Mercury 181ci Specs: 3.504 x 3.13 in

Mercury 181ci specs: 3.504 x 3.13 in (89 x 79.5 mm) bore and stroke, shared by all 2 versions. Displacement, compression and factory ratings, plus rod ratio.

At a glance

Displacement	181 ci
Cylinders	6
Bore	3.504"
Stroke	3.130"
Compression	10.0:1
Advertised power	221–240 hp
Years	2006–2011

Engines in this family

Engine	Displacement	Bore × Stroke	CR	HP
Duratec 30	181 ci	3.5039" × 3.1299"	10:1	221
Duratec 30 FFV	181 ci	3.5039" × 3.1299"	—	240

Factory cars with a Mercury 181ci

• Mercury Milan: 2006, 221 hp; 2007, 221 hp; 2008, 221 hp; 2009, 221 hp; 2010, 240 hp; 2011, 240 hp

What varies across the family

All are oversquare — bore larger than stroke, which favours revs over low-end torque.

Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.

← All Mercury engines