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SAR 940 Racing Engine - Beyond All Measure

Sonny's 940 Cubic-Inch Pump Gas Monster Gives Rise To A Whole New Genre.

By Rod Short, Photography by Rod Short

Bigger is proving to be better in this instance, but that doesn't mean there isn't a point of diminishing returns. The upper limits of current block technology have been reached for a race engine that's going to last.

"I could build an engine with 1,000 ci, but the durability would be suspect because of the long stroke that you would need," Sonny said when asked about how big an engine could go reliably. "The block would have to be really tall and you'd have a lot of issues with rod flex, side load, bad angularity and ratios.

"For an engine this big to perform, you also have to have anywhere from an inch up to 1.300 inches of valve lift," Sonny continued. "You really have to do your homework to get the valvetrain geometry right in order for the roller tip to stay on the middle of the valve stem for as long as possible. You've also got to have a valve lash cap that will accommodate it."

Besides sheer size, another attractive feature of SAR's 5.300 engine family comes in the choice of cylinder heads. When originally introduced in late 2007, these engines came with SAR's semi-hemispherical heads, which utilize a bathtub shaped combustion chamber rather than a true 360-degree cup. This arrangement not only gives the burnt exhaust gases a straighter path to the exhaust valve, but it also allows relocation of the spark plug to a much more desirable location for better flame propagation, which in turn leads to more power and less opportunity for detonation. Most recently, SAR also introduced a new wedge head, which is ideal for use in nitrous applications. In addition, the smaller sized wedge will also make head removal much easier trackside.

Racers, crew chiefs and street enthusiasts also like the flexibility afforded through Sonny's engine kit program, which makes heads and short blocks readily available for do-it-yourselfers and other engine builders. Sonny's also keeps a deep inventory of rods and pistons from a variety of manufacturers so parts availability won't be an issue.

Besides the accomplishment of being able to engineer and build an engine of this magnitude is that fact that it made over 1,700 peak horsepower on 93 octane pump gas. That, in itself, has raised the eyebrows not only of a number of muscle car enthusiasts, but also boaters as well.

"When people ask how long an engine will last, you really have to answer that in terms of operating hours," Sonny said about some of the more common questions he gets. "We recommend approximately 500 hours of run time under normal driving conditions before having it serviced for lifters and springs. You can find cheaper ways to make power on pump gas, but it's a little harder to get away with it on a big, naturally-aspirated engine. In the long run, that's why it pays to go with the best quality parts you can find."

By Rod Short
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