Here's what I know about the UR series from information I've gathered:
The UR series engines will be offered in 4.6L, 4.7L, 5.0L, and 5.7L displacements. The 4.6L is the direct replacement for the 3UZ, and the 4.7L is the direct replacement for the 2UZ. I believe Toyota felt the need to completely phase out the UZ series engines to reduce cost, and also for greater consistency throughout its lineup. The UR series engines also reduce maintenance costs for consumers, since no timing belt change interval exists. The timing chain is only adjusted or replaced when it begins to make noise or chatter during driving.
Here are the specs for all UR engines:
DOHC, 32-valve, dual VVT-i, chain driven, roller rocker valvetrain with low coefficient of friction roller bearings, molybdenum coated pistons with anti-friction coated #1 and #2 compression rings, available dual fuel injection on passenger car engines with single fuel injection on truck based engines, second generation high performance, low friction F head design stemmed from the GR series engines. ACIS II/III integrated into the intake manifold, which continuously varies the intake runner length depending on engine conditions and detection of air mass within the manifold. Roller rockers provide more valve lift in performance applications than previous cam lobe driven bucket type valves.
1UR-FSE 5.0L 90 degree V8 with dual VVT-i
Aluminum block and heads
Lightweight forged and sintered connecting rods for greater efficiency, revvablility, and reliability
Lightweight moly coated pistons with revised piston ring placement for greater fuel economy
Forged steel crankshaft with 8 weight balancers
Dual fuel injection with air assisted port injection and unassisted direct injection
Larger intake and exhaust ports and slightly larger valves for increased performance
Estimated power:
430-450hp @ 6400rpm
400-440lb-ft @ 4800rpm
2UR-FSE 4.6L 90 degree V8 with dual VVT-i
Aluminum block and heads
Lightweight forged and sintered connecting rods for greater efficiency, revvability, and reliability
Lightweight moly coated pistons with revised piston ring placement for greater fuel economy
Forged steel crankshaft with 8 weight balancers
Dual fuel injection with air assisted port injection and unassisted direct injection
Estimated power: (revs are estimates)
380hp @ 6200rpm
370lb-ft @ 4200rpm
3UR-FE 5.7L 90 degree V8 with dual VVT-i
Aluminum block and heads/Cast iron block w/ aluminum alloy heads (?)
Forged, high strength internals with 6 bolt main crankshaft bearing caps, fully balanced forged crankshaft with high strength connecting rod bolts
Large diameter forged connecting rods with heavy duty moly coated pistons - full floating type
Single fuel injection - air assisted port injection for greater fuel atomization
High compression relative to other truck engines
Estimated power:
400hp
470lb-ft
4UR-FE 4.7L 90 degree V8 with dual VVT-i
Aluminum block and heads/Cast iron block w/ aluminum alloy heads (?)
Forged, high strength internals with 6 bolt main crankshaft bearing caps, fully balanced forged crankshaft with high strength connecting rod bolts
Large diameter forged connecting rods with heavy duty moly coated pistons - full floating type
Single fuel injection - air assisted port injection for greater fuel atomization
High compression relative to other truck engines
Estimated power: (bridges gap between 1GR and 3UR)
335hp
380lb-ft
A bigger truck means it needs more power. Toyota will phase out the 2UZ and replace it with the all-new 4UR-FE (hence, the words "updated 4.7L" in a press release by Toyota). Keep in mind Toyota is replacing the current Tundra Double Cab with something a lot bigger. The new Tundra DC replaces the current Access Cab.
