I recently got a fairly detailed question from a different site from a guy who wanted to build and old school 302 sbc to put in his 1968 camaro with a long list of old school components , starting with a set of older stock fuelie heads and an original z28 single four barrel dual plane intake, a 10:1 compression short block and the old original flat tappet solid lifter cam. I thought it might be useful to run a few software dyno comparisons comparing old school parts vs newer parts to illustrate why most guys no longer bother building the high rpm 302 small block combos using the old 1960s technology fuelie heads.
note close ratio 4 speed 4.88:1 gears etc.
keep in mind theres no real replacement for added displacement
the increase from 350-383 in a sbc generally benefits you in two ways, it obviously adds the 33 extra cubic inches of displacement
and youll generally find your N/A engine makes about 1-1.3 hp and ft lb of torque per cubic inch, it also tends to effectively increase compression if the similar piston design is used simply because you compressing an increased volume per cylinder into the same size combustion chamber.
one other factor often over looked is the longer stroke of the 383 increase's mid and lower rpm port speeds this generally increases cylinder fill efficiency, in the lower and mid rpm ranges.
obviously if your going to supercharge or use turbos the piston and rods and crank assembly should be made to withstand the stress levels so a 4340 forged steel crank, forged pistons and after market forged connecting rods with the significantly stronger 7/16" ARP rod bolts are strongly suggested as is dropping the static compression to the 8:1 range to increase the potential volume of compressed fuel/air mix to be stuffed into and burnt above the piston.
Id point out that most transmissions are designed to shift at well under 6000 rpm and most hydraulic valve trains won,t retain best stability above about 6300 rpm, so going the 383 or the 406 SBC stroker route tends to maximize the SBC potential on a mild or mid range performance build
I did a quick DD2000 software dyno and heres what it predicted
roughly 390hp/370 torque
because he wanted to use fairly cheap heads , I suggested swapping to extensively reworked vortec heads with mild porting and much better valve springs,
https://sdparts.com/index.php?q=details ... s/12558060
and a roller cam and a high rise single plane intake , the resulting software showed dyno this result, keep in mind its still a 302 with vortec heads that are extensively reworked, not stock.
now I also pointed out that there are 215cc versions of the vortec heads but i did not use or compare those heads
READ THE LINKS YOULL MISS A GREAT DEAL IF YOU SKIP THOSE
viewtopic.php?f=52&t=266&p=40004&hilit=215cc+vortec#p40004
http://www.superchevy.com/how-to/project-cars/sucp-1004-high-rpm-302-engine-build/
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-52466
http://garage.grumpysperformance.com/index.php?threads/bare-minimum-tools.11026/#post-51823
http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46737
http://garage.grumpysperformance.co...ing-tools-abrasives-sources.10683/#post-46207
http://garage.grumpysperformance.com/index.php?threads/cam-degreeing.9010/#post-35474
http://www.superchevy.com/how-to/project-cars/sucp-0903-302-small-block-engine-build/
http://www.camaros.org/forum/index.php?topic=7774.0
http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/
http://garage.grumpysperformance.co...i-just-picked-up-fuelie-heads-for-cheap.2099/
http://www.vintagemusclecarparts.com/pages/302crossram1.html
http://www.cnc-motorsports.com/short-blocks/small-block-chevy-4195/sb-chevy-302-short-blocks.html
