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We Test Intake Manifolds and Carburetors on our 440 Stroker in Search of Ultimate Power

HOT ROD logo HOT ROD 11/22/2016 Hot Rod Network Staff
We spent a couple days on the dyno trying different intake manifolds and spacers to see what worked best with the new Trick Flow heads. We Test Intake Manifolds and Carburetors on our 440 Stroker in Search of Ultimate Power

We recently spent a couple of days dyno-testing several different rocker-arm ratios on our 470-inch Mopar big-block. The good news was the engine made 700 hp on pump gas, but we were disappointed when the higher-ratio rocker arms didn't generate any additional power. After reflecting on those test results, we got to thinking we needed to see what a bigger intake and carb combination would do on this engine.

Research

We know this engine is right on the edge of sonic choke with 470 inches pulling through only 2.80 square inches of cross-section area in the heads, but we hoped the right intake manifold could extend the powerband a little more.

The single four-barrel intakes include the Trick Flow 4150, a Mopar M1 4500 intake, and an M1 intake that was heavily ported by Wilson Manifolds.© Hot Rod Network Staff The single four-barrel intakes include the Trick Flow 4150, a Mopar M1 4500 intake, and an M1 intake that was heavily ported by Wilson Manifolds.

The Trick Flow intake we used for the rocker-arm tests was an excellent intake, but we had access to a professionally ported Dominator intake and a tunnel ram, so we scheduled some dyno time to see what would happen with those intakes. But before we swapped intakes, our first test was to use an adapter to put a Dominator carb on the Trick Flow intake to see if that worked. A Dominator carb usually makes more power due its superior venturi design, but that didn't happen this time. The big 4500 carb just wasn't happy being restricted by the adapter, and peak power dropped from 700 to 680 hp.

We are running the Harland Sharp 1.70/1.50 rocker arms from the previous article. All of the rocker arms tested the same, so we left the last ones tested on the engine. If we find more power elsewhere, we might revisit the rocker-arm ratio test again.© Hot Rod Network Staff We are running the Harland Sharp 1.70/1.50 rocker arms from the previous article. All of the rocker arms tested the same, so we left the last ones tested on the engine. If we find more power elsewhere, we might revisit the rocker-arm ratio test again.

With that done, we grabbed the wrenches and replaced the Trick Flow intake with a Mopar M1 4500 intake. Most people are familiar with the M1 4150 intakes, but Mopar also sells a line of M1 intakes with large plenums and a Dominator bolt pattern. The M1 4500 is an excellent race intake on the smaller 383- to 400-inch engines, but it struggled to feed our 470-inch engine. Peak torque picked up a bit, but peak power was only 687 hp at 6,300 rpm.

The Trick Flow intake is a very nice-looking design with runners extending out in a U shape rather than an X shape. The U shape lines the runners up with the ports in the heads a little better than the older X design.© Hot Rod Network Staff The Trick Flow intake is a very nice-looking design with runners extending out in a U shape rather than an X shape. The U shape lines the runners up with the ports in the heads a little better than the older X design.

Next up was an identical Mopar M1 intake that had been sent to Wilson Manifolds for its full competition porting package. Wilson extensively modified this intake manifold by welding extra material to the outside of the runners and opening up the ports internally and adding taper to the runners. Overall, the port work increased the volume by 10 percent and removed several pounds of chips. The engine really responded to the ported intake, picking up 31 hp in back-to-back runs. This power increase gave us a new peak of 718 hp at 6,500 rpm.

A tall tapered spacer was installed so we could use a Wilson shear plate.© Hot Rod Network Staff A tall tapered spacer was installed so we could use a Wilson shear plate.

While we still had the Wilson intake on the engine, we took an opportunity to test a 1-inch open carburetor spacer as well as a super-tall 3-inch open spacer. The 3-inch spacer created an interesting dip in the torque curve that we tried to cure with a shear plate. Eventually, we gave up and went back to a 2-inch merge spacer, which worked the best. It is really hard to beat the simplicity of a merge spacer; they almost always seem to be the way to go with a four-barrel carb.

For a final test, we dug up a Mopar M1 tunnel ram and outfitted it with a pair of 500-cfm Edelbrock carbs. The tunnel ram dropped right in place and the port alignment was excellent with our Trick Flow heads.© Hot Rod Network Staff For a final test, we dug up a Mopar M1 tunnel ram and outfitted it with a pair of 500-cfm Edelbrock carbs. The tunnel ram dropped right in place and the port alignment was excellent with our Trick Flow heads.

The final round of testing was with a Mopar M1 tunnel-ram intake. Mopar stopped making these tunnel rams several years back; that's too bad because they really worked well. We equipped ours with a pair of 500-cfm Edelbrock carbs and a set of velocity stacks. The dual Eddy carb setup worked fantastic, with a smooth idle and an excellent torque curve. This combination is probably the one to use for a hardcore street/strip car. The tunnel ram looks great and runs great.

The long runners help out the torque curve down low, while the pair of carbs provides plenty of airflow at peak power. Peak power with the tunnel ram was 713 hp, which was basically identical to the power made by the uber-expensive Dominator + Wilson intake combination. Our conclusion now is that the heads are near the limit of what they can flow, and moving to the next level of performance will require some port work. We've heard of some developments in this area, so hang on while we go check them out.

Engine Details

1978 Chrysler 400 engine block with SCAT 470 inch stroker kit (Superlight forged crankshafts and I-beam rods)

Diamond Racing pistons

Milodon oil pan and windage tray

Trick Flow 240cc heads with K-Motion K-950 springs

Comp Cams 264/268 solid roller with HXL and HXX lobes

Jesel beltdrive and distributor

Machine work, engine assembly, and dyno testing was performed by Gray's Automotive in McMinnville, Oregon

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