I assume the EJ257 block will be mated to your EJ20 heads??? As long as you are working with a pulled block, then it's an easy matter to replace (with OEM) oil and water pumps, thermostat, timing belt AND tensioner. It's the tensioner that goes bad, and it's not cheap. OEM gaskets and seals are more than adequate. For the price (about $170) ARP headstuds are a good idea, though not necessary if you don't plan on pulling big hp and trq.
Here's the thing, though. It's the nature of the beast (all of us WRX and STi owners) to want big power out of our engines. Sooner or later, and probably sooner, you are going to want your engine to be all that it can reasonably be. But, okay, for the sake of argument, let's say that you are that one WRX owner in a million who does not want big power out of his engine.
In that case, why not stay with the 2.0 block? It revs faster, and you won't have to worry about getting the 2.5/2.0 engine to breathe properly. And if you keep it under 300whp/270wtrq, you just might be able to keep the stock trans alive. Believe me, as a daily driver, these numbers will definitely curtail the desire for coffee on your way to work in the morning. AudioSlave at unnatural decibels and a 300whp WRX will clear the 'ol cobwebs out, that's for sure. Of course, if you are a Jack Johnson kind of guy . . .
But back to the hybrid:
The easiest and most cost effective way to get the hybrid to breathe properly is to add cams--which in turn means stronger springs and retainers and, EQUALLY important, a bigger, meaner turbo. It also means a better fuel rail, bigger fuel pump, aftermarket boost solenoid, bigger intercooler, uppipe, downpipe, exhaust, and, of course, injectors. The stock 2.0 injectors are fine. Witch Hunter will modify and flow test them to 815cc. Also, as long as you stay under about 500whp, a reflash is all you need. The OEM ECU is pretty amazing.
A lot of people are P&P-ing the heads. It's not necessary unless you are looking for obscene power. Take out the tumblers (the manifold is off. It's easy to do, and will help air flow). Have your heads cleaned and make sure the valves seal properly. Have a professional with a glass-bead cleaner do this, and have him put on the springs and retainers (about $250 to have a professional do all this). Cams are easy to install (you've got the engine on a stand), but you will probably need to replace all or most of the shims. You might want to have a professional do this (add about another $100-150 for the professional). Triple check your measurements if you do it yourself. No. Quadruple check your measurements. Your local dealership will have a list of shims, and the Portland warehouse will have whichever you need.
By now, if you've done all this, you are asking yourself why you didn't crack the block and put in aftermarket pistons and rods (the engine is still on a stand). And you are starting to ask yourself just exactly how much power this thing is going to produce, anyway. For sure, it's going to be A LOT.
Which brings us to, you guessed it, the transmission and the clutch.
I assume the EJ257 block will be mated to your EJ20 heads??? As long as you are working with a pulled block, then it's an easy matter to replace (with OEM) oil and water pumps, thermostat, timing belt AND tensioner. It's the tensioner that goes bad, and it's not cheap. OEM gaskets and seals are more than adequate. For the price (about $170) ARP headstuds are a good idea, though not necessary if you don't plan on pulling big hp and trq.
ARP studs are good for more then stretch prevention.. They also TQ more evenly due to the fact that the stud is TQed into the block and then the nut is TQed to the head. It’s just a better setup then a bolt.. But granted not “Needed”..
Quote:
Originally Posted by TwoCobras
Here's the thing, though. It's the nature of the beast (all of us WRX and STi owners) to want big power out of our engines. Sooner or later, and probably sooner, you are going to want your engine to be all that it can reasonably be. But, okay, for the sake of argument, let's say that you are that one WRX owner in a million who does not want big power out of his engine.
Who doesn’t want big power?? LOL..
Quote:
Originally Posted by TwoCobras
In that case, why not stay with the 2.0 block? It revs faster, and you won't have to worry about getting the 2.5/2.0 engine to breathe properly. And if you keep it under 300whp/270wtrq, you just might be able to keep the stock trans alive. Believe me, as a daily driver, these numbers will definitely curtail the desire for coffee on your way to work in the morning. AudioSlave at unnatural decibels and a 300whp WRX will clear the 'ol cobwebs out, that's for sure. Of course, if you are a Jack Johnson kind of guy . . .
First. The 2.5L block with WRX heads is a great setup.
Second. The stock transmission is easily broken at stock power levels.. I keep referring to the fact that gearsets are NOT broken by HP or TQ but rather by “Shock Loading” them.. Granted it’s easier to break them at higher power levels, power is not the issue..
