With the roller cam, our fat-headed...
With the roller cam, our fat-headed 426 Hemi was churning to the tune of 539 hp. We were pretty happy, but we knew there was plenty left without having to go back inside.
With the intake and carb change, our Hemi took on a different character, at least in the looks department. The wickedly sweeping divorced runners of the Barton intake and the fat King Demon carb had the look of serious hardware. While we found the appearance satisfying, we were more interested in the numbers. It seemed a shoe-in that the induction was the cork in our previous combo, and confidence was running high that the upgraded induction would let the rest of the combo swill some serious air and turn a number.
We found tuning the King Demon no more difficult than a conventionally sized carb, and we limited our tuning to running a standard jetting loop. The King Demon features replaceable air-bleed circuits; however, no changes were required to get a fine-looking fuel curve. With the induction change, we hit paydirt, recording 594 hp at 6,600 rpm within five dyno pulls. As is typical with a single-plane versus a dual-plane, the lower end of the torque curve softened some, but the high-end charge really woke up.
Topping the Barton intake...
Topping the Barton intake was a 995 King Demon carburetor. The combination of intake and carb gave our Hemi a look of pure power. We liked the look but wanted the numbers to back it up. We also changed out the stamped-steel valve covers for a set of cast MP pieces.
The intake and carb were worth another remarkable 60 hp, pushing the output of our 426-cube engine so close to the 600hp number we could taste it. We wanted to push the engine over the magic 600hp mark, but our dyno time was winding down. A little more flogging or a change to synthetic lube would have easily moved it over the hump.
Stashed in the corner at Westech was a set of TTI 2 1⁄4-inch big-tube Hemi headers. On a 426-cube engine, we suspected they would be a little too much, but at least we gave them a try. Time was short, so we left our oh-so-close-to-600hp previous combo and made the move to the fat-tube headers. Unfortunately, they were a little too much for our combo, and we saw power drop over most of the range, with the exception of a blip above our previous output line in the midrange. It was clear we weren't going to hit our magic number with this combo, but, sorry pal, we were way past the two-minute warning, and there was no time to go back. Too much header cost us torque, power, and time.
So, how do we sum up this little adventure? Well, we can say what Mopar fans have known for years-Hemis make power. We had close to 600 hp on hand, close enough to call it there. When you consider we got there with only 426 cubes and the stock cylinder heads, it walks the walk. Try writing a list of other production engines that will do the same, and you won't have to worry about running out of ink.
It only stands to reason that...
It only stands to reason that a roller-cammed Hemi needs a serious induction. To fill that bill, we opted for a Barton high-rise single-plane. The Barton manifold is flanged for a large Dominator-base carb.
The new combo put up the numbers...
The new combo put up the numbers when it came to the crunch, belting out a solid 594 hp at 6,600 rpm. What a difference an induction can make! We were within spitting distance of 600 hp, with a 9:1 426-cube motor through a pair of factory heads-but these are Hemi heads. We likely could have topped the 600 mark with a little tuning or by changing to a more slippery oil, but time was running short.
We used the twilight of our...
We used the twilight of our dyno time to try a set of big-tube TTI headers with 2 1⁄4-inch primaries. They were too much for our little 426-cube mill, and the numbers showed it. Had we run them on a blown, nitrous'd, or big-cube engine like a 528 Hemi, the story would have been different.