Turbo Baby Steps:Inducer and Exducer

[The Californian]

Inducer and exducer are OPPOSITE on the two wheels.

Turbine side.Exhaust COMES IN the scroll.OUT the center.

Compressor side.Intake GOES OUT the scroll and IN the center.

So it follows with the wheels being in the same position relative to the scroll inducer and exducer of wheels swap.

On turbine inducer.First thing the exhaust passes over is 'bottom' of wheel.That is the inducer on turbine wheel.Exducer is top.

On compressor wheel intake come in the center.First thing intake sees and passes over is TOP of compressor wheel.TOP is inducer.

Last thing intake sees and passes over is bottom of wheel on it's way out of scroll.Bottom is exducer on compresser.

So.Inducer and exducer labels are swapped from turbine to compressor.Same wheels to the eye.

Do I get an 'Atta' boy!'?

[englertracing]

so, what's the deal? Were you interested in racing 40-50 years ago and you just started thinking about it again now? Some sort of racing Encino man?

[Dust Buster]

Do I get an 'Atta' boy!'?

Turbo_Inducer_Exducer.PNG

Sometimes pictures explain things better. You could have also said that trim is the area ratio between inducer and exducer.

Trim = Inducer diameter squared divided by outer diameter squared and multiplied by 100

Being area (squared), it is not a linear comparison. Therefore, a trim of 55 is about 10% larger than a trim of 50. Try this with inducers of 52.7 and 50.5 vs exducer of 71.

Blade speed depends on blade contour, swept angle, and surface area of the blades which impact the overall flow characteristic.

When choosing a compressor wheel, lean towards a large trim rating in a smaller wheel instead of going to a larger wheel. Larger wheels are heavier and rotational weight equals lag. The trim of a wheel, whether compressor or turbine, affects performance by shifting the airflow capacity. All other factors held constant, a higher trim wheel will flow more than a smaller trim wheel. but does not necessarily mean that it will flow more.

You could also explain what a twin scroll is and the differences bearings make (ceramic vs steel ball, journal) on performance and repair-ability.

Then you can ask for your 'Atta' boy.

[The Californian]

Thanks Dust Buster!

Really good comments about inducers and exducers.

'You could also explain what a twin scroll'

Well.While we did 'explain' inducer/exducer.It was really just saying we had figured it out.

Do think it is still a good idea to learn the 'scientific method' of turbocharging while doing the trial and error.

Could you explain the bottom horizontal line of a compressor map? Corrected mass flow.

[Dust Buster]

Twin_Scroll_Turbo.PNG

A twin-scroll (pulse) turbocharger has the following advantages over a single-scroll (constant-pressure) turbocharger:
higher turbine inlet energy due to exploitation of pressure waves (pulse energy);
good performance at low – medium engine speed and load; and
good performance during transient engine operation (acceleration).
The disadvantages of twin-scroll (pulse) turbocharging systems are:
poor efficiency at high engine load and speed; and
complex and expensive exhaust manifold and turbine casing.

Interpreting turbo graphs: the vertical “y” axis is almost always the pressure ratio (Pr), which is an altitude corrected barometric pressure plus boost pressure in PSI divided by the altitude corrected barometric pressure. For example, 20 psi turbo boost at sea level would be: (14.7 + 20) / 14.7 = 2.36 pressure ratio.

Airflow is plotted on the horizontal “x” axis and is usually in some kind of convertible measure; the metric maps are nice because the kg / sec ratio is basically the MAF g/s divided by 1k. Multiply kg / sec by 2.94 to get cubic feet / minute (cfm). Divide cfm by 14.27 to get lbs / min.

[BLSTIC]

Don't forget, twin scroll also separates exhaust pulses from other cylinders, reducing, or in some cases eliminating, blowdown interference. It's like going from a single outlet manifold to a set of super long 4-2-1 (or 6-2-1 if that's your thing), except it only takes up marginally more room.

[lefty o]

so where does it get plugged in?