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Old 04-28-2002, 06:58 PM   #1
STiWRXdotcom
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Default What has more NA power? the 2.0 or the 2.5?

can you turbo a 2.5 to more overall power than the 2.0.. even though the 2.5 is SOHC and the 2.0 is DOHC??

What is the HP on the 2.0 BEFORE turbo?
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Old 04-28-2002, 07:38 PM   #2
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i'm going to reccomend you do a search...i don't like to be a jag...but i'd rec doing a lil research before posting.
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Old 04-28-2002, 08:40 PM   #3
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word^

you mean a us spec'd rex 2.0l turbo?

but in short a properly tuned 2.5 turbo will eat wrx's for breakfast lunch and dinner...then come back for dessert...then seconds....thirds...etc...

you get the picture?

Jay
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Old 04-28-2002, 08:44 PM   #4
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I think he was asking if both engines were N/A which would be better.

Generally when N/A there is no replacement for displacement.

RawCode
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Old 04-28-2002, 09:07 PM   #5
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I guess I have two questions..

#1 what is the HP of the 2.0l (without turbo)

and #2 what has more boost/power potential the SOHC 2.5 or the DOHC 2.0?

I am trying to talk myself OUT of a WRX, simply because money is tight, and if I could convince myself that the 2.5 has just as much, or MORE performance potential I would feel okay going with the RS instead of the WRX.

Thanks for any and ALL input
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Old 04-28-2002, 10:10 PM   #6
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Can you even get an NA New Age 2.0L????

I don't mean to sound abrasive, but if you have to ask....

Just get the WRX and start from there. The amount of tuning required to get to the RS-T level is quite a lot, and although I agree that a professionally tuned 2.5 could pose a threat to most cars, the WRX is already more than half way there in factory form. I've been participating on this board for quite some time, and if there's one thing I've learned (and this applies not only to Subarus) it's that there is no quick way to get to that neck snapping power.... it has always been, and will always be a matter of good tuning choices combined with a huge chunk of money.

As for the DOHC/SOHC debate... 2 things.

1. do a search
2. there are some really fine examples of each on this board...in order to find them, see point #1

and as for the money being tight issue...

save save save! I'm in need of a decent suspension setup, and at one point I even looked at those R1 coilovers on e-Bay!!
then I slapped myself and decided Comp-S!

Just like woodworking 101.... measure twice, cut once.
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Old 04-28-2002, 11:35 PM   #7
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with the compression on the wrx if you were to remove the turbo it may have 100hp probably less. The 2.5 could definetley be built to produce more torque and hp then the 2.0 because it's larger. The wrx is a better idea though unless you plan on heavily modding the 2.5. If you took the price difference between the two and put that into mods for the 2.5 it could be equally as powerful but most likely not as reliable, and if money is tight you won't want a non-reliable car that need crap done to it just to make it run.
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Old 04-29-2002, 12:30 AM   #8
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considering most of the highest hp imprezas in the world, such as the jun car, swap out the 2.0 for a 2.5, id say that the 2.5 has more ultimate potential. one of the most important ways to increase power in an engine is to increase displacement. assuming all other variables are equal, a higher displacement engine will make more power. since the 2.5 has more displacement, the 2.5 will make more power. BUT for the average everyday person, theyll probably get more from the 2.0, cuz its already turbo, so its therefore just plain easier.
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Old 04-29-2002, 02:36 AM   #9
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Dont forget Cobb Tuning sells that Turbo-designed 2.5l closed block that can pump out aloooot of HP
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Old 04-29-2002, 02:47 AM   #10
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Quote:
Originally posted by Kostamojen
Dont forget Cobb Tuning sells that Turbo-designed 2.5l closed block that can pump out aloooot of HP
Turbo designed... but doesn't come with a turbo nor does COBB make turbos... they are R&D a SC kit though... hmm
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Old 04-29-2002, 03:28 AM   #11
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Quote:
Originally posted by 2yLiTe
Can you even get an NA New Age 2.0L????

yes but certainly not on US shores.
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Old 04-29-2002, 03:32 AM   #12
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Josico: Kostamojen meant that Cobb is making the closed deck design to further improve the potential of the EJ25; thus it can handle further boost if it's meant to be turbocharged.

EJ20 w/o FI design then you are just comparing displacement, as the design of our engines are pretty much the same.

Good luck researching

-Benson (Another MY98 Owner)
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Old 04-29-2002, 12:30 PM   #13
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All things being equal (deck etc)

NA 2.5 will eat NA 2.0
Turbo 2.5 will eat turbo 2.0

'sides, you can get DOHC heads for the 2.5 if you really want them.

EJ25 is cool.

-IggDawg
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Old 04-29-2002, 05:02 PM   #14
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i remember reading that the 2.5 cant hold over 12psi of boost (i was told this by the guys from rallispec). with that being said, the 2.0 with turbo could out perform a 2.5 w/turbo, due to the 2.0 being able to handle up to 21. also the 2.0l engine was designed with turbo in mind (i was told that from one of the Japs here at my job, who recieves car magazines from japan). also the do have a 2.0l subaru in england dont know if its the same 2.0 the WRX has, i dont know the numbers but i guess you can do a search for subaru UK. hope this helps.
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Old 04-29-2002, 05:04 PM   #15
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I foyu close the deck of an EJ25 its a whole different story. Were the rallispec folks talking about a stock EJ25?

