Fastest Stock Bottom End 5.3 LS In The World Goes 7.81

We’ve known for sometime now that stock bottom end LS engines can take a lot of abuse. In fact, we’ve seen them take more abuse than even we thought possible and just keep on coming. You’d think, at some point, we’d have to stop being astonished by these things, but when this Mustang put down a 7.91 at 173.61 mph pass–on a 100 percent stock internal 5.3–we couldn’t help but be astonished yet again–and then it went faster.

Before we get down to the specifics, we’re sure that your first qualm with this setup is the fact that it’s an LS in a fox body Mustang, a combination that has pretty much been done to death by now. And though you may have preferred to see this record broken by a chassis that rolled off the General’s assembly lines, if it ain’t broke, don’t fix it. The LS/fox body combination has shown itself to be a potent and affordable platform, and this car is the perfect personification of that. So, in the spirit of compromise, lets just agree that it is a more-than-capable motor in a decent chassis.

The 5.3 in question is a junkyard-sourced L33 that hasn’t had a lot done to it. The owner, Jon Capizzi, who owns and operates Capizzi Automotive, claims that it has slightly worked over stock 799 casting heads and it’s obviously sporting a decent sized cam from the guys over at Baker Engineering. Jon attributes the success of the engine mostly to the camshaft design.

“TJ over at Baker Engineering selected the cam for the combo and he did an amazing job with it,” Jon said. “We were hoping to go 8.50s with the car at first, but when it went 8.90s on just 10 pounds of boost, we knew we had a runner on our hands.”

Another of the secrets to the 5.3’s success is how high Jon spins it. The engine regularly sees speeds above 8,000 rpm. Yes, you read that right. 8,000 rpm on stock pistons, rings, rods, rod bolts, bearings and gaskets. All of this on a hydraulic roller setup with LS7 lifters no less. Even the rockers are stock, albeit with Brian Tooley Racing trunnion upgrades. To say that we were shocked to find out how quickly it was turning without coming apart would be an understatement.

The turbo is an S485 from Forced Inductions Solutions and the engine is run by a Holley Dominator setup tuned by Jon himself. A Holley Hi-Ram handles induction duties and a custom fabricated hot side directs spent exhaust gases. The snail is throwing 32 pounds of boost at the relatively stock mill and is capable of producing up to 36.

“On its fastest pass ever, we were running on 32 pounds of boost,” Jon said. “We’ve turned it all the way up to 36 but it wasn’t making more power, it was all just boost from restriction at that point, so there was no reason to keep it that high.”

The mill is backed by a Powerglide that Jon built himself at his shop and feeds power out back to a 8.8-inch rear end that has been stuffed with a spool and Strange axles. A PTC converter keeps the engine in its powerband and Jon says that the combo of camshaft, torque converter, and gears are what make this car so fast.

The car has also received a mini-tub to give the 275 Mickey Thompson drag radials enough room to do their job. Twin adjustable shocks front and rear let the team quickly dial in the car and all the suspension bits are in their stock locations–aside from the rear shock which have been mounted inboard. All said and done, the car tips the scales at a svelte 2,950 pounds.

And while the pass in the video maybe astonishingly quick, this fox body has been faster–much faster. Jon tells us that his best pass in the car came from grudge racing, due to the fantastic track prep. At one of those races, Jon laid down a blistering 7.81 at 172.02 mph–all while running the car out to a whopping 8,450 rpm!

“We’re certainly not scared to turn them,” Jon said “Our next setup will probably be spinning 8,500-8,700 rpm.”

The next setup Jon was referring to is due to the 5.3 disintegrating on one of its latest passes. But if you’re sitting there thinking “well, yeah. It was only a matter of time”, you’d be dead wrong. Jon tells us that the 5.3 had over 120 quarter-mile passes when it expired and the only reason that it did was because they switch their source of E85.

“We changed where we were getting our fuel from and that must have been what caused a little bit of knock,” Jon said. “At that level, a little bit of knock is catastrophic for an engine like this.”

Who knows how long the engine would have lasted had it not encountered knock, but anyway you look at it, a stock bottom end rocketing a Mustang to a 7.80 pass is an astonishing feat for even one run, much less the 120 passes it lasted.

We asked Jon what his plans are now with the car and he told us that he has a stock bottom end L20 4.8-liter motor sitting on the engine stand waiting to go in. He says that he anticipates that the Mustang will be even faster with the smaller displacement engine and he plans to break all of the stock bottom end 4.8 records as well.

“TJ is spec’ing the cam for the 4.8 as well and he thinks it will run even better than the 5.3 did,” Jon said. “We think we’ll spin it to 8,500-8,700 rpm, combined with our new GTX 5518R Gen 1 Pro Mod turbo, it should be a pretty capable combo.”

We can’t wait to see what the 4.8-liter engine will be capable in this thing and we’ll be there to bring you the coverage. Stay tuned as Jon and the guys at Capizzi Auto go where no LS has ever gone before.

About the author

Chase Christensen

Chase Christensen hails from Salt Lake City, and grew up around high-performance GM vehicles. He took possession of his very first F-body— an ’86 Trans Am— at the age of 13 and has been wrenching ever since.
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