{"$schema":"nativecad-dfm-pack/1","id":"race-engines","title":"Race engines: how high-performance engines are made and what it asks of the CAD","sector":"race-engines","version":"2026-11-04","summary":"How race engine pistons, rods, cranks, blocks, heads, valvetrain, turbos and exhausts are made, tested and regulated (F1 2026 Section C, dated). Numbers tagged SRC or EST in basis.","aliases":["race engine","racing engine","performance engine","forged piston","billet crank","titanium rod","valve spring","engine block","cylinder head","cylinder liner","nikasil","dry sump","turbocharger","power unit","torque plate honing"],"crossSector":false,"size":"core","sources":[{"id":"fia-sc-i21","title":"FIA 2026 F1 Regulations Section C, Issue 21, 2026-10-19","accessed":"2026-11-04","url":"https://www.fia.com/system/files/documents/fia_2026_f1_regulations_-_section_c_technical_-_iss_21_-_2026-10-19.pdf","note":"Changes by issue. Entries cite the article, as PDF extraction scrambles clause numbers."},{"id":"honda-51","title":"Gotou, Yanagisawa: Reciprocating parts and crankshaft, Honda R&D TR 2009","accessed":"2026-11-04","url":"https://global.honda/en/technical-review/PDF/F1-SP2/F1-SP_51e.pdf"},{"id":"honda-42","title":"Honda R&D TR 2009: Formula One engine structural design","accessed":"2026-11-04","url":"https://global.honda/en/technical-review/PDF/F1-SP2/F1-SP_42e.pdf"},{"id":"epi-cup-f1","title":"EPI / Kane: NASCAR Cup and F1 engines compared (end-2006, 2014 update)","accessed":"2026-11-04","url":"https://wahiduddin.net/calc/refs/NASCAR_vs_Formula_One_engines_EPI.pdf","note":"Rod and piston package figures are the author's stated estimates."},{"id":"f1-dict","title":"Formula 1 Dictionary: F1 engine","accessed":"2026-11-04","url":"https://www.formula1-dictionary.net/f1-engine/","note":"Secondary reference, internally inconsistent in places."},{"id":"rtr-indycar","title":"RTR Sports: the engine used in IndyCar","accessed":"2026-11-04","url":"https://rtrsports.com/en/blog/the-engine-used-in-competitions-indycar/","note":"Secondary source, not the IndyCar rulebook."},{"id":"je-2618","title":"JE Pistons: 2618 vs 4032 material differences","accessed":"2026-11-04","url":"https://info.jepistons.com/2618-vs.-4032-material-differences"},{"id":"cp-rings","title":"CP-Carrillo piston and ring instruction sheet 2019 (ring gap chart, honing)","accessed":"2026-11-04","url":"https://www.cp-carrillo.com/files/cp_instructionsheet_2019final-web.pdf"},{"id":"el-ring-gap","title":"EngineLabs: setting piston ring end gap","accessed":"2026-11-04","url":"https://www.enginelabs.com/?p=6755"},{"id":"el-p2h","title":"EngineLabs: verifying piston-to-head clearance","accessed":"2026-11-04","url":"https://www.enginelabs.com/?p=6688"},{"id":"el-rod-bolt","title":"EngineLabs: measuring rod bolt stretch vs torque with ARP","accessed":"2026-11-04","url":"https://www.enginelabs.com/engine-tech/blueprint-series-measuring-rod-bolt-stretch-vs-torque-with-arp/"},{"id":"el-bearing","title":"EngineLabs: measuring and setting bearing clearances","accessed":"2026-11-04","url":"https://www.enginelabs.com/?p=6807"},{"id":"el-honing","title":"EngineLabs: cylinder honing (Total Seal Rpk, Rk, Rvk