FAQs

Q. My new turbo is installed, now what?

A. Before starting the motor, it is important to get an adequate supply of oil through the turbo. To do this, disable the ignition or injectors (different for various cars) so the car is able to crank without firing. Crank the motor over for 30-45 seconds in 10 second intervals. This will pre-oil the turbo, and prevent premature thrust bearing failure.

Q. What's the difference between internal and external wastegates?

A. Internal wastegates are comprised of a flapper door which is built in the turbine housing, usually operated pneumatically by a mechanical actuator. These flapper doors are limited in size, but work well in certain applications. Usually found in smaller turbos, internal wastegates are relatively inexpensive, simple in design, and very durable. Larger turbo can be fitted with internal wastegates, but boost control can be tricky. If you are looking to run high boost (20+ psi) all the time, then an internal gate may be fine. If you are looking to run lower boost levels, you will need an external wastegate.External wastegates are generally mounted to the exhaust manifold or to the O2 housing of a vehicle so equipped with one, and are self contained units. External wastegates have the ability to bypass large amounts of air, and can provide steady boost control at any pressure level. A common myth is that in order to run higher boost pressures, you need a larger wastegate. This is incorrect. Larger wastegates are necessary to run low boost levels on large turbos.

Q. I just bought Turbo-X, how much boost can I run?

A. This is a question we cannot answer for you. The amount of boost your car can handle is dependant on the rest of your setup, as every car has different flow properties and fuel capabilites. The best advice is to start low (10-15psi) and work your way up, paying close attention to your air/fuel and EGT gauges (you DO have these, right?).

Q. What are twin scroll or divided inlet turbine housings? What are the benefits of using a twin scroll turbo? Is Twin Scroll the same as a Divided Turbine housing inlet?

A. A "twin scroll" means that there are two separate volutes within the turbine housing. The main reason for doing this is to isolate the pulses coming from each exhaust port and maintain more of the pulse energy from each cylinder all the way down to the turbine wheel. A divided turbine housing only has this divided section for a few millimeters within the turbine housing before it merges into one volute. This is common on larger turbocharger applications that utilize a lot of torque and larger exhaust wheels. But it does not mean it is a "twin scroll turbine housing".  Generally speaking, the benefits of a twin scroll turbine housing are limited to smaller fraimed turbochargers under 45lbs/min and do not display the same behaviours as a variable vein turbo or an actuated veind turbine. Please check out our new write-up for more details on this trending phenomenon.

While it does not cause any problems or harm to run a divided inlet turbine housing on a manifold that is an "open" design, none of the benefits of the twin inlet will be seen.

Q. Why does my turbo not have a rubber "O-ring" surrounding the front portion of the compressor cover backplate? Isn't it needed to seal?

A. Generally, only the GT-R and STC GT-R based turbochargers use a rubber o-ring as part of their package. That is because the o-ring is simply used as a precaution for those turbochargers that are expected to be at extremely high boost pressures and thrust loads in that application in which the backplate is a cast piece.  Those that have a billet backplate or custom application may not have this rubber o-ring, which is very common and normal. The billet and custom turbochargers from STC use a compressor cover that is machined specifically to securely fit the billet and custom backplates that are used without any boost leaks.  If your turbocharger does not have a rubber o-ring seal on the turbocharger, it is normal, and there is no need to obtain one for the best fit.  

Q. I have a boost leak tester device hooked up to the inlet of my turbo and I can hear/see a leak going through this? Does that mean the turbo has a major boost leak?

A.  No. Contrary to popular belief, turbochargers are not "leak proof". In order for a turbocharger to survive extreme stresses given by higher boost pressure levels, compressor covers and inlets will have a small amount of pressure leak in order to retain the integrity of the compressor cover to keep it from any type of warping or flex.  It's quite common to hear small amounts of air or see "bubbles" coming from the backplates of turbochargers. Rest assured, that as long as the compressor cover is bolted properly with the correct torque given by the Garrett spec card included with your turbocharger, it should perform just fine without the need of additional sealants, o-rings or other apparatus. As always, if you're unsure, contact us for an inspection.

Q. Why do people say it's not good to get oil feed for the turbo off the cylinder head on some vehicles?

A. There are plenty of people who have oiled their turbo off the head and not had any problems, there are just as many if not more that have done it and had recurring turbo failure that was only vaguely described by the repair shop as "poor lubrication".

Oil pressure in the cylinder head on a stock 4G63 engine can be less than 5psi at times, while this may be enough oil for a factory 14b, T25 or even 20g it isn't enough to feed the high volume oil passages of the modified thrust setup in your upgraded turbocharger. For other platforms such as Honda, Nissan, or Mazda, Pressures can be as high as 100psi of oil pressure and as low as 10psi of oil pressure. The Garrett severe duty 360 thrust setups also have an increased appetite for lubrication. Think twice before feeding either of these type turbos from the cylinder head of your application.

Remember that you aren't just trying to keep some oil on the bearing, you are trying to float one piece of metal above another piece of metal on a pressurized film of oil, and at the same time keep the whole mess cool enough not to melt. A constant high volume stream of oil does just that, a measly trickle will send you back to the turbo shop.

One exception to this is the Ballistic Concepts Ball Bearing CHRA from Garrett. These turbochargers are totally different internally. Their operation is actually impeded by too much oil. It is fine to supply these turbos with oil from the head. These turbos, unlike our optional journal bearing series, require water cooling in the absence of the typical high volume of oil that would normally provide stable temperatures.

