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CMW Racing Valves

Now lets take some time to describe CMW Racing’s custom valve gear and its’ advantages over stock and other “standard” aftermarket components. CMW Racing has created valve gear for the Porsche engine that allows a 9200 rpm redline! CMW has made several changes and improvements over the stock valve gear that allow an engine to breath this freely.
Valve size is the first change we make in the valve gear for our motors. Stock intake valves are 49mm, and the stock exhaust valve measures 41.5mm. CMW Racing offers intake valves in the stock size, as well as 52 mm, 54 mm, and 56 mm sizes, while our exhaust valves are offered in 43 mm sizes. Both intake and exhaust valves are crafted from stainless steel or titanium, and are coated in molybdenum disulphide (MoS2) dry coating for heat rejection and long life.
You may realize this sizing technique results in mis-matched valve selection sizing. While other engine builders keep valve sizes more congruent between intake and exhaust, CMW runs these mismatched valve sizes with the knowledge that the exhaust gasses will exit the motor via superior porting, not equally sized valves.
The next improved feature of the valvetrain is the specially designed dual-spring set-up which delivers un-matched high-rpm performance. This design allows increased seat pressure (150 pounds) and the same over-the-nose pressure as used in the 962 motors. These valves also eliminate the “pounded-out” valve seats that can be a problem with lighter valve springs. We recommend these springs in every Porsche, even un-modified street cars.
The valve guides have even been re-worked for better performance. CMW offers two different styles of guides for street or race applications. The street versions are similar to stock except for superior strength, whereas the racing guides are finned for superior cooling that race applications demand.
Of course, CMW has done one better than our competition with our valve spring retainers. Our famous “Holey” valve spring retainers were designed with high performance and un-paralleled durability in mind. The secret lies in the holes, which not only result in a lighter retainer, but allow air and oil to pass through them. This eliminates air pressure on the exhaust stroke, and the possibility of oil being forced into the valve guides. This same feature also eliminates the danger of exhaust gasses from being drawn into the valve guides, reducing wear. These features result in the springs lasting longer than with standard valve retainers. You may be a little worried that these holes would result in a weaker retainer, but not a single one has ever failed!

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CMW Racing Technical Advice

12929 Telegraph Road, Unit H
Santa Fe Springs, Ca 90670
Phone (310) 903-4571

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