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| This sectioned head shows the LS3/L92 intake port contour. The port shape is derived from the Katech C6R ALMS car and improved upon by GM Powertrain. The intake port has a straight shot into the combustion chamber with a gradual radius in the critical short side of the port by the intake valve. |
The compactness is what makes the LS engine a great candidate for swaps as it is a small engine that packs a lot of displacement in a tight package. Just look at a DOHC V8 from Toyota or Nissan and you will immediately know what we are talking about. At 440 lbs, the LS3 is pretty lightweight as well, weighing in at nearly the same weight or even less than many import 4 cylinders! Dai Yoshihara’s LS powered Formula D S13 has a 50.8/49.2 front to rear weight distribution with no exotic tricks. This makes things look even more interesting!
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| The exhaust port is very similar to the older LS variants except that it is higher and straighter with a slightly larger cross section. |
4 valve twin cam engines usually have much more straightforward intake and exhaust ports with considerably more valve area for good flow and are usually designed with shallow, highly turbulent combustion chambers with lots of quench area. This promotes good combustion efficiency. The ports don’t have to miss push rods and head bolts like they did in the old small block. This is not true with the LS though.
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| Here is an example of the LS3/L92 intake port on the left vs the older LS1/LS2 cathedral intake port on the right. Note how the LS3 port is wider and higher than the LS1 port. |
The small block Chevy was an old design. It seemed like GM’s engineers of the time decided on where to put the push rods, head bolts and valves first and designed the ports to miss everything second. The ports had turns in them and sharp angles which were not conducive to good flow. The LS engines were different; the heads were designed with good flowing ports in mind. With 4 head bolts instead of 5 like the old small block, the ports could be more straightforward. The ports and their angles were considered for flow from the beginning in the basic design.
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| The larger, higher and straighter LS3 exhaust port is on the right. The older LS1/LS2 exhaust port is on the left. |
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| LS intake port map. |
