What naturally aspirated production engine makes the most torque?
At 600 lb-ft, the 8.4-liter V10 in the new SRT Viper is the reigning stump-puller in the non-power-adder, non-diesel automotive universe. It’s also rated at 640 horsepower.
The Viper is making headlines recently as it’s about to go on sale through only a few select dealers. With a base price of just under $100,000 (and $122,390 for the upscale Viper GTS), it seems like a good time for EngineLabs to review what’s under the hood (and chassis crossbars) of the new snake.
The all-alloy, deep-skirt block supports a forged-steel crankshaft with six 4-bolt main. Slightly oversquare, the bore is 4.055 inches (103mm) with a 3.96-inch (100.6mm) stroke. Other internals include forged, powder-medal rods and forged 10.2:1 pistons with full-floating pins.
According to Chrysler, engineers used extensive computer simulation to redesign the head gaskets and water jackets to balance the cooling. On the lubrication side, the Viper engine features a unique swing-arm pickup to feed oil from the 10.5-quart, cast aluminum pan to the single gerotor pump.
The cylinder heads feature 12-degree angles for both intake and exhaust valves. Combustion chambers are 72cc. The 52.8mm intake valves are hollow stem while the 40.8mm exhaust valves are sodium-filled.
A redesigned cam-in-cam hydraulic roller cam allows the exhaust valves to phase independent of the intake valves. All new to the Viper V10 is a composite 3-piece intake manifold with runners one inch longer than the previous model to help boost torque. Also new are electronically controlled twin throttle bodies. Ignition is handled through 10 coil packs, and exhaust is routed through stainless-steel, tube-in-shell manifolds.
The Viper controls limit engine speed to 6,400 rpm.