Turbo timer..

[Guest |229|]

Is it possible to make the V44 work as a turbo timer also? Maybe connected to the turbo rpm sensor. So it wont stop the engine until turbo comes down in revs, but ignition key has been turned off.

[rayhall]

The reason turbo timers were used in the past was to let the turbine wheel cool down and not slow down. Turbine wheels do no spin faster then the exhaust gas energy that is driving them. They loose any speed from a previous acceleration very very quickly.

The idling to let the turbine wheel cool down is no longer required as all automotive turbocharger's have a water jacket around the rear bearing. In the past before water cooling existed you would idle the engine so the oil from the engine would take the heat out of the turbine wheel. If you did not do this, the heat from the turbine wheel would cause the turbine shaft to get very hot and turn the oil to carbon. After many repeated hot shutdowns the carbon buildup would cause the rear bearing to fail.

Around 1980 water cooled bearing housing started to be used. This was needed when car manufactures started fitting turbocharger's to petrol engines. Without water cooling they just could not get the turbocharger's to live for much more then the warranty period. Many people think the water cooling is there to cool the turbocharger while the engine is running. This is incorrect. The water cooling does its job after you turn the engine off.

On a turbocharger with or without water cooling, the turbine shaft temperature while the engine is running is around 210 degrees C. When you turn the engine off with a water cooled bearing housing, the heat from the turbine wheel starts to soak into the shaft. The heat is then transferred to the water. This causes the water to rise and cooler water enters the bearing housing to soak up more heat. The water in the cooling system is slowly turning over due to thermo siphoning for around 20 minutes. Over this time period the shaft temperature does not go over 210 deg.

For thermo siphoning to work correctly, the water connection on the turbocharger must be from the lowest point in the cooling system to the highest. Far too often people do not connect the water correctly as they do not understand what it is for and how it works.

A turbo timer is of no use on a petrol engine that has a water cooled turbocharger. If you want to make your turbocharger not suffer from hot shutdowns, then make sure the water is plumed correctly, and use a synthetic oil like Mobil 1 or Castrol R.

There will be timers added to the Aux outputs in the future. These will be added for other reasons like water spray time period control.

Ray.

[Guest |118|]

that was a very informative read...thanks ray

[Guest |229|]

Thanks Ray.

Very good info. But would still like to get some kind of timer to my car... So please make the option for turbo timer also.

Also, is it possible to get water pressure added as an selectable option together with oil and fuel pressure?

Also is it pos

[rayhall]

I think you have missed the point I was trying to get across. Turbo timers had a use on diesel engines in the past. When turbocharger's were used on petrol engines they put a water jacket around the rear bearing so you could just turn the engine off. Petrol engines have much higher exhaust temp's then Diesel and the water jacket was the only solution to give the turbocharger's a reasonable life.

I have been trying since 1980 to educate people on water cooled bearing housing and why you do not need a timer. I still get customers that are happy with what I tell them, until they talk to one of their "expert" mates who tells them that if you have a turbocharger you must have a timer.

As this is one of my pet peeve subjects, I am not keen on continuing the misinformation by adding a turbo timer to the Vipec.

Ray.

[Guest |229|]

Okay.. Thanks. :-)

Isnt there any issues with the turbine wheels spinning too fast, when shutting the engine down and oil pressure goes away?

[rayhall]

Yes there is, but it is not something that can happen on a engine in a car. You would need to be under full power and have the engine instantly stop or loose oil pressure. On diesel tractors using a rotary hoe in a paddock that has three roots or stumps it is quite common for these engine to go from full power to zero rpm when they hit something. To overcome this, these engines use a 6 liter container that has a rolling diaphragm with air on the other side. This container is filled with oil when the engine first starts and will deliver full oil pressure for about 20 seconds after the engine stalls. This is enough to save the turbocharger bearings.

There is no way you can make your engine instantly stop turning at full power. It is an old wives tale that the engine needs to be idled for the turbo to slow down. They drop down to a low rpm very fast. The idling or turbocharger in the past was to make sure you did not get heat soak from a "Hot shut down".

If you want proof, I will make a log from my car that has a turbo speed sensor. It will show that the turbo losses speed very fast and is not spinning at a high rpm when you bring the engine back to idle and turn the ignition off.

Ray.