ACE Builds Custom Parts for “Precious Metal” Griffon Engine

Posted by:   |  July 17, 2015

When we are not designing our own parts to bring these antique aircraft engines into the 21st century we are helping several other customers with their difficult projects.  Recently, we completed helping the Precious Metal Air Racing Team totally rebuild their latest race engine with many modern components. There are few people in the world that have knowledge and ability to reproduce the components for a WWII fighter engine, let alone produce significantly better components.  This original Rolls-Royce Griffon v12 engine was capable of producing over 2000 hp. We expect much more from Precious Metal at this years Reno Air Races and we are privileged to be helping Thom with this very unique project. Some examples of items we built or restored for Precious Metal P51 Griffin Engine:



These are now made of a modern material, with considerably better mechanical properties. The machining accuracy is also vastly superior to what was achievable back in the 40’s and 50’s. The sleeve is now an impregnated, not just a coated sleeve. The technology is well proven and is excellent for the bore surface at the extreme pressures generated. ACE can produce these sleeves to suit both Griffon and Merlin engines.



We take a completely modern approach to piston design, not only is the component lighter, but it is also stiffer. Great care is taken in the choice of material to allow for significantly higher operating pressure and temperatures.

-piston pins


The piston pins we supply are of an exceptionally clean steel ground and super-finished and then DLC’d. This ensures good lubricity under limited oil regimes.


004 (1)Reconditioned rods, we clean and test them for cracks, once this is OK, they move onto inspection for detailed examination of all dimensions. Rods then undergo controlled shot peening, this process develops a compressive layer all over the rod. They are then machined where necessary and a steel bush is inserted, rather than the traditional bronze style bush, which moves around under high pressure.

-rod bolts


Finally all new bolts are manufactured to suit. Where it is appropriate and or necessary, we can manufacture completely new rods.



We produce new main bearings, you can see them in the case, but new I mean we actually fabricate a complete bearing. We use Hoyt 11R and 11Z3 tin based white metal for max reliability.

-crank case

crankcase, oil check

We assisted in the total restoration of the case and valve train.

If you are looking for reproduction or improvement of any engine components or even an idea for component, please email us with you request.