Project 5.0 Mustang: Getting More Power and Durability with Ford Racing

by Mike Kojima

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 Mustang here!

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.  
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Monday, November 02, 2015 7:50 AM
This is the flat-plane crankshaft if I'm not mistaken? I've heard these engines can make a lot more top-end power than the cross-plane cranks. I'm all in for a revvy American V8! It's about time!
Mike Kojima
Mike Kojimalink
Monday, November 02, 2015 8:33 AM
No the 5.4 liter is flat plane
Monday, November 02, 2015 8:59 AM
Great article as usual. Found a typo on page 2, last caption, last line; "Factory parts kick ass, especially when daily driiving durability is required." Driving shouldn't have two i's.
Monday, November 02, 2015 11:40 AM
Is there a specific reason neither the Cobrajet nor the 302R have the biggest combo of cams? What sacrifices do you expect from that combo that the factory may have been avoiding?
Mike Kojima
Mike Kojimalink
Monday, November 02, 2015 11:45 AM
I have no idea but we will see. It could have something to do with the different intake and exhaust designs between the two variations. The Cobra Jet intake manifold that we installed in the last article is really different than the Boss 302R (works a lot better too).
Monday, November 02, 2015 4:20 PM
This build is taking far too long to complete since the I initial Reaser was dropped. This thing is going to rip.
Monday, November 02, 2015 7:10 PM
Big V8's plus 8,000 rpm = totes awesome. How I wish my stock k24 would do that.
Thursday, November 05, 2015 6:37 PM
I have these on my Mustang, same cams too. Worked with the Ford engine designers on my initial tune then got more aggressive with E85 via tuning from Shaun at AED. with these heads and cams, the big CJ intake and TB, Kooks headers and E85 the power jumped from 365 / 365 stock to 493/413 - same Mustang Dyno. The car is a handful! it blasts to 8000 rpm w/o even thinking about it.

Only issue is carbon build up. We put so much overlap in the cam tune for HP that it carbon's up the valves pretty good. I recommend using B12 - that stuff is the only thing I've found that actually removes the carbon on valves. Its only $5 a can!

Can't wait to bolt up the new GT350 heads - same thing as these but more.
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