More EJ22T Head Questions

subachad · 05-17-2002, 11:39 AM

Hi all,

Lots of EJ22T questions today, that's nice. The thing I'm wondering is for those with EJ22T blocks and EJ25 Top ends, did you modify the heads at all to get them to work? The reason I ask is the different bore. Speaking of which, what is the Bore of a 2.5RS vs the Bore of a 2.2T? Will or does this cause a problem?

Chad
93 1.8T (possibly (very) soon to be 2.2T)

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Eric SS · 05-17-2002, 12:08 PM

The EJ25 (SOHC) heads bolts directly to the EJ22T without modification. Bore really doesn't affect what heads you can use because the combustion chambers are all going to be smaller than the block bore

Eric

wac · 05-18-2002, 07:44 AM

Chad,

The bore differences shouldn't matter too much, since along with the head gasket bore and thickness, that only affects the squish volume. You should be much more concerned about squish volumes, valve angle/timing, fuel management, ignition timing, and compression ratios instead. And choosing head gaskets that won't leak.

I have read elsewhere that engineers spend a lot of time optimizing squish volumes. But by the sounds of the wide variety of EJ22T hybrids using all sorts of DOHC/SOHC head gaskets, we're probably safe with the EJ series motor at the lower boost levels we run. Cobb's EJ20/EJ25 hybrids are extreme examples that seem to work.

You can find bore numbers by doing a search on the Net, and I have also compiled them at:
http://wac.addr.com/auto/obs/turbo/ejcalcs.html

Hope this helps,

-WaC
Wayne

subachad · 05-18-2002, 12:26 PM

Thanks for the good answers. Wayne, that's an excellent write up, I keep meaning to add you to my links page, I think I'll just do that now.

Chad
93 1.8T

05-17-2002, 11:39 AM	#1
subachad Scooby Specialist Member#: 8488 Join Date: Jul 2001 Location: Sin City Vehicle: 1993 Impreza GCStyle Teal	More EJ22T Head Questions Hi all, Lots of EJ22T questions today, that's nice. The thing I'm wondering is for those with EJ22T blocks and EJ25 Top ends, did you modify the heads at all to get them to work? The reason I ask is the different bore. Speaking of which, what is the Bore of a 2.5RS vs the Bore of a 2.2T? Will or does this cause a problem? Chad 93 1.8T (possibly (very) soon to be 2.2T) * Registered users of the site do not see these ads.

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05-17-2002, 12:08 PM	#2
Eric SS Sooby Guru Member#: 1914 Join Date: Jul 2000 Chapter/Region: SWIC Location: 2013 335i, 2011 G37 coupe Vehicle: 2000 2.5RS w/ EJ22T swap and N20. gone. : (	The EJ25 (SOHC) heads bolts directly to the EJ22T without modification. Bore really doesn't affect what heads you can use because the combustion chambers are all going to be smaller than the block bore Eric

05-18-2002, 07:44 AM	#3
wac Scooby Specialist Member#: 689 Join Date: Dec 1999 Chapter/Region: NESIC Location: Lebanon, NH, USA Vehicle: 2005 Outback 2.5 XT Champagne Gold Opal	Chad, The bore differences shouldn't matter too much, since along with the head gasket bore and thickness, that only affects the squish volume. You should be much more concerned about squish volumes, valve angle/timing, fuel management, ignition timing, and compression ratios instead. And choosing head gaskets that won't leak. I have read elsewhere that engineers spend a lot of time optimizing squish volumes. But by the sounds of the wide variety of EJ22T hybrids using all sorts of DOHC/SOHC head gaskets, we're probably safe with the EJ series motor at the lower boost levels we run. Cobb's EJ20/EJ25 hybrids are extreme examples that seem to work. You can find bore numbers by doing a search on the Net, and I have also compiled them at: http://wac.addr.com/auto/obs/turbo/ejcalcs.html Hope this helps, -WaC Wayne

05-18-2002, 12:26 PM	#4
subachad Scooby Specialist Member#: 8488 Join Date: Jul 2001 Location: Sin City Vehicle: 1993 Impreza GCStyle Teal	Thanks for the good answers. Wayne, that's an excellent write up, I keep meaning to add you to my links page, I think I'll just do that now. Chad 93 1.8T