targets)","accessed":"2026-11-04","url":"https://www.enginelabs.com/?p=6481"},{"id":"hpm-nitriding","title":"High Power Media: nitriding","accessed":"2026-11-04","url":"https://www.highpowermedia.com/Archive/nitriding-2"},{"id":"hpm-fillets","title":"High Power Media: fillets","accessed":"2026-11-04","url":"https://www.highpowermedia.com/Archive/fillets"},{"id":"hpm-oil-holes","title":"High Power Media: crankshaft oil drillings","accessed":"2026-11-04","url":"https://www.highpowermedia.com/Archive/crankshaft-oil-drillings"},{"id":"hpm-rod-mat","title":"High Power Media: connecting rods, material choices (4)","accessed":"2026-11-04","url":"https://www.highpowermedia.com/Archive/connecting-rods-material-choices-4"},{"id":"hpm-inconel","title":"High Power Media: welding Inconel","accessed":"2026-11-04","url":"https://www.highpowermedia.com/Archive/welding-inconel"},{"id":"smiths-en40b","title":"Smiths High Performance: EN40B (722M24) datasheet, 2025","accessed":"2026-11-04","url":"https://www.smithshp.com/assets/pdf/steel/engineering-steel/en40b-engineering-steel-english.pdf"},{"id":"wys-en40b","title":"West Yorkshire Steel: EN40B nitriding steel","accessed":"2026-11-04","url":"https://westyorkssteel.com/alloy-steel/nitriding-steel/en40b"},{"id":"am-300m","title":"Aircraft Materials: 300M (AMS 6417, AMS 6419)","accessed":"2026-11-04","url":"https://aircraftmaterials.com/data/alstst/300m.html"},{"id":"pat-11214852","title":"US11214852: Alloys for turbocharger components","accessed":"2026-11-04","url":"https://patents.google.com/patent/US11214852"},{"id":"pbs-turbine","title":"PBS: investment-cast turbine wheels","accessed":"2026-11-04","url":"https://www.pbsindia.com/investment-casting/turbine-wheels"}],"entries":[{"id":"f1-2026-pu-geometry","kind":"dimension","tier":1,"title":"F1 2026 ICE fixed geometry (Section C Issue 21)","summary":"2026 F1 ICE: 1600 cc +0/-10, 90 deg V6, bore 80 +/-0.1, bore spacing 101.0 +/-2, crank at Y 0 Z 90 +/-0.5, deck height >= 168, rod 119.5-120.5, CR <= 16.0, turbo <= 150000 rpm. Issue 21 dated 2026-10-19; re-check each issue.","applies":["f1 power unit","v6"],"basis":"SRC: FIA Section C Issue 21, C5.1/5.3/5.4. Rules for 2026, they change by issue.","sources":["fia-sc-i21"],"tags":["f1","2026"],"value":{"table":[{"item":"pin dia","mm":"18.0-19.0"},{"item":"stem min","mm":4.95},{"item":"intake head","mm":"32.5-34.5"},{"item":"exhaust head","mm":"27.0-29.0"}]},"see":["power-transmission/crankshaft-stroke-throw"]},{"id":"f1-2026-pu-materials","kind":"rule","tier":1,"title":"F1 2026 PU materials: steel pistons, one-piece rods","summary":"2026 F1: pistons only AMS 6487, 15CDV6, 42CrMo4 or X38CrMoV5-3 steel; rods iron or Ti, one piece, no joints but cap and bush; crank and cams iron-based, no welds between journals; crankcase and heads Al or iron. Issue 21.","applies":["f1 power unit","piston","connecting rod","crankshaft"],"basis":"SRC: FIA Section C Issue 21, C15.6 and C15.7. Rules for 2026, they change by issue.","sources":["fia-sc-i21"],"tags":["f1","2026"],"value":{"table":[{"banned":"Mg alloys; MMC > 2 % v/v; W-base alloys (except counterweights, damper, ballast); ceramics; density > 18400 kg/m3; Al > 1 % Li or Ag; Be > 0.25 % (Cu alloys 2.2 %); Pt, Ru, Ir, Re > 5 %"}]}},{"id":"piston-2618-vs-4032","kind":"material","tier":1,"title":"Forged piston alloys 2618 and 4032","summary":"2618: 0.18 % Si, 64 ksi tensile, 54 ksi yield. 