Internal Combustion engine - evolution regarding parasitics

In summary, the evolution of internal combustion engines concerning parasitics focuses on the development of technologies and design improvements aimed at reducing energy losses caused by auxiliary components. Over the years, advancements such as variable valve timing, turbocharging, and the integration of electric systems have been implemented to enhance efficiency. Additionally, the shift towards lighter materials and more streamlined engine designs has minimized parasitic drag, contributing to better overall performance and fuel economy. The ongoing research and innovation in this field aim to further optimize engine efficiency while meeting increasingly stringent emissions regulations.
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Ranger Mike
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I wrote this a while back

Mechanical design - cam timing chain versus gear-driven (1 Viewer)​


  • Thread starterpnorm91
  • Start date Sep 12, 2013
Sep 12, 2013

I have since found some new updates. Back in the early 1990s when the SB2 small block chevy engine was coming into play, they engine builders when to a 60mm cam bore diameter so commercially available roller bearings could be used. The reasoning was the camshaft was twisting during operation and timing was not optimum in the rear cylinders. Also the engine had a lot of parasitic drag from very high valve spring loading. About the max you could go was 8000 RPM with current 1990s technology. So they went to roller bearing camshafts and timing belts (see above old post )

Mechanical design - cam timing chain versus gear-driven​


Between these two changes you could pick up 30 to 50 HP over the competition. Later the engine builders went to super light weight titanium valves with 8 mm valve stems ( vs. 11/32" stems). You could up the RPM to 9000 RPM and run lighter valve spring pressures and still go 500 miles.

The weight difference between the old stainless steel 11/32" stem valve and titanium 8mm stem valves add up to reduction of over 1.6 pounds reciprocation and a reduction in contact are (parasitic drag) of .34" diameter reduced to .31 diameter times 16 valves.

Little things add up.
 
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FYI: you can insert a direct link to any post on PF. The posts you are referring to are:

https://www.physicsforums.com/threa...-chain-versus-gear-driven.710081/post-5153741
https://www.physicsforums.com/threa...-chain-versus-gear-driven.710081/post-5154901

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Then paste the URL in any text you type, like this new post I just wrote for example.

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  • #3
living proof you can teach an old dog new tricks! Thank you Jack!
 
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