V8 7.0L Pushrod

What it is

The bore is 104.8 mm, the stroke 101.6 mm and the compression ratio 11.0:1, which comes to 7,011 cc across eight cylinders in a 90 degree vee. Those figures match the Chevrolet LS7, which GM rated at 505 hp and 470 lb-ft. Nothing else here was copied from one. The torque on the dyno is a Wiebe heat release solved against crank-slider geometry, with the plenum, the runners and the collector filling and emptying around it.

Seven litres, two valves a cylinder and one camshaft in the middle of the block is a truck recipe, and this one turns 7,000 rpm. The VE peak lands at 5,600, eight tenths of redline to the rpm. Eight tenths is the ceiling the curve generator holds a four-stroke to unless the preset lifts it, and only the two Formula One engines here do that. This one is written hard against the stop, and a seven-litre pushrod that breathes best at 80 percent of redline is what makes an LS7 odd in the first place.

It pays for that with the stroke. The model charges friction on mean piston speed rather than on rpm, because rubbing follows how far the rings travel. At 7,000 rpm a 101.6 mm stroke moves 23.7 metres a second. The 5.0 litre V8 on the same redline moves 21.0, and that is why the base friction figure reads 0.846 bar here where the 5.0 reads 1.3: the piston-speed terms have already collected the difference.

Things to try

• Pull Redline down from 7,000. The curve generator pins VE peak rpm to eight tenths of whatever you set, so the breathing peak walks down with it and the top of the curve flattens rather than ending sooner.
• Take Compression up from 11.0:1. On 98 octane it keeps making torque well past stock and the knock reading stays at zero until around 14:1. What shows up then sits near 4,900 rpm, in the middle of the range and not at the top.
• Drop Flywheel below 0.30. The reciprocating and rotating masses here undercut the 8.4 litre V10's on an engine nearly as big, and pulling the flywheel down on top of that is something you hear: the revs pick up and drop away faster between gears.

Seen in

Chevrolet Corvette Z06 (C6)

Runs this engine

2006–2013. GM built the LS7 for this car, and the Z06 is the only Corvette that ever got it.

Photo: Ashlyn Decorges · Pexels

Dodge Ram (second generation)

Same layout

Same layout, different engine: the Magnum V8 that hauled these 1994–2001 trucks is a pushrod 90 degree V8 as well, two valves a cylinder and one camshaft in the vee.

Photo: Owen.outdoors · Pexels