There are a number of modifications that
need to be made to the 4AGZE in order to adopt a turbocharger
in place of the factory-fitted supercharger. Here I will outline
what has been done to the engine to prepare it for installation
into my AE92 Corolla Seca.
The most obvious change is the fitment
of a custom exhaust manifold and the turbo itself, in my case
an Hitachi HT18. Removing the old, rusted GZE exhaust manifold
was a bit of a challenge with a lot of the bolts fairly well seized
in place, but nothing a good soaking in CRC couldn't fix. As well
as the five bolts holding the flange, the manifold has a couple
of really tough brackets holding it to the block, almost an overkill!
Fitting the new exhaust manifold was, as you would expect, straightforward.
A new gasket sourced from Toyota was used.
The other major change that was made to
the GZE was the switch to an inlet manifold from a 100kw 4AGE.
The problem with the 4AGZE version (in a turbo situation) is that
the throttle body is on the inlet side of the supercharger. Perhaps
there is a way to adapt the throttle body to the standard inlet,
but in my case it was easier just to bolt on a 100kw inlet. The first picture shows the standard manifold (pointing up towards the bonnet).
Removing the inlet manifold required the
removal of the fuel rail, to get to the top bolts. This is also
a good time to pull out the wiring loom if you don't intend to
use the factory computer. You can see here with the standard manifold
removed and laid out beside the 100kw manifold, the bolt pattern
is an exact match. Good work Toyota ;)
Bolting on the new inlet manifold is,
again, a straightforward procedure. The blow-by hose plugs straight
in, the cold-start injector bolts in, the vacuum hose from the
plenum to the fuel pressure regulator can be reused, and there
are even a few spare holes for vacuum pipes. These came in handy
for the boost gauge, blow-off valve & map sensor.
The next step was to test fit the turbo
onto the exhaust manifold. If you have a close look at the photo
below, you will see a problem. The location of the actuator for
the wastegate is very close to the flywheel - not enough clearance
to bolt the gearbox on. I'd imagine this is a common problem when
fitting a turbo to a FWD car that originated from a RWD (mine
came from a Mazda RX7). This was resolved by making up a new bracket
for the actuator and mounting it further down the turbo housing,
then cutting and re-welding the rod that opens the wastegate.
Very important to make sure the wastegate stays in the fully shut
position when the rod is welded up, otherwise it will continually
bleed exhaust gas pressure and limit boost.
Another issue when using a turbo on a
non-turbo engine is oil supply for the turbo. As can be seen in this photo, we used a two-way
brass fitting in between the oil-pressure sender and the side
of the block, close to the oil filter. Braided high-pressure line
and brass fittings were used to run the oil feed to the turbocharger.
An oil return from the turbo was plumbed
into the sump, towards the top to avoid oil running back through
Here is the engine
hanging from the engine stand. You might notice the cam covers have been swapped for standard 1600cc 4AGE
covers. Shane now has "SUPERCHARGER" covers on his 4AGE powered
Levin, so don't believe him when he tells you it's blown :)
That's it for the major modifications
needed to prepare for the turbo 4AGZE conversion, I'll cover what's
left in the third article.
Nothing major purchased since
the previous article, so I'll update this in the final article.