How much HP can you get out of a Pontiac 455?

Pontiac responded by essentially increasing the displacement of its otherwise high-compression 1970 Ram Air IV to create the 1971 455 H.O. In its introductory model year as the division’s top engine, the round-port 455ci had a gross rating of 335 hp at 4,800 rpm and 480 lb-ft at 3,200 rpm.

How much horsepower does a 1970 Pontiac 455 have?

360 horsepower
The result was the 1970 Pontiac GTO 455, which was stuffed with a beefy 455 HO V8 long-stroke engine. Rated conservatively at 360 horsepower and producing a tremendous 500 pound-feet of torque, the 455 HO gave the GTO the powerful aggression needed to appeal to performance-minded buyers.

What are 4X Pontiac heads?

The 4X head was the 49-state casting used on all ’73-74 400 and 455ci engines. Since Pontiac offered the 400 2-barrel, the 400 4-barrel with both manual and automatic transmissions, and the 455 4-barrel for 1973 and 1974, separate applications of the 4X head were required to meet such broad usage.

What is the bore and stroke of a Pontiac 400?

With a 4.12-inch bore and a 3.75-inch stroke, Pontiac’s 400 had similar bore and stroke to Chevy’s big-block 396 (even when the Chevy actually displaced 402 cubic inches).

How do I identify a Pontiac 455?

On blocks produced in 1970 and after, you will find 350, 400, or 455 stamped towards the left side of the front of the block. There is no displacement stamp for 421, 389 or 326 blocks. To further identify the year and application, move to the top and rear of the block, where the distributor is mounted.

What is the bore size on a 455 Pontiac?

4.151
Pontiac Blocks- Bore and Stroke

PONTIAC ENGINE CHART
ENGINE		BORE
455 CU. IN.	Stock Bore	4.151
	30 over	4.181
	60 over	4.211

What is a Pontiac HO engine?

The Pontiac V8 engine is a family of overhead valve 90° V8 engines manufactured by the Pontiac Division of General Motors Corporation between 1955 and 1981. The engines feature a cast-iron block and head and two valves per cylinder.