Ok, Im kinda new to the turbo thing, I dont understand all the lingo, and I dont know a lot of the parts of a kit. Hopefully you'll bare with me here. Ive read a lot on here about turbo kits and swaps. From what Ive read, adding a kit such as the AVO kit to the RS's 2.5 "pretty much max's it out." Yet, for about the same money, you could swap a WRX engine in, have about 220 hp, and lots of room to grow. Why is this? Can you not do the same work on the 25 as you would on the 20 to get "room to grow?" For example, (totally hypothetical, I dont even know if this is needed) if you were going to up the boost on the EJ20 a lot, and needed new headgaskets to take the boost, could you not just do the same thing to the EJ25? I just dont understand why the EJ20 could take lots of power with mods, and the EJ25 couldnt with the same precautionary mods? Thanks.
6lug
One huge advantage of the EJ20 is low compression, something the 25 doesn't have. Lower compression allows you to run more boost. Also, the Ej25 has a very aggressive timing curve, so you have to pull timing to run boost safely, which can raise your EGT's. The wrx swap also includes the ecu to go with the engine whereas a turbo kit you have to either get a standalone or a piggy back, a wideband, get tuning etc. The ej20 will run smoother and be more reliable for a daily driver. Also, there are a lot more parts available for the wrx, which makes upgrading really easy. I seem pro wrx but I actually built a turbo kit and love it, but if I had the money I would have gotten a swap.
They aren't quite the "same" price if you can find the parts yourself. A wrx swap will be 4-5k but a turbo kit setup only cost me about $1400, so it all depends. Hope this helped.
They aren't quite the "same" price if you can find the parts yourself. A wrx swap will be 4-5k but a turbo kit setup only cost me about $1400, so it all depends. Hope this helped.
The EJ20 "WRX" motors were built for boost in stock form... (low compression pistons, better fuel injectors, yada yada yada)
The EJ25 "RS" motor was built for high compression and N/A applications basically built for torque...
In actuallity any of those 2 motors could be built for boost... The reason why more people tend to go the swap route is because the power is there and you wouldnt need much to get that motor really rolling... If you turbo the stock "RS" motor, you would get lots of power at the low boost that its set at but if you wanted more, you would have to start building the block up with low compression pistons, and all the other goodies that the WRX already has stock... In other words cheaper and more reliable in the long run to swap rather than turbo kit...
Eric
The EJ25 "RS" motor was built for high compression and N/A applications basically built for torque...
In actuallity any of those 2 motors could be built for boost... The reason why more people tend to go the swap route is because the power is there and you wouldnt need much to get that motor really rolling... If you turbo the stock "RS" motor, you would get lots of power at the low boost that its set at but if you wanted more, you would have to start building the block up with low compression pistons, and all the other goodies that the WRX already has stock... In other words cheaper and more reliable in the long run to swap rather than turbo kit...
Eric
The ej205 is open deck and the ej257 is semi-closed (added to supports around the cylinders). the RS motor of any year is open deck
Just for 6lug's information, the ej257 is the USDM STi 2.5L. In addition to the semi-closed deck it has lots of nice forged internal stuff that can take plenty of boost without blowing up.Brydon said:
Yes WRXs run about max 22 degrees at full boost and WOT. The USDM STI has high pressure cast pistons not forged but the crank is much nicer then the RS it is slightly knife edged where the RS doesn't quite look as nice. I compared all of the parts when I did a RS to STI internal swap. Rod legths are different but the rods themselves look very similar. In bottom end of subarus the pistons almost always go first then people replace them with forged and the rods go. But if the car is well tuned it should have no problem holding boost.
IMO you should keep the RS motor and find STI bottom end and save some money on the deal. With the extra money invest in some good EM. you could go way over 400Whp with this setup and a larger turbo.
IMO you should keep the RS motor and find STI bottom end and save some money on the deal. With the extra money invest in some good EM. you could go way over 400Whp with this setup and a larger turbo.
I'm sorry I just relized it said valve timing. I assume you mean overlap! The overlap is not the much different. When you upgrade the cams people generally go with cams for Boost or cams for NA. more overlap in NA while with boost you like more lift.will98rs said:
The two I looked at where not the same. The weighted ends of the RS where bigger. But you are right that the stroke is the same as the 99+ RS. The car was a 00 RS and the STI crank was from a Shortblock bought from Subaru that someone blow a ring land on. The shortblock was bought at the end of 05 so I don't know if there was any changes in 06 cranks but it was slimmer.
The rods on the STI block were different length and the pistons wrist pins were offset more.
As a thought since STI rods are shorter maybe the rods could be put into a stock RS shortblock and the compression would lower slightly. The only thing you would have to worry about is the rings going below the wrist pin holes. Just a thought.
The rods on the STI block were different length and the pistons wrist pins were offset more.
As a thought since STI rods are shorter maybe the rods could be put into a stock RS shortblock and the compression would lower slightly. The only thing you would have to worry about is the rings going below the wrist pin holes. Just a thought.
woah, brydron, STI rods are the same length as WRX rods. Yes you are correct about the pin height being changed on STI pistons. If you use STI rods and RS pistons, you will change the compression to around 5:1 or something stupid. The rods will make the pistons sit below the deck that much. But i have had our local subaru dealer order us RS and STI cranks. When they got there. They were both identical. The weighted edge surfaces did look at a little different, but we had them checked for balance and both were almost identical. We have our cranks tested to 12,000rpm. I know no subaru engine will ever go that far in RPM's but we did it and keep doing it just to make sure the factory has not goofed. As of yet, we have found no flaws.
-Thomas
-Thomas
5:1! Think of the boost. Ha Ha Ha. Yes WRX and STI rods are the same but RS rods are 5.181"(SOHC) 5.167"(DOHC) while the WRX is 5.137"
So what about a RS DOHC rod? That seems to be in the middle. I loved my 7.7:1 ej22t motor. No ping, and lots of boost.
So what about a RS DOHC rod? That seems to be in the middle. I loved my 7.7:1 ej22t motor. No ping, and lots of boost.
Thats a great idea! I've done lots of those with great results. RS heads make lots of powers in stock form. The valve springs are alittle weak though.
Hi mates, i'm looking forward to buy a 2005 or 2006 white or black impreza(still thinking on which model i'm going to choose). I'm looking for power and tuning etc... any suggestions which model or type is the best to look for? Like for example uk/us/japan type.....engine type...any advantages and disadvantages on the widebodied ones etc...help appriciated.....thanks
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
