Can I reach cooler turbo temps with an oilcooler?
11-01-2000, 07:26 AM
#2
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1.8/2.7/I-5? Details?
Which motor? Most Audi turbos already have oil coolers that are sufficient for all but full racing. The real difference is in the watercooling for reliability, NOT the oil regardless. Turbos need to be hot in order to work.
11-01-2000, 09:41 AM
#6
a turbine works off the pressure
taken as:
pressure is force/area
force x time = work
a jet engine works on the principle of suck burn work blow
the burn or heat addition increases the pressure due the chemical/combustion generation of heat. The heat produces a higher pressure. The pressure works the turbine.
The oil system in a car is used to cool the bearing surfaces of the turbo and other components, and to keep the turbo temp down to prevent damage to the rotor components.
pressure is force/area
force x time = work
a jet engine works on the principle of suck burn work blow
the burn or heat addition increases the pressure due the chemical/combustion generation of heat. The heat produces a higher pressure. The pressure works the turbine.
The oil system in a car is used to cool the bearing surfaces of the turbo and other components, and to keep the turbo temp down to prevent damage to the rotor components.
11-01-2000, 10:00 AM
#7
i should clarify more
beside pressure being force/area
it is also the potential of velocity.
therefore the pressure delta from the exhaust across the turbine generates an acceleration of fluid velocity. The higher velocity imparta a higher lift profile, which in turn rotates the part.
it is also the potential of velocity.
therefore the pressure delta from the exhaust across the turbine generates an acceleration of fluid velocity. The higher velocity imparta a higher lift profile, which in turn rotates the part.
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11-01-2000, 11:03 AM
#8
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Info..
I added an Oil cooler to my 1.8t. My peak to peak temp drop has been 40 degrees. Not only is the Oil cooler but the entire Motor is cooler.
My car now runs at 200 or so where it used to run 235. Running the car on the track I could see up to 280. 40 minutes of HARD road race laps with the cooler in place led to 240 or so. In 115 degree temps with the AC on in traffic I would see 245-250. With the cooler is 215.
A cooler engine is less prone to detonate. This = more timming advance. Power is more consistant.
During cool down after a hard run my turbo cools off MUCH faster. Especialy with my electric fan kit running pulling air through the oil cooler core. An amazing amount of heat radiates of my cooler.
I am working on a new unit with a lower price point. The one I have now was a full custom core with cost no object in mind. Due to this it is not cheap. I have located a core that will withstand the 110psi of oil pres this motor has. I will offer this kit with a Thermostat in the very near future.
Clark
My car now runs at 200 or so where it used to run 235. Running the car on the track I could see up to 280. 40 minutes of HARD road race laps with the cooler in place led to 240 or so. In 115 degree temps with the AC on in traffic I would see 245-250. With the cooler is 215.
A cooler engine is less prone to detonate. This = more timming advance. Power is more consistant.
During cool down after a hard run my turbo cools off MUCH faster. Especialy with my electric fan kit running pulling air through the oil cooler core. An amazing amount of heat radiates of my cooler.
I am working on a new unit with a lower price point. The one I have now was a full custom core with cost no object in mind. Due to this it is not cheap. I have located a core that will withstand the 110psi of oil pres this motor has. I will offer this kit with a Thermostat in the very near future.
Clark
11-01-2000, 11:42 AM
#9
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Equations...yuck. Hear's a simpler way of looking at it.
There's a good write-up in the this month's European car that helps clarify this question. Check it out if you can.
Here's the intuition behind a turbo's benefit. No need to break out the thermodynamic and fluid-dynamics text book.
The typical 4 cycles of our car engine corresponds to (1) suck, (2) squish, (3) boom, (4) blow. Gasoline contains a great amount of energy. In burning the gasoline, energy is created to "run" the car. However, not all of the energy goes to run the car. A good portion of it is simply dissipated as heat (friction). A good amount of energy is also dissipated as exhaust. Exhaust heat contains potential energy and exhaust velocity stores kinetic energy.
The turbo aims to capture some of that exhaust energy and "recycle" the energy into the combustion process. However, the heat energy of the exhaust is effectively useless as far as a turbo (and engine) is concerned. Rather, the turbo uses the kinetic energy of the exhaust to cram more air into the combustion cycle. This in affect, "recovers" some of the "lost" energy in the exhaust.
The translation: turbo's run hot not because they need to. Rather the heat is simply a by-product of the "recycling" system that we've created.
Here's the intuition behind a turbo's benefit. No need to break out the thermodynamic and fluid-dynamics text book.
The typical 4 cycles of our car engine corresponds to (1) suck, (2) squish, (3) boom, (4) blow. Gasoline contains a great amount of energy. In burning the gasoline, energy is created to "run" the car. However, not all of the energy goes to run the car. A good portion of it is simply dissipated as heat (friction). A good amount of energy is also dissipated as exhaust. Exhaust heat contains potential energy and exhaust velocity stores kinetic energy.
The turbo aims to capture some of that exhaust energy and "recycle" the energy into the combustion process. However, the heat energy of the exhaust is effectively useless as far as a turbo (and engine) is concerned. Rather, the turbo uses the kinetic energy of the exhaust to cram more air into the combustion cycle. This in affect, "recovers" some of the "lost" energy in the exhaust.
The translation: turbo's run hot not because they need to. Rather the heat is simply a by-product of the "recycling" system that we've created.
11-01-2000, 12:13 PM
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Simple instead of obfuscatory answer, and I'm not selling anything.
Two identical turbo motors, one at operating temperature with the turbo hot, the other with a cold turbo. The hot turbo makes more power.
Why? Because a cold turbo will absorb the exhaust heat and not convert it to accelerating the turbine. Hot air hitting cold metal reduces the rate of expansion (or [rate of]velocity[delta]). The oil performs the job of lubrication of the center "floating" bearing. The oil/water cooler is simply an efficient means to reduce coking in conventional oil and improve warmup of the coolant on a cold engine.
It is the job of the water cooling to reduce the turbo temperature. The first generation of modern automotive turbo didn't have the water cooling and they had a very short service life (saab sobs). With water cooling turbo service life is equivalent to the engine and the transmission.
Note that the water cooling only brings the temperature down to the coolant temp 190-220. They could simply run an independant water/water cooler to the turbo if you gained any efficiency by running it cooler. Nobody does this.
Any decent (setrab/mocal, etc.) oil cooler has a thermostat setting because you don't want the oil temp to drop too low to volatize out the water and VOC's in the oil.
Why? Because a cold turbo will absorb the exhaust heat and not convert it to accelerating the turbine. Hot air hitting cold metal reduces the rate of expansion (or [rate of]velocity[delta]). The oil performs the job of lubrication of the center "floating" bearing. The oil/water cooler is simply an efficient means to reduce coking in conventional oil and improve warmup of the coolant on a cold engine.
It is the job of the water cooling to reduce the turbo temperature. The first generation of modern automotive turbo didn't have the water cooling and they had a very short service life (saab sobs). With water cooling turbo service life is equivalent to the engine and the transmission.
Note that the water cooling only brings the temperature down to the coolant temp 190-220. They could simply run an independant water/water cooler to the turbo if you gained any efficiency by running it cooler. Nobody does this.
Any decent (setrab/mocal, etc.) oil cooler has a thermostat setting because you don't want the oil temp to drop too low to volatize out the water and VOC's in the oil.