There is no magic, carb nor anywhere else.
HP and SA Design put out some basic books. These are available from any speed shop.
Race engines start with knowing the class rules.
Once rules are known and understood, performance starts with cylinder head.
Once you have the best heads the rules will allow, for performance you need:-
Block, pistons and crank to give required capacity.
Inlet manifold to suite the heads, rules and rpm.
Exhaust system to suite the heads, rules and rpm.
Camshaft and followers to suite the heads, rules and rpm.
Valves, springs and retainers to suite cam and heads and rpm.
Ignition system to suite rpm, compression ratio and fuel type.
Carburetor(s) or fuel injection to suite rules and speed range of engine and environment of use (straight line, corners, bumps, marine).
Pistons to yield the correct compression ratio for your fuel, with the heads you have.
Pistons and rods to give minimum reciprocating weight with adequate durability.
A sump and windage tray to minimise losses from crank and rods thrashing around in oil.
Rocker arms to suite heads, cam and rpm.
Correct length push rods to suite deck height, valve length, valve springs cam followers, rocker arms and heads.
Light weight crank, flywheel or flex-plate, and other rotating parts.
Block filled, part filled or water passages left stock.
Once you have power, you also need durability.
For durability, it depends largely on the rules, power level, race environment and duration of race.
You need a suitable crank for the rpm power level and durability required. This might be stock cast iron or nodular iron, OEM forged, after market cast steel (really a fancy name for nodular iron), forged, non twist forged, 4030 steel, billet.
High quality cast or forged pistons depending on power level and rpm.
Better rod bolts.
Aftermarket rods.
Better oil pump (maybe, but not necessarily bigger).
Sump to supply good non aerated oil under maximum acceleration, braking, bump and cornering forces at any inclination likely to be encountered.
Wet or dry sump.
Best available block be it 3.875, 4.000 or 4.125 original bore, special casting number like 010, special material (block has 3 big numbers followed an S on the side like 010S or 254S or whatever numbers, 4 bolt mains, splayed outboard main bolts, aftermarket or Bowtie stock configuration, aftermarket or Bowtie tall deck raised cam, wide sump gasket rail, or even an aluminium block, solid or water jacketed.
Timing chain or gear drive.
Distributor/magneto gear to suite cam gear material.
Stainless steel or titanium valves.
Chrome molly or titanium retainers.
Valve stem oil seals.
Bearings to clear crank journal radius.
Correct clearances for rpm and materials used, including:-
Piston to bore.
Piston to valve.
Piston skirt to crank counterweight.
Ring end gap.
Piston to head or deck clearance.
Piston to spark plug.
Big end and main bearing to journal.
Bearing crush.
Cam end float.
Rocker arm to valve spring.
Rod and rod bolt head or nut to gasket rail.
Rod side clearance.
Rod shoulder and bolt head to bottom of bore.
Rod shoulder and bolt head to cam.
Oil return path from valley to keep return oil off crank and rods.
Screens on oil returns to keep valve train shrapnel in valley.
De-burred valley, oil return holes and rocker box area of head to aid oil return.
Non bypass oil filter.
Removable screen oil filter for inspection of metal contamination from failing parts.
Oil cooler.
The list goes on, depending on budget, rules and application.
A Sprint car motor is different to a Junior fuel, or NASCAR, or off road, or circuit race boat, stock engine class, or supercharged alcohol.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
