Chevy Small-Block 327 Outputting 462 Horsepower

15. Exhaust was sent through a set of 1-3/4-inch Hooker Super Comp headers to 18-inch collector extensions.

15. Exhaust was sent through a set of 1-3/4-inch Hooker Super Comp headers to 18-inch coll

This Comp cam was easily 35-40 hp better than the Duntov grind with no other changes, but as we will see, it also worked very well with the new heads and intake. Certainly effective, the factory intake was nonetheless upgraded with a single-plane design from Procomp Electronics. Because of its reputation as a short stroke, rev-happy motor, we tested both a single plane and dual-plane intake on this 327.

With our heads, cam and intake choices sorted out, we finished up the motor with an MSD billet distributor, Holley 950 HP carburetor and a set of Hooker headers. The 327 was first run with the dual-plane Edelbrock Performer RPM Air Gap intake. Since the short- block had already seen plenty of dyno action, there was no need for a break-in procedure and we immediately let the hammer fly. After a timing sweep and minor jetting to the 950 Holley, we were rewarded with peak numbers of 441 hp at 6,600 rpm and 408 lb-ft of torque at 4,900 rpm. Torque production from the 327 exceeded 400 lb-ft from 4,000-5,300 rpm.

16. Run on the dyno with the single-plane intake from Procomp Electrionics, the modified 327 produced 462 hp at 6,800 rpm and 412 lb-ft of torque at 5,200 rpm. This represented a jump of nearly 110 hp over the L76 configuration.

16. Run on the dyno with the single-plane intake from Procomp Electrionics, the modified 3

After replacing the dual-plane intake with a single-plane, high-rise unit, the peak numbers jumped to 462 hp at 6,800 rpm and 412 lb-ft of torque at 5,200 rpm. As expected, the single-plane intake offered more peak power by shifting the torque curve higher in the rev range. The dual plane offered more power and torque up to 5,000 rpm, but the single plane took top honors from 5,000 rpm to 7,000 rpm.

327 Chevy-L76 vs. Modified
To illustrate the effectiveness of the 327 build up, we used the L76 configuration to serve as a baseline. Note that swapping the heads, cam and intake offered a substantial jump in power, with huge gains coming at the top of the rev range. Where the L76 configuration produced 353 hp and 368 lb-ft, the modified 327 produced 462 hp and 412 lb-ft of torque, pulling hard all the way to 7,000 rpm.

327 Intake Test-Single vs. Dual Plane
The question on every small-block owner's mind is does a single-plane intake make more power than a dual plane? The quick answer is yes, but the graph indicates that there is more to the answer than a simple yes or no. The single-plane intake did make more peak power (462 hp vs. 441), but the dual-plane intake offered more power up to 5,000 rpm. For street use, 327 owners spend much more of their time below 5,000 rpm, meaning they would make better use of the extra power offered by the dual plane. For maximum performance, the single plane is the way to go.