Lots of good details here on the new 2.4L engine (T24A-FTS) in the 4G Tacoma:
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The new 2.4 turbo engine replaced the previous 2-liter 8AR-FTS and primarily appeared under the hood of FF-platform crossovers starting with the 2nd gen Lexus NX. And as recent practice shows, it is designed to replace the naturally aspirated V6 2GR- as well. Although technical affinity with A25 engine seems obvious, the differences are much more fundamental than just a crankshaft or turbine... let's take a closer look.
Engine mechanical
The cylinder block - open-deck type, made of aluminum (light-alloy). The cast iron liners are fused into the block material, and their special uneven outer surface provides the durable connection and improved heat sink. here are sloping coolant channels drilled between the cylinders.
The oil sump assy consists of a cast top and a steel bottom.
The crankshaft is installed with a 10 mm offset (the axes of the cylinders do not intersect with the longitudinal axis of the crankshaft), thus reducing the lateral component of the force exerted by the piston to the cylinder wall, reducing wear.
The crankshaft has 5 journals and 8 counterweights. The massive crankcase is integrated with crankshaft journal caps, which gives the structure the necessary rigidity. The conrod and main bearings - with a resin coating.
The separate balancer mechanism is driven by crankshaft via train with polymer gears.
The pistons made of light-alloy, T-shaped, lightweight. The upper compression ring is installed in Ni-resist insert. The edge of the upper compression ring has PVD-coating, oil rings edges have anti-wear carbon coating (DLC - "diamond like"). The skirt is covered with a polymer coating. Pistons are connected to the connecting rods by fully floating pins and locking rings.
The "walls" of the piston are noticeable sloped, which should better distribute the load to the piston pin at the expansion stroke.
Connecting rods - forged, with knock pins for caps; top heads tapered to reduce weight.
The camshafts are installed in a separate housing, which mounted on the cylinder head.
The new 2.4 turbo engine replaced the previous 2-liter 8AR-FTS and primarily appeared under the hood of FF-platform crossovers starting with the 2nd gen Lexus NX. And as recent practice shows, it is designed to replace the naturally aspirated V6 2GR- as well. Although technical affinity with A25 engine seems obvious, the differences are much more fundamental than just a crankshaft or turbine... let's take a closer look.
| Engine | Displacement, cm3 | Bore x Stroke, mm | Compression ratio | Output, PS | Torque, Nm | RON | ECS | Market |
| T24A-FTS | 2393 | 87.5 x 99.5 | 11.0 | 279 / 6000 | 430 / 1700-3600 | 95 | D-4ST | EEC |
| T24A-FTS (2.4 D-4ST) |
Engine mechanical
The cylinder block - open-deck type, made of aluminum (light-alloy). The cast iron liners are fused into the block material, and their special uneven outer surface provides the durable connection and improved heat sink. here are sloping coolant channels drilled between the cylinders.
|
| 1 - cylinder block, 2 - crankshaft bearing cap. a - cylinder bore, b - cylinder liner, c - bore cross hatching, d - 30°, f - cooling passage, g - bottom of water jacket elliptical shaped, h - larger breather hole |
The oil sump assy consists of a cast top and a steel bottom.
|
| 1 - stiffening crankcase, 2 - oil pan #2. a - oil drain passage, b - oil filter bracket, c - high pressure oil passage |
The crankshaft is installed with a 10 mm offset (the axes of the cylinders do not intersect with the longitudinal axis of the crankshaft), thus reducing the lateral component of the force exerted by the piston to the cylinder wall, reducing wear.
|
| a - bore centerline, b - crankshaft center, c - intake side, d - exhaust side, e - maximum pressure, f - offset crankshaft, g - non-offset crankshaft |
The crankshaft has 5 journals and 8 counterweights. The massive crankcase is integrated with crankshaft journal caps, which gives the structure the necessary rigidity. The conrod and main bearings - with a resin coating.
|
| a-e - main bearing journal, f - balance weight, g - balance shaft drive gear |
|
| 1 - crankshaft bearing (upper main bearing), 2 - crankshaft bearing (lower main bearing), 3 - upper crankshaft thrust washer. a - oil groove, b - oil groove depth, c - center, d - edge |
The separate balancer mechanism is driven by crankshaft via train with polymer gears.
|
| 1 - crankshaft, 2 - balance shaft housing #2, 3 - balance shaft #1, 4 - balance shaft #2, 5 - balance shaft housing #1. a - balance shaft drive gear, b - resin gear, c - balance shaft gear #2, d - resin gear |
The pistons made of light-alloy, T-shaped, lightweight. The upper compression ring is installed in Ni-resist insert. The edge of the upper compression ring has PVD-coating, oil rings edges have anti-wear carbon coating (DLC - "diamond like"). The skirt is covered with a polymer coating. Pistons are connected to the connecting rods by fully floating pins and locking rings.
|
| 1 - compression ring 1, 2 - compression ring 2, 3 - oil ring. a - spherical shaped, b - ni-resist cast iron, c - alumite coating, d - resin coating, e - PVD coating, f - DLC coating |
The "walls" of the piston are noticeable sloped, which should better distribute the load to the piston pin at the expansion stroke.
|
| a - weight reduction, b - inclined side wall |
Connecting rods - forged, with knock pins for caps; top heads tapered to reduce weight.
The camshafts are installed in a separate housing, which mounted on the cylinder head.
