| The entire install was handled by the Stillen Service Department. Since we had already run Blue Bomber on Stillen’s DynoJet dynamometer after the supercharger installation, we wanted to be able to scientifically quantify the changes created by the installation of the performance exhaust parts. Back to back on the same dyno under similar conditions gave us the smartest results. With an ASE Master Technician installing our parts and tweaking the computer’s tune to accept them, we knew we would be happy with the results from Stillen. If your truck could use more power, give the pros at Stillen a call.
Last month, Project Blue Bomber was at Stillen’s performance center, receiving an Edelbrock E-Force supercharging system for the Silverado’s 4.8L engine. Strapped down to Stillen’s chassis dyno, the 2011 Silverado spun the rollers to the tune of 374.18 hp and 366.36 lb-ft of torque. The one caveat was those numbers were pushed through the original exhaust system. We made zero supporting modifications to allow the engine to properly exhale all the air being forced into it. This month, we chose to change that and the power results were better than expected.
We began by exchanging the factory exhaust manifolds for long-tube headers from Dynatech. GM has come a long way in development of its LS-series manifolds, and for most applications they work amazingly well. We’re power junkies at heart and Dynatech’s SuperMAXX headers and Y-pipe system offered us the fix we needed. We chose the intermediate piping with the cats to keep the exhaust noise down to a reasonable level and not pump carcinogens into our already polluted air. The goal of Blue Bomber is, after all, to build a street-driven truck that can hit the track when the desire arises.
| 1. Under our new project, things were still very clean, but our stock exhaust was mocking us. Check out how the stock Y-pipe is captured behind the transmission crossmember. Keep that in mind should you choose to do this install at home. The rest of the original system looked to be easy to pull free.
Once the exhaust was expelled from the converters, we needed an after-cat system to collect, silence, and aim the spent fumes away from the truck. MagnaFlow’s Performance Exhaust system fit the bill perfectly. Once Stillen tuned the ECU parameters, our Silverado was lighting up the tires with ease. More power, better sound, and an easy install made this month’s upgrade money well spent.
| 26. Stillen had to perform a bit of tuning to the truck (adjusting fuel, spark, and timing) so it would accept its new exhaling apparatus and we were rewarded with a healthy jump in performance. How much? How about an extra 41.17 hp and 30.71 lb-ft? Our new numbers on the dyno had us at 415.35 hp and 397.07 lb-ft, with increases from the bottom all the way to the top.
After driving around with our new-found power from the exhaust, we made the decision to delve deeper into the EFI tuning to see what was lurking in the shadows. We knew there was plenty more to be had, but it needed to be coaxed out of hiding. With a couple parts in hand, we set off to Mira Loma, California, to visit with Ernie Mena and the crew of Westech Performance. Our visit there made substantial gains in not only the peak numbers, but in the overall drivability of the truck. Ernie spends plenty of time working every portion of the scale to create a smooth running engine from idle all the way to redline. With his tuning expertise, Blue Bomber now runs and drives just like it did when it was stock, but has a huge pile of tire shredding torque when the accelerator is mashed. Additionally, Ernie went into the transmission controls and dialed up firmer shifts with less overlap to keep the transmission fluid from heating up due to the soft shift parameters set at the factory.
| 4. Check out the difference we were able to achieve with a pulley, throttle body, and custom tune! We went from 415.35 hp to 442.5 hp and 397.07 lb-ft of torque to 445.6. Those numbers represent an increase of 27.15 hp and an astonishing 48.53 lb-ft of tire-melting torque.