4032: 12.2 % Si, 55 ksi tensile, 46 ksi yield. 2618 grows 15 % more, so needs more cold clearance; use it for boost and high cylinder pressure, 4032 for tight street clearance.","applies":["forged piston"],"basis":"SRC: JE Pistons table, a piston maker. JE gives no clearance numbers.","sources":["je-2618"],"tags":["piston","2618"],"value":{"table":[{"alloy":"2618","Si_pct":0.18,"UTS_ksi":64,"YS_ksi":54,"fatigue_ksi":18},{"alloy":"4032","Si_pct":12.2,"UTS_ksi":55,"YS_ksi":46,"fatigue_ksi":16}]},"see":["race-engines/piston-thermal-clearance-calc"]},{"id":"ring-end-gap-chart","kind":"tolerance","tier":1,"title":"Piston ring end gap as bore (in) times a factor","summary":"Top ring gap = bore in inches x factor: 0.0045 street NA, 0.0050 high-perf or drag NA, 0.006 circle track or low boost, 0.0065 mid-high boost, 0.007+ high boost. Second ring 0.004-0.010 in larger than top. Oil rails min 0.015 in. Minimums.","applies":["piston ring"],"basis":"SRC: CP-Carrillo 2019 chart, stated as general minimums; ring supplier rules. Not a CAD dimension: it sets ring OD and groove back clearance.","sources":["cp-rings","el-ring-gap"],"tags":["ring","gap"],"value":{"min":0.0045,"max":0.007,"unit":"in","note":"per inch of bore; each 0.001 in over bore adds 0.00314 in gap"}},{"id":"piston-to-head-clearance","kind":"dimension","tier":1,"title":"Piston-to-head clearance by rod material","summary":"Piston-to-head minimum: steel rods 0.038-0.045 in (0.040 common, some 0.036); aluminium rods 0.050-0.065 in; domes check near 0.050 in with clay. Total = piston below deck + compressed gasket; read at pin centreline, rock 90 deg to pin.","applies":["piston","cylinder head","gasket"],"basis":"SRC: EngineLabs street-engine table. High-rpm engines need their own rod stretch check.","sources":["el-p2h"],"tags":["clearance","quench"],"value":{"min":0.038,"max":0.065,"typical":0.04,"unit":"in","note":"steel 0.038-0.045, aluminium rod 0.050-0.065"},"see":["automotive/rotating-assembly-clash-audit"]},{"id":"rod-material-choice","kind":"material","tier":1,"title":"Connecting rod materials: 4340, 300M, titanium","summary":"Forged 4340 then 300M (AMS 6417 270 ksi, AMS 6419 280 ksi) for steel; steel at 7.85 g/cm3 is almost 80 % denser than Ti rod alloy but much stiffer, which eases bolt fatigue. Cup rules: steel (EPI 2006); 2026 F1 allows iron or Ti.","applies":["connecting rod","titanium rod"],"basis":"SRC: Aircraft Materials typical values; HPM density comparison; EPI Cup rule; FIA C15.7.","sources":["am-300m","hpm-rod-mat","epi-cup-f1","fia-sc-i21"],"tags":["rod","300M"],"see":["materials/ti-6al-4v"]},{"id":"rod-bolt-stretch","kind":"rule","tier":1,"title":"Rod bolts: set preload by stretch, not torque","summary":"About 75-80 % of torque goes to friction; ARP specs load to 75 % of yield. ARP 3/8 in SBC bolt: 55 lb-ft with Ultra-Torque gives 0.0055-0.0060 in stretch. 