Valve Guide materials

What is the difference between the materials used in valve guide? Why do performance engines use bronze or Manganese ? Pros cons?

OE valve guides are typically a cast iron material which work well with stock valves. In a race engine we more often end up running stainless or even titanium valve material and these technically aren't compatible with a cast iron guide which is why bronze is the guide material of choice in a competition engine. Cast iron guides in some engines also have a reputation for cracking and falling to pieces which can destroy your engine very quickly - The Nissan RB26 is just one example where this is common.

Hello Andre, I'm wondering if you can elaborate on this further regarding durability.

Are Bronze/Manganese valve guides compatible with standard valves? If so what durability do they have vs standard cast items?

Also, can you elaborate further on what kind of power/load per litre, rpm etc. you need to seriously consider going to Bronze/Manganese valve guides and Stainless Valves?

As a general rules, cast iron is used because it's cheap and does the job, and bronze alloys may offer better wear characteristics, allow tighter clearances, and pull more heat out of the valves.

Again, as a general rule, aftermarket valves are used to counter the short-comings of OEM valves, usually because they're made of inferior materials and/or are two piece, and/or larger valves are required. Material will depend on use - usually rpm and/or heat limit the OEM's strength, and different materials are available for different needs - SS (different alloys for different applications) and Iconel are good for heat resistance but are relatively heavy, titanium is significantly ligher for RPM but some alloys are susceptible to heat and/or deformation under high spring loads and/or valve float - oh, because it's a relatively 'soft' material, you'll need lash caps and stem coatings.

As a general rule, you should fit bronze for any 'performance' application, and talk to the valve manufacturers - or at least check out their catalogues which usually have good guides - for the valves that best fit your use and budget.