ACL Race Series Main Bearing Set, extra oil clearance — the same ten tri-metal main shells as our standard set, machined with a thinner wall so the finished engine runs an extra 0.001 in (0.025 mm) of oil clearance.
Read this before you order: this is the extra-clearance set. It is a specialist part for high to extreme power builds. On a standard crankshaft in a normal street engine it is the wrong choice — it costs oil pressure and can make the engine noisy on a cold start for no benefit. If your crank is finished to factory specification, buy our standard-clearance main set instead.
Fitment — ACL's own application guide names the i30 N: Hyundai i30 N 2018 on, Veloster N 2019-2022, Elantra N 2022-2026 and Kona N 2022-2023 — 2.0L Theta II turbo (G4KH). Clearance is a build choice, never a fitment choice, so this set fits exactly the same engine as the standard one.
What the extra clearance buys you, in ACL's words: additional oil flow through the bearings, to improve delivery to high load zones and improve cooling; room for increased housing distortion under very high inertial and firing loads; room for increased crankshaft flex under high load; and space for specialised anti-friction coatings.
No thrust washers are included. Ten shells only.
Details: 10 shells, 5 upper and 5 lower, positions 1 to 5; standard journal size, which is the only size ACL offers in this clearance; extra clearance of 0.001 in (0.025 mm) over standard; wall thickness 2.009 mm at the crown, 0.013 mm thinner per shell than the standard set; block tunnel bore 56.000-56.018 mm; crank main journal 51.942-51.960 mm; design vertical oil clearance 0.036-0.088 mm.
Mixing grades is normal practice. ACL expect builders to mix adjacent grades on one journal to reach a target clearance — one extra-clearance shell paired with one standard shell halves the change, to 0.0005 in (0.0125 mm).
A note on appearance. Race Series shells arrive dark and tarnished, with no cosmetic tin flash. Deliberate, not a defect.
Availability: ON ORDER at our distributor as of 5 November 2026.
Not sure this suits your car? Ask us before ordering — we would rather check the fitment than process a return.