In 1994, Holley introduced its HP-series carburetors—a line of unique 4150- and 4500-type four-barrels designed for race engines competing in any class that allows carburetors. The HP incorporated many of the features racers longed for in a performance carburetor right out of the box. These include airhorn enhancements to maximize airflow into the venturis, four independent idle circuits with screw-in air bleeds to improve tuning, high-flow metering blocks with race-calibrated fuel curves, and Dominator-style fuel bowls that accept fuel lines from either side. Racers raved about the HP's effectiveness and the performance it could achieve with minimal tuning.
"The entire HP line has proven hugely popular for us, and we're seeing it establish itself as the preferred carburetor in a number of racing arenas," says Blane Burnett, Holley's marketing and public relations specialist. Despite the lack of a functional choke, many performance enthusiasts are using a 4150-type HP on the street with excellent results after carefully leaning the idle and/or primary circuits to provide a smoother fuel curve and transitions.
Holley impressed the carburetor world in 2011 with the introduction of its new Ultra HP carburetor line, which boasts 30 new features and upgrades when compared to the original. HPP contacted Holley to learn more about the major changes that differentiate the 4150-type Ultra HP from the original HP.
"The features we incorporated into our original HP line were earth- shattering for the carburetor world of 1994," says Burnett. "It's imperative that Holley stays on the forefront of carburetor innovation. We were aware of a number of changes we could make to our HP lineup that would benefit consumers from an ergonomic standpoint, as well as provide performance gains. Additionally, with the corrosive additives found in today's gasoline, it was important to develop a durable coating, which offers aggressive aesthetics. We also needed to offer larger carburetors and new fuel calibrations to keep up with today's larger, higher-horsepower engines."
We believe when you take a look at this, you'll agree the Ultra HP may very well be the most versatile and capable Holley carburetor ever produced!