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427 Chevy Short Block Engine - Seven Liter Foundation - Tech

Inside Katech Engine's 427-Cube Value Short-Block

Barry Kluczyk Jan 1, 2008

GM late-model performance enthusiastsare currently living through a new golden age of performance. Like what the original Chevy small-block engine did for engine builders duringthe previous 50 years, so now the"LS" series is doing by providing a wealth of performance potential.

At the forefront of development is suburban Detroit's Katech Engines.In fact, Katech was tinkering with LS engines before others really knew they existed. The company has long been a racing engine builder and worked with Chevrolet on the wildly successful Corvette C5-R racing program-a relationship that continuesto this day with the C6.R program.

It was only recently that Katech decided to open its doors to streetoriented enthusiasts, but it has quickly filled the pipeline with a plethora of parts, engines, and obscenely fast street cars. We've recently sampled Katech's 10-second Camaro (seen elsewhere in this issue) and blasted around the 'burbs in a 520-horse, 427-powered TrailBlazer SS.

Neither the company's lightningfast Camaro nor its Texas customer's deceptively quick TrailBlazer would be considered inexpensive projects in most enthusiasts' books, but Katech is reaching out to the performance masses with targeted engine components and short blocks. One of its most interesting offerings is the 7L assembly dubbed the "Value Short-Block."

As its name suggests, the Value Short-Block is a budget-minded 427- inch engine foundation. It includes a balanced and blueprinted aluminum cylinder block, forged crank, rods,and pistons-all preassembled and ready for final assembly with heads,a cam, intake, etc.

Katech lists the Value Short-Block at $6,950, with items such as a camshaft, heads, and a 58X crankshaft trigger available as extra-cost options.The rotating assembly components are first-class items from Cola,Callies, and Mahle.

If nearly seven large seems like a stretch to connote with "budget," consider that a bare C5-R block costs nearly as much without the rotating assembly. An LS7 block costs around $3,000. Throw in the premium rotating parts from theKatech short-block and it's almost like buying the parts and getting the assembly for free.

450-Degree Temperature Differential
Of course, nothing is reallyfree-especially when it comes to building high-performance engines-and Katech squeezes some of the value from its short-block by using a production GM 6L cylinder block and resleeving it in-house with 4.125-inch bore liners.

The sleeves are Katech's design and made of centrifugally cast ductile iron. To install them in the block, liquid nitrogen is used to help create a 450-degree temperature differential between the block and sleeves. This allows the iron sleeves to slide into the aluminum block without the pounding that occurs with a typical press-type fitment.

When the sleeves are seated within the block, the block and sleeves are carefully brought to temperature equilibrium. A special fixture is used to apply torque on the liners toprevent them from lifting duringthe process.

Additional details of the sleevesand resleeving process include:
*The sleeves are machined and inspected, then grouped in sizes within 0.0003 inch.
*Connecting rod clearance is machined into the bottom of the sleeves to ensure adequate clearance for the 4.000-inch stroke.
*4.125-inch bore sleeves for a 427-inch engine have a 0.075-inch wall thickness all around.
*The finished block is double-vacuum impregnated to ensure against leaking.

"With our tight quality control process, we think the resleeved 6L block makes a great product," Katech's Caleb Newman says. "We have seen great success with it in very powerful engines."

Assembly processes of the Value Short-Block are as regimented as the block preparation. The reciprocating assembly is balanced and blueprinted, including the use of highly accurate air-based measuring devices from Air Gage Company, which are used to blueprint the crankshaft journals, main bores, etc. Katech uses these tools when building Corvette racing engines, lending a nice rub-off effect for a higher degree of precision on its customer-based street engines.

Also, each short-block-actually, every engine Katech touches-is serialized and logged into a database. That means years down the road, the assembly details and specifications can be retrieved, even if the engine changes hands.

As for the reciprocating assembly parts themselves, they're all expectedly high-strength, all-forged materials from names like Cola and Callies. The Value Short-Block assembly only includes the crank, rods, and pistons, but the blueprinting steps make it a painstaking build process.

"Based on customer preferences, we found that the basic reciprocating assembly is what people really wanted," Newman says. "Things like the camshaft, heads, and more are the items that are individualized. We're happy to help in those areas, too, but the Value Short-Block is the foundation everybody can build on."

The accompanying photos provide an overview of the short-block blueprinting and assembly process. There's also a sidebar story on what an engine built from a Value Short- Block delivers on the dyno.

Every strong engine needs a sturdy foundation, and it appears Katech delivers it at a reasonable price. It's fun living in the new golden age!

Vetting The Value Short-Block
After following the assembly of our Value Short-Block project,we were more than a little curious about its potential as a completeengine.

"No problem," Katech's Caleb Newman said. "Follow me." He led us to one of the company's several engine dynamometers -Katech builds racing engines for the C6.R effort, remember-where a fully dressed Value Short-Block-based 427 was getting a workout. It was an engine built to a customer's specifications, but the block and reciprocating assembly were the same as we outlined in our main story.

On top of that, this engine also featured:

11.1:1 compression
L92 ported cylinder heads
L76 intake manifold
GM Stage III camshaft with 0.595/0.595-inch lift and 233/277 degrees of duration; 107 LSA and 103-degree timing
1.7-ratio rockers
LS7 fuel injectors and ignition coils
90mm throttle body
MEFI-4 controller (for dyno use)

This combination of off-the-shelf parts demonstrated once again that, unlike modern engine families from other manufacturers,LS-based engines don't need a power adder to make killer dyno numbers. In this case, the naturally aspirated 427 made 604 hp and 566 lb-ft of torque.

And the peak numbers are only part of the story. Peak horsepower occurred past the 6,000-rpm mark, but the engine was making more than 500 horses before 4,800 rpm, and never dropped below 580 horses between approximately 5,550 and 6,800 rpm.

The torque story was equally compelling: 500 lb-ft was achieved at a low 3,100 rpm and held above that mark past 6,100 rpm. Yes, the phrase "stump puller" is tossed around liberally in car magazines, but how else could this engine be described? A "forest puller"?


Katech Inc.
Clinton Township, MI 48035



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