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This article was first published in 2005.
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Upgrading a turbo or installing a turbo on a previously naturally aspirated
engine? Here are some do-it-yourself tips to help you on the way.
Turbo Connections
If you’re buying a secondhand turbo, it’s important to try to source one that
has all its oil and water fittings still in place. Doing so can save literally
hours and lots of dollars.
In a wrecker-sourced turbo, the fittings will either have been removed
completely (bad), or the hoses and pipes cut off (much better). If the hoses and
pipes are still in place, it’s a lot easier to make the connections. For
example, a banjo fitting is often fitted to the oil inlet, a flange and large
diameter metal tube to the oil exit, and barbed metal pipes to the water inlet
and outlet connections. If all the fittings are missing, you’ll have to source
new ones – an expense that can quickly add up.
Another reason for sourcing a turbo with its fittings still intact is they show the manufacturer's preferred sizing. So it gives you
a guide for the required size of the oil return fitting for the sump, the oil
supply line and the water connections. In roller bearing turbos, the inlet oil
fitting can also include a restrictor.
Spinning Around
In nearly all turbos, one end or the other (or in some cases both) can be
rotated relative to the position of the centre bearing. The centre bearing
normally has to stay in the one orientation (ie it has an ‘up’ direction) but
often the compressor cover lugs can be unbolted and the cover rotated, allowing
the outlet to come out at a new position. However, other turbos have bolted-on
compressor covers, where the cover may be able to be attached only in the one
position. Still other turbos have the turbine housing connected to the centre
bearing by a V-band – loosen-off the V-band and the turbine can be spun around
as well.
But while there is often plenty of flexibility, it is far better if the turbo
can be used as it was sold off the shelf, or as it was configured in another
car. Rotating the turbine housing can cause interference between mounting bolts
and the centre bearing housing fittings (eg the water fittings) and rotating
either the compressor cover or the turbine housing can cause wastegate actuator
mounting problems. As in, a whole new mount for the wastegate may need to be
made!
That was what was required in this fitment, where one of the turbos from a
Liberty twin turbo was being fitted
to a Toyota four cylinder engine.
Rotating the turbine housing was required, but as a result, the wastegate
actuator (which normally bolts to cast-in threaded bosses on the compressor
cover) lost its mounts. To replace them was quite an involved procedure.
A lathe was used to turn-up a thick aluminium ring (arrow). This is sized so
that it is a snug fit over the top of the compressor cover, and is sectioned to
allow for the compressor exit. The ring is held in place by longer-than-standard
stainless steel cap bolts that also hold the compressor cover in place. Spacers
(nuts drilled out) were used to distance the ring from the compressor lugs –
without these, the ring would have had to be a very complex shape to provide
sufficient ‘meat’ around the bolt-holes. The wastegate actuator bolts to the
ring.
The wastegate actuator rod (arrowed) already had a kink in it but the rod
needed to be bent just a little more so that the wastegate operated smoothly.
Its operation was tested with a large syringe on the wastegate actuator
hose.
All in all, it was a lot of hassle to remount the wastegate actuator – so if at all possible, avoid this sort of fiddling.
How Much Work?
It’s not something that people will normally tell you, but in the
home installation of a turbo, the
organising of the oil and water systems and the making of a stainless steel
heatshield can total as much time as making the exhaust manifold!
How come? Well, the oil supply line and oil return fitting both need to be
made-up by an industrial hose supplier, the water supply and drain and the oil
drain pipes may all need to be modified and then silver soldered back together
by a welder, and despite looking quite simple, heat shields can be absolute
bastards to shape so that they clear the turbo, block and all the connections.
In short, by the time the cutting and trial fitting of heatshield pieces is
complete, and all the running around to suppliers and the welder is done, it can
take days to put together these bits and pieces... longer than it takes to make
the manifold!
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Laying Out the Plumbing
Installing a turbo on a previously naturally aspirated engine comes down to
nearly one thing: plumbing. Think about all the pipes: the exhaust manifold
(after all, just an arrangement of plumbing that connects the exhaust ports to
the turbine), the inlet from the airfilter, the outlet to the intercooler, the
exhaust pipe out of the turbine, cooling water in and water out, the oil
pressure feed and oil drain...
