Making 500 hp+ with a cheap 4.8L Vortech LS junkyard engine
LS power on the cheap is easy if you know where to look and what to do.
500+ hp from a junkyard 4.8L Vortech LS? Yep, and it’s easier than you think. Sure, new crate engines are great if you have the cash, but there millions of engine possibilities sitting in junkyards all across the county. One of the most abundant are the 5.3L and 4.8L Vortech LS-variants that GM has produced since 1999. These were typically stuffed into 1999 and up GM trucks and SUVs. So, when you spy that Tahoe, Silverado, Yukon, or other candidate the first thing you want to do is check the engine tag (usually on the radiator core support or bottom of hood), which typically lists what engine is in the vehicle. You can also check the front of the block, below the head on the driver side of the block.
How Can You tell a 5.3L LM7 from a 4.8L LR4 Vortech?
Now the hard part; 5.3L and 4.8L Vortech engines use the same block, so both numbers will be cast into the block. In fact the two engines are identical, so it’s pretty much impossible to tell them apart externally. About the only way to know, besides tearing them apart to check the internals, is to use a borescope to look inside at the top of the pistons. LR4 4.8L engines will have flat-top pistons while 5.3L LM7 mills will have slightly dished pistons. The price for these engines varies quite a bit, but at our local Pick-A-Part in Southern California we can buy them for around 275 bucks! At that point all you need to do is clean it up and change the oil. Personally we would suggest pulling the pan and checking the main bearings and doing a thorough inspection of the internals, but that can be your call based on the condition of the engine, the vehicle it came out of, and the mileage on the odometer if can be determined. Oh, when scouring boneyards for candidates be careful of LS4s. They were used by GM in FWD applications and are not suitable for traditional engine swaps.
We thought we had a 5.3L LM7, but it turns out we ended up with the smaller 4.8L LR4. Oh well. If we can make decent power with this, then you would make even more with a 5.3L. The engine cost us a whopping $274 as pictured from our local yank-a-part place. They charge the same for a 5.3L because they can’t tell the difference, either, unless they use a borescope to see if the pistons are flattop (LR4) or dished (LM7).
How Much Stock Power Does 4.8L LR4 Vortech Make?
The factory truck intake is ugly and a bit tall, but it makes great torque. If you have the hood room to run it, then it’s the cheapest option to go with. Of course you’ll need a harness and computer to run it. For that we would suggest Holley’s new Terminator X system, which runs around a grand. That means you could have this EFI mill in your car and running for the miserly sum of $1,300! You’ll some installation expenses, though, like engine mounts and such, but getting an EFI engine in your car isn’t going to get any less expensive than that. Dyno tested, and bone-stock internally, with headers a single-plane intake and 650 cfm carb, the 4.8L LR4 made 333 hp at 5,400 rpm and just over 343 lb-ft of torque at 4,700 rpm. With the truck EFI intake and GM throttle body we typically see just over 350 hp.
These 5.3L and 4.8L engines really respond well to cam swaps. The cheapest route would be to find a GM LS6 or other factory cam, but we opted for a Comp stick (PN 54-454-11). This cam offered a 0.614/0.624 lift split, a 227/243-degree duration split, and 113-degree LSA.
Adding an Edelbrock Intake, cam, and 650 Carb, the 4.8L Vortech made 441hp.
After testing the 4.8L with the Victor Jr single-plane intake and a wallet-friendly 650cfm Holley Brawler carb we added Comp camshaft and matching valve springs. To fire the coils we went with a box from MSD. Add this all up, and it’s around $1,300 including the engine! The 4.8L had a cracked oil pan so we swapped to a Holley LS pan, changed the oil to some fresh Lucas 10w30 and strapped it to the dyno at Westech before making any baseline pulls. Timing was 26 degrees, which seemed to be the sweet spot, for these pulls.
Run with the Comp 54-454-11 cam and new 26918 springs, the 4.8L responded with peak numbers of 441 hp at 7,000 rpm and 354 lb-ft of torque at 5,400 rpm. Yeah, that’s a huge 100-plus hp gain, and while the peak torque number wasn’t that much higher, you can see that it picked up lots of torque across the entire pull. A dual plane would have lost a bit of top-end hp, but it would have picked up low- and midrange torque. It all comes down to how you plan to drive your car. Who doesn’t love a 7,000-rpm LS engine?
For a total cost of $2,400, the 4.8L Vortech made 554hp.
The wallet-friendly NOS Sniper kit (under 500 bucks) was perfect for our budget junkyard 4.8L. Run with jetting to provide an extra 100 hp, the Sniper kit helped the little LS pump out 554 hp and 501 lb-ft of torque! We were able to us the MSD box to knock four-degrees out of the timing, which is important when running nitrous.
Between the cam and the nitrous, this budget LS was putting out impressive numbers. All together we had $1,300 in the engine with the carb, $600 for the cam and springs, and another $500 for the NOS kit. Add it all up, and you would be under $2,400. The best part is you could build this up over time, in stages, as funds allow. Remember, you don’t need to go broke to go fast and have fun.
Why a used 5.3L LM7 or 4.8L LR4 Vortech LS is the best deal out there:
- 3L and 4.8L Vortech engines can be bought for under $300
- Can be bought and installed in your car, with a carb and intake, for as little at $1300
- Can make 350 hp stock or nearly 450hp with a cam swap
- Combined with a nitrous kit you can easily make over 500hp
- To tell the difference between 4.8L and 5.3L Vortech engines use a borescope
- 3L engines will have slightly dished pistons
- 8L engines will have flat top pistons
- These smaller Vortech engines are found in RWD GM trucks and SUVs from 1999 forward
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