What can be more fun than...
What can be more fun than a dyno, a stack of 440 intakes, and all day to test 'em?
It seems everyone has a favorite intake manifold. Some guys scour swap meets, garage sales, and dumpsters looking for long discontinued intakes because they know "they're the best." Others are convinced the old 440 Magnum four-barrel iron piece is as good as it gets, although a little heavier than that aluminum aftermarket stuff. Tell them it's the exact same intake used on Grandpa's standard 440 Chrysler New Yorker of the same year, and chances are they'll call you a liar. What's the truth? To some extent, that depends on what you're after. It's said that two-plane intakes produce more power lower in the rpm range, while single-planes offer more power higher in the range, given an engine built for high-rpm performance. I've seen it in enough dyno runs to know it's more than a myth. This is a good place to start, but most people have to rely on past experience. To get some real-world data, we lined up some intakes and ran a dyno test.
The Setup We jetted the carb...
We jetted the carb for max performance and monitored the dyno readings on fuel flow, ratios, and BSFC throughout the test.
Here's a simple piece of engine-building theory to consider: The more power the engine makes, the more critical manifold selection becomes to peak power output. Take a stock big-block and run a comparison on intakes-there may be 15-25 hp between the best and worst. Run the same intakes on a radical drag motor, and the range will broaden dramatically.
Of course, there are considerations other than peak power output when selecting an intake for a specific combo. For instance, factors such as the rpm range and low rpm torque requirements of the application require attention. However, if the goal is to put a selection of intakes through the acid test, the way to do it is to run them on a high-powered engine that will really pull the air. Our objective this time was to test for higher rpm power. We gathered as many 440 intakes as we could get our hands on and did just that.
All the intakes were single four-barrel 4150-flanged designs; and all, with one exception, were run out-of-the-box stock. When custom porting enters the equation, a big variable is thrown into the results. Some intakes naturally benefit from porting or even port matching, but the end user's results also vary depending on who does the port work. While hardcore builders wouldn't consider running a manifold without doing some carving first, the majority of intakes are likely just unwrapped and bolted on. This is exactly what we did here. Note that our high-powered test engine and test rpm range greatly favored the single-plane designs, so all of the single-planes had an advantage.
The mule for our test wasn't your ordinary street mill, but rather a stout 440 combo that could use all the intake it could get. The block was .060-inch-over production 440, with Arias-forged 12.5:1 domed pistons, Eagle H-beams, the factory-forged crank, and a Milodon oiling system. The heads were production-915 castings and the ports were seriously reworked with max effort (no welding or epoxy) porting job and fitted with custom Manley 2.25-inch intake valves and 1.81-inch exhausts. Working the valves was a full Competition Cams' cam-and-valvetrain package, including a custom Comp roller, with their NC4149 intake lobe and High Tech .420-inch exhaust lobe. It worked out to 260/258 at .050-inch and over .650-inch lift with Comps 1.6:1 aluminum roller rockers. A Milodon gear drive turned the cam. We called it the "Iron Head Air Hammer."See Mopar Muscle March 1999, May 1999, and Sept. 2001 for more on this engine.
Factory Iron Circa '70-'7...
Factory Iron Circa '70-'71
1. Factory Iron circa '70-'71
For our first test, we bolted on a factory #2951736 cast iron intake, the four-barrel intake used on '70 and '71 440s. We'd like to think that no one in their right mind would bolt one of these onto a high compression, big-valved, roller-cammed 440, but we had to start someplace. Even we were surprised to see the numbers we got, although the engine was way off its potential. On stock and mild engines, we've seen meaningful gains easily achieved with aftermarket intakes.
|The Intake:||Chrysler #2951736|
|Type:||Cast Iron Two-Plane Four-Barrel|
|Rated rpm range:||N/A|
|Max hp:||575.4@6,200 rpm|
|Max Torque:||581.2@4,000 rpm|
|Avg. hp 4,000-6,600 rpm:||534.3 hp|
|Avg. Tq 4,000-6,600 rpm:||:535.1 lb-ft|
This engine has seen the dyno...
This engine has seen the dyno before, always with a 1 7/8-inch header. This time we bolted on a 2-inch tti header, and the power was up noticeably. Although not a scientific back-to-back, it seems the 2-inch is worth considering in this power range.
The lineup, from front to...
The lineup, from front to rear: Weiand Action+; Edelbrock CH4B; Edelbrock Torker; Edelbrock Victor; Edelbrock Torker II; Weiand Team G; Holley Street Dominator; Edelbrock TM-7; Edelbrock Performer RPM; and the Mopar Performance M-1.
The Carb Precise fuel metering...
Precise fuel metering is mandatory for this kind of test, as is enough airflow to not hold the manifolds back. We used a 950 annular discharge booster Race Demon for the entire test, and it performed flawlessly. We've used this engine on the dyno before, at one time running nearly the exact same combo with just two exceptions. One is this large Race Demon carb. The other is a move up from a 1 7/8-inch header to a set of tti 2-inch pipes used on this day. Between the two, the engine picked up more than 25 hp from the original run.