727 cid Hemispherical Headed Engine - Engine Builder Magazine
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Engine of the Week

727 cid Hemispherical Headed Engine

Valued at over $66,000, this 727 cid Hemispherical Headed engine built by Sonny’s Racing Engines was prominently displayed at the 2018 PRI Show in Indianapolis as Sunnen’s 30th Annual Charity Sweepstakes engine. The proceeds benefitted Victory Junction, a camp for children living with serious medical conditions. Find out how much horsepower and money this powerplant made!


Sonny’s Racing Engines celebrated 50 years in business in 2018. From humble beginnings in December of 1968, Sonny Leonard rose in prominence thanks to his innovative engine designs and uncompromising performance. Sonny’s Racing Engines, located in Lynchburg, VA, has over 100 national and world records on land and sea, and has amassed 17 world championships across PDRA, IHRA and ADRL.

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The engine shop is known for 500 cid to 1,000 cid engines for drag racing, truck pulling, extreme muscle car, and boat applications. The shop also sells engine components to other engine builders.

Sonny’s has 16 employees with 10 of them having been with the company for over 20 years. The shop is capable of doing everything in-house and designs and manufacturers its own cylinder heads and machines them using 5-axis CNCs.

Sonny’s Racing Engines offers wedge and hemispherical configurations to accommodate its powerplants. The mainstay wedge engines have racked up a myriad of event wins and national championships. The more recently instituted hemispherical heads are quickly catching up.

To coincide with the shop’s 50th anniversary, Sonny’s was chosen to build Sunnen’s 30th Annual Charity Sweepstakes engine to be given away at the 2018 PRI Show in Indianapolis.


“This is a great way for us to celebrate 50 years in business,” Leonard says. “We are building one of our electronic fuel injected 727 cid engines with our in-house designed hemispherical cylinder heads. This EFI engine will be designed to operate on 92 octane unleaded gas for street use and will produce over 1,500 horsepower that can be driven daily.”

All proceeds from the sweepstakes go to Victory Junction, a camp founded by the Petty family for children living with serious medical conditions. The winning ticket was drawn on Saturday, December 8 at the PRI Show in Indianapolis. The winner of the engine was Mark Wolfe.

The 727 cid engine is valued at over $66,000 and includes Sonny’s fully in-house ported hemispherical cylinder heads, Sonny’s Brodix 5.000˝ bore space block with a 1.000˝ raised cam with special hi-flow water jackets, a Bryant billet crankshaft, GRP billet aluminum rods, Big Stuff 3 EFI, and many other top quality components to finish the build.

This 1×4 billet intake combination with Sonny’s hemispherical heads is a great engine choice for bracket racing or Top Sportsman and Top Dragster racing as well.


The engine also features a 2100 cfm custom carburetor with 2.750˝ throttle bores, a Moroso wet sump oiling system with a Moroso oil pump, a Jesel cam belt drive, an ATI balancer, a T&D shaft rocker kit, Diamond custom pistons, Jesel 1.062˝ roller lifters, Trend pins and pushrods, Manley valves, PSI valve springs, Total Seal piston rings, and an MSD ignition and starter.

As built, this naturally aspirated 727 cid engine cranked out 1,500 hp at 7,200 rpm. The engine will also be offered in two other versions – a Pro-Street 1,400 hp version and a 1,280 hp Cross Country version.

“We are extremely honored and proud to be chosen to build this year’s charity engine,” Leonard says. “Victory Junction is an honorable cause and we hope this will make a lasting impact on the lives of those children. What better way to celebrate 50 years in business than by giving back?”


The engine sweepstakes raised over $100,000 for Victory Junction, which is enough money to send 40 children with medical problems to camp.

The Engine of the Week eNewsletter is sponsored by PennGrade Motor Oil.

If you have an engine you would like to highlight in this series, please email Engine Builder magazine’s managing editor, Greg Jones at [email protected]

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