Hotrodding the BBC 454 engine
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==Specific tips== | ==Specific tips== | ||
| − | Replace peanut port heads on dish piston truck engines with oval port closed chamber heads for a quick and relatively cheap power increase. | + | Replace peanut port heads on dish piston truck engines with oval port closed chamber heads for a quick and relatively cheap power increase. Smaller chamber heads like the c/n 215 could be used for better compression than the larger chambers found on c/n 049 or 781 heads. |
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| − | + | ==Power below 3000 RPM:== | |
| − | + | Larger intake ports are the wrong move entirely. In fact, peanut-ports with good valves but no porting, on a domed-piston 9.5:1 454, will do 446 HP with a street-friendly cam, headers and a decent intake. | |
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| + | Peanut ports heads on a 454 will typically give peak HP at 4900 RPM, with cams from 212 to 228 degrees intake duration at 0.050" lift. | ||
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| + | Swapping to the large-oval (intake port) heads can help make power further up the rev range. Most of the '70s, '80s and early '90s pickups had around 7.9:1 compression with flat-top pistons and large "open" combustion chambers. | ||
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| + | None of the "closed" chamber heads had hardened exhaust seats needed for unleaded gasoline, and these heads are coveted, plus the production numbers were far less than the peanut ports. | ||
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| + | ==Static CR== | ||
| + | *[http://www.wheelspin.net/calc/calc2.html SCR] | ||
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| + | ==Dynamic CR== | ||
| + | *[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator] | ||
| + | *[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly DCR calculator] | ||
| + | *[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator] | ||
| + | *[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator] | ||
| + | {{Note1}} Some dynamic compression rtatio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate. | ||
| − | + | {{Note1}}If the intake valve closing (IVC) point isn't known, it can be calculated: | |
| + | # Divide the intake duration by 2 | ||
| + | # Add the results to the lobe separation angle (LSA) | ||
| + | # Subtract any ground-in advance | ||
| + | # Subtract 180 | ||
| + | This result does not need to have any amount added to the IVC point, like the KB calculator calls for. | ||
==References== | ==References== | ||
| + | [http://www.carcraft.com/techarticles/ccrp_1010_cheap_big_block_chevy_engine_build/index.html Car Craft 454 build] baselined with peanut port heads, 446 hp at 4,900 rpm and 542 lb-ft at 3,600 rpm. | ||
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[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:Undeveloped articles]] | [[Category:Undeveloped articles]] | ||
| + | [[Category:GM]] | ||
| + | [[Category:Undeveloped Engine articles]] | ||
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