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The Cheapest Way to do the Discovery 2 LS Swap

We frequently get questions similar to “what is the cheapest way I can do a Disco 2 LS swap”. Here a hypothetical walkthrough of the parts that we would select for a budget swap. As you can see below, if you do a lot of it yourself, you can save quite a bit.

LM7 engine ready for install into a Discovery 2

The Engine

Many garden-variety iron-block 4.8L LR4 or 5.3L LM7 engines are available for cheap. The point here is to try to get everything (engine / harness / PCM) you need in one place. For the swap, we need an engine with the drive-by cable setup, so ideally we want a 1999-2002 Silverado 1500 4.8L or 5.3L engine.


Since we are looking for a deal, we looked around on Craigslist and Facebook marketplace instead of through salvage yards. We found a 2000 4.8L LS with a harness, ECM and everything for $750 on Facebook Marketplace. This even included a 4L60 transmission, which we won’t use and can resell later.

This deal included the engine, the drive-by-cable throttle body, the drive-by-cable harness, and the red-blue (411) PCM that we need for the swap. Obviously with any deal like this with no warranty, check that the engine turns over smoothly and is in good condition. Now we’ve got nearly all the parts we need for the swap (like the starter, and sensors) that can really raise the overall price.


Total: $650 ($750-100 for selling the transmission for a core).


The Wiring Harness

Usually we recommend purchasing a harness from PSI or another harness manufacturer. However, a budget-conscious swapper can also rewire the harness that came with the engine. This can be a tedious process, but there are many resources for thinning out the harness yourself. For example, we typically recommend LT1swap.com as a key resource for rewiring your GM harness.

A couple of things we need: First, we have to buy a new fuse block for the harness. This will simply the wiring and get rid of the massive GM fuse block. Second, we need some new wiring loom and electrical tape for cleaning up the wiring.


Total: $85 ($59 for fuse block + tape and loom).


The PCM

Usually we recommend purchasing a tuned PCM directly through the company building your wiring harness. However, since the engine came with a PCM to reuse, there are cheaper methods. For example, mail order tuners, such as LT1swap.com, only charge $75 to delete VATS and tune a PCM for standalone use. This is an easy process — just send the PCM out in the mail and get it back ready-to-go in a few days.


Total: $75


Fuel Rail

The early LS truck engines had a fuel rail with a return. Since the Discovery has a returnless system, we need to convert the return system to a returnless system. Instead of ordering an entirely new rail, we can replace just the part that contains the return. This means using a later driver’s side fuel rail — ACDelco 2171542 — for a 2005+ Silverado.

Total: $71 (plus o-rings)


Conclusions

The math for the parts works out like this:


Engine $650

Harness $85

PCM $75

Fuel Rail $71

Miscellaneous Parts $500 (required hoses, piping, and fittings)


Using this method, the total cost comes out to around $3.8k. Usually we say the total cost for everything is around $4.5-5k depending on parts selection. This is a significant cost savings for DIYing only a couple of things and some clever Craigslist shopping. Feel free to share your bargain LS finds with us below!

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