Why does a Porsche Flat 6 with 256 cu in able to push 500 horsepower, while the AMC 258 Flat 6 in my Jeep barely hitting 100 horse power? The Porsche flat 6 feels right at home up to 8000 rpm, while the AMC 258 is screaming by 4000. Why can do engines with very similar blocks be so different performance wise?
I am talking about naturally aspirated of course.
In: 3
There are so many things going on in an engine that all I can really do is list examples.
Horsepower is limited in large part by RPM, but also by airflow and compression ratio. Something like a turbo can improve the horsepower a ton by cramming more air into the same displacement.
Compression ratio is limited by intake temperatures, as well as the engine’s structural strength and the fuel.
RPM is held back by the weight of the parts as well as their strength. The use of alloys and computer-generated structures can raise the RPM ceiling quite a bit, but so can reducing the compression ratio and changing the stroke width.
Airflow is very complicated and depends on the shape of the parts.
Other things come into play, too, like ignition timing and fuel/air balancing.
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