Click image to view full size

The first stages of running a turbo after a new installation is crucial to its performance and reliability. We highly recommend looking over the following checklist after installation but before starting the engine for the first time:

 

Oil Supply

Oil is crucial to the operation of a turbocharger as it can see rotational speeds of over 100,000rpm. Failure to provide a clean and consistent oil supply can cause an immediate failure. If replacing an old turbo it is recommended to replace the oil feed hose and any fittings or filters between the engine and turbo. Certain vehicles run banjo fittings with an internal filter screen which should be replaced when installing a new turbo and checked regularly.

 

Oil Return

Whilst a turbo needs oil to operate reliably it also cannot have too much inside the bearing cage and must be able to exit from the turbo freely. Special attention must be paid to the oil return/drain hose to ensure it is free of debris and oil can move easily. If replacing an old turbo it is recommended to replace this hose. If oil cannot exit the turbo it can pool inside and cause premature bearing failures leading to oil leaking into the compressor or turbine housing.

 

Intake and Exhaust Piping

Ensuring all piping before and after the turbocharger is leak free and secure will help prevent turbocharger over-speed conditions and producing excess heat. A small boost or exhaust leak will mean the turbo has to work harder to hit target boost and could cause failures to the turbo or surrounding components.

 

Wastegate Setup

For internally wastegated turbos please ensure adequate pre-load on the wastegate actuator rod. A general rule of thumb is to have the clevis hole 1/4 to 1/2 a hole off the centre of the pin so that the rod must be "stretched" to slip over, creating tension and ensuring the wastegate flap is firm against the housing.

For both internally or externally wastegated turbos ensure the correct spring is fitted inside and a hose is connected from the compressor cover to the top of the wastegate housing.

 

Turbocharger Priming

After all above points have been checked over and the car is ready to start it is recommended to prime the turbo with fresh oil first. This can be achieved multiple ways but an example procedure is as follows:

• Install oil feed line to engine but leave the turbo end of the line disconnected
• Place the oil feed line fitting that's not connected in a receptacle to catch any oil
• With engine in a NO-START condition, crank engine WITHOUT firing until oil drains freely from the oil feed line
• Connect oil feed line to turbo (with restrictor if provided), and install the oil drain hose, leaving the engine end of the turbo oil drain hose disconnected and directed into a suitable receptacle
• With engine still in a NO-START condition, crank the engine WITHOUT firing until oil flows freely from the turbo oil drain
• Connect oil drain, and dispose of any oil caught in the receptacle - your turbocharger is now primed with oil and ready for first start

 

First Start

• Start the engine and allow to idle for approximately 3 minutes to purge any air in the system
• Check all unions and fittings are tight and free from leakage
• Check all hoses are routed away from heat sources and any potential chafing risks
• Stop engine, re-check engine oil level and top up as necessary
• Your turbocharger is now ready for use

 

 

Shaft play is caused by the bearings in the center section of the turbo wearing out over time. When a bearing is worn, shaft play, a side to side wiggling motion of the shaft occurs. This in turn causes the shaft to scrape against the inside of the turbo and often produces a high-pitched whine or whizzing noise. This is a potentially serious condition that can lead to internal damage or complete failure of the turbine wheel or the turbo itself.

Turbocharger shaft play is a term that applies to the actual shaft which runs between the intake and exhaust housings of a turbo. There are many types of turbochargers that each will have acceptable shaft play. Most turbo units are floating bearing turbos which means that the oil pressure is required to stabilize the shaft completely. This means that there will be a slight amount of shaft play in the unit when no oil pressure is present. Knowing the tolerances of these turbos is key to diagnosis. Ball bearing turbos will have no shaft play at all when they are in working order. Ball bearing turbos are not as common due to the high cost of the units.

The tolerance for shaft play on a floating bearing turbo is enough that it can be seen but the blades of the unit will not touch the sidewall of the housing. If the blades of the impeller can touch the side with very little force then the unit should be replaced. That said if the blades are forced to touch the sidewall with excessive pressure then the turbocharger has just been damaged by the person doing this. Shaft play in an in and out fashion is never acceptable and means that internally there is serious damage to the turbocharger.

 

Most shaft play cases are caused by oil contamination which can be caused any of the following:

• If the oil filter is damaged or a poor-quality oil filter is used
• Excess moisture can lead to premature oil degradation, increased corrosion and increased wear
• High carbon build up present in the engine can quickly contaminate new oil
• Contamination of new oil whilst servicing (accidental)
• Unchanged oil containing detergent deposits can become very abrasive to the turbos precision components Engine wear, which can leave swarf deposits in the oil
• Degrading oil caused by excessive temperatures or extended service intervals
• Internal engine leaks, such as fuel or coolant mixing with oil supply
• Residue from blasted components, during the remanufacturing process
• Particles from carbon build up in oil feed pipes

 

Signs of oil contamination:

• Scoring to thrust components
• Scoring to journal bearings
• Scoring to journal bearing diameter of shaft and wheel Smell of fuel in the oil
• Particulates in the oil

 

Preventing turbo failure caused by oil contamination:

• Using new oil and filters helps to reduce the risk. We advise that filters recommended by the engine manufacturer are used when refitting the turbo
• Replacing or cleaning the oil inlet pipes and in-line micro filters helps to prevent carbon deposits entering the oil flow to the bearings
• Take care when changing oil during servicing to prevent accidental contamination
• Check for engine wear that could leave swarf deposits
• Check the vehicle is up to date with services
• In high performance applications, change oil more regularly

A/R stands for Area over Radius.  Area is the size of the housing inlet and radius is the the diameter of the housing. The larger the AR number, the larger the housing is. Larger housings support higher horsepower levels, but take more exhaust gasses to turn the wheel and make boost. Smaller housings spool up faster, but become a restriction and generate back pressure for the engine because the exhaust gas has no where to go. This is why it is important to find a housing that works best for your specific application.  

