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Mach V Cylinder heads
Non Ported Supercharger Results - Below are engine dyno results from a stock cubic inch 6.2L LT engine with a factory unported 1.7L supercharger and a camshaft, dyno-d at Westech Performance. The graph below shows the difference in horsepower and torque between stock LT cylinder heads and our Mach V cylinder heads. All other variables were kept the same. Testing was done on the same day, one hour apart, and the same set of springs were moved from the stock heads to the ported heads to keep all things equal. Horsepower and torque gains exist everywhere along the curve, no compromises are made with these cylinder heads.
*At peak torque, torque gains were +66 lb-ft, but at closer to 4,000RPM and below, torque is up to +78 lb-ft over the stock heads. The torque improvement may have been higher at lower RPM, but our testing window was from 4000-7000.
Kong Ported Supercharger Results - Below are engine dyno results from a stock cubic inch 6.2L LT engine with a Kong ported 1.7L supercharger and a camshaft, dyno-d at Westech Performance. The graph below shows the difference in horsepower and torque between stock LT cylinder heads and our Mach V cylinder heads. All other variables were kept the same. Testing was done on the same day, one hour apart, and the same set of springs were moved from the stock heads to the ported heads to keep all things equal. Horsepower and torque gains exist everywhere along the curve, no compromises are made with these cylinder heads.
*At peak torque, torque gains were +41 lb-ft, but at closer to 7,000RPM torque is up to over +85 lb-ft over the stock heads. The horsepower is still carrying positively 600 RPM higher than factory heads. We stopped the test at 7,000 but the trajectory tells us it would have continued to carry.
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Flag Motorsports offers the Mach V cylinder heads with stock powdered metal seats, but we also offer two valve seat upgrades. *Please note that the factory powdered metal seats have been known to frequently chip, or fall out - which is why we offer seat replacement options. We are not liable for failed powdered metal seats as it is a known factory defect.
Ductile Iron Seats - these seats are a stronger replacement option to ensure the seats in the heads can hold up better to high lift camshafts or camshafts with aggressive ramp rates. If you have a large or high lift camshaft we recommend these seats over the stock seats to prevent chipping.
AMPCO45 & CHE BX - these are the nicest possible seat materials on the market. We recommend these for road racing or any sustained high RPM applications, especially with titanium valves. The main advantage is the thermal conductivity of the seat is much higher, as the seat is the main path for heat to travel out of the valve. This helps keep your valves cooler, which increases longevity and reliability, as well as increasing the tuning window for timing by reducing detonation risk. AMPCO 45 is a nickel-aluminum bronze alloy, and it is used on the intake seats. CHE BX is a proprietary copper-bronze alloy valve seat material made by CHE Precision specifically for the exhaust side of high-performance and racing engines.
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Flag Motorsports offers both factory GM intake and exhaust valves, as well as Ferrea Super Alloy intake and inconel exhaust options.
For NA applications we recommend the GM intake and exhaust valves due to their weight and performance, and the cooler temperatures that NA engines experience in the exhaust compared to boosted engines.
For boosted applications we recommend the Ferrea’s and inconel exhaust due to the higher heat resistance and better material quality.
*Titanium valves are available upon request, please select the No Valves option in the cylinder head product above, and then contact us to discuss. Clients are also welcome to supply their own Titanium valves which we will install free of charge. The part number is 12650770 from GM.
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We offer a USA made dual spring kit for these cylinder heads, rated for .700 lift. The springs are 165lbs on the seat (closed pressure) and open pressure at .700 lift is 490lbs. Coil bind is .980. The kit has two retainer options, Chromoly and Titanium.
Chromoly retainers are recommended for lower RPM applications such as street cars.
Titanium retainers are recommended for higher RPM or racing applications due to weight.