If your intent on building a high rpm 302 think through the basics, its an engine that can only reach its potential with a SOLID LIFTER VALVE TRAIN that will allow it to operate in the 7000rpm plus range,and heads designed to flow at least 250 cfm at .500, and a cam with enough duration to allow the engine to breath effectively in the 6000rpm-7500rpm range easily, this will require matching the cam to a minimum of 10.5:1 compression,and a cam lift of over .500, it will REQUIRE a forged crank, a good quality forged rotating assembly components a dependable 6-7 quart baffled oil pan with a windage screen, that adds durability, all factory 302 z28 SBC cars used manual transmissions,and remember the power to weight ratio, a 302 may make good peak power in a fairly narrow rpm range but it will lack the potential torque of a larger displacement like a 377-406 SBC, so youll NEED to gear the car to operate within that effective power range, this traditionally requires 3.90:1-4.88:1 rear gears on a car used for 1/4 mile racing, and a 30-36 lb SFI billet steel flywheel and blow proof clutch for the inertia for a great launch and safety for 7500rpm gear shifts
read related links
http://garage.grumpysperformance.com/index.php?threads/a-brief-look-at-clutches.447/
http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/
http://garage.grumpysperformance.co...late-gear-ratios-and-when-to-shift-calcs.555/
http://garage.grumpysperformance.co...hing-the-drive-train-to-the-engine-combo.741/
http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/
http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/
http://garage.grumpysperformance.com/index.php?threads/connecting-rod-strength-h-vs-i-beam.1168/
http://garage.grumpysperformance.com/index.php?threads/whats-a-windage-tray-do.64/
roughly 500hp/420 torque [/b]
notice the actual dyno test is not that far different
http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-53061
keeping all those components above ,but swapping to a stroker crank to build a 383 displacement engine instead of a 302 ,with basically the same components being used as the second 302 showed this result
now obviously I could get the combos to all produce better numbers and the vortec heads are a big restriction on the last 383, but I think its a useful bit of info showing the better parts boost the results noticeably and the roll a roller cam and increased displacement have in changing the basic power curve potential, and keep in mind the 383 has heads and a cam that are far from ideal, so its not showing its true potential
roughly 502hp/490 torque [/b]
this last software dyno shows the same 383 with the only additional change being the reworked vortec heads being swapped out for some 210cc afr aluminum heads to let the 383 breath
roughly 550hp/500 torque ....roughly 130 horsepower and a 180ft lbs more torque, and most impressive is the jump in power in the 4000rpm-6000rpm power band over the original combo[/b]
heres something similar with a crane 114681 flat tappet solid lifter cam
AFR 210 cc heads
edelbrock 2925 intake, holley 850 carb
roller rockers, long tube headers
http://garage.grumpysperformance.com/index.php?threads/heads-for-302-sbc.11492/#post-52993
In 1966, General Motors designed a special 302 cu in (referred to as 5.0 L) engine for the production Z/28 Camaro in order for it to meet the Sports Car Club of America (SCCA) Trans-Am Series road racing rules limiting engine displacement to 305 cu in from 1967 to 1969. It was the product of placing the 283 cu in 3.00 in. stroke crankshaft into a 4.00 bore 327 cylinder-block. The 1967 302 used the same nodular cast-iron crankshaft as the 283, with a forged-steel crank that was also produced. This block is one of three displacements, 302/327/350, that underwent a crankshaft bearing diameter transformation for 1968 when the rod-journal size was increased from the 2.00 in. diameter small-journal to a 2.10 large-journal and the main-journal size was increased from 2.30 in. to 2.45. The large-journal connecting rods were thicker (heavier) and used 3/8 in. diameter cap-bolts to replace the small-journal's 11/32. 