Looking at the stock intake runner (left photo, roughly 270cc) there are a few bumps and lumps in the roof (the heads are upside down; notice the valve guide boss), causing turbulence. Also, the bowl to seat area has machining ridges.Looking at the stock intake runner (left photo, roughly 270cc) there are a few bumps and With rain approaching on the radar screen, we could only chance a 20-minute cool-down. We made a couple more passes, posting an 11.87 and an 11.91 at over 119 mph. Totally satisfied with our results, we packed up and headed home. Before our strip test, we wanted to test Performance Distributors Mini VIP 18-volt step up regulators, but time constraints and a heavy work load at Tune Time's shop prevented it. A few days later it was showtime for the 18-volt Mini VIPs. They added an impressive 8 hp and 7 lb-ft of torque to the equation (458 rwhp, 407 lb-ft). That's enough power to easily be worth a tenth at the track. Due to a stronger spark igniting the fuel in the combustion chamber, the A/F (air/fuel) mixture ratio was a tad leaner, going from 12.7 to 12.9. Tuning in a touch of enrichment could have given us a few horses, but the tune was left untouched. An experienced head porter can add flow (roughly 15 to 20 cfm) to a pair of stock castings, but can never come close to airflow of the CNC-ported Mast heads. The Mast intake runner is smaller in size (right photo, 256cc), along with a unique port shape, to flow more air at a faster velocity than stock or CNC-ported L99/LS3/L92 head castings.An experienced head porter can add flow (roughly 15 to 20 cfm) to a pair of stock castings The Mast Motorsports Black Label heads impressed us beyond our expectations. When you can bolt-on a set of heads that are 46 rwhp better than the great LS3/L99/L92 heads, it's amazing. The Mast Motorsports 12-degree heads show the latest improvements in LS cylinder head technology. We're sure a larger displacement or a forced induction LS engine would be rewarded more power from these massive-air-moving heads. STRIP TEST RESULTS MODS 60-FOOT 1/4 - MILE / MPH BASELINE, BONE STOCK 2.05 13.25 @ 106.42 BONE STOCK W/TUNE 1.99 12.94 @ 108.39 CAM, HEADERS/EXHAUST, TUNE 1.93 12.27 @ 114.54 HEADS, TUNE 1.86 11.81 @ 119.27 LS3//L99/L92 FLOW DATA Courtesy of GMPP Catalog LIFT 0.200 0.300 0.400 0.500 0.600 INTAKE 151 208 256 294 316 EXHAUST 111 152 174 183 189 Mast Black Label FLOW DATA Courtesy of Mast Motorsports LIFT 0.200 0.300 0.400 0.500 0.600 0.700 INTAKE 148 237 295 328 351 370 EXHAUST 118 165 208 227 235 241 Note: Looking at important mid-lift (0.300 and 0.400 lift) flow values, besides peak (0.600 and 0.700 lift), the MM heads show they are the highest flowing bolt-on heads available for the LS engine. In recent years (and after much research and development), the clover-shaped combustion chamber has proven itself superior to the heart-shaped, fast burn, closed and open chamber of years past. The valve seats feature multi angles for additional flow at low and mid-lift. It's easy to notice the precision CNC work to the combustion chamber (69cc) and port runners. Again, notice the port's gentle turn and approach to the valve seat-this is a major advantage these taller heads provide.In recent years (and after much research and development), the clover-shaped combustion ch Here's looking at the L99 before we pull it apart for the Mast heads. The only visible deviations from stock are TTP's own carbon fiber air intake pipe, headers and Taylor plug wires. Not visible but from our first installment is a Mast Motorsports VVT Stage 1 cam package (cam, springs, ti retainers and cam phaser limiter). The Mast VVT (variable valve timing) Stage 1 camshaft features 0.573/0.588 lift and 220/234 at 0.050-lift duration with a lobe separation angle of 116-degrees. The cam package is designed to match the flow and power potential of their high-flow Black Label cylinder heads.Here's looking at the L99 before we pull it apart for the Mast heads. The only visible dev We took off the intake, headers, coil packs, valve covers, rockers, and pushrods to access the head bolts. When we put it back together, you'll see the DOD (Displacement-On-Demand) lifter valley cover (notice the veins) was replaced with a flat (no veins) non-DOD LS2 valley cover. DOD removes the oil out of the stock DOD type lifters so the valves don't open in the respective cylinders for fuel savings. By eliminating the DOD we'll be able to run LS9/CTS-V lifters and say goodbye to the valve float we were experiencing above 6,300 rpm.We took off the intake, headers, coil packs, valve covers, rockers, and pushrods to access « | 1 | 2 | 3 | » | View Full Article By Dan Foley Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!