Pontiac L36 specs: 231 ci (3.8L) 6-cylinder, 3.799 x 3.402 in (96.5 x 86.4 mm) bore and stroke, 9.4:1 compression. Rated 205 hp, 1995–2005.
The Pontiac 231ci (L36) is oversquare — the 3.7992" bore exceeds the 3.4016" stroke by 11.7% — a layout that favors airflow and RPM over leverage at the crank. The 3.4016" stroke does not reach 4,000 ft/min of mean piston speed until about 7,050 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 38.5 ci (631 cc).
9.4:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 17 engines in the Pontiac 231ci family, all of them 231 ci — the differences between them are in compression, heads and rating, not displacement. 5 factory variants share these dimensions, rated at 205 hp across 1995–2005.
Dimensions
Displacement
231 ci / 3.8 L
Bore
3.7992"
Stroke
3.4016"
Cylinders
6
Configuration
V6
Compression ratio
9.4:1 *
Bore/stroke ratio
1.117
* Compression ratio from a single source; not yet cross-verified.
Construction
Block material
cast iron
Head material
cast iron
Valvetrain
OHV
Fuel type
gas
Firing order
1-6-5-4-3-2
Redline
6,000 rpm (factory limit)
Advertised HP
205 hp
Years
1995–2005
Factory ratings by year
Year
Version
HP @ rpm
Torque @ rpm
Comp.
1998
L36 net
205 @ 5200
230 lb-ft @ 4000
9.4:1
Factory specification sheet.
What these numbers mean
Bore/stroke character
1.117 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM
3,402 ft/min — conservative for a street engine
Displacement per cylinder
38.5 ci
Static compression
9.4:1 — low by modern standards, generally happy on regular pump fuel
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