1968 blocks were made in 2-bolt and 4-bolt versions with the 4-bolt center-three main caps each fastened by two additional bolts which were supported by the addition of heavier crankcase main-web bulkheads. When the journal size increased to the standard large-journal size, the crankshaft for the 302 was specially built of tufftride-hardened forged 1053-steel and fitted with a high-rpm 8.00 in. diameter harmonic balancer. It had a 3/4-length semi-circular windage tray, heat-treated, magnafluxed, shot-peened forged 1038-steel 'pink' connecting rods, floating-pin in `69, forged-aluminum pistons with higher scuff-resistance and better sealing single-moly rings. Its solid-lifter cam, known as the '30-30 Duntov' cam named after its .030/.030 in. hot intake/exhaust valve-lash and Zora Arkus-Duntov (the first Duntov cam was the .012/.018 1957 grind known as the '097, which referred to the last three digits of the casting number) the "Father of the Corvette", was also used in the 1964-65 carbureted 327/365 and F.I. 327/375 engines. It used the '202' 2.02/1.60 valve diameter high-performance 327 double-hump `461 heads, pushrod guide plates, hardened 'blue-stripe' pushrods, edge-orifice lifters to keep more valvetrain oil in the crankcase for high-rpm lubrication, and stiffer valvesprings. In 1967, a new design high-rise cast-aluminum dual-plane intake manifold with larger smoother turn runners was introduced for the Z/28 that the LT-1 350 1969 Corvette and 1970 Z/28 engines were equipped with until the Q-jet carburetor returned in 1973. Unlike the Corvette, the exhaust manifolds were the more restrictive rear outlet 'log' design to clear the Camaro chassis's front cross-member. It had a chrome oil filler tube in the front of the intake manifold next to the thermostat housing from 1967 to 1968, and the first year unique chrome valve covers that had Chevrolet stamped into them without an engine displacement decal pad. In 1968 the engine had the chrome covers, but without the Chevrolet name, that had air cleaner breather and PCV valve grommets. In 1968, a chrome 14.00 x 3.00 in. drop-base open-element air cleaner assembly on a 780cfm vacuum secondary Holley 4-Bbl carburetor. A 'divorced' exhaust crossover port heated well-choke thermostat coil was used to provide cleaner and faster engine warm-up. Its single-point distributor had an ignition point cam designed to reduce point bounce at high rpm along with a vacuum diaphragm to advance ignition timing at idle and part-throttle for economy and emissions. Pulleys for the balancer, alternator, water-pump, as well as optional power-steering, were deep-groove to retain the drive belt(s) at high rpm. In 1969, the 302 shared the finned cast-aluminum valve covers with the LT-1 350 Corvette engine. Conservatively rated at 290 hp (216 kW) (SAE gross) at 5800 rpm and 290 lb-ft at 4800, actual output with its production 11:1 compression ratio was around 376 hp (280 kW) with 1.625 in. primary x 3.00 secondary tubular headers that came in the trunk when ordered with a 1967 Z/28, and associated carburetor main jet and ignition timing tuning[citation needed]. In 1968, the last year for factory headers, they had 1.750 in. primaries x 3.00 secondaries on our . A stock 1968 Z/28 with the close-ratio transmission, optional transistorized-ignition and 4.88 gear, fitted with little more than the factory plenum cowl cold-air hood induction and headers, was capable of running 12.9 second/108 mph 1/4-mile times on street tires.
note close ratio 4 speed 4.88:1 gears etc.
keep in mind theres no real replacement for added displacement
the increase from 350-383 in a sbc generally benefits you in two ways, it obviously adds the 33 extra cubic inches of displacement
and youll generally find your N/A engine makes about 1-1.3 hp and ft lb of torque per cubic inch, it also tends to effectively increase compression if the similar piston design is used simply because you compressing an increased volume per cylinder into the same size combustion chamber.
one other factor often over looked is the longer stroke of the 383 increase's mid and lower rpm port speeds this generally increases cylinder fill efficiency, in the lower and mid rpm ranges.
obviously if your going to supercharge or use turbos the piston and rods and crank assembly should be made to withstand the stress levels so a 4340 forged steel crank, forged pistons and after market forged connecting rods with the significantly stronger 7/16" ARP rod bolts are strongly suggested as is dropping the static compression to the 8:1 range to increase the potential volume of compressed fuel/air mix to be stuffed into and burnt above the piston.
