How much horse power can u possibly add?

[jumpman23_08]

can anyone tell me how much horse power can u possibly add to a 2.5l a/c? and wat can u do to gain some horse power out of ur stock cts, before buying the and adding, like would adding some racing spark plug help?

[jumpman23_08]

my bad i meant to say altima coupe* not a cts

[JDRosenberg07]

this has been argued over and over again.. Lol

On a 2.5 if you upgrade the intake, headers, and exhaust you could possibly get 20+ although I have read that you can get between 15-20 with just an exhaust. There is also a new tuner out that is supposed to have some reasonable gains as well. Spark plugs would probably help but i'm not sure on that, probably nothing really noticeable

[Ricko]

Best way to get real gains out of the AC is to strip it down! Less weight is better all around. Tuner is think is a joke. Intake and Exhaust do help but maybe 15hp to be realistic. Will not do headers if they don't pass carb regs. Getting AAA and loosing the spare tire and jack. Buy lighter seats. Take out the back seat. Carbon fiber hood and trunk lid (if they are lighter, heard they are actually heavier) loose weight yourself if you can. Upgrade to synthetic oil.

I am sure you will notice the difference

[JDRosenberg07]

Stripping weight will improve acceleration but will not add power. And the back seat is only foam and weighs about 3lbs so that wont help.

The tuner i dont think is a joke, im not saying you will get 20 horsepower from it but i would use it more to raise the rev limiter and remove the WOT limiter which would def help with accelerating and power. As well as calibrating your speedo for aftermarket wheels and tires.

Synthetic oil wont prove gains, its just better for your engine, esp in colder weather, and lasts longer than conventional oil, and its about twice as expensive, but i would still recommend switching.

And as far as the exhaust, the exhaust on the 2.5 is extremely restricted and as per a technical nissan artical on the QR25DE you can get between 15-20hp by upgrading and i completely agree, cause i can chirp my tires in second now and it really pulls at peak power a hell of a lot more than it did stock. Lighter weight wont help that, aside from maybe only being able to lighten your A/C by 50lbs or so which will help just not much.

[CoupeVQ35CVT]

The back seat is only 3 THREE pounds??? I dunno..... I can already tell you from having folded the seats down and handled them, that just the back rest/cushion felt like a few pounds. THEN add the framework that holds the whole rear seat to the car. That's gotta be 15-20 lbs.

Removing the spare tire should give you what, another 15-20 lbs? That's 40lbs right there. Remove the trunk carpeting, another 5-10 lbs.

Remove all sorts of other stuff you don't need in the car, I'm sure you could hit 50-75 lbs without much effort.

Point being every little bit counts, even if it is just acceleration. Actually, with the car even 100 lbs lighter, you'll have less weight on the tires = less friction = better rolling resistance = more top speed. Oh, and less weight = better handling and braking distance.

It all depends how far you want to go with it.

But definitely, if the 2.5's exhaust is THAT limited, than some simple bolt-ons should let you reach similar hp rating that the Sentra SE-R Spec-Vs get (200 hp at the crank) which would be awesome, considering the Altima 2.5 coupe weighs about the same as the new Sentra S-ER Spec Vs' (< 3100 lbs).

Unfortunately, I'm sure it's not that simple. There is probably some factory tuning involved which bumps the Spec V's power to 200 hp while we get the regular 2.5 rated at 175 hp rating for the Altimas (and even worse at 170 hp in the Rogue... lame, considering it's 3300 lbs and could use the extra 5 hp)

[JDRosenberg07]

The back seat is only 3 THREE pounds??? I dunno..... I can already tell you from having folded the seats down and handled them, that just the back rest/cushion felt like a few pounds. THEN add the framework that holds the whole rear seat to the car. That's gotta be 15-20 lbs.

Point being every little bit counts, even if it is just acceleration. Actually, with the car even 100 lbs lighter, you'll have less weight on the tires = less friction = better rolling resistance = more top speed. Oh, and less weight = better handling and braking distance.

I meant the bottom cushion is only 3+- lbs. and your right about less weight giving you better acceleration but it wont give you a higher top speed, our A/C's have a limiter on them so no matter how light or how much power you you add it wont give you a higher top speed. you would need a tuner for that.

As far as better handling goes if you remove a lot of weight from the back of the car then you can actually make your handling worse. the A/C is already front heavy as is just about every car on the market. a 50/50 weight distribution is ideal for great handling. Plus if your coupe is a DD then it doesnt make sense to remove all but the drivers seat.

and i meant not losing much weight by changing out the seats, hood, and trunk as the replacement parts wouldnt weigh much less than OEM.

[Nissan_luver08]

Put in a turbo, if you have that kind of money to blow. Guranteed HP there. how much, I dunno...maybe gets the coupe up, with all other possible bolt on's up to 300hp?

[CoupeVQ35CVT]

I meant the bottom cushion is only 3+- lbs. and your right about less weight giving you better acceleration but it wont give you a higher top speed, our A/C's have a limiter on them so no matter how light or how much power you you add it wont give you a higher top speed. you would need a tuner for that.

As far as better handling goes if you remove a lot of weight from the back of the car then you can actually make your handling worse. the A/C is already front heavy as is just about every car on the market. a 50/50 weight distribution is ideal for great handling. Plus if your coupe is a DD then it doesnt make sense to remove all but the drivers seat.

and i meant not losing much weight by changing out the seats, hood, and trunk as the replacement parts wouldnt weigh much less than OEM.

Yeah practically it wouldn't be worth it. And yes removing weight or lightening the car would have to be done as such that the distribution is correct.

And I was speaking in general terms about top speed. Obviously the limiter is an issue in our case.

And yes with enough money it is possible to get 400 whp if you wanted. But again, do you have the money for it? Nevermind the upkeep of the turbo and other nuisances.

[Throckmorton]

CoupeVQ35CVT,

Here is info on how Nissan got 200hp from the Spec-V 2.5

NISMO’s breath upon the Altima-sourced 2.5-liter engine hath bumped compression with special pistons and some tasty trick pieces (e.g. a cast-resin manifold). The resulting lump boasts a higher redline (6800 rpm) and more horses (200hp). The Sentra’s modified mill stumps up 180 lb/ft of torque. Though the twist now arrives higher up in the rev range, that’s the same grunt as the previous gen SE-R. Despite 3100lbs. of not so curvaceous curb weight and reduced low-end torque, the Sentra pulls a respectable 0 to 60mph time of around six-and-a-half seconds.

Wherever you go, there you are.

[CoupeVQ35CVT]

Thanks, I totally forget that I read the same exact paragraph elsewhere, about the higher compression pistons and such. Hmm wonder if it's worth it for the 2.5 crowd to use the same on the Altimas...Probably not worth the trouble, considering similar performance could be had with proper tuned bolt-ons etc.

[jumpman23_08]

i found this on another thread where they where talking about the way the car breaths, cause some guys want to get a spacer, and a sentra uses the same engine as the a/c. They rased the rpm almost to its peek and the torque also rises. thier has been arugments where people say torque could be better the hp, but dont kno.Sentra

QR25DE – 2.5-liter DOHC 16-valve 4-cylinder engine177 hp @ 6,000 rpm172 lb-ft of torque @ 2,800 rpm Compression ratio – 9.6:1 QR25DE – 2.5-liter DOHC 16-valve 4-cylinder engine200 hp @ 6,600 rpm180 lb-ft of torque @ 5,200 rpm Compression ratio – 10.5:1

Altima

QR25DE – 2.5-liter DOHC 16-valve 4-cylinderHorsepower – 175 hp @ 5,600 rpm [1]Torque – 180 lb-ft @ 3,900 rpm