91 Legacy 2.2 turbo rebuild Pt. II - Heads
Posted: Fri Mar 30, 2001 3:09 am
I thought I would summarize the thread I started on I-club on head
swaps, as it stands so far. I want to thank everyone on I-club for
posting, and apologize for the cut and paste and back fill I did
here. I don't mean to misrepresent anyone's opinion. I also want to
thank the kind folks from the various tuning shops for their time and
consideration in replying to my emails. (Hope I didn't sound like
Julia Roberts there!)
Suffice it to say, most of the swaps over there are 2.2T block swaps
into the Impreza and there seem to be several people who have
successfully swapped in the 2.2T block and used either the SOHC or
DOHC heads, and then added an aftermarket turbo unit. They have all
of course, kept their entire top end. So it seems our main problem
would be related to the ECU.
It was stated that putting the DOHC heads on will definitely work,
but your compression ratio is going to drop to about 7.7:1. The
legacy turbo, all DOHC (incl WRX) and the model '99 SOHC heads have
the same cam sensor. All use a cam sprocket with seven protrusions on
it. Everything else bolts up. The 'CA' spec '99 SOHC and '00' and
later SOHC heads use a 2 protrusion cam sprocket. So, you can bolt on
the SOHC or DOHC heads easily. You just need to make sure your cam
sprocket LH intake cam sprocket has the 1-2-1-3 protrusions. The only
real benefit of the DOHC heads over SOHC are that they are 'capable'
of running higher RPMs. Valve sizes are the same. However, valves in
either of these heads are 36/32mm- your legacy is only 31/28mm, so in
either case, you will be seeing better flow- cams are also bigger.
This is basically saying that since the cam sensors are the same that
either head will work… but then you get comments like this…
If you want to make a safe bet, I'd find the Phase 2 (SOHC) EJ25's
heads, so at least it'll match up with your ECU (b/c you have a SOHC
2.2). The cam profiles might indeed screw up the timing of the
injectors and spark. Maybe this is why most people doing this swap
usually have a boatload of piggyback controllers or a whole new
engine management system.
I would like to talk with `most people', where are they? Again it
seems these are all Impreza owners, although the `most people' quote
was from a guy with a legacy.
Then of course there are those who don't appreciate a challenge…
For simplicity sake, the easiest way to get more power is to extrude
hone your intake manifold, heads and get a 3-angle valve job. Then
get an electronic boost controller, larger down pipe, larger
intercooler (if you don't have one), and a larger diameter cat-back.
If you're changing over to the EJ25 Phase 2 SOHC heads, you'll raise
your compression from ~ 8.5:1 to ~ 9.2:1. You'll effectively have
lower end Torque vs. using your old heads. Personally, for costs
purposes, I'd go with extrude honing and head work... definitely a
lot less effort, and definitely no fit problems.
There seems to be some disagreement with the compression estimates
from people running these engines. I asked one guy to slap a
compression gauge on his engine and post the results. We will see if
he can do that.
I also sent a email to Mike Shields of SPD Tuning Service and he
said "You will not want to use non-turbo heads...combustion chamber
shape and valve timing are not right". I did not think that there
were any turbo 2.5 model cars, but then again I have not looked.
Anyone got any insight on this comment, as it does not make a lot of
sense to me. Maybe he is implying that I look for the 2.0-turbo
heads, like Larry Witherspoon has suggested. He also said that "There
are after market ECU that will run this motor quite well from Link"
so that would seem to imply that our ECU would not work... but I
think it may just be tuning issues he is referring to.
It is also worthy to note that Dale Teague is putting together an
Impreza project car using parts from a turbo Legacy. He had
originally intended to use the Legacy wiring harness but now he
states on his website, "I decided to go in a different direction with
the wiring because I did not feel the turbo Legacy harness would
allow me to tune the car like I want. So I will be installing the
wiring out of a 99 RS 2.5 and then using a freestanding system to
manage the motor. I will also be using the 99 2.5 RS heads on the 2.2
Turbo block." I sent him an email and he also said "I plan on using
the 99 Single OHC heads on my 2.2 Turbo block for my project Impreza.
On the compression I am still not sure myself how it will turn out.
But I do know that the 2.5 SOHC heads flow better than the stock
turbo 2.2 even after they have been ported and polished."
For myself, I am still researching this, and have not decided yet. I
suppose a lot of it will boil down to part availability and cost. But
it seems that all options are still open and possible. I think my
next step is to start calling wrecking yards and go out and get the
shop manual for the Impreza and take a look!!
By the way, I have got everything I need for my bottom end. Crank is
polished up, got my new bearings and oil pump, and it is all sitting
pretty waiting for me!!
