383/388 Chevy stroker
(Add links) |
(Add text, table, links; minor clean up) |
||
| Line 76: | Line 76: | ||
One way to arrive at a ~0.040" quench distance is to cut the block decks to zero piston deck height and to use a head gasket that compresses to around 0.040". This allows a quench (or squish, or "squench") measurement of 0.040". Squish is the high speed jetting of fuel air mixture from the dead zone opposite the combustion chamber. When the piston approaches top dead center, the clearance between the crown of the piston and the underside of the cylinder head diminishes to just short of a collision. This squeezes or "squishes" the mixture that is there, across the cylinder toward the spark plug. This high-speed jetting of the mixture not only eliminates any dead spots in the chamber, but also creates turbulence to achieve a more homogeneous mixing of the fuel/air mixture so that there are no lean or rich areas in the chamber. When using steel rods on a street/strip performance engine, having a tight squish of 0.035" minimum to 0.045"-0.050" will allow a high performance street/strip motor to run on pump gas without detonation, providing that all the other important areas are also covered, like the static and dynamic compression ratios. | One way to arrive at a ~0.040" quench distance is to cut the block decks to zero piston deck height and to use a head gasket that compresses to around 0.040". This allows a quench (or squish, or "squench") measurement of 0.040". Squish is the high speed jetting of fuel air mixture from the dead zone opposite the combustion chamber. When the piston approaches top dead center, the clearance between the crown of the piston and the underside of the cylinder head diminishes to just short of a collision. This squeezes or "squishes" the mixture that is there, across the cylinder toward the spark plug. This high-speed jetting of the mixture not only eliminates any dead spots in the chamber, but also creates turbulence to achieve a more homogeneous mixing of the fuel/air mixture so that there are no lean or rich areas in the chamber. When using steel rods on a street/strip performance engine, having a tight squish of 0.035" minimum to 0.045"-0.050" will allow a high performance street/strip motor to run on pump gas without detonation, providing that all the other important areas are also covered, like the static and dynamic compression ratios. | ||
<br style="clear: both" /> | <br style="clear: both" /> | ||
| + | |||
| + | ==GMPP HT383 crate engine== | ||
| + | This engine was introduced in response to the wildly popular SBC 383 stroker engine made popular by backyard mechanics, machine shops, and later on the aftermarket. | ||
| + | |||
| + | ===Differences=== | ||
| + | While the HT383 is not that different than many SBC engines, the differences are important ones: | ||
| + | *[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. | ||
| + | *[http://www.summitracing.com/parts/nal-12489436 '''Crankshaft'''] is a quality, forged 4140 steel unit made for the 1-piece rear main seal configuration. 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. | ||
| + | *[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. | ||
| + | **The HT383 pistons 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). | ||
| + | **It appears the head gasket is 0.028" thick, and 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"). | ||
| + | |||
| + | ===Approximate dish volume=== | ||
| + | Using the quench distance of 0.053", a piston dish size of 22cc would be about right for a 9.1:1 CR. | ||
| + | Quench of 0.040" = 24cc dish. | ||
| + | ===HT383 technical specifications=== | ||
| + | <table> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Part Number: </td><td style="background-color: rgb(230, 255, 255);">12499101</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Engine type: </td><td style="background-color: rgb(237, 243, 254);">Chevy small-block V8</td></tr> | ||
| + | |||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Displacement (ci): </td><td style="background-color: rgb(230, 255, 255);">383</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Bore x stroke: </td><td style="background-color: rgb(237, 243, 254);">4.00" x 3.80"</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Block (P/N 88962516): </td><td style="background-color: rgb(230, 255, 255);">Cast iron with 4-bolt main caps</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Crankshaft (P/N 12489436): </td><td style="background-color: rgb(237, 243, 254);">4340 forged steel</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Connecting rods (P/N 12497624): </td><td style="background-color: rgb(230, 255, 255);">Heavy-duty powdered metal steel, screwed-in studs</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Pistons (P/N 12499103):</td><td style="background-color: rgb(237, 243, 254);"> Hypereutectic aluminum, round dish w/4 valve reliefs</td></tr> | ||
| + | |||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Camshaft type (P/N 14097395): </td><td style="background-color: rgb(230, 255, 255);">Hydraulic roller</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Valve lift: </td><td style="background-color: rgb(237, 243, 254);">0.431" intake/0.451" exhaust</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Camshaft duration (@.050 in): </td><td style="background-color: rgb(230, 255, 255);">196º intake/206º exhaust</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Cylinder heads (P/N 12558060): </td><td style="background-color: rgb(237, 243, 254);">Vortec iron; 64cc chambers</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Valve size: </td><td style="background-color: rgb(230, 255, 255);">1.94" intake/1.50" exhaust</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Compression ratio: </td><td style="background-color: rgb(237, 243, 254);">9.1:1</td></tr> | ||
| + | |||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Rocker Arms (P/N 10089648): </td><td style="background-color: rgb(230, 255, 255);">Stamped steel</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Rocker arm ratio: </td><td style="background-color: rgb(237, 243, 254);">1.5:1</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Water pump (P/N 88894341): </td><td style="background-color: rgb(230, 255, 255);">Cast iron</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Recommended fuel: </td><td style="background-color: rgb(237, 243, 254);">87 octane</td></tr> | ||
| + | <tr><td style="background-color: rgb(230, 255, 255);">Ignition timing: </td><td style="background-color: rgb(230, 255, 255);">32º BTDC total @ 4000 rpm w/o vacuum advance</td></tr> | ||
| + | <tr><td style="background-color: rgb(237, 243, 254);">Maximum rpm: </td><td style="background-color: rgb(237, 243, 254);">5000</td></table> | ||
==Resources== | ==Resources== | ||
Your Privacy Choices