Quote:
Originally Posted by AL427SBF
I'll check those forums out. Agree, seems some of these "advise givers" are not so much interested in answering the question turbo vs supercharger - and more interested in sharing their problems do to poor choices for their motor/driving preferences lol.
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Only a small percent of Cobra's have forced induction, so its no surprise a lot of folks here say you don't need it.
On the other hand your question is too broad and undefined. It's like asking "gasoline engine verses diesel engine, which is better?" How can anyone answer this? Are we talking 2 stroke or 4 strokes? Weed eaters, boats, cars, planes, or 18 wheeler?
There are so called positive displacement forced induction. Roots (lobed type) blowers, scroll, and screw compressors would be in this category. The lobed blowers are less positive than a screw compressor, especially as the pressure goes higher.
Centrifugal blowers are not positive displacement. A turbo is in this category.
With a centrifugal blower, the pressure it can generate is a function of the tip speed of the wheel. So on a belt driven centrifugal blower, the boost at low rpm is near zero. The boost and therefore the torque at the flywheel increases as the rpm increases. This results in an engine that has no balls until it revs up.
On the other hand, a positive displacement blower can give 100% boost from idle to maximum rpm. This results in an engine that has massive torque from off idle to red-line.
The Turbo wheel speed is not connected to the crank and is driven by exhaust gasses. At WOT low rpm the turbo wheel will speed up and make more boost than its belt driven counterpart. A turbo is not positive displacement and will not make the low rpm torque, however it can spin up and make maximum boost well before the red-line, which is an improvement over its belt driven cousin. Then it dumps exhaust out a waste gate to control the boost to its maximum as rpm climb.
So on the surface the turbo splits the differences between centrifugal and positive displacement. However since nothing is free it does so at a cost - lag time. Turbo lag is well known. It takes time for the turbo wheel to build up speed and make boost. Turbo proponents will tell you turbo lag is a thing of the past. Although it has been greatly reduced, it is still there, and it always will be. They will tell you that there are tricks to stage a turbo car at a drag strip to eliminate the lag. This is the proof that the turbo lag is still there. The lag is not eliminated in their staging technique. It is compensated for, by it, but rest assured it is still there.
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