The Thought Process Behind Lunati’s Bootlegger Camshaft Designs

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Camshafts are the most critical component in an engine, Despite what you may think, it’s not the crankshaft, or the connecting rods, or the pistons or cylinder heads, but the camshaft. Why is that? Because without the camshaft dictating the opening and closing events of the poppet valves, the engine would not be able to function properly.

Lunati can trace their history back to the late 1960s, when former Street Eliminator drag racer Joe Lunati’s vision came to life in the back room of a local Memphis production engine rebuilder. It was there that Lunati ground his first camshafts on the company’s cam grinder; after years of trial and error with the camshafts he tested in his own racing program, and building camshafts for local racers, Lunati decided it was time to open his own cam grinding shop.

Joe Lunati in his XX Eliminator roadster.

Joe Lunati in his Street Eliminator roadster, before Lunati Cams came to be.

Those late-night sessions on the grinder still resonate with everyone in the Lunati headquarters today, and it’s with Joe’s vision in mind that they’ve created their newest line of cams, the Bootlegger Series.

“This is the most tested and well-developed camshaft series we’ve ever done,” says Lunati’s Matt Patrick. “They are the most aggressive and powerful street hydraulic and flat-tappet cams that we offer.”

The Bootlegger cams are not race camshafts; they are designed for the user that’s looking for their engine to provide great power up to 6,500 rpm—perfect for that street brawler that makes a track trip two or three times a year.

“As we try new things and gain different experience in different venues of racing, we learn new tricks. The ultimate goal is to try to open up the valve and close it as quickly as we can without damaging parts. There’s always a limit; the ultimate constraint on the valvetrain are valvespring loads and rpm limits,” Patrick explains.

The relationship between valve float and how quickly the camshaft can open and close the valve was at the forefront of the Bootlegger development process. The realization that the majority of Lunati’s customers aren’t going to spin their street engines past that 6,000-6,500 rpm range dictated the selection of valve events and what was possible within those given parameters.

“While we could have an ultra-smooth camshaft lobe profile that could go to 8,000 rpm, the issue with that is that you’d have a valve profile that’s so smooth it wouldn’t make any power down low, from 3,500-5,500 rpm where it’s useful on the street,” says Patrick.

Keep in mind that the Bootlegger is not a budget line of camshafts. Patrick recommends a quality set of rocker arms, lifters, and pushrods to take advantage of the camshaft profile. Determining how quickly they could program the valves to open and close with modern valvesprings and hardware determined the limits of what could be achieve with the Bootlegger series.

“We recommend high-grade hardware for these products—one notch short of what would be considered a full-race valvespring. This cam series is for the guy that wants the baddest, toughest, meanest cam grind he can stick in his engine for the application,” says Patrick.

The development process started with a Chevrolet Performance ZZ4 350 cubic inch crate engine, and Patrick says that experience has taught them what is possible with other engine platforms.

Computer-aided design is used in every Lunati camshaft profile.

Computer-aided design is used during the creation of every Lunati camshaft profile.

Lunati’s experience tells them how to alter the profiles developed in that engine to work with other engine platforms. By developing the profile for one engine, the company can then extrapolate the data to work with other engines to make the camshaft work properly.

“At the end of the day, it comes down to valve motion, and that’s what we stay focused on. There are certain nuances between each engine platform depending on rocker arm ratios and geometries; the actual net valve motion can be very different from what you intend, and we tweak each design for the particular engine family,” explains Patrick.

Currently there are three camshaft grinds each for the small- and big-block Chevrolet and small-block Ford, with hydraulic flat tappet, retro-fit hydraulic roller, and hydraulic roller grinds available. Each particular camshaft comes with recommended modifications, such as higher-stall torque converters and steeper rear-end gear ratios.

“These are not camshafts that will spin to 7,000 rpm—you’ll be limited to approximately 6,200 rpm on the hydraulic roller cams and 6,400 rpm on the flat-tappet designs, which are great for a street engine. We wanted to make the most powerful camshafts possible within these RPM constraints,” he says.

(Left) One of Lunati's Bootlegger camshafts on display at PRI 2014. (Right) Stacks and stacks of camshafts awaiting final machining.

For example, the “small” XXX11224H hydraulic flat-tappet grind for a big-block Chevrolet carries a 2,400-5,600 rpm powerband, .525-inch intake and exhaust lift, with duration at .505-inch coming in at 224 degrees on the intake side and 236 degrees on the exhaust side. It’s recommended to use a 2,500-plus stall converter, rear gears steeper than 3.42:1, and 9.0-9.5:1 compression.

On the top side of the big-block Chevrolet offerings, the XXX11240H HFT cam works with a 2,900-6,000 rpm powerband and makes more power in the upper realm of the tachometer. It’s recommended to have 10.5:1 compression and 3.90:1 gears with this bumpstick.

(Left) A grinder forms the camshaft core into a finished product with the desired profile. (Right) Cam lobes are polished by hand before final packaging.

Other engine platforms, such as the small- and big-block Chrysler, will be addressed in the near future in terms of shelf stock, but Patrick says that the company can put these profiles into practice for those application in a custom cam core until then.

One thing to note; each of the Bootlegger camshaft profiles are designed with a 108-degree lobe separation angle and 104-degree intake centerline to provide plenty of low- and mid-range power while providing the rumble from the exhaust that lets everyone know you’re coming. Couple the rumble with performance gains they’ve noted in testing, and it appears Lunati has its finger on the pulse for the street enthusiast.

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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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