SOLD Butler Crate Engine 389 Block 447 cu.in. Turn Key EFI

544 horsepower, 576 lb-ft — on pump gas, naturally aspirated

A Butler Performance in-house build: 447 cubic inches of Pontiac V8 with CNC-ported round port heads and self-tuning Holley EFI. Assembled and blueprinted here in Lawrenceburg, run and tuned on our own engine dyno, and the numbers below are what it actually made — corrected, in our cell, on the day.

Why the curve matters more than the peak

A lot of big-inch Pontiacs are sold on a peak number that arrives at an rpm nobody drives at. This one does the opposite. Torque is above 500 lb-ft everywhere it was tested, peaks at 576 at 4500, and is still over 500 at 5,700. Horsepower climbs steadily to 544 at 5600 and holds flat either side of it.

That is a street engine. It pulls from just off idle, has no flat spot to drive around, and does it on pump gas with no power adder to maintain.

Built from a 389 block — and that is the interesting part

This started as a Pontiac 389 casting. It was sonic tested, rebored and honed with a torque plate, square decked, align honed and magnafluxed before assembly. With a 4.250" Eagle forged crank and a 4.092" bore it comes out at 447 cubic inches — more displacement than a factory 455, from a block most people overlook.

The rotating assembly is a forged Eagle crank on 6.800" H-beam rods with bushed pins, DSS forged 2618 flat-top pistons and Total Seal file-fit rings, balanced as a complete assembly.

Round port heads — where the power comes from

The heads are Butler 87cc Edelbrock round port castings, CNC ported to 325+ CFM, supplied complete. Round port flows more than a D-port and is the reason this engine keeps making horsepower past 5,000 rpm rather than falling over.

The 87cc chamber sets pump-gas-friendly compression, and the Edelbrock Torker II intake is port matched to those specific heads rather than bolted on out of the box — a step most engines never get and one that costs nothing in power to skip, which is exactly why it usually gets skipped.

Camshaft and valvetrain

A Butler/Comp SP Street Performance billet hydraulic roller: 288/294 advertised, 236/242 at .050", .521"/.540" lift on a 112 lobe separation. Wide enough to idle civilly and keep vacuum for a street car, big enough to use the heads.

Behind it: Morel hydraulic roller lifters, Scorpion 1.65 Endurance roller rockers and custom Smith Bros chromemoly pushrods cut to length for this engine.

Self-tuning EFI, ready to run

Fuel is Holley Sniper 2 self-tuning EFI with the handheld monitor, paired with a full Holley HyperSpark ignition package — distributor, CD box and coil — so timing is under EFI control rather than fighting it. It was dyno tuned here before it shipped.

Specification — as built

Built the Butler way

Butler has been building Pontiac engines since 1974. Every engine that leaves here is assembled and blueprinted in our own shop and run on our own dyno before it ships — we don't ship an engine we haven't heard run. The dyno sheet goes with it.

If you want this combination in a different displacement, with a different cam, or set up for a carburettor instead of EFI, talk to our tech department — that is what we do all day.