Id point out that most transmissions are designed to shift at well under 6000 rpm and most hydraulic valve trains won,t retain best stability above about 6300 rpm, so going the 383 or the 406 SBC stroker route tends to maximize the SBC potential on a mild or mid range performance build
I did a quick DD2000 software dyno and heres what it predicted
roughly 390hp/370 torque
because he wanted to use fairly cheap heads , I suggested swapping to extensively reworked vortec heads with mild porting and much better valve springs,
https://sdparts.com/index.php?q=details ... s/12558060
and a roller cam and a high rise single plane intake , the resulting software showed dyno this result, keep in mind its still a 302 with vortec heads that are extensively reworked, not stock.
now I also pointed out that there are 215cc versions of the vortec heads but i did not use or compare those heads
viewtopic.php?f=52&t=266&p=40004&hilit=215cc+vortec#p40004
http://www.superchevy.com/how-to/project-cars/sucp-1004-high-rpm-302-engine-build/
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-52466
http://garage.grumpysperformance.com/index.php?threads/bare-minimum-tools.11026/#post-51823
http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46737
http://garage.grumpysperformance.co...ing-tools-abrasives-sources.10683/#post-46207
http://garage.grumpysperformance.com/index.php?threads/cam-degreeing.9010/#post-35474
http://www.superchevy.com/how-to/project-cars/sucp-0903-302-small-block-engine-build/
http://www.camaros.org/forum/index.php?topic=7774.0
http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/
http://garage.grumpysperformance.co...i-just-picked-up-fuelie-heads-for-cheap.2099/
http://www.vintagemusclecarparts.com/pages/302crossram1.html
http://www.cnc-motorsports.com/short-blocks/small-block-chevy-4195/sb-chevy-302-short-blocks.html
If your intent on building a high rpm 302 think through the basics, its an engine that can only reach its potential with a SOLID LIFTER VALVE TRAIN that will allow it to operate in the 7000rpm plus range,and heads designed to flow at least 250 cfm at .500, and a cam with enough duration to allow the engine to breath effectively in the 6000rpm-7500rpm range easily, this will require matching the cam to a minimum of 10.5:1 compression,and a cam lift of over .500, it will REQUIRE a forged crank, a good quality forged rotating assembly components a dependable 6-7 quart baffled oil pan with a windage screen, that adds durability, all factory 302 z28 SBC cars used manual transmissions,and remember the power to weight ratio, a 302 may make good peak power in a fairly narrow rpm range but it will lack the potential torque of a larger displacement like a 377-406 SBC, so youll NEED to gear the car to operate within that effective power range, this traditionally requires 3.90:1-4.88:1 rear gears on a car used for 1/4 mile racing, and a 30-36 lb SFI billet steel flywheel and blow proof clutch for the inertia for a great launch and safety for 7500rpm gear shifts
read related links
http://garage.grumpysperformance.com/index.php?threads/a-brief-look-at-clutches.447/
http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/
http://garage.grumpysperformance.co...late-gear-ratios-and-when-to-shift-calcs.555/
http://garage.grumpysperformance.co...hing-the-drive-train-to-the-engine-combo.741/
http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/
http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/
http://garage.grumpysperformance.com/index.php?threads/connecting-rod-strength-h-vs-i-beam.1168/
http://garage.grumpysperformance.com/index.php?threads/whats-a-windage-tray-do.64/
roughly 500hp/420 torque [/b]
notice the actual dyno test is not that far different
http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-53061
keeping all those components above ,but swapping to a stroker crank to build a 383 displacement engine instead of a 302 ,with basically the same components being used as the second 302 showed this result
now obviously I could get the combos to all produce better numbers and the vortec heads are a big restriction on the last 383, but I think its a useful bit of info showing the better parts boost the results noticeably and the roll a roller cam and increased displacement have in changing the basic power curve potential, and keep in mind the 383 has heads and a cam that are far from ideal, so its not showing its true potential
roughly 502hp/490 torque [/b]
this last software dyno shows the same 383 with the only additional change being the reworked vortec heads being swapped out for some 210cc afr aluminum heads to let the 383 breath
roughly 550hp/500 torque ....roughly 130 horsepower and a 180ft lbs more torque, and most impressive is the jump in power in the 4000rpm-6000rpm power band over the original combo[/b]
heres something similar with a crane 114681 flat tappet solid lifter cam
AFR 210 cc heads
edelbrock 2925 intake, holley 850 carb
roller rockers, long tube headers
http://garage.grumpysperformance.com/index.php?threads/heads-for-302-sbc.11492/#post-52993
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