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Hi duration/low lift vs. low duration/high lift cam in turbocharged ICE

Hi duration/low lift vs. low duration/high lift cam in turbocharged ICE

Hi duration/low lift vs. low duration/high lift cam in turbocharged ICE

There are numerous and often confusing postings throughout the internet on this subject. Not too many on turbo engines/camshafts, though.

Let's assume, we have two identical 4 cyl 16V, DHOC engines, boost onset at 3,500rpm, same SLA values and the only difference is in intake camshafts. Both have the same identical exhaust cams.
One engine has a moderately hi duration and 0.380" lift, and the other has smaller(12°)duration with 0.410" lift.

What would be the difference in power/torque extracted and their distribution in 0-7500rpm range?

Mater artium necessitas

RE: Hi duration/low lift vs. low duration/high lift cam in turbocharged ICE

Look into something called a Miller Cycle engine. Using late closing of the inlet valve allows the turbocharger to do part of the compression. In conjunction with intercooler it has greatly booster the specific output of engines. Most new diesel engines I know of are running some form of the Miller Cycle.

RE: Hi duration/low lift vs. low duration/high lift cam in turbocharged ICE

The low duration alternative is usually favored in turbo engines since high rpm are usually not necessary to achieve the target power. The shorter duration usually results in a wider power band, earlier boost and better driveability. The lower rpm peak permits more-aggressive valve acceleration hence the high lift, low duration profile.

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