Best valve guide material?

[TT Oversteer]

Doing a quick search of several vendors it looks like phosphorus bronze is the commonly used material for 911 valve guides. I have heard that manganese bronze are also available and better. What's the material of choice among top builders and what is the difference between these two materials?

[Henry Schmidt]

We use manganese bronze on normally aspirated street engines and phosphorus bronze on turbo and race engines.
MB is more durable and PB transfers heat better.

Beware of claims of magic/ propitiatory materials. Most are just advertizing gimmicks.
Bronzonium comes to mind as a perfect example.

[TT Oversteer]

Sounds like MB is the way to go for a mostly stock 3.2 that will see the occasional DE event. Thanks Henry.

[chris_seven]

The Heat Transfer Coefficient of Phosphor Bronze is strongly affected by its alloy content.

A 5% Tin PB material would have a typical Heat Transfer Coefficient of about 69 Wm^-1.degK^-1

An alloy with 10% Tin would have a significantly lower value of around 50Wm^-1.degK^-1

Maganese Bronze is quite different and is much more consistent at about
105 Wm^-1.degK^-1

The materials that have been designed for high performance valve guides such as Colsibro and Hidurel are Precipitation Hardening Nickel-Silicon Bronzes and have Heat Transfer Coefficient of about 190 Wm^-1.degK^-1

This is around 4 times that of the high Tin content Phosphor Bronzes.

The Colsibro and Hidurel materials have excellent strength and relatively high modulus values but possibly lower lubricity than Phosphor Bronzes.

I have priced up Colsibro in the last couple of weeks and it would be about $3.00 per guide before machining.

[AlfonsoR]

Great info Chris and Henry. Thanks..

[h.wong]

Henry,

Do you send your heads out for a valve job or is it done in house?

Thanks,
Harry

[h.wong]

Sorry...

just went to your website...in house!


h