THE KA24 12 VALVE ENGINE
SIMILARITIES TO L AND Z ENGINES
The KA24E engine has a long history. The engine's roots can be traced back to the Prince motor company G18 engine.
The G18 engine was a cross flow overhead camshaft design with hemi combustion chamber. It was a very advanced engine for its day. It seems the L family of engines resulted from the need to reduce the G18's high production cost.
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G18 ENGINE |
A WELL MODIFIED L SERIES ENGINE |
In the L series engine, the main changes from the G18 block was the water path from the block to water pump. Also the L series head was changed to a non cross flow OHC design that was remarkably similar to a Mercedes design. These changes reduced costs, increased reliability and still gave good performance. The L series block also received additional strengthening ribs to stiffen both block and crank webs.
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Z18T |
The L engine gave excellent service in its various forms until the mid 70's when vehicle emissions became a significant design factor. The answer to emission control was to use a more efficient combustion chamber design based on the OHC cross flow G18 head. The head casting was updated and revised and placed on the evolution of the L series engine bottom end as the Z16 (83 bore and 73.7 stroke) and Z18 (85mm bore and 78mm stroke). Eventually the Z18 grew into the legendary Z18T turbo engine. |
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THE BIG BLOCK Z24 |
In the early 80's the Z series of engines grew in bore size and stroke to become the Z20 (85mm bore and 86mm stroke). To get the extra stroke with reasonable rod length, the block height grew from 208mm to 227.45mm. The next evolution was the Z22 engine with 87mm bore and 92stroke. The Z22 block was the same deck height as the Z20 and L20B but had thicker bore castings for the 87mm bore. In the torque hungry 80's the "big block" Z24 engine was born. The Z24 block was raised a further 20mm to a total of 247.45 mm above crank centre to cater for the 89mm bore size and 96mm stroke. This is the engine that spawned to KA24E. |
The KA24E has the same bore and stroke as the Z24 at 89mm bore and 96mm stroke. One of many differences in the blocks is that the KA sump has half the number of bolts securing it. Another difference is the sump and base of the timing cover both extend forward further than the L and Z series engines, so to use an L sump on the engine a plate will have to be welded to the base of the cover to seal it. An angle cut is placed on front of the sump to clear the oil pump. The L type rear main cap has been replaced by a bolt on alloy seal cover.
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The oil pump is the same as used in the L and Z series engines. The KA24 pump has the large rotor common to the L28 turbo from the 280ZX, LD20 diesel engine and the Z18 turbo from the 910 Bluebird. A series 2 L20B 910 distributor drive shaft fits the cover and can be used to drive a 910 electronic distributor. |
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Crankshafts are different in the KA24 as a smaller snout is used and the earlier pulleys will not fit. The bolt pattern on the rear of the crank is the same as the earlier L 6 cylinder, L20B and Z20, Z22 and Z24 engines. |
