There's great news for builders, drivers, and racers of 426-style Hemi engines. Stage V Engineering has just introduced the Rat Buster single-plane aluminum intake manifold. Unlike many of the latest aftermarket offerings for the 426-style elephant, the Rat Buster is a dual four-barrel design. We don't know about you, but single four-barrel carburetor manifolds, even those boasting a big Holley Dominator, look lost between the broad-shouldered Hemi's rocker covers, not so with the Rat Buster.
But the classic dual-quad look of the Street Hemi is only part of the Rat Buster story. Because its designers added 2 inches to the distance between the carburetors, the Rat Buster finally allows Hemi owners to explore and enjoy the performance of Holley carburetors without resorting to a cross-ram or tunnel-ram configuration. That's right, you can finally put Holleys on your Hemi, and it all fits underhood.
Street Hemi Versus Rat Buster...
Street Hemi Versus Rat Buster Manifold
From below, the dual-plane architecture of the vintage Street Hemi intake (left) contrasts sharply with the Rat Buster's single-plane configuration. The rectangular section spanning the two x-forms contains a passage to equalize manifold vacuum between the separate plenums beneath each carburetor.
Best of all, with prices of original '66-'71 Chrysler Street Hemi intake manifolds approaching the stratosphere, the Rat Buster sells for $495. Pretty low bucks, considering it's a modern street/strip design, and it opens a whole new world of carburetion possibilities, while maintaining the classic dual-quad vibe we've come to associate with the mighty 426 and its even larger, stroker-equipped offspring.
To see what the new Rat Buster has to offer, we stuck one on a 520ci Stage V Hemi conversion motor, added a set of short-bowl-equipped Holley 750 vacuum secondary carburetors, and picked up 22 hp over a Vanke-modified '67 Street Hemi intake manifold and dual 750 AFB-style carburetors on the chassis dyno. Comparison testing on an eighth-mile dragstrip of the same motor in a 3,400 pound Dart saw the Rat Buster and Holleys increase trap speed by better than 4 mph and reduce the e.t. by nearly two-tenths of a second. Remember, that's on an eighth-mile track. On a full quarter, these improvements would nearly double. All the while, the Dart's docile street manners and 11-mpg fuel economy remained on par with the Street Hemi/AFB baseline induction combo. These are good times for Hemi fanatics, and the new Stage V Rat Buster makes them even better.
At 19 pounds bare, the new...
At 19 pounds bare, the new Rat Buster is four pounds lighter than our Vanke-modified Street Hemi intake. The Vanke modification is named after Super Stock drag racing legend Arlen "Akron" Vanke and involves milling away the dividing walls and cylindrical passages that separate the left and right banks on a stock Hemi. This vastly increases the volume of fuel available to each piston during the intake stroke. The huge open plenum chambers of the Rat Buster do the same job, but with even greater efficiency.
The Rat Buster (left) is nonheated...
The Rat Buster (left) is nonheated and does away with the stock Street Hemi's exhaust heat transfer tubes. Elimination of hot spots beneath the rear carburetor increases intake charge density and adds power. Guys who buy Rat Busters aren't sticklers for originality and are likely to run headers rather than expensive iron manifolds. They want to go fast.
Rat Buster plenums empty directly...
Rat Buster plenums empty directly into individual runners for maximum breathing. Despite a free-flowing design, the manifold is only .100 inch taller than a Street Hemi manifold and fits beneath stock hoods.
The Rat Buster accepts original...
The Rat Buster accepts original or reproduction MP Street Hemi oil splash shields (PN P4529431) to further reduce intake charge temperature. We attempted to transfer the ten stock attaching bolts, but they were .020 inch too long and bottomed out in the .730 inch deep bolt holes, so we ground .250 inch off each bolt to correct the problem. Be sure to use a high-strength, thread-locking compound to prevent loose fasteners from entering the lifter valley.
Installing the Rat Buster...
Installing the Rat Buster on our '67 Dart test car was a simple matter of removing the Street Hemi induction (after the conclusion of baseline chassis dyno and dragstrip testing) and replacing it with the new goodies. We like to squeeze a thin bead of Fel-Pro yellow gasket adhesive (PN YEL5) to stick the gaskets to the heads.
While MP intake manifold gaskets...
While MP intake manifold gaskets (PN P4120086) are acceptable, Stage V Engineering offers these .060-inch thick paper composite gaskets that offer wider sealing surfaces for less chance of leaks. The application of a thin film of white grease allows for easy, no-stick manifold removal, so the gaskets can be reused several times. A thick bead of RTV silicone seals the ends of the manifold to the block. Just trim the excess with a knife after it cures.