Exhaust Valve Rotators?

[WarWagon]

Don't forget the Duramax is not advertised as having 4 valves per cylinder but it does. The valves would be smaller and less area to overheat vs. the big single 6.2 valve. Carbon and hot spots are the reasons for rotors. Smaller valves are cooled better by the stem and seat vs. a larger valve. NOx emissions concerns also dictate cooler peak combustion temperatures as well as lower compression to meet those emissions.

Yet, it isn't about the temperature of the valve as much as it is rotating the valve head away from local hot spots. Imagine the thin spot between the intake and exhaust could be a cold spot from intake air or a hot spot away from coolant in the head.

Single cylinder lawnmowers and other air cooled low compression engines have carbon deposits break loose and bring the engine to a loss of power stop without enough compression to restart when the carbon sticks in a valve. Automotive engines with carbon stuck in a valve will continue to run on 7 of 8 and burn the valve and sometimes the seat. These cheap lawnmower engines need the valves lapped on a regular basis to get the carbon build up off them and reset the wear so they seal good. Industrial Commercial single cylinder engines have these exhaust valve rotors and last longer between service. Valve guide wear is another matter. Interesting that an engine will run with the valve guide worn larger than a replacement valve guide sleeve will fit in - that well worn engine on a commercial use lawnmower has us all standing around in awe.

So two good reason's that valve rotors are an upgrade to an engine for longer life. Life being time between valve jobs.

It is possible that the seat and valve materials have advanced to allow many miles before wear or carbon become an issue without rotors.

So are you going for positive rotation or just free rotation type rotor?

http://www.helical-technology.com/content/view/67/65/lang,en/

 

[buddy]

Thanks for that link WW, I'll ask them if they make a 1.3" rotator that could be used under the spring.

I am familiar with the carbon build up and hot spots as a reason to use the rotators, but I just keep going back to everyone ditching them, except in high hour high power equipment and marine applications that go high RPM and also run for a lot of hours and need to be high reliability. Part of the reason they became less important was the use of inconel and stellite, which doesnt wear, burn or lose hardness with the heat like other metals so the hot spots arent as concerning. Stellite coated seats and valves, and that coating is not just a spray on like coating, its a thick external layer. The precups are also probably Stellite and they live through the worst of it. And apparantly with loss of lead and sulfer in fuel the less lubrication on the valves and seats was a concern for wear on the valve seats when they would be turning, not sure how valid that is. Or less soot from todays fuels may have been a reason.

The gas engines have exhaust temps higher than diesels in a lot of cases and none of them are using rotators anymore, none of the small block V8 engines and older big block guys get rid of them.