Beryllium seats or Nickel bronze

I want to know if there is a difference between the two as fare as using it as a seat material for titanium valves, other that one is toxic. Does any one have experience with both? I only know the Nickel Bronze Its what we use on our race heads, but don't know if there is a benefit to the beryllium. 

 

Thanks for your time. 

I would say beryllium seats would last longer much longer. I dont have first hand experiance in there use but we do use beryllium copper and it sure is alot stronger and tougher than nickel bronze. not sure on hardness though

I have a Honda CRF 250 R head on my 250X. It had copper beryllium seats installed when it was new and the head was built with del west Ti intake valves. I have ridden and raced this bike hard for the last two seasons and the valves still have perfect clearance. The shims have not been changed since installation, didn't even have to change them after break in. I don't know if one is better than the other but this is my experience with CB valve seats.

But is not an issue of the valve beating up the seat. Its the seat beating up the titanium valve. Nickel bronze holds up very well on some of our race heads like busa and GSXR 1000, but no real experience with Beryllium. 

I think that what you are going to find is that the Beryllium copper seats have a better heat transfer rate than the nickel bronze.

 

your valve seat is the area that all the heat from the valve face is transferred to the head and the cooling system.

 

this leads to less valve seat erosion and a longer lasting valvetrain as the valves stay cooler and wont deform.

 

if you have a cam that has mellow ramp angles you arent going to have to worry about your seats or valves beating eachother to death either. 

 

So, in my opinion-

 

If you were planning on running an intense high lift high duration cam ( very intense ramp angles) i would run the beryllium copper seats.

 

if you are running something more mellow that isnt going to beat the hell out of the valve train you can use the nickel bronze.

 

 

hope this helps!

I didn't say anything about who threw the first punch. Just my experience with CB valve seats.

Don't you guys ever wonder how YZF's work so well with iron seats?

Don't you guys ever wonder how YZF's work so well with iron seats?

Yeah why is that? A gentle closing ramp and light springs?

A better valve alloy? A better valve coating?

Some kind of yamaha wizardry?

Yeah why is that? A gentle closing ramp and light springs?

A better valve alloy? A better valve coating?

Some kind of yamaha wizardry?

 

It's probably not rocket science.  Or voodoo.  They hold up well even with aftermarket cams. 

 

Bronze seats really are ultimately the way to go, but I've always been intrigued by how much longer the YZF will run with the same valves compared to other stuff using titanium. 

Cast iron does have very good dimensional stability with temperature changes and gray cast iron has pockets of graphite which help self-lubricate (valves are usually spinning as they land on the seat).

Yes, but the rotation is not exactly what the word spinning connotes when you hear it.  It will ordinarily take 10 or more openings and closings for the spring to "walk" the valve around one full rotation.  The exception is with valve spring retainers having built-in "rotators", essentially a thrust bearing included in the retainer that allows the valve to rotate (or not, in some cases, depending on the valve train geometry) independently of the spring.  You won't see these in a motorcycle, though.
 

But even at 10 openings per revolution at 10,000 rpm the valve is opening 5000 times per minute which means its turning at 500 rpm vs the seat.  That's a lot of rotation under the high pressures exerted by the valve springs.

 

I always liked this video done with a stroboscope.  It shows many interesting phenomena including valve seat bounce, valve spring rotation, the valve itself rocking in the head, valve rotation, and even valve spring harmonics.  Towards the end of the video they show everything from the combustion chamber side.  It appears the valve continues to rotate even while it is seated though they admit the engine is running insufficient valve spring tension.

 

Edited by 1987CR250R

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