When considering engine performance, if anything has been a game changer, it is the advancement in cylinder heads. Back in the '60s and '70s, and even the '80s, the average street machine's engine typically wore the same iron heads the engine left the factory with. In those days, the typical hot-street cylinder heads might have received a three-angle valve job and a set of springs to match a hotter cam. Sure, there were some serious performance cylinder heads, like the famous iron W2 small-block units from Direct Connection, but the vast majority of street engines ran stock production heads. These days, aftermarket cylinder head choices are broader than ever, and given the potential performance gains versus the cost, they offer an excellent value compared to rebuilding old factory iron. Aftermarket cylinder heads are available in aluminum and iron construction. While there are iron heads that definitely offer a performance advantage over the factory units, we will save that discussion for another day. Our focus here is on the street/strip style aluminum aftermarket heads that will bolt onto a factory 59-degree engine block.

When considering an upgrade in cylinder heads, it is important to have clearly defined goals in mind. If the engine is going to be a mildly modified stock displacement street cruiser, there is little point in going beyond an entry level aftermarket head, such as the Edelbrock or Mopar Performance units. From that entry level point, the scale moves up in cost, complexity, and ultimately power potential. Differences such as offset rocker valve trains, W2 style intake and exhaust patterns, or additional porting can easily double the cost of a cylinder head conversion. Depending upon your budget and goals, those feature quickly become desirable or necessary. Ultimately, it is going to be cylinder head airflow that limits rpm and horsepower potential. When dealing with today's big-inch stroker small-blocks in particular, cylinder head airflow becomes even more critical in getting the most from the useful rpm potential of the engine.

Brodix / Koffel

Koffel's B1BA cylinder head is one of those parts that seem to fly just under the radar screen, but it is definitely worth some attention. Cast by Brodix, the B1BA cylinder head was intended to be a straightforward, bolt-on upgrade for a stock LA-style head. The B1BA retains the stock, non-offset valvetrain utilizing B1BA specific rocker stands. The heads also features the production bolt pattern on the intake and exhaust flanges, retaining compatibility with common LA-Series parts. The departures from the stock layout include raised exhaust ports and relocated spark plugs, requiring header modifications in some installations. Breathing through 2.08-inch intake valves, the as-cast flow is better than any other as-cast stock configuration head. The potential only goes up from there with porting, with Brodix reporting 303 cfm @ 0.700 for the ported B1BA.

Koffel also offers the B1BA MC cylinder heads, which feature relocated valves for a major increase in valve size. The B1BA MC has unmachined pushrod slots, requires a race-style shaft mounted rocker system, and uses a W5 or W7 intake manifold. The exhaust face is also left blank so that a W5, W7, or stock exhaust pattern can be drilled. These B1BA MC heads can be considered specialty race heads outside of our focus here.

We would put the power potential of the B1BA in the 450-500 horsepower range for an as-cast head, depending upon the seriousness of the effort, while fully ported we would expect to be around the 600 horsepower mark with a serious small-block stroker combo.

Head: B1BA
Intake Port Volume: 195cc
Chamber Volume: 65cc
Intake Flow: 269 @ 0.700 As-Cast
Exhaust Flow: 198 @ 0.700 As-Cast
Intake Valve Size: 2.08
Exhaust Valve Size: 1.60
Rockers: Standard LA-Series
Bolt Pattern Int/Exh: Standard LA-Series

Dr J's Performance

The AirWolf cylinder heads from Dr J's Performance are designed to take the conventional bolt-on cylinder head configuration to its airflow and performance limits. The head features a standard, non-offset valvetrain, as well as stock LA-Series bolt patterns on the intake, exhaust, and deck. The heads are only offered in fully CNC ported form, with unique castings to accept the developed ports. The intake volume stretches the standard configuration to a whopping 220cc, with peak intake flow in the mid 320s through a 2.08-inch valve, with equally impressive exhaust flow maxing out at the mid 240s utilizing a 1.60-inch exhaust valve dimension.

Power potential of the AirWolf is impressive, as we have seen 630-plus horsepower with a moderate 408 stroker combination, and expect the upper range potential to crowd the 700 horsepower mark in an all-out race small-block. By keeping the stock architecture, the AirWolf offers a cost-effective approach to serious small-block power.

Head: AirWolf Mopar 220 CNC
Intake Port Volume: 220cc
Chamber Volume: 60-70cc
Intake Flow: 316 @ 0.700 Full CNC
Exhaust Flow: 236 @ 0.700 Full CNC
Intake Valve Size: 2.08
Exhaust Valve Size: 1.60
Rockers: Standard LA-Series
Bolt Pattern Int/Exh: Standard LA-Series

Edelbrock

If any aftermarket cylinder heads redefined the small-block Mopar, it is the Edelbrock RPM offerings. Available in both LA and Magnum Series, the idea was to build a direct replacement aluminum cylinder head with improved power as the goal. With the moderate cost of the conversion, these heads have become extremely popular as an upgrade over OEM iron heads. Featuring the popular 2.02/1.60-inch valve sizes, the heads retain the OEM intake, exhaust, and rocker configuration. This means that these parts can be carried over when retrofitting from a stock head, a big cost savings if you already have a performance intake, valvetrain, and headers. The Magnum version retrofits the rocker arrangement from the stock pedestal mount to a small-block Chevy stud mounted arrangement, for a virtually unlimited selection in aftermarket rockers.

Out of the box, peak intake flow is in the mid 250 cfm, with max-ported versions typically falling in the upper 200 range. The heads have an easy bolt-on 400-plus horsepower potential on a mild street combination, and can support over 500 horsepower in ported form. For an all-out race small-block, the RPM heads definitely have their limitations, but for a nice street or moderate performance engine, the Edelbrock cylinder heads are a home run.

Head: Performer RPM LA
Intake Port Volume: 171cc
Chamber Volume: 63cc (65cc relieved optional)
Intake Flow: 251 @ 0.600 As-Cast
Exhaust Flow: 190 @ 0.600 As-Cast
Intake Valve Size: 2.02
Exhaust Valve Size: 1.60
Rockers: Standard LA-Series
Bolt Pattern Int/Exh: Standard LA-Series
Bolt Pattern Deck: Standard 10-Bolt

Head: Performer RPM Magnum
Intake Port Volume: 176cc
Chamber Volume: 58cc
Intake Flow: 260 @ 0.600 As-Cast
Exhaust Flow: 190 @ 0.600 As-Cast
Intake Valve Size: 2.02
Exhaust Valve Size: 1.60
Rockers: Chevy SB Stud Mount
Bolt Pattern Int/Exh: Magnum Vertical