Editing 383/388 Chevy stroker (section)
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===Differences=== While the HT383 is not that different than many SBC engines, the differences are important ones: ====Bore and stroke==== *Bore is 4.00" instead of the usual 4.030" or 4.060" *Stroke is 3.80" instead of the usual 3.75". ====Rods==== *[http://www.gmpartsdirect.com/performance_parts/2012/ChevroletPerformance_Catalog_2012193.html '''Rods'''] are powdered metal with a pressed pin, but are clearanced for a stroker application. The retaining hardware consists of a threaded tapered stud in the rod (giving added clearance between the rods and the cam, etc.). This is different than the usual bolt and nut used on most other engines. Said to be good to 550 HP. ====Crankshaft==== *[http://www.summitracing.com/parts/nal-12489436 '''Crankshaft'''] is a quality, forged 4340 steel unit made for the 1-piece rear main seal configuration. It is externally balanced. Instead of the usual 3.75" stroke, it is a 3.8" stroke, so the displacement will still be 383 ci, but with a 4" bore block. Chevy saw no reason to bore out a new block just so a 3.75" crank could be used. **This crank in a 0.030" over block gives a displacement of 388ci. ====Pistons==== The HT 383 [http://www.summitracing.com/parts/nal-12499103 '''pistons'''] are a letdown. They're the same old tired, cheap-to-make 4 valve relief, pressed pin, round dish pistons GM has been foisting off on the public since years ago when the drop in CR was mandated. These pistons have no redeeming qualities, unless you consider the aluminum alloy being hypereutectic a plus. What is known about these pistons: *They're hypereutectic aluminum alloy. *They give a 9.1:1 CR with a 0.028" thickness head gasket and the Vortec chamber size of 64cc. **Chevy shoots for a 9.0" stack of parts for SBC engines. Using a 9.025" block deck height, 3.8" stroke, and 5.7" rods, the piston CH would need to be 1.4” for the stack to equal 9” (1.9 + 5.7 + 1.4 = 9.0). The actual compression height of the HT383 piston is presently unknown. **Using the quench distance of 0.053", a piston dish size of 21cc would be about right for a 9.1:1 CR. A 9.1:1 compression ratio using a quench of 0.040" will require a 24cc dish. ====Head gasket==== *It appears the head gasket is composite and 0.028" thick. The CR is advertised as 9.1:1. **A 0.028" gasket using the numbers above will give a quench distance of 0.053". To bring the quench down to 0.040" would require a piston CH of about 1.413" (or a head gasket thickness of 0.015").
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