Ron Weldy
91 Turbo Legacy Sedan
------------------------ ---------------------~-~>
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swaps, as it stands so far. I want to thank everyone on I-club for
posting, and apologize for the cut and paste and back fill I did
here. I don't mean to misrepresent anyone's opinion. I also want to
thank the kind folks from the various tuning shops for their time and
consideration in replying to my emails. (Hope I didn't sound like
Julia Roberts there!)
Suffice it to say, most of the swaps over there are 2.2T block swaps
into the Impreza and there seem to be several people who have
successfully swapped in the 2.2T block and used either the SOHC or
DOHC heads, and then added an aftermarket turbo unit. They have all
of course, kept their entire top end. So it seems our main problem
would be related to the ECU.
It was stated that putting the DOHC heads on will definitely work,
but your compression ratio is going to drop to about 7.7:1. The
legacy turbo, all DOHC (incl WRX) and the model '99 SOHC heads have
the same cam sensor. All use a cam sprocket with seven protrusions on
it. Everything else bolts up. The 'CA' spec '99 SOHC and '00' and
later SOHC heads use a 2 protrusion cam sprocket. So, you can bolt on
the SOHC or DOHC heads easily. You just need to make sure your cam
sprocket LH intake cam sprocket has the 1-2-1-3 protrusions. The only
real benefit of the DOHC heads over SOHC are that they are 'capable'
of running higher RPMs. Valve sizes are the same. However, valves in
either of these heads are 36/32mm- your legacy is only 31/28mm, so in
either case, you will be seeing better flow- cams are also bigger.
This is basically saying that since the cam sensors are the same that
either head will work… but then you get comments like this…
If you want to make a safe bet, I'd find the Phase 2 (SOHC) EJ25's
heads, so at least it'll match up with your ECU (b/c you have a SOHC
2.2). The cam profiles might indeed screw up the timing of the
injectors and spark. Maybe this is why most people doing this swap
usually have a boatload of piggyback controllers or a whole new
engine management system.
I would like to talk with `most people', where are they? Again it
seems these are all Impreza owners, although the `most people' quote
was from a guy with a legacy.
Then of course there are those who don't appreciate a challenge…
For simplicity sake, the easiest way to get more power is to extrude
hone your intake manifold, heads and get a 3-angle valve job. Then
get an electronic boost controller, larger down pipe, larger
intercooler (if you don't have one), and a larger diameter cat-back.
If you're changing over to the EJ25 Phase 2 SOHC heads, you'll raise
your compression from ~ 8.5:1 to ~ 9.2:1. You'll effectively have
lower end Torque vs. using your old heads. Personally, for costs
purposes, I'd go with extrude honing and head work... definitely a
lot less effort, and definitely no fit problems.
There seems to be some disagreement with the compression estimates
from people running these engines. I asked one guy to slap a
compression gauge on his engine and post the results. We will see if
he can do that.
I also sent a email to Mike Shields of SPD Tuning Service and he
said "You will not want to use non-turbo heads...combustion chamber
shape and valve timing are not right". I did not think that there
were any turbo 2.5 model cars, but then again I have not looked.
Anyone got any insight on this comment, as it does not make a lot of
sense to me. Maybe he is implying that I look for the 2.0-turbo
heads, like Larry Witherspoon has suggested. He also said that "There
are after market ECU that will run this motor quite well from Link"
so that would seem to imply that our ECU would not work... but I
think it may just be tuning issues he is referring to.
It is also worthy to note that Dale Teague is putting together an
Impreza project car using parts from a turbo Legacy. He had
originally intended to use the Legacy wiring harness but now he
states on his website, "I decided to go in a different direction with
the wiring because I did not feel the turbo Legacy harness would
allow me to tune the car like I want. So I will be installing the
wiring out of a 99 RS 2.5 and then using a freestanding system to
manage the motor. I will also be using the 99 2.5 RS heads on the 2.2
Turbo block." I sent him an email and he also said "I plan on using
the 99 Single OHC heads on my 2.2 Turbo block for my project Impreza.
On the compression I am still not sure myself how it will turn out.
But I do know that the 2.5 SOHC heads flow better than the stock
turbo 2.2 even after they have been ported and polished."
For myself, I am still researching this, and have not decided yet. I
suppose a lot of it will boil down to part availability and cost. But
it seems that all options are still open and possible. I think my
next step is to start calling wrecking yards and go out and get the
shop manual for the Impreza and take a look!!
By the way, I have got everything I need for my bottom end. Crank is
polished up, got my new bearings and oil pump, and it is all sitting
pretty waiting for me!!
Ron Weldy
91 Turbo Legacy Sedan
------------------------ ---------------------~-~>
Make good on the promise you made at graduation to keep
in touch. Classmates.com has over 14 million registered
high school alumni--chances are you'll find your friends!
http://us.click.yahoo.com/03IJGA/DMUCAA ... /X7OVlB/TM
---------------------------------------------------------------------_->
To unsubscribe from this group, send an email to:
BC-BFLegacyWorks-unsubscribe@egroups.com