The Legendary EJ20 heads on an EJ18 block experiment

Kostamojen · 01-10-2004, 03:00 AM

So yes, today I tried them out. Took apart a ej18 left over at EddyRS's house and tested how the EJ20 heads will work with it. Good learning experience for me, and heres what I learned:

A) The EJ18 heads suck. They have far smaller intake holes, and inky dinky ports and valves...

B) Everything bolts up perfect. The headgaskets from the EJ20 head work perfect on the EJ18 block, and allow the coolant channels to get through properly. And on a side note, the ej18 head channels are far smaller than the ej20 (no surprize). Even the coolant aluminum channel on top uses the same bolt locations as the ej18 one...

C) Despite the fact that everything bolts up fine, there is a serious problem. The valves. The EJ20 valves are so much larger, and spaced so differently that they will most definatly hit the EJ18 pistons at the valve relief cuts in the piston

This means that aftermarket pistons will be required for the EJ20 heads to work with the EJ18

Here are some pics:

http://community.webshots.com/album/110209915vXVzdU

If anyone has any questions or comments, feel free to post.

* Registered users of the site do not see these ads.

xxtwowheelfiendxx · 01-10-2004, 02:24 PM

Isnt the EJ18 a SOHC while the EJ20 is a DOCH? Or at least thats how it looks in the pics, and if it is how do you set up the belts?

scoobyimprza · 01-10-2004, 02:34 PM

Quote:

Originally posted by xxtwowheelfiendxx
Isnt the EJ18 a SOHC while the EJ20 is a DOCH? Or at least thats how it looks in the pics, and if it is how do you set up the belts?

You are correct, but I don't know the answer to the belt quesiton.

Good info, I think you have me convinced on what I want to do.

Brent

Kostamojen · 01-10-2004, 06:32 PM

Quote:

Originally posted by xxtwowheelfiendxx
Isnt the EJ18 a SOHC while the EJ20 is a DOCH? Or at least thats how it looks in the pics, and if it is how do you set up the belts?

Yes, the EJ20 is DOHC. For the belts, you just use EJ20 timing belts, no biggie.

Kostamojen · 01-10-2004, 06:33 PM

Quote:

Originally posted by scoobyimprza
Good info, I think you have me convinced on what I want to do.

Brent

What are you going to do?

Imprezd · 01-11-2004, 10:16 AM

pretty cool experiment I would have loved to hear how that work out to be a bolton operation. Eh that sucks..

Hey if you want i have a ej20 short block for $500 that would make you an N/A ej20 but probably be pretty interesting to see how it runs in N/a form.

Good Luck anyway.

Imprezd~

Kostamojen · 01-11-2004, 11:15 PM

Naw, its ok, im getting a whole 260ps closed deck EJ20G including turbo among other things for not much more than that

So im good

redwagon · 01-12-2004, 01:13 PM

Your EJ18 heads have one exhaust port or two? I can't see them in the pix.

Just curious, I have a P2 EJ18 with twin exhaust ports and wonder if there would be such a difference with the EJ20 heads.

scoobyimprza · 01-12-2004, 01:49 PM

They're twin ports.

Jaxx · 01-12-2004, 03:48 PM

... well that and the engine mangment not sure how the ecu would deal with the smaller DOHC timing belt wheel on the cam sensor

want to sell that turbo ...
please?
-j

Kostamojen · 01-12-2004, 06:30 PM

Quote:

Originally posted by Jaxx
want to sell that turbo ...
please?
-j

Which turbo, from the EJ20G? Thats a possiblity.

Jaxx · 01-13-2004, 12:07 PM

yeah yeah the td05...will swap you for a nice vf-10

Homemade WRX · 01-13-2004, 03:25 PM

In you case the lower compression pistons...if made should fix your problem....go to www.jepistons.com and check out what some custom pistons will run you. I was looking into it. but you will need measurements from your engine.
Take it easy, Micah

Kostamojen · 01-13-2004, 06:27 PM

Quote:

Originally posted by Jaxx
yeah yeah the td05...will swap you for a nice vf-10

FYI, I was told the turbo needs to be refreshed, ill know more about it this saturday.

Kostamojen · 01-13-2004, 06:28 PM

Quote:

Originally posted by Homemade WRX
In you case the lower compression pistons...if made should fix your problem....go to www.jepistons.com and check out what some custom pistons will run you. I was looking into it. but you will need measurements from your engine.
Take it easy, Micah

Oh dont worry, I wont be going through with this. But thats good info for anyone who would be

kidatari · 01-14-2004, 01:10 PM

Kosta- Long time no see. If you need a hand turning wrenches on your swap, let me know. I'll be back to CA around 21Jan.

Chuma87 · 01-18-2019, 08:11 AM

hello dears.

The owner of my ex-impreza wants to make a head swap.

The car is a impreza 95 EJ18 SOHC and want to put a Legacy 96-97 EJ25 DOHC heads, yes, only heads. ECU will be de original ej18, injectors, sensors, intake, etc etc.

When not finding information about it, we have some doubts, since they are old versions without so many sensors.
There will be any problem with intake manifold? Will the pistons touch the valves? From the one to ten, how efficient can swap be?

Thnks

Homemade WRX · 01-21-2019, 12:07 PM

I'd first be concerned of the combustion chamber being too large for the EJ18 bore.

