2.5i Premium - Looking for additional hp

18311 Views 15 Replies 10 Participants Last post by GeoJosh, Dec 13, 2013

Black Pearl

Discussion Starter · Dec 13, 2013

Good Evening-

I love my new Forester 2.5i Premium with the 6mt and like many of you, my first choice would have been the turbo 2.0xt if it came with a manual trans option....like it should have...but that's a different rant...

I feel the n/a engine could really use a boost in hp between 2000-4000 rpm; nothing crazy, but just enough to add a bit of drivability to the car....I've had more than a few precarious moments try to accelerate and maneuver through these crazy Los Angeles freeways full of traffic and fellow yahoo drivers. Mostly I feel the engine doesn't have enough power to get me around and out of the way as effortlessly as I feel comfortable with.

I'm well aware of what this car isn't and may opt for an STI drivetrain swap 4-5 years down the road when I have more time to do the work myself.....and yes, I'm willing to void my new car warranty to build and maintain my car that suits my driving preferences.

So, question to the community: for now, what would be the best way to reliably add a bump in HP in the 2-4k rpm range....maybe 10-20ish hp...??

The research starts today and am open to and curious to your opinions and suggestions.

Thanks much

~chris :icon_cool:

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soloz2

· #2 · Dec 13, 2013

There really aren't any power mods for na subies. You can install a less restrictive panel filter and different exhaust but that's about it. The only real option is a tune for your specific gas and driving style.

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Mandersen

· #3 · Dec 13, 2013

Black Pearl,

I'm with you on the power increase, I own an `11 Premium, but an open air filter and WRX/STI exhaust are the only power mods available that I've reading on here and on SCOOBY MODS. On the other side, you can swap in a premium gas turbo setup......

Good Luck!

Mark

Fate

· #4 · Dec 13, 2013

Ranting about the CVT is a rant increasing confined to the initiated. A significant percentage of us who own the 2014 FXT came from MT performance cars... and overwhelmingly love and appreciate the HDCVT it has. The automotive journalist community, who first panned the CVT with sour faces have started to change their tune now that the 2015 WRX is optioned with the same powertrain. That is, they LIKE the FA20DIT/HDCVT combo.

Lots of people, like you, miss out on the extraordinary experience the '14 FXT provides due to similar attitudes. So be it. Their choices. However, by such choice they also "throw out the baby with the bathwater," and miss out on not only a superior driving experience, but a BETTER equipped automobile... the MT driveline is comparatively "dumb" relative to the CVT one. The CVT-equipped FA20DIT has a more sophisticated vehicle control system that the MT is simply unable to match, in addition to the significantly inferior performance envelope that you are posting about.

Were I, and I suspect many others will who understand both systems, to chose a performance car like the upcoming WRX I would still chose the CVT transmission over the new 6MT. The CVT option brings the SI Drive variable tune system that controls both engine performance as well as the various auto/manual modes of the CVT, and, significantly, superior handling due to the new Torque Vectoring (VTD) capability.

The direct answer to your post has been adequately covered. The other answer is to trade your 2.5i for a new FXT.

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Shredmo

· #5 · Dec 13, 2013

Sigh.

kold911

· #6 · Dec 13, 2013

I beg to differ...

Head on over to rs25.com and search til your hearts content.

Is there HUGE gains? No.

But on my 1998 2.5rs, I changed to UEL Headers, catback exhaust, and changed to a lightened flywheel. Those mods have drastically improved the drivability. Overall I probably gained ~10 hp, but the car revs freely now. When I blip the trottle, the engine actually reacts, instead of the 1-2 second delay that is built in from OEM. I admit, we could've gained more HP by going to an Equal length header, but what's a sube w/o the rumble.

Fate

· #7 · Dec 13, 2013

kold911 said:
I beg to differ...

Head on over to rs25.com and search til your hearts content.

Is there HUGE gains? No.

But on my 1998 2.5rs, I changed to UEL Headers, catback exhaust, and changed to a lightened flywheel. Those mods have drastically improved the drivability. Overall I probably gained ~10 hp, but the car revs freely now. When I blip the trottle, the engine actually reacts, instead of the 1-2 second delay that is built in from OEM. I admit, we could've gained more HP by going to an Equal length header, but what's a sube w/o the rumble.

Answer? A better, more powerful, and safer running Subie.

Also, as for the blip throttle response, the 2014 2.5i has an incredibly responsive throttle... surprisingly like a well-tuned cable system of old. Definitely the best DBW response ever.

There won't be any of those mods done to a 2014 Forester... until, maybe, fifteen years from now, like yours. That's because all those mods are either impossible or inadvisable. The 2014 2.5i is a very powerful engine for its displacement already and anything anyone's going to do to it will detract from one aspect of it or another.

The OP isn't going to find any more horsepower in his present car. It's already making more hp per cu in than pure race engines of not that long ago. It's also quite adequate for virtually any normal activity, IMO. I drive our 2.5i more than the FXT and find it to be a fully satisfying Forester... but then, it does have the CVT which changes everything relative to a MT.

