The Small-Block Ford 500-Horsepower Curse – Is It Real?

Everyone has heard it before… “Stock 302 blocks split in half when you make more than 500 horsepower.” That has been an axiom that has been perpetuated longer than some of the staffers here have been alive (and frankly, before the internet as we now know it even existed). But, it seems recently, there has been a push to prove the 500 horsepower limit to be nothing more than an old wives’ tale.

Maybe it’s the fact that social media is now connecting people who previously hadn’t read the internet to know that their block was only good to 500 horsepower (kind of how gravity doesn’t affect Wil E. Coyote until he looks down), and so their 500-plus horsepower 8.2-inch-deck Windsor engines didn’t know they were supposed to turn into a two-piece casting when they exceeded that mark.

However, as Richard Holdener says in this video, “The reality is, the internet isn’t always accurate.” Troubled by the persistence of this belief, Holdener compiled some of his past small-block Ford projects, including his personal street car and Silver State Challenge powerplant, to debunk the idea that at 501 horsepower, an 8.2-deck block will split down the middle.

In this video, Holdener breaks down a total of 10 small-block Ford combinations he’s had a hand in, in addition to his personal blown 302, all of which make more than 500 horsepower, and do so in a number of ways. Little shots of nitrous, big shots of nitrous, roots superchargers, centrifugal superchargers, and even turbochargers all cracked the mythical barrier with no ill-effect.

Some short-blocks were bone stock, some had an aftermarket rotating assembly in them, but all of them used a factory block. Here is a list of combinations featured in the video:

Holdener’s personal 302 with a Vortech centrifugal supercharger which competed in 12 runnings of the Silver State Challenge, where the engine would stay at WOT for 32 minutes. 440 horsepower at the rear wheels (over 500 at the crank).

  1.  Nitrous EFI 5.0-liter, stock bottom end: 385 hp, 375 lb-ft N/A; 540 hp, 526 lb-ft on nitrous.
  2.  Nitrous Carbureted 5.0-liter Explorer short-block: 415 hp, 362 lb-ft N/A; 530 hp, 512 lb-ft with 125-shot.
  3.  Turbo EFI 5.0-liter, stock bottom end (same engine as #1) GT45 turbo: 549 hp, 553 lb-ft at 7.8 psi
  4.  Nitrous Carbureted 347: 441 hp, 405 lb-ft N/A; 610 hp, 574-lb-ft with 150 shot.
  5.  Turbo EFI 306, .030-over forged pistons, forged rods, stock crank: 395 hp, 380 lb-ft N/A; 622 hp, 637 lb-ft at 10.3 psi
  6.  Roots-Blown Carbureted 331, forged bottom end; Weiand 174: 392 hp, 386 lb-ft N/A; 533 hp, 512 lb-ft at 8 psi
  7.  Centrifugally Supercharged Carbureted 331, forged bottom end, Paxton Supercharger: 392 hp, 386 lb-ft N/A; 622 hp, 560 lb-ft
  8.  Turbo Carbureted 331, forged bottom end: 392 hp, 386 lb-ft N/A; 599 hp, 617 lb-ft
  9.  Centrifugally Supercharged EFI 5.0-liter, Explorer short-block, TorqStorm supercharger: 407 hp, 397 lb-ft N/A; 638 hp, 545 lb-ft at 10 psi
  10.  Centrifugally Supercharged EFI 347, forged rods and pistons, cast crank, Vortech S-Trim: 449 hp, 420 lb-ft; 665 hp, 555 lb-ft at 8.5 psi

These are several of the dyno sheets from the 10 different small-block Ford engine projects Holdener mentions in the video. These engines aren't three-run dyno queens, either. Some of Holdener's dyno-mule short-blocks have upwards of 300 pulls on them. Either Holdener has some magic OEM blocks, or there are some pretty big holes in the "5.0L blocks split in half at 500 horsepower" theory.

“Admittedly, doing it on the dyno is easier on the engine than doing it in a car,” says Holdener. “But some of these test motors have 200 to 300 dyno pulls on them. It’s not just a matter of putting a motor together and making four or five pulls on it and calling it good. I run these engines over and over.” The fact does remain, there are real examples of 8.2-deck Windsors “splitting” down the valley. Holdener shares the one experience he’s had with a failed stock block.

There are enough examples of stock blocks making more than 500 horsepower out there to prove that it’s not some arbitrary power number that is the block’s downfall. Is it the stresses of drag racing? Does it have something to do with modern tuning solutions being better able to control the power production and application? Holdener’s results from years back seem to disprove that hypothesis.

Or, could it be, that a few people had a bad experience with a stock 5.0L block (due to bad castings, brutal power application, and/or a tuning hiccup) and it propagated like urban legends often do? (No, a water-bomber did not pick up a scuba diver, and no, Mr. Rogers wasn’t hiding a “Born To Kill” tattoo with his sweaters.)

Regardless of how the urban legend came to be, there are quite a few examples out there, including the ones Holdener has personally had a hand in, showing that OEM small-block Ford castings don’t magically split in half at 500 horsepower. Maybe it’s time for that myth to be put to bed, or at the very least, taken with a grain of salt.

Besides Holdener’s test engines, there has been a recent run of six-, seven-, and eight-hundred horsepower factory-block SBFs popping up in various Facebook groups, fighting the 500-horsepower-limit stereotype. While there is evidence of block which have split in the past, the issue seems to be much more complicated than a simple power level.

About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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