With bigger tires and heavier rims on your list of Jeep mods, the stock gear ratio may not be enough to get you where you want to go. This is where changing the gear ratio comes in handy and reduces unreasonable stress on the engine. If the wheels are too tall for the stock gear ratio, there will be a noticeable power drop off from its stock build.
Like the old COPOs of the 60s, the 2011-14 models adhered to strict NHRA guidelines. That meant super-small production numbers and a price payable only by professional race teams. It also meant the car’s engine could only make 530 horsepower. But much like the Japanese engine restrictions of the 1990s, that figure seems to have been framed in air quotes. In 2016 a (not extensively) modified 2014 COPO Camaro ran an 8.323-second quarter mile at 165.80 miles per hour. Doing the math, that car was making closer to 1200 horsepower. 1200.
If any car was worthy of carrying the original ZR1’s torch, it was that one. The numbers are huge: 638 horsepower and 604 lb-ft, with 90% of peak torque available from 2600 to 6000 rpm. Translation: lots of power on tap, whenever you want it.
Plus, in the late 60s, Chevy didn’t use engines over 400ci in midsize cars this meant COPOs were far and away the fastest Chevelles and Camaros on the road. From day one they were, and still are, offensively expensive.
This crate engine is hand-assembled in its own special facility, presumably so as to not risk contamination by one of those plebian engines we saw earlier. Gone are the days of solid lifters and cast-iron heads this beast combines an LSX cast-iron block, LS7/Z06 aluminum heads, forged steel crank and rods, forged aluminum pistons, hydraulic roller cams, and 10.2:1 compression.
It almost goes without saying but the weight allowance should give more than enough to haul your vehicle up or out. As a general rule of thumb, the winch should be rated for a minimum of 1.5 times the gross vehicle weight.
This has been but a taste of the vast GM Performance Catalog. GM crate engines run the gamut from affordable and economical four-cylinder mills to gallon-per-mile big blocks that sound like the devil gargling Listerine. And the future is bright: Chevrolet is bringing back the COPO Camaro and the newly-launched 2019 ZR1 packs 755 horsepower and a 210-mph top speed.
A big block has higher weight and density in the block, as well as larger valve bores, a longer stroke, and a generally larger exterior size. A big block can have the same displacement as a small block, but only the most extreme small blocks encroach on this territory.