What if you could take an overhead-valve V-8 engine and add 4 more cylinders to it making it a V12? How cool would that be?
Unlike the old fire truck V-12's that are either flathead designs (Seagraves, Pierce-Arrow) with the exhaust coming out of the top of the engine or 30-degree engine designs (LaFrance, Auburn) that look like a wide straight 6 engine (ugly and built unbalanced like a model T engine), the ThunderV12 engine looks like a long modern overhead-valve V8...but longer.
The width compared to a bigblock Chevy or Ford is the same to slightly narrower depending on valve covers and heads used on the big blocks.
The height of the V12 is around 9" taller. Nearly all of this additional height is an oil pan. The Y block design of the V12 causes only about 1" of the crankshaft to show below the block. The V12 oil pan can be shortened substantially if required for clearance. The pan is 10 5/8" tall. We have built a dry-sump oil pan in-house that is only 2" tall.
Length. This is what puts the hot in hot-rod! This engine is roughly 20" longer than the big block comparisons!
The original 702 V12 had a front center mount under the accessory case and two rear mounts on each side of the bellhousing. A ThunderV12 does not use the original industrial bell housing. The rear adapter plate developed by ThunderV12 has incorporated mid-plate ears on both sides to allow for engine mounting. The front center mount is used as designed by GMC.
Width = 21" outside valve cover to outside valve cover.
Height = 36" from the bottom of the oil pan to the top of the carb.
Length=53" from the front of the mandrel pulley to the rear of the transmission adapter.
Weight = 1,405 lbs with 3 gallons of oil. (We had a guy with a straight 8 Packard respond "My straight 8 with the transmission was 1,750 pounds."