Quote:
Originally Posted by TwoCobras
But back to the hybrid:
The easiest and most cost effective way to get the hybrid to breathe properly is to add cams--which in turn means stronger springs and retainers and, EQUALLY important, a bigger, meaner turbo. It also means a better fuel rail, bigger fuel pump, aftermarket boost solenoid, bigger intercooler, uppipe, downpipe, exhaust, and, of course, injectors. The stock 2.0 injectors are fine. Witch Hunter will modify and flow test them to 815cc. Also, as long as you stay under about 500whp, a reflash is all you need. The OEM ECU is pretty amazing.
Head work and cams is always a positive however not “needed”.. The stock wrx heads run very well with the STi block with out modifications.. Also one could put in a mild cam upgrade to an STi spec cam with out modding the springs, valves, retainers and all that.. As for the turbo that is all personal preference.. I know a stock trubo that runs like a beast.. Granted he doesn’t have the top end but he pulls on me out of the hole like mad and I’m launching with PPGs at high revs. The Fuel pump, injectors, blah blah blah have already been discussed.. As for modding the stock injectors this is a bad idea. Opening up the stockers like that will literally “DRIP” fuel into the intake, you cut off the screen and they don’t atomize properly anymore.. Poor setup.. A reflash ECU is good to any power level.. Big Valley STI for instance was running 800whp with and EcuTek flash and a blow through..
Quote:
Originally Posted by TwoCobras
A lot of people are P&P-ing the heads. It's not necessary unless you are looking for obscene power. Take out the tumblers (the manifold is off. It's easy to do, and will help air flow). Have your heads cleaned and make sure the valves seal properly. Have a professional with a glass-bead cleaner do this, and have him put on the springs and retainers (about $250 to have a professional do all this). Cams are easy to install (you've got the engine on a stand), but you will probably need to replace all or most of the shims. You might want to have a professional do this (add about another $100-150 for the professional). Triple check your measurements if you do it yourself. No. Quadruple check your measurements. Your local dealership will have a list of shims, and the Portland warehouse will have whichever you need.
Porting and Polish the heads is a great idea any time your working on them.. The flow increase is crazy which aids in spool up for ANY turbo or setup.. I agree that a Ported and Polish TGV is a great way to go as well in addition to P&P everything.. I agree that having a shop install the heads as good option.. With all the rest of the work being done there is no room for error here..
Quote:
Originally Posted by TwoCobras
By now, if you've done all this, you are asking yourself why you didn't crack the block and put in aftermarket pistons and rods (the engine is still on a stand). And you are starting to ask yourself just exactly how much power this thing is going to produce, anyway. For sure, it's going to be A LOT.
The stock STI pistons are good to about 21psi on a “decent” flowing turbo (about 800-900 cfms) above that and they have been know to crack.. The STi rods are fine for a decent amount of power.. Granted if your doing as much as you described I would do the Rods, and have the crank worked over for better oiling and balance everything..
Quote:
Originally Posted by TwoCobras
Which brings us to, you guessed it, the transmission and the clutch.
As I said, why not stick with the 2.0 block?
The transmission is ALWAYS a factor in a WRX no matter the power level..
The 2.5L is night and day different.. The bottom end TQ is ridiculous driving both side by sides you can really feel it.. Also the 2.5L fattens out the TQ curve which is better then peak numbers and makes a “Lower peak number” car (with a fatter curve) turn better times in ANY event…
Thank you for your time.
____________________________
02 WRX.. Tearing up the streets Yet again.. "Hells Yea"..
You'll get no argument from me on any of what you said. It all depends on what someone wants their WRX to be capable of. If you don't want big numbers, then I reckon it's a waste of money to go the 2.5/2.0 route. The point I was trying to make, is that if you go the hybrid route, there's really no half way. With few exceptions, it's pretty much all or nothing in terms of what needs to be put into the build.
P&P is one of the few places the build can save a little money. You can still get big numbers without it. But, again, I agree. If the porting is done well, it makes a big difference.
And, of course, I agree about shock load being the principle cause of trans failure. In fact, in cars that have torque numbers below 300, shock load is probably the culprit nearly all the time. However, once you get above 300, the torque demon rears its nasty head, and then you have BOTH shock load and torque to contend with. In gear, especially 2-3, and 3-4, when that big power band kicks in, it's sayonara transmission (if the trans is still stock).
However, if the torque number is below 300, and if--and this is a big and if--the clutch is not dumped or slipped (at any revs, not just high revs), then the trans will last for quite a while. In theory. Personally, that's too many "if's" for me.
hey you need the arp head studs the head bolts will stretch i have done some projects just for the research and a cosworth 101m head gasket go perfect and with the blues you will need to run them for some reason the pink dont have the right resistants for the stock ecu
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