Building A High Performance Boss Mustang 409 Engine - Big Boss Buildup
Check out these CP-coated, custom, lightweight pistons. This is a flat-top, 0.043-inch ring-groove, low-friction slug with gas slots and high ring placement. Because MPG employs unique, low-friction connecting rods, we have an 0.890-inch piston pin. A thermal-barrier coating across the piston crown protects the piston and pin from extreme temperatures on top. An antifriction coating on the skirt reduces cylinder-wall friction to free up more power. Gas slots channel combustion pressures against the back of the top ring to improve cylinder sealing during wide-open throttle. The down side to low-friction rings is longevity. They don't last as long as wider rings. This is all about power in the short term and less about reliability in the long term. | 
When we place a stock 302 piston (right) next to the CP piston from MPG (left), the difference is clear. A stock piston gives extended life because there's mass and more load-bearing surface area. When it's time to make power, it isn't about longevity, but more about having less reciprocating mass and internal friction. We're also stuffing more displacement into the same bore, hence the mandate for less piston and different piston geometry. | 
Down under, there's an obvious difference in rod journal size-1.848-inches-less journal than we see with most 289/302/351W strokers... | 
...A smaller journal size reduces journal friction and frees up power. | 
We're knocking down the MPG Boss 409 for a closer look inside. Bob Moore lifts off the MPG 3V (does not mean three-valve) Cleveland head for an in-depth look at how to make more power with a set of cylinder heads. According to MPG, these heads are good for approximately 100 hp just bolting them on. | 
Let's start inside with close inspection of the 3V chamber. This Australian head gets the added benefit of CamResearch stainless steel 2.15-/1.65-inch valves. What's more, these canted-valve heads have intake ports downsized to 218 cc for greater flow (yes, greater flow). Exhaust ports are raised 0.400 inch for better scavenging. Where the heat gets hot, there's revised spark-plug positioning and a contemporary, heart-shaped, high-quench 64.5cc chamber. | 
The MPG 3V Cleveland head is designed out of the box for 351C, 351M, and 400M engines. When it goes onto a 289/302/351W block, we have to plug the 351C coolant passages and make coolant passages for the 289/302/351W block. The 351C has a dry manifold void of cooling passages. The 289/302/351W has a wet manifold with cooling passages. | 
At a quick glance, the 3V Cleveland head resembles the factory iron head. Closer inspection yields a lot of internal improvements that make it a better investment than 351C 2V or 4V heads. Standard are screw-in rocker arm studs and guideplates, larger stainless steel intake and exhaust valves, high-tech quench chambers, and better spark-plug positioning. | 
With the intake ports side by side, it's easy to believe the larger 351C-4V ports (top) flow better.During extensive testing and massaging, Scott learned exactly the opposite is true. The MPG 3V head not only flows more air (343 cfm at 0.650 inch lift), but it also yields more velocity, which improves torque. Scott achieved this success with minor intake port massaging at the short turn and a space-age thermal coating that reduces temperature. |
Discuss in Our Forums
|
|
|
|
|