01-10-2004, 03:00 AM	#1
Kostamojen Scooby Guru Member#: 2272 Join Date: Sep 2000 Chapter/Region: BAIC Location: Fire Caves Vehicle: 2018 Type-RA 196/500 1999 OBS Camo Wagon	The Legendary EJ20 heads on an EJ18 block experiment So yes, today I tried them out. Took apart a ej18 left over at EddyRS's house and tested how the EJ20 heads will work with it. Good learning experience for me, and heres what I learned: A) The EJ18 heads suck. They have far smaller intake holes, and inky dinky ports and valves... B) Everything bolts up perfect. The headgaskets from the EJ20 head work perfect on the EJ18 block, and allow the coolant channels to get through properly. And on a side note, the ej18 head channels are far smaller than the ej20 (no surprize). Even the coolant aluminum channel on top uses the same bolt locations as the ej18 one... C) Despite the fact that everything bolts up fine, there is a serious problem. The valves. The EJ20 valves are so much larger, and spaced so differently that they will most definatly hit the EJ18 pistons at the valve relief cuts in the piston This means that aftermarket pistons will be required for the EJ20 heads to work with the EJ18 Here are some pics: http://community.webshots.com/album/110209915vXVzdU If anyone has any questions or comments, feel free to post. * Registered users of the site do not see these ads.

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01-10-2004, 02:24 PM	#2
xxtwowheelfiendxx Scooby Newbie Member#: 47597 Join Date: Nov 2003 Location: Vermont Vehicle: 1997 ///M3 '93 Impreza	Isnt the EJ18 a SOHC while the EJ20 is a DOCH? Or at least thats how it looks in the pics, and if it is how do you set up the belts?

01-11-2004, 10:16 AM	#6
Imprezd Scooby Specialist Member#: 3357 Join Date: Dec 2000 Chapter/Region: MAIC Location: Gburg, Maryland (East Coast) Vehicle: 2002 WRX Black	pretty cool experiment I would have loved to hear how that work out to be a bolton operation. Eh that sucks.. Hey if you want i have a ej20 short block for $500 that would make you an N/A ej20 but probably be pretty interesting to see how it runs in N/a form. Good Luck anyway. Imprezd~

01-11-2004, 11:15 PM	#7
Kostamojen Scooby Guru Member#: 2272 Join Date: Sep 2000 Chapter/Region: BAIC Location: Fire Caves Vehicle: 2018 Type-RA 196/500 1999 OBS Camo Wagon	Naw, its ok, im getting a whole 260ps closed deck EJ20G including turbo among other things for not much more than that So im good

01-12-2004, 01:13 PM	#8
redwagon Scooby Specialist Member#: 2181 Join Date: Aug 2000 Chapter/Region: SCIC Location: So Cal Vehicle: 2003 Forester XS	Your EJ18 heads have one exhaust port or two? I can't see them in the pix. Just curious, I have a P2 EJ18 with twin exhaust ports and wonder if there would be such a difference with the EJ20 heads.

01-12-2004, 01:49 PM	#9
scoobyimprza Scooby Guru Member#: 24956 Join Date: Sep 2002 Chapter/Region: MAIC Location: Littlestown PA Vehicle: 1997 Impreza WRX Steel Blue Mica	They're twin ports.

01-12-2004, 03:48 PM	#10
Jaxx Scooby Guru Member#: 177 Join Date: Aug 1999 Chapter/Region: NWIC Location: Austin, Texas, USA Vehicle: The 93 W/EJ20K-sold Subaru-less :(	... well that and the engine mangment not sure how the ecu would deal with the smaller DOHC timing belt wheel on the cam sensor want to sell that turbo ... please? -j

01-13-2004, 12:07 PM	#12
Jaxx Scooby Guru Member#: 177 Join Date: Aug 1999 Chapter/Region: NWIC Location: Austin, Texas, USA Vehicle: The 93 W/EJ20K-sold Subaru-less :(	yeah yeah the td05...will swap you for a nice vf-10

01-13-2004, 03:25 PM	#13
Homemade WRX Scooby Guru Member#: 33782 Join Date: Mar 2003 Chapter/Region: MAIC Location: Mooresville, NC Vehicle: 96 in the garage search FIRST, then PM!!!	In you case the lower compression pistons...if made should fix your problem....go to www.jepistons.com and check out what some custom pistons will run you. I was looking into it. but you will need measurements from your engine. Take it easy, Micah

01-14-2004, 01:10 PM	#16
kidatari Scooby Specialist Member#: 10441 Join Date: Sep 2001 Chapter/Region: BAIC Location: Northern California	Kosta- Long time no see. If you need a hand turning wrenches on your swap, let me know. I'll be back to CA around 21Jan.

01-18-2019, 08:11 AM	#17
Chuma87 Scooby Newbie Member#: 470383 Join Date: Jul 2017 Chapter/Region: International Location: Argentina Vehicle: 1994 Impreza GL AWD Gris	hello dears. The owner of my ex-impreza wants to make a head swap. The car is a impreza 95 EJ18 SOHC and want to put a Legacy 96-97 EJ25 DOHC heads, yes, only heads. ECU will be de original ej18, injectors, sensors, intake, etc etc. When not finding information about it, we have some doubts, since they are old versions without so many sensors. There will be any problem with intake manifold? Will the pistons touch the valves? From the one to ten, how efficient can swap be? Thnks

01-21-2019, 12:07 PM	#18
Homemade WRX Scooby Guru Member#: 33782 Join Date: Mar 2003 Chapter/Region: MAIC Location: Mooresville, NC Vehicle: 96 in the garage search FIRST, then PM!!!	I'd first be concerned of the combustion chamber being too large for the EJ18 bore.