Engine Swapping a Gen IV In Place Of A Gen III

LS engines are no longer the new kid on the block, and it’s crazy to think they have been available since 1997. Yet they’re still super popular with people doing engine swaps in new and old cars. But, what if you have a vehicle that was equipped with the Gen III LS and you want to upgrade to a GEN IV engine? Nick Adams of Scoggin Dickey shows us what’s needed to perform this swap with minimum effort.

The first step to this swap is knowing the differences between the two engines. The early version of the Gen III is equipped with a 24x reluctor wheel, drive-by-cable throttle body, rear mount cam sensor, and single-wire knock sensors are under the valley cover. The later version of the Gen III had all of these same features, only replacing the manual driven throttle body with an electronic unit. The Gen IV engines utilize a 58x reluctor wheel, relocated the cam sensor to the front cover, and moved to a smaller, more advanced two-wire knock sensors.

With the differences between the two engines, you might think that swapping the GEN III to a Gen VI would be difficult. However, it’s not that involved. There are a couple of different routes you can go depending on your build.

Let’s say that you found a smoking deal on a Gen IV LSX376-B15 from Chevrolet Performance to replace your worn out Gen III power plant. You might think that it would be easy to just wasp the ECU from a Gen III to a Gen IV. While this has been done, according to Adams, this option does not offer a very high success rate. Instead, Adams shows us what modifications are needed to retain the factory Gen III computer.

The first obstacle is the knock sensors. As mentioned before, the Gen IV uses a more sophisticated two-wire sensor the bolts to the side of the block. You will need to drill and tap these holes to accept the larger Gen III knock sensors.

Secondly, you will need to convert the 58x signal back to 24x. This conversion is simple thanks to Lingenfelter’s 58x-24x Crank Sensor Trigger Conversion Module. According to Lingenfelter, “The TRG-002 module allows Gen IV GM V8 engines with the 58x crankshaft trigger or reluctor wheel and the 4x camshaft timing gear to be installed in earlier vehicles designed to accept the 24x crankshaft trigger wheel and the 1x camshaft trigger wheel without having to take the engine apart to change the cam timing gear or the crankshaft reluctor wheel.”

Finally, you will also need Caspers Electronics knock sensor/cam harness. This harness will plug into your OEM connectors and allow for the hook up of the remote-mounted knock sensors and the front mount cam sensor.

All of the parts are available through Scoggin Dickey or can be purchased from the manufacture’s websites.

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About the author

Brian Havins

A gearhead for life, Brian is obsessed with all things fast. Banging gears, turning wrenches, and praying while spraying are just a few of his favorite things.
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