A quick basic guide to turbos

I have just written a feature for Fast Ford magazine and thought i’d post some of it up here, as kind of a beginners guide to turbos. This isn’t at all Technical but more for beginners. It might prove useful to some people.

1 - How long does a turbo last?

Turbos, on average, last about 75,000 miles with regular engine servicing with good quality engine oil.

2 – What is a hybrid turbo?

A hybrid turbo is a turbo specially designed to produce good power while still maintaining good response and is built using parts from a number of turbos. For example, a T3 can be built using the original turbine wheel and housing to give good response, but with a larger compressor wheel and housing to increase power capabilities above that of the standard turbo. A hybrid can also include one-off special parts such as cut-back turbine blades and 360 degree thrust bearings.

3 – Why is it important to balance a turbocharger?

Every turbocharger needs to be balanced to ensure efficient operation. Turbos can spin up to 200,000 rpm and if they are not balanced correctly they can fail catastrophically, potentially causing serious damage. Turbos that are out of balance can cause vibration which creates a whining noise and these vibrations can reduce bearing life and turbo efficiency and cause premature failure.

4 – What is a 360 Degree Thrust bearing?

A 360 Degree thrust bearing is an uprated turbo bearing. It sits between the turbine wheel and Centre Housing. In standard turbos this only covers 270 degrees of the face of the impellor, but can not cope with the increased shock loads as a result of high boost applications. A 370 degree bearing covers the whole face and is normally only used in race or hybrid turbos.

5 – What are the main signs of turbo failure?

Worn or damaged turbos can become evident through a number of symptoms. Blue smoke out the exhaust can indicate worn seals as the oil leaks past into the compressor/turbine side. It is often possible to see evidence of excessive oil in the inlet tract between turbo and intercooler/engine. A loud whining sound coming from the turbo is often a sign of worn bearings which can be checked by removing the pipe from the air filter that attaches to the front of the turbo. If the bearings are worn, there will be excessive play in the shaft. Up to about 1mm of up and down play is acceptable but there should be no end float.

6 – What is a water-cooled turbo?

The central part of the turbo, housing the bearings, is surrounded by a water jacket through which the engine’s water coolant is passed. This water continues to circulate after the engine is turned off, cooling the turbo, and preventing heat soak from the turbine (hot) side to the compressor (cold) side.

7 – What is an intercooler?

An intercooler is an air to air radiator that helps to cool the charge air from the turbo before it enters the engine. Turbos work by compressing cool air and forcing it into the engine. The cooler the air, the more it can be compressed and the more power can be made. Turbos can get extremely hot and the intercooler helps to reduce charge temperatures back down to acceptable levels otherwise detonation can result as the air-fuel mixture gets too hot.

8 – What type of oil and how often should it be changed?

Turbos must have good quality oil. Use either semi or fully-synthetic engine oil. Turbo Technics recommends Shell Helix Plus, Shell Helix Ultra or Mobil 1 in a 10W 40 Grade. Oil changes should be done regularly and at least at the intervals specified by the vehicle manufacturer.

9 – Should I let the vehicle idle before driving/ turning it off.

When the vehicle is started from cold, it is important to let the oil get up to working temperature before using full throttle to protect the turbo against damage. Do not rev the engine from cold as oil takes a small amount of time to reach the turbo and can cause significant damage. When turning off the vehicle, it is only necessary to let it idle for a while if the car has been driven hard. The turbo itself can get red-hot after a spirited drive and needs some time for the cooling oil to bring it back down to normal working temperatures. Numerous spirited drives followed by immediate switching off can cause the oil to bake on to the internals causing accelerated wear. Never rev the car before switching off as the turbo will still be decelerating without any lubricating oil.

10 – Can I increase the boost pressure on my engine?

Increasing the boost pressure on any vehicle can be extremely dangerous unless it has been modified to accept these changes. Air and fuel must be mixed and ignited in a set ratio and too much air can cause lean conditions leading to potential fatal detonation. General fuel modifications in the form of revised EPROM’s, larger injectors and better fuel pumps together with a rolling road session with a good engine tuner for accurate set up are required.

Hope this is of some use.


I know this is a link that is from a page in the links section but thought I’d put it here if thats ok. I think it would be a good read for anyone who is thinking about upgrading http://www.stealth316.com/2-turboguide.htm

Please feel free to remove this if you think its not relivant.