-IggDawg
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Old 04-29-2002, 10:00 PM   #16
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probably, but unless you want to shell out some 6k on a turbo preped 2.5 the stock one isnt the greatest idea to turbo charge.
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Old 04-30-2002, 07:52 PM   #17
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Yeah, those boost numbers were for stock blocks. The 2.0 in WRC form runs like 36 psi of boost. The STI version is going to come with a semi-closed deck on it, and will be more boost-capable than the regular version. Doing a closed deck service on an engine is not that difficult. Any good tuning shop should be able to do it without problems, and with very good results. It basically amounts to welding a plate on your engine where the piston rings go (I believe, but I don't work on engines). A closed deck 2.5 liter can support a lot of boost if it's properly tuned, has proper fueling, a good intercooler, etc. Engine management is key.
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Old 05-01-2002, 02:39 PM   #18
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In the japanese market they have an Impreza 2 liter NA that produces a bit more HP than our 2.5 liter. It has the variable valve timing and revs much higher. I can't find the page that has the info on it right now. Sorry.

Greg
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Old 05-20-2002, 07:40 PM   #19
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And now, finally, to answer to original question
The normally aspirated New Age Impreza 2.0GX has
got 125bhp.

I don't know why they sell 2.0litres over here in Europe
and 2.5litres in the US, but I guess it has to do with
a) road tax bracket
b) fuel prices ? (can someone give me the price of 1 litre
of 95RON fuel in euros, just to compare)

cy'all
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Old 06-05-2002, 01:23 AM   #20
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we dont have 95 octane ehre. we do have 93 and a gallon... it's at about 1.75

93 octane - US$1.75/Gallon

-Eric
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Old 06-05-2002, 09:42 AM   #21
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The 2.0 NA sold in Europe is probably running higher compression than a wrx here. Same with the 2.5 here. It's very difficult to really answer the original question with any authority because of the differences in the basic engine configurations. With all other things being equal, a 2.5 will give you more power than a 2.0. But all things are not equal in this comparison.

If you are thinking about future upgrades (and who isn't) there are more things in the driveline to think about. If you turbo/supercharge your motor, will the tranny take it? Diffs? Do you plan to reduce the baseline compression ratio to around what the wrx starts with? There are a lot of things to consider. There are other ways to make your car faster...like loosing weight in the car...that don't stress the drivetrain. I'm in the process of doing that now. One advantage to that is the local Subaru dealer could care less that your hood is lighter, if you have a warantee issue, but would certainly have a dim view of an added forced induction system.

my $0.02 worth...... jack
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Old 06-05-2002, 01:24 PM   #22
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This strikes me as a question that should answer itself.

If you have a 2.5L engine with a CR of 9.7:1 and you have a 2.0L that has the same CR. Which one will produce more horses.

No answer needed. Just look at the question.

More air= more power.

That is the same as asking, if you have a 600ci v-10 and a 150ci with the same configuration. Which will produce more power.

I realize that there is a ton of variables but displacement always mean more power. If you can turbo a 4 banger to get the same output as v-8 than you can cram more air in the v-8 to again get mote output over the 4 banger.
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Old 06-05-2002, 01:24 PM   #23
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How abour 98 octane ? Will EJ25 run better with 98 ?
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Old 06-05-2002, 02:23 PM   #24
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ok, you'll get more torque with the larger displacement engine.


the general relationship between torque and hp is:

hp at a given rpm :
hp (rpm) = torque(rpm) x 5252/rpm;

with more air = more power, you get more torque.

with more torque ( usually w/ larger displacement NA engines )
you get a good amount of hp without having to rev it so high.

key with honda engines why they get so much "hp per liter" is cuz they rev the hell out of their engines to get the hp, with really low torque.

in case of turbo: w/ lets say a 2.0 4-cylinder engine displaces ~2 liters of air, vs lets say a 3.0 liter engine. If you're boosting ~1/2 bar of boost into the 2.0, you'll be pushing 50% more air, so it'll feel like the 3.0 engine and so on...



Quote:
How abour 98 octane ? Will EJ25 run better with 98 ?
the us spec ej25 was designed to run on 87 octane. The higher octane just tells you the fuel's resistance to knock. With a 10:1 ratio on the new ej25, with 98 octane won't do anything to performance. If you want to take advantage of the 98 octane, then you can either increase your compression ratio or turbo the car

don't wanna write anymore, i gotta get back to work

-vic
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Old 06-05-2002, 02:33 PM   #25
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Thanks but ... are you sure ?!!

If I use gas with more octane, say 94, I feel the car push harder than normal octane say 87.

I think more octane will produce more turque and hp...



correct me if wrong...thanx
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