Airworx 180HP O-300 STC

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Re: Airworx 180HP O-300 STC

Postby TFA170 » Thu Feb 02, 2023 2:40 pm

GAHorn wrote: They’d have to take your engine with and without the polished ports with absolutely no other differences in atmosphere, temp, and dozens of other things exactly equal…to make that claim.

Actually, most modern dynos correct to standard day every run is apples to apples from an atmospheric perspective. Older mechanical dynos did not, but most operators have a "cheat sheet" (or did back in the day) to make approximate corrections to standard day.

Regardless, increasing VE generally increases HP. I agree with you that any HP/TQ measurement needs to have an RPM associated so as to make an apples-to-apples comparison over original. The actual dyno run chart would be even more useful overlaid on an original chart.

Port work can be tailored for RPM range though, so given someone who knows what they're doing for specific applications, like Lycon, it is realistic to assume the port work is tailored for the anticipated RPM range and not maximum RPM necessarily.
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