We have just about maximized the bolt on potential of Project 5.0 Mustang in our last installment with the addition of the Ford Racing Cobra Jet intake manifold. Now, in order to attain still higher power levels from our engine, we will have to dive into the internals
We are big believers in the benefits of parts designed by factory engineers with factory technical resources for factory race programs. Many of the parts we will be using for our build are straight from the Boss 302R Grand Am and Cobra Jet NHRA drag racing programs. Factory engineered and best of all factory validated and proven on the track is good enough for us.
So take a look at what we selected from the Ford Racing parts catalog and we think you’ll be impressed with what Ford has to offer for late model Coyote engines.
Read more about Project S197 Mustang
For more NA power. better breathing is a must so we selected none other than Ford’s Boss 302R heads. The 302R heads are directly from Ford’s racing involvement with the Continental Tire Sports Car Challenge. Basically, we will be building an engine similar to the one that propelled Billy Johnson to many wins in the series but just a little bit more radical. We’re building a hybrid of the Boss 302R and the Cobra Jet. The 302R head is complete and race ready. All you need to do is bolt it on.
The Boss 302R head comes complete with valves, high performance springs and retainers. All the stuff needed to make a durable 8000 rpm capable engine.
The Boss 302R head has a CNC machined combustion chamber with a consistent 55.6cc volume. The CNC machining is needed to unshroud the 31.8mm exhaust valve which is 1 mm larger than stock while still maintaining good quench. The exhaust valve is sodium filled for improved cooling. The intake valve is the same size as stock but features a lighter, hollow stem. The valves are recontoured and swirl polished for better flow.
The valve springs are stiffer than stock at 300 newtons closed compared to 260 stock and 700 newtons open compared to 650 stock. The springs can take more lift before coil bind, a maximum of 13mm and they are safe to over 8000 rpm.