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7.1L Duramax Stroker Buildup - It's A Diesel!

There's No Replacement For Displacement

Photography by Gary Blount

In 1966 General Motors took its famous 396ci gas-burning big-block and increased its bore to 4.25 inches. With that one simple machining process, GM gave birth to the famous 427ci Rat motor, and Chevy carved its notch into American muscle car history forever.

Ever since the 6.6L Duramax became a viable performance engine, it was only a matter of time before some horsepower junky took the 402ci diesel, ripped out its guts, and stuffed it full of forged, billet, and coated power parts in search of more cubic inches--and Guy Tripp of SoCal Diesel is just that junky.

While working on his mechanical engineering degree in college, Tripp spent his spare time building and tuning performance engines. His expertise led him to a position at Air Flow Research (AFR) where he spearheaded the task of integrating CNC machines to sculpt AFR's raw casting into performance cylinder heads. With all that experience under his belt, Tripp is not only a power junky, he's fully capable of engineering and manufacturing performance engine parts. After he purchased a Duramax in 2003, his addiction was soon directed toward GM's diesel platform.

Tripp opened the doors of SoCal Diesel three years after his Duramax purchase. Till now, SoCal Diesel has been known for its five-axis CNC-ported Duramax cylinder heads, but that may change soon. New to the market is SoCal Diesel's 427ci Duramax stroker kit that increases the size of a Duramax engine from 6.6L to 7.1L (427ci) by fitting the engine with a -inch- longer stroke. That's right, the big-block 427 is back. Only now, it's a diesel!

How Much Power Can The 7.1L Stroker Kit Add?
The only answer we can supply is a percentage increase as it relates to the increase in displacement. For example, if we agree that a 6.6L Duramax can be tuned to make 750 hp and 1,400 lb-ft of torque, then by dividing the horsepower and torque output by the engine size (402 ci), we get how much power per cubic inch the Duramax makes. Then, if we multiply that number by the number of cubic inches available from the stroker kit, we can estimate the power gain. So if a 6.6L (402ci) Duramax can make 750 hp and 1,400 lb-ft of torque, we'll divide 750 hp and 1,400 lb-ft of torque by 402ci to get 1.865672 hp and 3.482587 lb-ft per cubic inch.

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