As far as filters go, This decision does not have a specific "yes" or "no" answer associated with it.. Typically one should not need one in the oil line. Failures occur due to dirt/grit in the oil making it into the turbocharger. In addition, failures also can occur due to plugged filters. Both scenarios are possible. If you are going to use an aftermarket "in-line" oil filter, do the right thing and check it often. The most important thing one can do to avoid oil contamination of a turbocharger is to THUROUGHLY wash everything more than once before assembling your engine. Avoid sandblasting anything that goes inside or onto the engine. Specifically avoid sandblasting your valve cover. If you suspect that the machine shop that did your valve job sandblasted your head then make sure you wash the gallies out with HOT SOAPY WATER, or mineral spirits before re-installing the valve cover.

Q. The shaft in my turbo feels loose. How much freeplay should I have?

A. While this specification does vary from one brand to another and rule of thumb is less than .030" radial freeplay and less that .002" axial freeplay.

This amount of freeplay is required to allow the bearings to "float" in a pressurized film of oil while the engine is running. The flow of oil through the clearance around the bearings is what helps the bearings stay cool. This oil film around the bearings also help dampen vibrations that occur to the rotating assembly as it moves through it range of RPM. Ball bearing turbochargers do not have this pressurized film of oil around the bearings; this is why they are somewhat more noisy than floating journal bearing turbos.

In addition, contrary to popular belief, Garrett Ball-bearing turbochargers will experience some amount of axial play over time, as the ball-bearings will slighty reduce in size due to the wear from the amount of friction it experiences in the ball-bearing cage. This insignificant amount of axial "play" is normal , and should not be considered as any indication of failure of the turbocharger or in need of a reseal. If there are questions about whether or not, the amount of play is more than normal, please contact us via e-mail. Any video documentation will greatly assist us in determining any issues.

Q. My turbo is smoking and it's brand new. The shaft has normal play in it so is one of my seals blown?

A. The term "blown seal" is widely used to describe a turbo that has oil coming out of it. In reality a turbocharger oil sealing ring similar to a piston ring cannot become damaged until the freeplay of the shaft has increased to the point where the blades of the turbocharger have been rubbing against the housings. Blade contact usually requires more than .035" of side to side movement of the shaft. In some cases it is even possible to rub the blades and still not damage the seals.

If the turbo is new and the shaft isn't loose and bouncing off the housings, but oil is coming out of it chances are you can correct the problem without even taking the turbo back off the car. Check the oil return line to ensure it has a smooth transition into the oil pan with few or no 90 degree elbow fittings on the line, that is over 1/2" in diameter (or-10AN for most applications). Also ensure that you have not over-restricted the oil feed line. If the feed line is over restricted, it could cause oil starvation, which may eventually cause the compressor or exhaust wheels to make contact with the housings.

These oil sealing rings within the turbo are not meant to hold back a bearing housing that has become full of oil. They are designed to sling the oil mist and spray within the bearing housing away from the point where the shaft comes out each end. If the bearing housing becomes full of oil it will ooze out past even brand new seal rings.

The oil should freely drain out of the bearing housing as quickly as the engine supplies it. This is why the drain tube is so much larger than the supply tube. Gravity is the only force moving the oil out of the turbocharger. Any slight restriction in the oil drain tube, even a small silicone dingle berry, can slightly impede the draining of the oil and cause oil to back up into the bearing housing.

The crankcase vents are the second largest cause of oil loss from a good condition turbocharger. The seals in the turbocharger were designed with expectation that the pressure inside the compressor and turbine housing will always be greater than the pressure in the bearing housing. If this is ever not the case then oil will come out pass these rings. A restricted crankcase vent will cause this to happen. If the amount of ring blowby exceeds the ability of the crank vents to release the pressure positive pressure will build within the crankcase. This pressure within the crankcase can exceed the pressure inside the compressor and turbine housings under some operating conditions resulting in oil being driven pass the seals by the improperly biased pressure gradient across the seal rings. In severe cases it may be necessary to introduce vacuum pumps to deal with crankcase pressure, but these would be very severe high boost applications where even low percentages of blowby produce a high volume of crankcase vent.

 

 

Turbo Failure Information

 

 

Speed Trapp Consulting offers an individual repair program that covers any sort of manufacturer error but does not cover end user error. Below you will find examples of what type of damage is not covered by our policy.

Lack of Lubrication

Lack of Lubrication

Any lack of lubrication will result in heat marks on the turbine shaft (see picture). A lack of oil will turn the shaft blue and make score marks in it. If there is a blue shaft we will not cover it.

 
Hot Shut Down

Hot Shut Down

Damage from hot shut down will appear as a lack of lubrication. If you are under full boost, the turbo will be spinning close to 100,000 rpm. If the motor is shut down or stalls under full throttle and high boost, the turbo is still spinning at extremely high speed with no oil pressure. Also shutting down a glowing hot turbo with out allowing time for it to cool down will cause coking (excess carbon deposits) that will block oil supply. To prevent hot shut down damage, use a turbo timer to cool your turbo down every time you turn your car off.

 
Fin Damage

Fin Damage

Damage to the compressor wheel is cause either by foriegn objects being injested into the turbo, or severe compressor surge. Turbine wheel damage results from objects being expelled from the motor through the head (pieces of your valves, pistons, etc).

 

Shipping Damage

When your turbo arrives, inspect it thoroughly. If there is any damage to the compressor wheel, wastegate actuator, housing, etc, you must report it immediately, so that we can file a claim with the carrier. Shipping claims that are received more than a few days after delivery will not be accepted.