Since the 273 V-8 was introduced, the Chrysler LA series small-block engine has become a hit with Mopar performance enthusiasts. Packaged in a small, lightweight block, the small-block Mopar is some 150 pounds lighter than a comparably equipped big-block. When the 340 engine was introduced, it sealed the deal, as it was quite a match for any off-brand small-block, and the 360 LA and Magnum versions of this engine are proven powerhouses as well. Thanks to great aftermarket support for the Mopar small-block, displacements, and power levels, are far greater now than they have ever been, allowing the small-block Mopar to make power numbers previously reserved for big-block or Hemi engines.
One company that has embraced the Chrysler small-block is Indy Cylinder Head. Taking advantage of our annual Engine Challenge several years ago, the crew at Indy used their entry to team up with RHS, developing the Indy LA-X line of cylinder heads. Indy also won our Engine Challenge that year, as their small-block made more power and torque than any of the other seven entries. Indy has a full line of parts you need to build your own Mopar small-block engine, or they offer complete engines if you'd rather not do it yourself. During this year's annual Chrysler technical seminars and swap meet at the Indiana State Fairgrounds, we noticed one small-block offered by Indy Cylinder Head that could make three different levels of power, all with the same intake manifold. Intrigued, we decided to visit them and check out what it takes to build this potent 408-inch small-block, and then test it on the dyno using a single four-barrel, dual-quads, and a supercharger with dual-quads.
The basis of this engine is a 360 block with a 4.030-inch bore size and an Eagle forged crankshaft with a stroke of four inches, for a total displacement of 408 cubic inches. Forged dish pistons with coated skirts combined with Indy's LA-X cast-iron cylinder heads give the engine a pump-gas friendly 9.0:1 compression ratio, and I-beam forged connecting rods are utilized. A Milodon road race oil pan and Melling oil pump handle the lubrication duties.

We all know Indy Cylinder...

We all know Indy Cylinder Head for their big-block and Hemi race engines, but this versatile small-block is an economically priced powerhouse.

01 The foundation for this...

01 The foundation for this 408-cubic-inch small-block is a fully prepped 360 Magnum block combined with an Eagle forged crankshaft with a four-inch stroke. Forged I-beam connecting rods are utilized along with forged pistons with coated skirts.

02a Dish pistons and Indy's...

02a Dish pistons and Indy's LA-X cylinder head combine for a compression ratio of 9.0:1. This engine runs great on pump gas..
For improved flow and power potential, Indy treated the LA-X cylinder heads of this engine to CNC bowl porting, and the heads feature 2.055-inch intake and 1.625-inch exhaust valves. These heads offer longer valves than standard LA heads, with Magnum style combustion chambers and ports, while retaining the shaft mounted rocker arms. Indy also offers a version of this cylinder head featuring individual Magnum-style rocker arms, making this a versatile, great performing head.
Since this engine was designed to run well both naturally aspirated or with a blower providing boost, camshaft selection was critical. Engine builder Ken Lazzeri of Indy Cylinder Head chose a Comp Cams hydraulic flat-tappet cam for this engine, for simplicity and cost effectiveness. This special grind camshaft features .544-inch intake lift and .541-inch exhaust lift, with 240- and 246-degree duration ratings for the intake and exhaust respectively. Lobe separation for this grind is 110 degrees, and Ken installed the cam at 108 degrees. Indy Cylinder Head roller rocker arms are utilized with a ratio of 1.6 on both the intake and exhaust side.
The item that makes this engine so versatile is the Mod Man intake manifold built by Indy Cylinder Head. This intake allows the user to change between a single four-barrel, two four-barrel plate, Six-Pack plate, or even a blower plate. This is an exceptional benefit on the small-block engine since on a small-block, the intake manifold houses water jackets requiring the coolant be drained to change the intake. For our dyno session, we decided to test the single four-barrel version using a 750-cfm Holley, then use a pair of 500-cfm Edelbrock carbs on the dual-quad top plate, before finishing off our test with a 671 Littlefield blower attached to the blower top plate.

02b ...maybe even regular...

02b...maybe even regular when normally aspirated, and the compression is low enough to install a blower for a big power increase.

03 Indy's cast-iron X head...

03 Indy's cast-iron X head is available in two versions, the LA-X with shaft mounted rocker gear or the MA-X with Magnum style rockers. Both heads utilize the same great combustion chamber with plenty of quench area, as well as the Magnum style ports.

