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834hp 429 Boss Ford Engine Build - 834HP Kaase Bos

Jon Kaase Has Cast A New Boss 429 Hemi Head With Wind Tunnel Airflow That Begged Us To Build An Equally Angry 460 Ford. That Became Our . . .

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Makin' Power
During the warm-up, our 521ci Boss just sounded angry. We've heard hundreds of race engines, so the rough idle and shaking on the dyno wasn't unusual. We were standing on the other side of a concrete wall looking through reinforced glass, but the combination of that big cam and sewer-pipe-sized 21/4-inch open headers just made this engine sound even more lethal. After a mere seven pulls, we had our peak at 834 hp, and once the euphoria subsided, we investigated the power numbers more closely. Most normally aspirated engines that make really big power tend to be very peaky, meaning the rpm spread between peak torque and peak horsepower is usually very narrow. But Kaase's combo managed to spread the twin peaks by an amazing 2,100 rpm compared with more common spreads of 1,500 rpm.

It would have been fun to see how much a larger 1,150-cfm Dominator carburetor would have worked. Plus, keep in mind that these heads and the intake manifold are right out of the box. Even really good castings can benefit from mild tune-ups, so we don't doubt that with a few tweaks, our Kaase Boss could easily reach the 900hp mark. For us, 834 is a personal best for a normally aspirated engine generating an impressive 1.6 hp per cubic inch. If nothing else, all this power will make for an outstanding top-end charge on the dragstrip.

Power Numbers

RPM TQ HP BSFC
4,000 550 419 0.49
4,200 554 443 0.48
4,400 575 482 0.47
4,600 651 570 0.47
4,800 661 604 0.48
5,000 674 641 0.48
5,200 667 669 0.49
5,400 667 686 0.48
5,600 667 711 0.48
5,800 657 726 0.50
6,000 656 749 0.50
6,200 651 768 0.49
6,400 643 783 0.49
6,600 637 801 0.51
6,800 631 817 0.51
7,000 623 830 0.53
7,100 617 834 0.52
7,200 606 831 0.54

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