Thursday, December 13, 2007

waterbox delete mod on ej20

so Ej20's have a Waterbox bolted on the intake manifold with a radiator cap

-NA engines have radiator cap on radiator
-turbo engines have radiator cap on waterbox
-2003 wrx and newer have a round radiator cap without ears on their radiator (this is useful for filling level)

for a GC8; the most ideal radiator setup is:

only works on RHD conversion car, or non AC car-

+52mm all metal Koyo for 1991-1994 usdm ej22t legacy turbo - capless
+gc8 jdm radiator brackets
+gc8 jdm metal fans
+gc8 jdm x over coolant pipe
+gc8 jdm fendermounted overflow tank

+stock style intake mounted waterbox (or header tank) with radiator cap

issues: Gc8 turbo Radiator (either stock or aftermarket) does not fit LHD NA AC condensor (you can bend or relocate if you wish to suit, been done by several) -it dosnt fit properly because the JDM RHD AC condensor has in and outlet on the battery side, the LHD part has one in/out on each side of the condensor - hits the radiator design.

IF you have a LHD NA car and you want to fit a turbo motor/cooling system there are a few choices:

Traditional hack style - originally developed on nasioc in the SCC ej20 swapping days:

-gut original radiator cap to be dummy cap and hold pressure (not clean and leaks sometimes)
-play routing hose games and connect to NA overflow somehow

My suggeston: if you have a LHD NA car, keep your NA radiator style, the stock raditor cap and overflow setup, and DELETE the metal on intake manifold waterbox. Yes- REMOVE it completely.

This was first invented for our 6 hour swapped full WRX-RA project, let our thought benefit you.

Remove waterbox. theres basically 3 connections on the waterbox - one from cap is overflow, one to bottom from the shortblock X over pipe is coolant feed from shortblock, one outlet is waterbox to turbo feed. Subaru oem turbochargers are oil and watercooled, you can remove the watercool if you want and run pure oil, keeping watercool is suggested though if possible.


1. remove waterbox completely.
2. make a L bend pipe to connect the

xoverpipe -> turbo feed

instead of

Xover->waterbox->turbo feed.

3. Use NA radiator, Na overflow tank, NA fans. substitute 52mm KOYO NA fitament aluminum radiator if desired.

4. What does the oem watertank do?
- creates temperature differance to circulate water in system after car is shut down; cools down turbo center bearing for you (thats why subaru does not need turbo timer).

5. what happens after i remove this waterbox? Nothing really, if you are tracking your car you should let it cool down manually between sessions, for street driving a cool down is not required on a modern turbo system - unless u call a Z31-T modern.

6. Have you proven this?
-yes. our 95 WRX-RA swap ran oem 1995 impreza L ej18 radiator and full cooling setup from SF->LA->houston. 1800 miles, non stop with a break to race a crotch rocket uphill inbetween on a mountain pass. He was completely happy, your results may vary.

pictured is EJ20G swap into 95 impreza with waterbox delete (with makeshift crappy green metal tube, done in 5 minutes while swapping)


brian said...

I see..

Antonio said...

I have a GF8 i see u removed the big box that usually sits between the turbo and the Maf. Where did you get that piece from. I'm looking for one of those