Stroked WRX vs. Tubro 2.5 R

[AstroRide44]

all right guys, im getting a new car in october and im gonna get a impreza.

i dont know which i sould get, a Stroked WRX to 2.4 liters, but i havent found a kit yet.

or i could get 2.5 RS and slap a turbo on it. i think it would be cheaper to do the 2.5 cuz i wont have to crack open the block.

so tell me what u think and if you know of any stroker or turbo kits please let me know, thanks MAX

[ScoobySnacks]

A WRX is the better choice stroked or not! It might be cheaper to modifgy the 2.5rs, but the engine is nowhere near turbo ready like the WRX is, and if you manage to get a stroker kit for the WRX you'll be even more pleased.



Scooby Doo

[AstroRide44]

well if im gonna turbo the 2.5 ill have to upgrade the fuel and cooling and new psitons. thats it right?

[ScoobySnacks]

Depending on how much boost your going to run...maybe not, but anyone will tell you that turbocharging a non turbo ready engine requires fuel mods and pistons.

If I was to turbo charge a 2.5 rs I would be sure to have the following parts:

1. Upgraded fuel pump
2. Upgraded ignition spark....maybe with boost retard too
3. Fuel rail/Injectors

These are the basic essentials to any good turbo kit.



Scooby Doo

[SuBaRuRuLeS]

And a new tranny.

[ssjwizard]

i like the 2.5 bodys better. personaly id go with the 2.5rs and do alot of modding. a quality turbo kit will cost you about the same as a rebuilt engine will. you can check out cobbturning they sell prebuilt stroker 2.4 engines that should bolt right into the chasis.

[LjasonL]

You will have to crack open the 2.5 block if you want to run any more than 6 or 7 psi (which, BTW, 6 psi on a 2.5 is plenty to take down stock WRX's ). But it will still be cheaper than stroking the WRX. Seems like an easy choice to me...

[akfx0]

you guys keep mentioning stroked wrx or something. what does that mean. and also if you get the 2.5 and put on a turbo will you get almost the same amount of hp as the STi for less?

[MB38]

"Stroked" basically means that they will bore out the block to increase its displacement, add bigger pistons, etc. In essence, it just lowers the compression... a lot.

[Marc-OS]

Stroked = new pistons, rods, and possibly crankshaft, which create a shorter stroke (hence the name "stroked"), and shorter stroke means more displacement.

[MB38]

what company makes a good WRX stroker kit, anyways?

[Nismon]

Originally Posted by Marc-OS

Stroked = new pistons, rods, and possibly crankshaft, which create a shorter stroke (hence the name "stroked"), and shorter stroke means more displacement.

Both you guys are on drugs.go to your local library and read up on it before you go talking about what you dont understand.
"stroked" is when you lengthen the stroke therefore producing more swept volume of your cylinder creating more capacity.
(a taller glass holds more than a short one yes?)
The bore to stroke ratio of the EJ series motors lends to stroking quite well due to its well over square dimensions, but you can bore them out which is completely irrelevant to compression ratio as you get new pistons which will dictate the final compression ratio.
As for stroker kits, TRP Australia sell 2.1,2.2,2.3,2.4,2.5 kits and are in the process of developing a 2.6 version soon.
www.rigoliracing.com.au for more information.
they have just run a 9.57@138mph on a test pass in australia last weekend.

[MB38]

No need to get upset over this. What you corrected us with is nearly identical to what Marc-OS wrote. The shorter rods and lower compression pistons (and a new crank) by definition shorten the stroke. When compression ratio is decreased, the compression volume of the cylinder is, by definition, increased, through the inverse relationship from compression ratio to compression volume. He may not have phrased it in the exact way that you would've preferred, but it doesn't mean he's wrong. You two wrote the same thing, just phrased differently.

With regards to my comment about boring out the block, as you said, it is sometimes utilized. While there is no direct relationship between the volume of the block and the final compression ratio, it is assumed that when one bores out the block to a larger size, it is their goal to gain a lower compression, and they would, as a result, use lower compression pistons. It is not uncommon for some cars (Supras, for instance) to be bored out a fairly substantial amount to allow for ridiculous boost levels.

And thanks for the link.

[ssjwizard]

also in the swap you tend to reenforce difrent parts of the motor to allow higher rpm ranges. check out axis power racing.

http://www.axispowerracing.net/engine.html

[Nismon]

Originally Posted by MB38

No need to get upset over this. What you corrected us with is nearly identical to what Marc-OS wrote. The shorter rods and lower compression pistons (and a new crank) by definition shorten the stroke. When compression ratio is decreased, the compression volume of the cylinder is, by definition, increased, through the inverse relationship from compression ratio to compression volume. He may not have phrased it in the exact way that you would've preferred, but it doesn't mean he's wrong. You two wrote the same thing, just phrased differently.

With regards to my comment about boring out the block, as you said, it is sometimes utilized. While there is no direct relationship between the volume of the block and the final compression ratio, it is assumed that when one bores out the block to a larger size, it is their goal to gain a lower compression, and they would, as a result, use lower compression pistons. It is not uncommon for some cars (Supras, for instance) to be bored out a fairly substantial amount to allow for ridiculous boost levels.

And thanks for the link.

OK, where do i start..
Stroking an engine can be done 2 ways, a new crank with a longer throw or offset grinding the crank journal to achieve the same effect.
In this way the piston travels further down the bore and therefore has more swept volume and hence you achieve more capacity.
This has nothing to do with how much space there is in which the intake charge has to be compressed or even its volume. the capacity being equal to the bore radius x pi x stroke x no of cylinders.
Compression ratio is calculated by chamber capacity (clearance volume) divided by cylinder capacity(swept volume).
Clearance volume is a combination of chaber cc, piston dish cc or crown(+ or -),head gasket thickness and deck height.
If you had only shorter rods, all you would be doing would be lowering comp and piston would travel same distance, further down but not as high up.
At no time is there a specific aim to lower the compression, the pistons you chose will be the main defining factor in the compression ratio-the rod and piston at TDC should be at deck height give or take 0.5mm or 20thou, this combined with the head gasket thickness, combustion chamber cc, piston dish or crown will give you comp.
If you leavethe piston design same and chamber same big increase capacity, you also increase the comp and there is more swept vs same clearance volume.
In regard to boring to acheive greater boost levels, the more meat you take off the bore and therefore the weaker the engine becomes as you reduce wall thickness and increase chance of cracking the bore and heat control.Most heavily boosted engine will try to maintain close to stock bore size due to this specifically, or at least within very safe tolerance.Lowering the compression helps with big boost a lot but once again you can achieve this with only a new set of pistons and not increase bore , stroke or even capacity at all.
Hopefully i have cleared this up. thanks.