Proof-Positive-Power Part 2

Here Comes The Power

Jason Walker Nov 15, 2002 0 Comment(s)

Last month, we took a look at the assembly of the Vrbancic Brothers' 414ci ATI blown short-block. To successfully build an engine that will consistently withstand the added internal pressures that come with supercharging and racing, we need to not only think about the strength of the parts but also the design and construction that has been painstakingly built in to these parts ensuring efficiency and longevity. This compiling of certain parts comes from years of dyno pulls and the right (and wrong) results on the track. The Vrbancic Brothers take all of these experiences very seriously. With respect to that statement, we are going to spend a little time on the Brodix aluminum heads and the work that went into preparing them for this engine--and why. Remember, when adding a supercharger (or the like) to an engine, you are simply adding a great deal more air and fuel, causing an increase in internal pressure. With that in mind, the first thing to think about is creating an unrestricted, consistent flow through the heads.

Jennings Racing Heads (formerly Air Flow Dynamics of Upland, California) did a superb job porting, polishing, and performing a valve job. That's just the start. These heads go far beyond any normal port and polish. Even the T&D rocker setup is about as trick as you can get these days. This setup utilizes a one-piece steel base that will keep the rockers in place with no worry of pulling studs. Better yet, take a closer look through the photos, and we will attempt to explain these parts as you see them. Oh yeah, just to keep your saliva flowing (or just to keep you reading), after all was said and done, this small-block pumped out over a 1,000 hp with almost 800 lb-ft of torque. If that doesn't pique your interest, skip to the next story.

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While we were gone, the Vrbancic Brothers decided to get a leg up and throw a cylinder head and rocker assembly on to make sure everything was...headed in the right direction (yes, I was trying to be funny).

It may be hard to see in this photo, but even the intake valveguide stems have been shaped using existing material along with some that was added. The stems have been shaped much like the wing of an airplane, with a peak facing into the direction of flow to allow the fuel and air mixture to smoothly flow around the stem with the least amount of restriction. Left alone, the flow can get caught behind the stem, thereby reducing the efficiency and speed as the mixture enters the cylinder.

This is the same intake port as above. From this angle we can see even more reshaping and can understand the resulting increase in flow efficiency when comparing the bottom of the intake guide to that of the stock exhaust valveguide.

Material was also taken away and added to reshape and clearance the pushrod passageways--more on this as you read further.

With the Manley valves slid into place, it was determined that a .015 valvespring shim would be necessary for the correct installation height.

The right combination of Manley Severe Duty valves, Manley NexTek Series double valvesprings, and COMP Cams valve seals are all old favorites, because they are strong, reliable, and work.

Now that the head is nearing completion, Bob prepares the COMP Cams Hi-Tech roller lifters by carefully linking them together with COMP's patented link system that utilizes the convenience of a removable link and the safety of a captured link.

After a liberal amount of engine oil was applied to the lifters, they were dropped into position making sure to place the offset lifters in the correct slots. The block was then prepped for the head by installing the SCE copper head gasket with a small amount of a silicone-based sealant around each water jacket, on both sides of the gasket.

As you can see in this shot, the oversized springs made it necessary to grind two sides of the center head washer. You can also see the added aluminum next to the intake ports in this shot. These areas were added in order to enlarge the intake ports. This is great work and should always be left to the professionals.

As for the center head nut, Bob simply chucked it into the lathe and cut only the minimum amount necessary to properly clear the valvesprings.

This shot clearly shows how snuggly the turned-down head nut fit between the oversized valvesprings.

Next in line is the T&D Machine Products trick rocker shaft setup. You won't have to worry about rocker studs pulling out with this kit. The rockers are machined from billet 2024 aluminum and mounted to a one-piece steel stand, making for a very strong and sturdy package.

We started off by applying a thin coat of silicone that will create a seal between the rocker stand and the boss on the head.

Next, the steel stand is bolted in place. Incidentally, this stand can be adjusted side-to-side for perfect alignment.

After the stand is torqued to the manufactured specs, the Manley 4130 swedged-end pushrods were given a lacquer thinner bath and dropped into place. Now you will find out if you placed the offset lifters in the correct spots.

Yep, everything lines up perfectly, as planned. You really get a good idea of how much work went into these heads in this shot. Take a close look at the relationship between the intake pushrod and lifter and the intake port.

George makes sure the lifters are adjusted and working properly before anything else goes on the engine.

This is a turning point in the engine's assembly. Internally, everything is done and ready to be sealed in by mounting the intake and valve covers.

The Brodix intake has been manufactured with special water bypass ports to better circulate water through the heads.

To top off the intake, a massaged Carb Shop carburetor was built for the blow-through-style ATI D-3 supercharger.

After a couple of dyno pulls, it was decided that a larger-sized pulley was needed to slow the supercharger down a bit. This not only changes the speed of the flow but will probably save a lot of stress on the engine while not robbing power.

Isn't she pretty? As pretty as she may look, this small-block huffed out power like crazy. Just take a look at the dyno sheet for the proof.

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