When you start to throw in ideas like keeping the intake air plumbing as far
apart from the exhaust plumbing as possible (to prevent the combustion air being
overly heated), making sure that hoses cannot rub against hot bits or heat
shields, and keeping the oil drain to the sump as close to vertical as possible,
it can all start getting quite complex.
That’s why it’s important to mock-up where all these pipes are going before starting to weld them.
This view shows just such a mock-up, with the lower heat shield removed. A
single turbo from a Liberty twin
turbo was being installed on a
Toyota four cylinder engine. Two inch
copper plumbing fittings were being used together with copper tube for the air
plumbing (see
Copper Intercooler Plumbing
for more on this
approach) while the exhaust was also two inch, this time in steel mandrel bends.
The configuration of the turbo prevented the exhaust and intake ends being
nearest the on-car exhaust and air filter locations, necessitating the use of
lots of bends.
(1) The exhaust pipe, comprising one mandrel 180-degree bend and two mandrel
45-degree bends. (2) The turbo air outlet plumbing. Here the adaptor from the
turbo outlet’s relatively small hose to the 2-inch intercooler plumbing has yet
to be made – just a temporary one is doing service. (3) The inlet plumbing
connecting the airflow meter to the compressor inlet. Note how the bends are
held together at this stage with electrical tape. (4) The water hoses. (5) The
braided oil pressure feed hose. Missing from this view, because it was yet to be
completed, is the oil drain hose from the turbo.
Note that with this engine, the turbo is mounted on the rear of the
transverse engine (ie nearest the firewall) where access is difficult. The
ability in this case to lay out the plumbing on a second engine being suspended
from an engine crane was absolutely invaluable.
Heat Shields
Heat shields tend to be overlooked in aftermarket turbo installations and
upgrades – but are near universal in factory systems. Heat shielding of the
exhaust manifold, turbine and exhaust off the turbo are all extremely important.
But first, how does this shielding work?
The shields prevent the radiation of heat. If you imagine watching the
red-hot exhaust manifold of a hard-worked turbo engine on the dyno, placing even
a thin sheet of metal between the glowing manifold and your face will cut down a
lot on the amount of heat you’re subjected to. So long as the heat shield itself
doesn’t start to get red-hot, far less heat will be radiated from the manifold
to the surroundings, even if only a thin shield is used.
Because they’re primarily radiant heat barriers, heat shields don’t have to
be made from insulators, so explaining the use of factory pressed metal shields.
Without heat shields being fitted, two things happen. Firstly, any object
under the bonnet that is close to a hot bit - and is in direct line of sight to
it - will also get very hot. Depending on where the turbo is mounted, that could
include wiring, the radiator, the firewall, the bonnet, air con hoses, and so
on. Wiring, for example, can easily have its insulation melted, and bonnet paint
can bubble. Secondly, once the radiant heat has escaped from its source, the
whole underbonnet environment will get hotter, resulting in increased intake air
temps.
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Theoretically, the hotter the exhaust manifold is kept, the more heat that
gets to the turbo, resulting in better turbo performance. However, improved
performance from heat-shielded turbo engines is normally the result of the
decreased intake air temps.
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If a turbo is being fitted to a previously naturally aspirated engine, and
the new turbo manifold is shaped somewhat like the original exhaust manifold,
the original heat shield may be able to be modified to fit in its new
application.
That’s what’s been done for the top heat shield here. The lower flat one has
been formed from scratch from stainless steel sheet (you can easily buy small
stainless offcuts like this from scrap metal dealers and also manufacturers of
stainless steel products... like urinals!)
Extra Dollars
Finally, don’t forget that installing a turbo will result in plenty of
expenses that you might not have catered for. These include coolant (you may
need to remove the radiator to get enough clearance for the installation of the
turbo), engine oil (best to remove the sump when installing the turbo oil
drain), and transmission fluid (in the Toyota modification described here, one
driveshaft had to be removed to give sufficient room for the turbo and exhaust
manifold to be fitted past the lower part of the engine).
And those costs aren’t including the more obvious extras like hoses, clamps,
spray paint and so on!
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