04 We bolted the 408 to Indy's...

04 We bolted the 408 to Indy's Superflow dyno, and engine builder/dyno operator Ken Lazzeri verified ignition timing while the engine warmed up. The 750 Holley single four-barrel is likely a little small for this stroked small-block, but still impressed us with a peak torque of more than 480 lb-ft and a peak horsepower number of 495.9.

05 This is the dyno sheet...

05 This is the dyno sheet with a single 750 Holley installed on the 408 small-block we tested. With over 450 lb-ft of torque, from 3,900 rpm all the way to almost 6,000 rpm, even with a single four-barrel, this is a stout combination. Horsepower topped out at 6,100 rpm at almost 495.

06 A big part of this engine's...

06 A big part of this engine's versatility is the Mod Man intake manifold. This intake allows you to change just the top plate, changing from single four-barrel, to dual-quads, three deuces, or even a blower in just minutes. The bottom part of the intake stays in place, eliminating the coolant spills associated with small-block intake swaps. Ken easily had the single four-barrel plate removed, and dual-quads installed and ready to run in about 25 minutes.

07 With a pair of Edelbrock...

07 With a pair of Edelbrock 500-cfm carburetors installed, Ken quickly made some preliminary tuning adjustments and we were ready to make another pull. The dyno verified that this healthy small-block liked the extra air and fuel, as power was significantly improved over the single four-barrel.
Starting with the single four-barrel, we fired the engine up on the dyno to begin our testing. This is a throaty small-block, and with 408 inches of displacement and sounds more like a big-block when it's running. Indy offers a version of this same engine with the MA-X (Magnum style) cylinder head and a slightly milder camshaft and slightly smaller valves rated at 450 horsepower with one four-barrel, so we were eager to see what this little powerhouse could produce. On the first dyno pull, it was evident that this small-block ran well, as peak torque was 481.8 lb-ft and peak horsepower was 495.9 horsepower at 5,900 rpm. A big part of this story, however, is the Mod Man intake this small-block is equipped with.
Thanks to Indy's Mod Man, we could quickly make dyno pulls, then change the top plate of the intake in about 20-30 minutes and be ready to dyno the engine again. We accomplished multiple pulls on this engine with three different induction setups, and easily accomplished all of our work in a day on the dyno. Even more impressive is the power this engine made. Check out the dyno results below and we're sure you'll agree that this 408 shows its potential both normally aspirated and with the blower. Also be sure to check out moparmusclemagazine.com for a video of this powerful small-block making pulls on Indy's dyno.
Price Tag
|
| 450hp 408 small-block complete | $6,479 (single four-barrel) |
| 520hp 415 small-block complete | $7,595 (single four-barrel) |
| Indy Mod Man intake | $499 |
| Mod Man top plates | $135 each |
| The power and torque of a supercharged small-block | priceless |

08 With dual-quads on this...

08 With dual-quads on this engine, horsepower improved to 512.8, and was still climbing at 6,100 rpm. Peak torque also topped the 500 mark, as the engine made 500.7 lb-ft at 5,100 rpm. The engine sounded clean and seemed to like the Mod Man intake with one carb-barrel over each port.

09a Swapping to the 671 blower...

09a Swapping to the 671 blower is slightly more complicated. As before, the required Mod Man blower plate needed to be installed...

09b ...but since a blower...

09b...but since a blower is topping the engine, Indy's specially designed offset distributor is also required to clear the rear of the blower housing.

10 With the blower and two...

10 With the blower and two 600-cfm carburetors installed, this engine sounds like an entirely different animal. Making a short dyno pull to verify everything was working properly, we quickly noticed on the computer screen in the dyno operating room that power and torque were way up.

11 With the 671 blower underdriven...

11 With the 671 blower underdriven 7.7 percent, this engine made amazing power and torque. Peak torque was over 695 lb-ft at 4,300 rpm, and peak horsepower was 738.7 at 6,100 rpm. If over-the-top looks and power are your style, adding a blower to this engine will produce what you're looking for.

12 Check out the broad torque...

12 Check out the broad torque and power curves this 408 produces in supercharged form. It was a blast testing this engine on Indy's dyno. Be sure to check out the video footage we took on moparmusclemagazine.com.