy 3.0R (maybe a wagon) For whatever reason, the only car they sell with an H6 in the US is the Outback. And it's upwards of 30K, out of my price range. IMO they should sell both the Baja and the Legacy with it as an option. Friends don't let friends drink cheap beer. Link to comment Share on other sites More sharing options...
Garandman Posted December 4, 2005 Share Posted December 4, 2005 For whatever reason, the only car they sell with an H6 in the US is the Outback. And it's upwards of 30K, out of my price range. IMO they should sell both the Baja and the Legacy with it as an option. I paid $2,700 more for the Outback 3.0R - $25750 plus options = $26,100 - over the 2.5i automatic, and that includes other "stuff" 3.0L H6 cylinder engine, 250hp with Active valve control 5spd SportShift automatic transmission Upgraded VTD all wheel drive system Tire Pressure monitoring sytem TPMS 6disc CD changer Dual zone front climate control Body colored mirrors with turn signals Rear seat armrest The turn signals in the mirrors are a great safety feature, if you use your turn signals. Most people in Boston do not..... The 5spd auto is a big improvement over the 4 spd 2.5 setup in my 97 OBW. Who Dares Wins スバル Link to comment Share on other sites More sharing options...
stanjk3 Posted December 4, 2005 Share Posted December 4, 2005 I was going by MSRP, website lists $28,995 for the Outback 3.0R. Friends don't let friends drink cheap beer. Link to comment Share on other sites More sharing options...
GeorgeB Posted December 4, 2005 Share Posted December 4, 2005 i don't need an OB . and wagon for future kids Link to comment Share on other sites More sharing options...
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