Car Craft is all about waving the underdog flag. Most car crafters don't have the funds to plunk down $17,000 on a fresh, new Chevrolet Performance LS7 crate engine. It's tempting to bring up that $22,000 supercharged Corvette LS9. It's fun to dream about these engines, but the odds are better that we'll be named in a Kardashian paternity suit than it will be to find an LS9 on our doorstep. There are reasonable alternatives—for an LS engine, that is. We figured our real-world chances were far more favorable for finding a 5.3L iron-block truck engine, so we scoured Craigslist until we found what seemed like a deal on a used 5.3L for $200. It was a long-block with no intake but did have the accessory drive (minus the alternator and A/C pump) and a flexplate. What we learned later was the "5.3L" turned out to be the bottom-of-the-displacement-barrel 4.8L. This engine sports the same small 3.78-inch bore as the 5.3L but with a shorter 3.26-inch stroke that creates a mere 292 ci. The 4.8L is basically a longer-stroke version of the half-century-old 283 (3.875 bore and 3.00-inch stroke). We didn't discover what we had until it was too late to find another engine, so we just dropped it into our Orange Peel 1966 Chevelle. All of the details on this swap were covered in the cover story of the Summer 2012 issue of Engine Swaps. But after we completed the story, things took an interesting twist.
After mashing the throttle a few times on its maiden test drive, we decided this brick was not quite ready to be committed to boat-anchor status. We'd added a mild Comp Extreme Energy street cam, and with the Orange Peel's 3-inch exhaust, it had a bark that belied its bite. A friend suggested, "You should take it to the track," so we did. Now, hang with us on this. It's difficult to get bubbly about a 13-second car. Frankly, we expected less. But after a trip to Irwindale's eighth-mile on a Thursday night, the Chevelle bogged its way to a best of 8.588 at 84.98 mph. That converts to a surprising 13.48 at 105 mph in the quarter-mile. Given its snail-like 2.125 60-foot time, the little 4.8L was doing its best honkytonk bimbo tease—and begging us to hit it with a snoot full of nitrous. The Chevelle was already equipped with a mounted NOS Cheater bottle, so all we had to do was add the plate, hook up the hydraulics, and hit the button. There was a little bit more to the job than that, but by the following Thursday, we were ready to run.
Back at the track, our carb and ignition tuning had cured the starting-line hesitation, but our 60-foot times only improved about a tenth, with the Chevelle running a best of 2.02 and an 8.506 at 85.35, which is equivalent to a quarter-mile time of 13.35 at 105 mph. If we were going to stick with the normally aspirated program, this little motor really needed a 4.10:1 gear, instead of our 3.55:1 setup, but we decided this was as good as it was going to run normally aspirated. It was time to turn up the wick.
In the week before this test, we had spoken with NOS about nitrous jetting. The published chart for a Cheater kit listed the nitrous jet at 63 with the same size for the fuel. But our experience with John McGann's E85-fueled Blue Collar 454 (Car Craft, Mar. 2013) taught us that with a dependable 6 psi of fuel pressure, a matching fuel jet produced an excessively rich air/fuel (A/F) mixture. This moved us to use a 63 nitrous jet and a 57 fuel jet for our 4.8L motor. We also pulled a very safe 10 degrees out of the total timing, using the built-in ignition retard in the MSD 6010 LS ignition box. We thought we might be able to hit the nitrous right on the starting line.
Unfortunately, our 26x10x15 Mickey Thompson E.T. Street tires went into spin mode the instant the nitrous hit, so we lifted and got back into it roughly 50 feet out. This produced a pathetic 1.966 60-foot time, but for the remainder of the run it pulled hard and knocked down a 7.73 at 94.54 mph effort (12.17 at 117 mph in the quarter). We tried three different passes, experimenting with the launch with our best effort a 7.66 at 93.75 that equates to a 12.03 at 116 mph in the quarter. All three of these passes had us convinced this little 4.8 could push the Chevelle into the 11s. That will have to wait until next month. We want to try the new Lingenfelter nitrous controller, a BMR antiroll bar to better help plant the tires, and new Global West front control arms to replace the nearly 50-year-old front suspension pieces. All we have to do is knock that 1.9 60-foot time down a couple of tenths and we'll have ourselves an 11-second baby LS—and all of this with a little help from our friends.