30wt oil varied preload 17 %, Ultra-Torque 3 %. Leave both bolt ends reachable by a gauge.","applies":["connecting rod","fastener"],"basis":"SRC: EngineLabs with ARP figures; the bolt or rod maker spec governs. EST: gauge access as a CAD need follows from how the gauge seats on both bolt ends.","sources":["el-rod-bolt"],"tags":["bolt","arp"],"value":{"min":0.0055,"max":0.0065,"unit":"in","note":"examples: 3/8 in 0.0055-0.0060; Manley 7/16 in ARP 8740 0.0060-0.0065"},"see":["hardware/bolt-torque-and-preload-classes"]},{"id":"crank-steels-nitride","kind":"material","tier":1,"title":"Billet and forged crank steels, nitrided","summary":"EN40B (722M24, 3.0-3.5 Cr, 0.45-0.65 Mo): 850-1000 MPa T condition, 61-65 HRC nitrided case. Honda GKHYW (AFNOR 32CDV13) crank steel. EN40 forging or billet: bored, stress-relieved, nitrided. Nitriding runs 450-600 C and suits only steels tempered above that.","applies":["crankshaft","billet crank"],"basis":"SRC: Smiths and West Yorkshire Steel datasheets, HPM nitriding, Honda paper. Stockist typical values; case depth not on those sheets.","sources":["smiths-en40b","wys-en40b","hpm-nitriding","honda-51"],"tags":["crank","en40b"]},{"id":"crank-fillet-oilhole-rule","kind":"rule","tier":1,"title":"Crank fatigue starts at fillets and oil holes","summary":"Model fillets and oil-hole exits as finished, and carry a pre-nitride offset: radius oil exits before nitriding at 450-600 C, polish after, never grind through the case. In one FEA, ellipses gave no benefit over a plain 3 mm radius: no need for conics.","applies":["crankshaft"],"basis":"SRC: HPM oil drillings, nitriding and fillets articles. The FEA was one low-overlap bending case, stated as limited by its author.","sources":["hpm-oil-holes","hpm-nitriding","hpm-fillets"],"tags":["fillet","oil-hole"]},{"id":"bearing-clearance-rule","kind":"tolerance","tier":1,"title":"Plain bearing oil clearance per inch of journal","summary":"Start at 0.001 in per inch of journal: a 2.200 in main gets 0.0022 in, a 2.500 in main 0.0025 in. Never mix shells over 0.001 in apart or across makers. Measure in torqued housings to 0.0001 in.","applies":["crankshaft","connecting rod","bearing"],"basis":"SRC: EngineLabs builder rule, a starting point for street V8 journals.","sources":["el-bearing"],"tags":["bearing","clearance"],"value":{"typical":0.001,"unit":"ratio","note":"clearance / journal diameter"}},{"id":"bore-finish-rpk-rk-rvk","kind":"tolerance","tier":1,"title":"Plateau bore finish targets Rpk, Rk, Rvk","summary":"Total Seal, micro-inch: NA competition Rpk 7-10, Rk 18-22, Rvk 28-32; street 8-12, 30-35, 40-45; boost 10-15, 35-40, 50+. Moly or PVD rings: Ra 10-12 with 20-22 deg crosshatch (CP). Hold bore out-of-round to 0.0002 in. Ring maker governs.","applies":["cylinder liner","engine block"],"basis":"SRC: Total Seal via EngineLabs, CP sheet. Printed in micro-inch; 1 micro-inch = 0.0254 um. Call it out on the bore face, do not model it.","sources":["el-honing","cp-rings"],"tags":["honing","bore"],"value":{"table":[{"use":"street","Rpk":"8-12","Rk":"30-35","Rvk":"40-45"},{"use":"NA race","Rpk":"7-10","Rk":"18-22","Rvk":"28-32"},{"use":"boost","Rpk":"10-15","Rk":"35-40","Rvk":"50+"}],"note":"micro-inch"},"see":["standards-testing/surface-finish-by-process"]},{"id":"exhaust-inconel-fabrication","kind":"rule","tier":1,"title":"Thin-wall Inconel exhausts: limits and welding","summary":"F1 2026: Inconel 625, 625 LCF or 718 only, wall >= 