Below is a small chart translating the turbocharger information into more common A/R ratios that we are all used to seeing
these days as used with Garrett turbochargers.

• 6 cm2 = 0.41 A/R
• 7 cm2 = 0.49 A/R
• 8 cm2 = 0.57 A/R
• 9 cm2 = 0.65 A/R
• 10 cm2 = 0.73 A/R
• 11 cm2 = 0.81 A/R
• 12 cm2 = 0.89 A/R

All TD04 based turbochargers use from 5 to 7cm turbine housings (to my knowledge) and TD05 series turbochargers generally use anywhere from 6 to 10cm housings.

A parallel discussion here is whether or not a wastegated or non-wastegated housing is best.  A wastegated housing has a small port hole in it with a door that is controlled by an actuator.  The actuator can be air powered or electronically controlled.  When the door/gate is commanded to open, it allows exhaust gas to bypass the turbine wheel and be "wasted" into the exhaust system.  This has 2 main functionalities: 1) It keeps the turbo from being over sped and failing, and 2) it prevents excessive back pressure because it gives the exhaust gas a place to bleed off. 

A wastegated housing allows for fast spool up when the gate is closed, and minimal backpressure when the turbo is at operating speed and the gate is open.  The draw back here is that you can only achieve a certain level of boost because the wastegate opens and prevents the turbo from being spooled up further.  An appropriately sized non wastegated housing will allow you to achieve higher peak boost numbers while maintaining adequate spool up.

Back to sizing....

While the above information applies to all turbochargers, we are going to now focus on our own expertise, which is large diesel displacement turbocharger systems. Take a Cat 3406/C15 engines for example that it is a 78/1.32 turbo.  This is an S410SX turbo with a 78MM compressor wheel inducer and a 1.32 A/R non wastegated exhaust housing. While this turbo is ideal for a 550-600HP truck, you may want to run it on a larger file and add more fuel; this is where a larger exhaust housing comes into play.  By adding a 1.45 A/R housing, you are effectively slowing the turbo down and increasing the spool up time, but the additional size will support higher horsepower levels because the turbo can now make more boost and have less back pressure at operating speed. 

If you add a larger turbo and experience high EGTs, this can often be caused by a housing that is too large for your setup.  High EGTs occur when there is lots of fuel and not enough air.   This is why EGT's will cool off as the boost goes up.  Some times EGT will skyrock too fast and the turbo cannot come in fast enough to compensate.  In this scenario, a smaller housing can spool up faster to supply the correct amount of air to the combustion chamber to prevent excessive EGTs.

Ideal turbo setups will always have some variance, what works in one situation might not work in another.  This is largely because of different tunes, driving styles, and support modifications (Cam, injectors, displacement/compression ratio, etc)

An anti-surge housing is designed to prevent compressor surge which can occur during Wide Open Throttle (WOT) conditions, not to a replace a Blow Off Valve or Bypass Valve which are designed to relieve charge air when the throttle closes. Its purpose is to relieve pressure on the throttle and is designed to move the Surge Line over on the compressor map. Thus ANTI SURGE. Surge under WOT is much more destructive to a compressor wheel and bearing assembly.

The Surge Line is the left hand boundary of the compressor map and represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading. Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. 

There were many customers who asked us if their turbos require a restrictor. Here's a brief summary of our suggestions and practices. The function of the oil restrictor is an adjustment of the oil pressure feeds into the bearing system.

Ball Bearing

We recommend oil pressure of the ball bearing is 40 – 45 psi at maximum engine speed to prevent damage to the turbocharger’s internals. To achieve this pressure, a restrictor with a 1.0 mm~1.5 mm orifice will normally suffice. But you should always verify the oil pressure entering the turbo after the restrictor to ensure the components function properly. we recommend oil feed -4AN line or hose/tubing with a similar ID. As always, use an oil filter that meets or exceeds the OEM specifications.

Journal Bearing

You may probably hear journal bearing turbos do not require a restrictor, however, a restrictor, ensures better lubrication and keeps the components separated by an oil hydrodynamic film to prevent the metal components from premature wear and ultimately a failure, greatly reducing the chance of oil leakage and smoke coming out of the exhaust, consequently prolongs turbo life , so that most of our turbo install kits come with oil restrictors whether the ball bearing or journal bearing type. The GT B.B series we applied with 1.0 mm and the TD series (Ball Bearing and Journal Bearing) comes with a 1.5 mm orifice.

BE CAREFUL OF OIL DRAIN DIRECTION

Generally, the larger the orifice of the oil drain, the better. Thus, we usually offer -8AN or -10AN size comes with an install kit. If yours, try not to have an inner diameter smaller than the drain hole in the housing as this will likely cause the oil to back up in the center housing. Speaking of oil backing up in the center housing, a gravity feed needs to be just that! The oil outlet should follow the direction of gravity +/- 15° when installed in the vehicle on level ground. If a gravity feed is not possible, a scavenge pump should be used to ensure that oil flows freely away from the center housing.

When installing your turbocharger, insure that the turbocharger axis of eotation is parallel to the level ground within +/- 15°. This means that the oil  inlet/outlet should be within 15° of being perpendicular to level ground.