In the Words of Freiburger…
We made 1,543 hp at 29.5 pounds of boost with a stock, junkyard-fresh, LY6 6.0L shortblock and it didn’t blow up. Three weeks later, I wrapped up my next land-speed-racing short-block, which is destined to make “only” 1,000 hp at “only” 17 psi and it has about $10,000 worth of beefy parts. Why? You can bet I’m asking myself the same question.
This started in 2011 when Richard Holdener conceived a HOT ROD story called “Big Bang Theory,” wherein a 4.8L truck engine made 1,203 at 26.8 psi on an engine dyno. Holdener has since done a bunch of other “Big Bang” engines on nitrous and boost, pushing used LS short-blocks well north of 1,000 hp before having to mop the crank off the floor. These days, perhaps hundreds of people have proved the merits of SBE (stock bottom-end) LS engines running below the breaking point in 8-second drag cars or at least in chassis-dyno sessions. The highest known power on an engine dyno is Holdener’s 1,543hp Gen IV engine, and you’ll see the story here in HOT ROD soon and also in the Engine Masters video series on MotorTrend.com.
It should shock you that a 200,000-mile engine with cast pistons, powdered-metal rods, and a cast crank can withstand about the same power as an early 1960s Top Fuel Hemi made blown on 100 percent nitro. How do LS engines endure it when 1960s-era OE engines won’t? My opinion: Stock cross-bolted mains, better castings with fillet radii on the crank, even the powdered-metal rods are stronger than old castings, and the manufacturing on cast pistons is better than it was. The head-clamping structure is better and MLS head gaskets are standard. Today’s machining practices are better, thinner piston rings are superior, and factory EFI is so precise that engines don’t wear like they used to. In high-boost projects, smart EFI tuners keep the engines out of detonation, which is the number-one killer of parts. With turbo boost, you can keep rpm below 7,000, and boost reduces snatch load on the pistons and rods.
So why would you ever invest in quality forged parts for your own engine? First, I’d say that these absurd dyno tests on SBE engines are a bit of a sideshow trick. The real world punishes an engine more than a dyno does. It feels like an overly adult argument considering how many LS engines have made hundreds of passes at 1,000-plus horsepower, but you have to consider the consequences of engine failure near the finish line as you drive through oil and hurt yourself or the guy in the other lane.
It’s also my opinion that fewer people are actually racing these combos than the internet would make it seem, and the ones who make lots of laps are smart tuners. Other guys are Dynojetting 1,000 rwhp and then just hitting the streets on radials and doing burnouts.
As for my megabuck Dart short-block with a Crower crank and rods and JE pistons? I plan to run it at Bonneville, wide open for nearly 5 miles at high coolant temps. I can’t have a connecting rod change its mind and lead to an oil fire or wheel lockup at 260-plus mph.
That’s all I’ve got. Oh, and if you prefer your old Mopar or Buick to the bellybutton LS, or you want a stroker, or you’re building an NA powerhouse,
I’d still opt for the forged stuff.
I’d also use quality parts for any road-course or endurance application. Or anything with a roots blower or nitrous. Yet I’m afraid I haven’t convinced myself that a boosted junkyard LS isn’t the best bang for the buck for any street/strip car between 700 and 1,000 hp.
[ My Crower rods and JE pistons alone cost roughly 16 times as much as Holdener’s junkyard shortblock. But I’d do it again.