The guys at BBK understand what goes into the design of an intake manifold. Their Single Stage Induction (SSI) intake promised effective power gains, so we decided to put one to the test on Modern Mouse. You will remember that Modern Mouse had long since been converted from a stock LM7 to a 383 stroker courtesy of Procomp Electronics, Probe Racing, and L&R Autotmotive. The 5.3L stroker short-block featured a Comp LSR cathedral-port cam, and was topped with a set of Gen X 215 heads from Trick Flow Specialties. For our testing, Modern Mouse was also treated to an 80mm Accufab throttle body, a set of American Racing Headers, and Holley 75-psi injectors. The engine was also sporting a Meziere electric water pump, FAST XFI/XIM management system, and a fresh oil change with Lucas 5W-30 synthetic oil (and K&N oil filter). The 75lb injectors were overkill for this application, but we had them on hand for another round of forced induction. Look for boosted results in the next installment of Modern Mouse.
To establish our baseline, the motor was first run with the stock 5.3L truck intake and Accufab 80mm throttle body. Once the air/fuel and timing curves were optimized with the FAST computer, the modified LM7 produced 515 hp at 5,800 rpm and 506 lb-ft of torque at 4,700 rpm. Obviously tuned for truck applications, torque production exceeded 475 lb-ft from 3,600 rpm to 5,600 rpm.
Installation of the BBK SSI intake also required replacing the factory truck fuel rail with a billet unit from Wilson Manifolds. After swapping over the Accufab throttle body, the peak power numbers jumped to 524 hp at 6,100 rpm and 503 lb-ft of torque at 4,800 rpm. The BBK intake improved the power output of the 383 by as much as 15-16 hp at the top of the rev range, but it is hard to beat the torquey truck manifold in the lower rev ranges.
Note that both the peak horsepower and torque values with the BBK intake occurred at higher engine speeds than the truck manifold. We suspect the BBK intake would show even better results on a larger stroker or one with even wilder cam timing.