What octane is E30 equivalent to?

E30 behaves like roughly 94–98 octane with better charge cooling than the number suggests — most of the practical knock benefit of race gas on a street budget.

Can a stock fuel system run E30?

Many can: E30 needs only about 10% more fuel volume than E10, which is inside the injector and pump headroom of a lot of stock systems. A tune calibrated for it is still required. Confirm headroom for your specific platform.

How do I mix E30 at the pump?

Split the fill between the E85 pump and regular pump gas — the right split depends on tank size, what's already in the tank, and the E85 pump's actual ethanol content. A blend calculator does it in seconds.

The E30 Blend — Octane Sweet Spot for Street Cars

Thirty percent ethanol is the street sweet spot — enthusiasts call it the poor man's race gas. Most of E85's knock benefit, a fraction of its drawbacks.

WHY E30 PUNCHES ABOVE ITS WEIGHT

Knock resistance doesn't scale linearly with ethanol content — the first 30% does a disproportionate share of the work. E30 behaves like ~94–98 octane with charge cooling on top, which is why dyno plots of 93-octane vs E30 tunes routinely show meaningful gains on turbo cars, while E30→E85 adds less than you'd expect.

WHAT IT COSTS YOU

MPG: about 7% vs E10 — a rounding error next to E85's 25–30%. Check your prices on the worth-it page; E30 is often the best cost-per-mile ratio of any blend.
Fuel system: ~10% more volume than E10. Many stock injectors and pumps have that headroom — verify for your platform.
Tune: still required. The blend without the calibration is money left on the table (and risk added, on MAF cars especially).

MIXING IT

With typical summer E85 (test it — it varies) and E10 pump gas, E30 lands near a 1:3 ratio of E85 to gas. But the honest answer depends on your tank size, what's already in it, and the season — which is literally what the calculator solves:

THE E30 BLEND

WHY E30 PUNCHES ABOVE ITS WEIGHT

WHAT IT COSTS YOU

MIXING IT