1.0 mm to the turbine, mass >= 97 % of CAD. AM only at stub (150 mm max), 3-into-1 (230) and turbine joint (150). Practice: pre-annealed 625, TIG, pure argon back purge, no post-weld heat treat.","applies":["exhaust","manifold"],"basis":"SRC: FIA Issue 21 C5.8, C15.8; HPM welding article, no dimensions there. Rules for 2026, they change by issue.","sources":["fia-sc-i21","hpm-inconel"],"tags":["exhaust","inconel"],"value":{"min":1,"unit":"mm","note":"F1 2026 exhaust pipe wall"},"see":["automotive/exhaust-clamp-joint"]},{"id":"turbo-wheel-materials","kind":"material","tier":1,"title":"Turbocharger wheels: alloys and F1 2026 limits","summary":"Turbine: cast IN713C/LC, B1914, MAR-M247; inlet gas up to about 1050 C, wheel to 280000 rpm. F1 2026: compressor 100-110 mm Al-Li (<= 2.5 % Li) or Ti; turbine 90-100 mm iron or Ni; 150000 rpm; 4.8 barA; single stage; TC >= 12 kg.","applies":["turbocharger"],"basis":"SRC: PBS foundry, US11214852, FIA C5.3, C15.8. Billet 2618 compressor wheels appeared only in retail search results, so unsourced here.","sources":["pbs-turbine","pat-11214852","fia-sc-i21"],"tags":["turbo","mar-m247"],"value":{"table":[{"item":"compressor axial","mm":"30-35"},{"item":"turbine axial","mm":"35-40"},{"item":"wheel to wheel max","mm":175}]},"see":["turbomachinery/lost-wax-process-stages"]},{"id":"measured-engine-figures","kind":"dimension","tier":1,"title":"Published BMEP and piston speed by series and year","summary":"Published: F1 2006 15.17 bar at 17000 rpm, 26.5 m/s mean at 20000, peak accel 10622 g. Cup 2006 15.12 bar, 27.5 m/s at 10000, 5821 g. DFV-era NA about 14 bar. Boosted IndyCar about 24 bar is EST. Size rods and pistons from rpm and stroke, not by analogy.","applies":["race engine"],"basis":"SRC: EPI, F1 Dictionary. EST rows: mean piston speed 2 x stroke x rpm/60; BMEP 2P/(V n) at the rev limit from a secondary 700 hp, 2.2 L figure, so a floor.","sources":["epi-cup-f1","f1-dict","rtr-indycar","fia-sc-i21"],"tags":["bmep","piston-speed"],"value":{"table":[{"y":1967,"e":"DFV 3.0 V8","bmep_bar":14},{"y":2006,"e":"F1 2.4 V8","rpm":20000,"bmep_bar":"15.17/14.6","mps":26.5,"g":10622},{"y":2006,"e":"Toyota RVX-06","rpm":19000,"bmep_bar":14.3},{"y":2006,"e":"Cup 358","rpm":10000,"bmep_bar":"15.12/14.0","mps":27.5,"g":5821},{"y":2014,"e":"Cup 358, 890 hp","rpm":9000,"bmep_bar":"EST 15.7"},{"y":"2012-on","e":"IndyCar 2.2 V6TT","rpm":12000,"bmep_bar":"EST 23.7+","mps":"EST 20.7"},{"y":2026,"e":"F1 1.6 V6","stroke_mm":"EST 53.05","mps_at_15000":"EST 26.5"}],"note":"bmep at peak torque/peak power; mps mean m/s; g peak"}},{"id":"crankcase-windage-gap","kind":"rule","tier":1,"title":"Keep 3 mm between rotating parts and crankcase wall","summary":"Honda 2005 test: friction rises rapidly once the gap between rotating parts and crankcase wall is 3 mm or less, both radially to the rod and counterweight locus and axially to the counterweights. The rod bolt head usually sets the lowest locus.","applies":["engine block","crankcase","dry sump"],"basis":"SRC: Honda 2005 F1 test; engine and rpm not stated. Applying it to a slower engine is EST.","sources":["honda-42"],"tags":["windage","clearance"],"value":{"min":3,"unit":"mm"},"see":["automotive/rotating-assembly-clash-audit"]}]}