Small-block Mopar fans have always had to make do with slim pickins in the cylinder head department. Back in the '60s, '70s, and even the '80s, the average street machine 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 W-2 small-block units from Direct Connection, but because of the expense and complexity of the conversion, 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 with 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 focushere is on the street/strip-style aluminum aftermarket heads that will bolt on to 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 valvetrains, W-2-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 features 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.
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, nonoffset 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 at 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 W-5 or W-7 intake manifold. The exhaust face is also left blank so that a W-5, W-7, 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 450-500hp range for an as-cast head, depending on the seriousness of the effort, while fully ported we would expect to be around the 600hp mark with a serious small-block stroker combo.
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, nonoffset 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 220 cc, 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 700hp 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.
If any aftermarket cylinder heads redefined the small-block Mopar, they are the Edelbrock RPM offerings. They are available in both LA-series and Magnum series, and the idea is 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 valve sizes, the heads retain the OEM intake, exhaust and rocker configuration. This means 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 two-handle range. The heads have an easy bolt-on 400-plus-horsepower potential on a mild street combination and can support more than 500 hp 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.
Indy's T/A heads are a proprietary modification of the Edelbrock cylinder head castings by Indy Cylinder head. The concept here was to take what is already a popular and excellent-quality casting and address some key issues to raise the ultimate power potential of the heads. To accomplish this, the heads are provided to Indy as semimachined castings, allowing for the unique Indy T/A configuration. The primary modification is to alter the intake pushrod clearance location away from the intake ports, which removes the primary restriction on port width. This allows Indy to widen the runner at the pushrod restriction by 0.190 inch compared with a standard Edelbrock LA head.
The angled pushrods require an offset rocker arrangement. Indy relocates the rocker mounts for longer, 440-style Indy offset rockers, upgrading the fastener size and alleviating the restricted spring clearance found in a standard small-block Mopar head. The heads feature larger valves than the stock Edelbrock, with 2.05-inch intakes. While the Indy T/A utilizes an offset rocker arrangement, it retains the OEM LA-series intake and exhaust bolt patterns for compatibility with standard intake manifolds and exhaust headers. The heads are an excellent choice for a hot street or strip stroker looking for more power potential than a standard-style head or a smaller-displacement engine looking for outright high-rpm power. With full porting, the right combination should top the 600hp mark.
Moving up to make power on a more serious level takes moving up to a more serious cylinder head configuration. The 360-1 and 360-2 cylinder heads take the top-end combination to race-level performance, with essentially the Mopar W-series-style mods. Here, the first thing we find is the offset rocker arrangement using Indy's big-block-style rockers with 0.800-inch offset on the intake. This gives the clearance for the large valvesprings required in a serious engine and also allows larger, unobstructed intake ports. The 360-1 features rectangular intake ports, while the 360-2 carries a smaller, oval port. These cylinder heads are fitted with oversized 2.100/1.625-inch valves and have the W-2-style intake manifold bolt pattern and both the standard and W-2 exhaust bolt patterns. Additionally, these heads have the extra bolt provisions for the race-block, 18-bolt deck pattern and are still compatible with the factory 10-bolt pattern.
If you are looking to take power to the next level, the Indy cylinder heads have what it takes. The fully CNC-ported versions from Indy offer the required flow, and the race-derived cylinder head configuration takes care of the rest. Indy puts the power capability of the 360-1 at 750 hp, and at 700 for the 360-2 oval-port. If you are building a serious Mopar small-block, the Indy 360 heads are definitely designed to take care of business.
(306 at 0.700 Full Indy porting)
(197 at 0.700 Full Indy porting)
(360-2 CNC Optional)
(230 cc CNC)
(65 cc CNC)
(322 at 0.700 CNC)
(255 at 0.700 CNC)
(360-1 CNC Optional)
(245 cc CNC)
(65 cc CNC)
(330 at 0.700 CNC)
(255 at 0.700 CNC)
Mopar Performance's entry into the aluminum small-block cylinder head market starts with the Aluminum Magnum and the Aluminum Commando LA-series cylinder heads. These heads are based on the Edelbrock castings, and in terms of the relative configurations, they are virtually identical to the Edelbrock RPM offerings. Like the Edelbrock heads, the Mopar versions make nice street performance heads as bolt-on, 400-plus-horsepower assemblies in mild small-blocks and max out in the mid-500s with competent full porting.
The Super Commando cylinder heads are also based on the Edelbrock castings, however, these heads feature larger intake valves and the offset rocker modification, allowing the intake port to be wider and unencumbered. As with the Indy T/A, this modification allows more intake port cross-sectional area and an improvement in intake port flow potential. The Super Commando utilizes a unique rocker offset and is serviced by Mopar PN P5153995 rocker arms, though the availability of these corresponding rockers has been sporadic.
In terms of additional aluminum small-block cylinder heads from Mopar Performance, the company does offer a range of full-on race heads in its W-9 and P5 series. These heads are designed for use on the Mopar Performance race blocks. Although it is possible to utilize these heads in an all-out build, they and are outside the realm of the street/strip cylinder heads we are detailing here.
The Mopar Performance Super Commando ups the ante on the Commando heads with an offset rocker arrangement allowing for a wider intake port. This is the cylinder head used on the Mopar 440 small-block crate engine.Brodix/KoffelBrodix/Koffel SpecsDr J's PerformanceEdelbrockIndy Cylinder HeadMopar Performance