Actor, automotive fanatic, and co-host of the MotorTrend App’s new Top Gear America, Dax Shepard is constructing a Chevrolet 454 SS pickup with a supercharged LT4 engine and six-speed automated transmission. HOT ROD Storage co-host Fortunate Costa is doing the work at his private store and invited us to examine in on his progress.
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It’s a reasonably well-known proven fact that Dax is a dyed-in-the-wool gearhead. He hails from Detroit and grew up within the business. We’ve featured a few of his automobiles, like his hot-rodded Lincoln Continental and LS-swapped 1996 Buick Roadmaster wagon. He lately bought this low-mileage 454 SS, and it’s actually clear.
We drove it across the block and have been impressed with its tight really feel and journey high quality. The throttle-body-injected (TBI) 454 positively makes extra torque and accelerates with extra aplomb than Challenge Jake, the in-house, small-block-powered OBS (outdated physique fashion) 1993 GMC C1500 from our sister publication HOT ROD. Nonetheless, an 8:1 compression big-block with peanut-port cylinder heads, a tiny cam, and hard-to-tune, airflow-limited induction and fuel-delivery techniques doesn’t evaluate very favorably with even the usual engines in as we speak’s pickups.
Say what you’ll about taking out the big-block in a 454 SS and changing it with an LS or (on this case) LT engine, it’s arduous to argue with the logic. Fortunate advised us he and Dax mentioned a number of choices on the right way to construct the prevailing big-block for extra energy, however Dax selected the LT4 E-Rod crate engine from Chevrolet Efficiency in an try and hold the pickup emissions-compliant. This engine package deal acquired an govt order (E.O.) quantity from the California Air Sources Board (CARB) permitting it to be put in in 1995 and older passenger automobiles and vans as much as 5,725 kilos GVRW.
The LT4 initially appeared within the C7 Corvette Z06 and is rated at 640 horsepower and 630 lb-ft of torque due to its 6.2 liters of displacement and a 1.7L Eaton R1740 TVS supercharger that generates a conservative 10 psi of enhance. Even with the additional weight of the supercharger, the all-aluminum engine will probably be lighter than the 454, which Fortunate has put aside in case Dax decides to place his pickup again to inventory sometime.
Is the LT4 Engine a Small-Block?
Though folks consult with the LS and LT household of engines as small-blocks, the LT4 takes up a substantial quantity of actual property, due to its intensive supercharger and accent drive pulleys. Fortunate eliminated the hood, grille, and entrance bumper assemblies as a result of it will be a lot simpler to carry out the engine change that method.
Elevated Ideas, Inc. is an organization that makes a speciality of LS and LT engine swaps for the ’88 to ’98 Chevy and GMC pickups and SUVs. Proprietor Derek Parker sells LT-swap motor mounts that place the engine at a really perfect location inside the engine compartment. Fortunate drilled entry holes to succeed in the within of the fasteners on the body stands. They’re in any other case inaccessible with out eradicating the decrease management arms.
As is commonly the case with engine swaps, the equipment can generally get in the way in which of the body in older automobiles. Different accent drive techniques can be found, however Fortunate prefers Holley’s LS and LT techniques for his or her high-quality match, end, and reliability. Distinctive to the LT4 due to its supercharger drive and throttle physique location, the LT4 accent drive package places the alternator low and on the best facet of the engine. Fortunate notched and bolstered the body to clear the alternator, leaving sufficient room round it in case it ever must be eliminated sooner or later. We’ve seen body modifications like this executed on dozens of automobiles with no proof of compromised structural integrity.
Dax selected the Supermatic 8L90-E eight pace automated transmission from Chevrolet Efficiency to behave as middleman between the LT4 and the 12-bolt axle within the 454 SS. It’s rated to deal with 650 lb-ft of torque and is obtainable with a alternative of a 2,400-rpm or 3,000-rpm stall converter. First gear is a steep 4.02:1, and sixth is a low 0.67:1, so Dax will expertise the scrumptious distinction of neck-snapping launches (offering he has adequate traction) and sedate freeway cruising as soon as he lets off the fuel. This factor will in all probability get fairly respectable mileage, all issues thought of.
The inventory transmission crossmember in these pickups is principally a stamped piece of sheetmetal that’s so straight it may double as an ironing board. The shortage of complexity makes it simple to accommodate the brand new transmission, which looks like it takes a regular GM mount. Fortunate simply wanted to maneuver the crossmember again a few inches to its new mounting place. Keep tuned for extra as work progresses, and make sure you try the new Top Gear America when it debuts on January 29, 2021 on the MotorTrend App.
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