jam007

iTrader: (1)

So just wanted to get some suggestions on either a motor swap or re-build. What would be more cost efficient and more stout, a complete EJ207 STI motor with a blouch 18g and methanol water injection with a target horsepower of 380-400hp with supporting mods of course or re-build the existing EJ20 in my 2004 wrx, sleeved, aftermarket con rods and pistons, crower stage 2 cams, with same turbo set up as above and meth/water as well. This will be used as just something fun to drive, have the power available when i need it, everyday daily driver, could see some light track duty, you guys know the drill. So hit me with some advice, thanks..

meilers

Meth = not daily driver. O4 WRX + 400hp = transmission replacement. 18g + 2.0l = no power until 4400 RPM.

jam007

iTrader: (1)

So tune two seperate maps for the meth, HI-LO boost setting. Trans dont be a complete idiot while shifting, and was going to use the meth to help spool 18g....

Shazam321

iTrader: (1)

A buddy of mine has an 18g on a 2.0l and hes at full boost at about 3400(no meth). i think your talking about something quite a bit bigger.

Your going to need a new tranny with that much power, unless you don't want to be able to use the parts you spent all the money on.

meilers

I've got no intention of being insulting here, but do you know what methanol injection is and what it does? It has NOTHING to do with how quickly a turbo spools, only the amount of boost you can put through it without premature detonation. How fast a turbo spools has to do with how much exhaust pressure reaches the turbo vanes how fast, and the diameter of the turbine inlet.

jam007

iTrader: (1)

Help me again if im wrong, meth/water injection helps cool intake temps, which makes air more dense, the more dense the more you can compress, which makes a faster motor correct? So turbo works off exhaust impulse of the motor, if the motor his rotating and reciprocating faster with the meth/water the turbo will spool faster...correct?

meilers

Sure, that's part of it. However, turbo spool-up happens *before* full boost, and all the injection systems I have seen do not trigger until you've actually reached full boost (or within 1 or 2 psi of that). The meth injection isn't going off until you've reached the safety limit of your boost PSI, and then letting you go beyond that safety limit by simulating higher-octane fuel (suppression of combustion) and a slightly denser intake charge. The effects of meth injection can also be created by just getting a bigger, more efficient intercooler, spraying CO2 on the intercooler or using 93 or 100-octane fuel.

Turbo spool-up is a function of the internal size of the hot-side compression chamber, the drag of the spindle (ball bearing, etc.) and the volume of exhaust coming down the turbine inlet. You will get more exhaust with more RPMs and a leaner fuel mixture, but that's pretty much a function of the engine and how many cfm's of exhaust it generates. Once the hot-side chamber is pressurized, only then can it begin to compress the cold side (which is in vacuum until boost). A bigger turbo can support more CFMs of flow and has greater potential for peak boost, but also takes more time to pressurize the hot side. "Porting" the hot side inlet sometimes increases spool, but most turbos are pretty well designed from the factory and I haven't seen drastic improvements with ported turbos.

I've driven a friend's 2.0l WRX with an 18g, as well as the same car a few months later with a PE18 -- NUTS power, but definitely more lag than a VF34 and weak as a kitten below 3000 rpm. Literally, stock Accords and Civics and Camrys were constantly leaving me at the stoplight unless I gunned it to get it moving. Also, he had a stock clutch and the R/A gearset, and you could feel the transfer case flex on launch and on the 2/3 shift, the entire car would lurch. I think 300whp is doable with the 2.0l and the 5MT, but you would really have to baby it, keep the stock clutch (don't get an aftermarket carbon fiber) and don't do 4500-rpm drops or launches. I've only got a measly 210 whp in my 02 WRX, and I already feel like the transmission is on borrowed time. Shifting from 1 to 2 at high rpms/full boost is a struggle, and 4 is also hard to find at full boost/torque, as if the entire transfer case was distorting.

jam007

iTrader: (1)

thank you for the extra knowledge of this system, it clears up alot of things. So pretty much stay conservative on the transmission, alright one more thing ive read some pretty good things about these Big 16g's any experience with these?

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