G

· #8 · Dec 13, 2013 (Edited)

Go to RS25. You're not going to get any help here in the N/A tuning department. A catback and a tune is your best option.

Fate said:
The 2014 2.5i is a very powerful engine for its displacement already

Not really; Honda gets 100hp/L out of their 2L four-bangers regularly. Subaru has just about maxed out this design, though. The EJ253 had pretty high compression from the factory.

slowhatch

· #9 · Dec 13, 2013

Probably not the first thought but you could put nitrous on it.

. A little 15-20hp shot will make a world of difference. Nitrous also adds an equal or greater amount of torque, which is what you will feel the most. Plus it's removable and undetectable if you needed to remove for warranty work.

Btw, I have a naturally aspirated 13' with an auto. I agree it's pretty slow and can be precarious when negotiating aggressive traffic. I don't think you will gain any power from typical bolt on mods but you may get a placebo effect that might make you feel better about your ride.

Good luck.

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kold911

· #10 · Dec 13, 2013

Fate said:
Answer? A better, more powerful, and safer running Subie.

umm What? An aftermarket EL header is just as safe, & more powerful than OEM headers.

Also, as for the blip throttle response, the 2014 2.5i has an incredibly responsive throttle... surprisingly like a well-tuned cable system of old. Definitely the best DBW response ever.

lol.. says who? OEM's build cars for the average consumer (who likes to leave stuff stock, like you), there is ALWAYS room for improvement. Just ask the thousands of people who mod their brand new sti's/evos/porsches/ferraris/etc and YES foresters ALSO.

There won't be any of those mods done to a 2014 Forester... until, maybe, fifteen years from now, like yours. That's because all those mods are either impossible or inadvisable. The 2014 2.5i is a very powerful engine for its displacement already and anything anyone's going to do to it will detract from one aspect of it or another.

This just goes to show how much you really know..There is Already mods.. Go search on this forum all the 2013's (and 2014s) that are modded.. Changing exhaust/headers does nothing to detract from the vehicle (aside from void the OEM exhaust warranty, which OP already said he doesn't care about). So..

Go troll somewhere else.

The OP isn't going to find any more horsepower in his present car.

Is that a fact? Or is this whole post covered in trollisms?

It's already making more hp per cu in than pure race engines of not that long ago.

You're kidding right? That's like comparing the 5.9 Cummins from 10 years ago to a 2014 6.7 Cummins. irrelevant comparison. And you do realize that vehicles today weigh a HELL (3-4X) of alot more than race cars of yesterday?

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neall_v

· #11 · Dec 13, 2013

kold911 said:
I admit, we could've gained more HP by going to an Equal length header, but what's a sube w/o the rumble.

Twin-scroll capable?

stan_t

· #12 · Dec 13, 2013

Weight reduction -- expensive, but your only safe choice IMO. Lighter wheels/tires.. that's about all I can think of on a new car. Filter will not gain you any power, exhaust will only add noise (if it's much lighter it can serve as weight reduction though). I guess if you could tune for those changes it could be interesting, but will void warranty, so be aware of it. Lighter flywheel does not add power either, but that could be a nice touch if you can take the engine out.

Cam(s) and compression ratio is the proper way to get more power out of N/A car. And, larger displacement.

Stan

kold911

· #13 · Dec 13, 2013

neallv said:
Twin-scroll capable?

I wish.. Nope the 2.5RS is N/A.

But to clarify, it's been proven that an aftermarket Equal length (EL) header produces more power than an aftermarket UnEqual Length (UEL) header.

It has to do with smoothing out the exhaust flow (air pulses), which when placed in an UEL header produces that boxer rumble most of us prefer.

neall_v

· #14 · Dec 13, 2013

It's no different than any other NA engine: intake, cams, headers, exhaust, increase displacement, tune.

Anything simple doesn't do much, and anything that does much is going to be expensive and invasive. A lot of NA tuning just moves the curve around. It'd probably be easier to develop a mild supercharger setup.

stan_t

· #15 · Dec 13, 2013

Kosei K4R 17x7" wheels are 14lbs and are $200 each on tirerack. Your stockers are probably around 22lbs each, that's a HUGE difference in unsprung weight, HUGE! Put some 225/45 tires on them -- yep, undersize to change the gearing (your speedo will read higher). Leave gas tank 1/4 full and remove the spare tire, then go for a drive in your favorite twisties.

I guarantee you will feel a large difference in performance everywhere in the powerband, and handling will be better too. Have fun while the others figure out filters/exhausts and other stuff lol.

Stan

GeoJosh

· #16 · Dec 13, 2013

I would agree with Stan here. It seems logical that the simpler way to increase the power to weight ratio would be to decrease the weight, rather than increase the power.

Here is a thread on weight reduction with a couple of helpful suggestions: http://www.subaruforester.org/vbulletin/f83/weight-reduction-10897/

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