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Project Off Road Buggy Small Block Chevy Engine - Dream Machine Power

Gm Small Block
Fred Williams
| Brand Manager, Petersen’s 4Wheel & Off Road
Posted September 1, 2005
Photographers: GM Performance Parts

Part 2: Fun Buggy Gets Some Torque

I told you last month that Project Fun Buggy has got to be just that-fun-so like any red-blooded American boy I went out hunting a proper engine for peeling out. I wanted an engine that could chug over rocks and up wooded trails, but still get allfour tires smoking or huck giant roosts in sand or mud. Mileage is important, but not as much on a dedicated trail rig. This one's called Fun Buggy, after all. And finally, it had to look cool under the hood and give off a rumble that would scare the yuppies down the street.

So what to use? Four-cylinder engines are great for economy and putt-putting around. I've seen many awesome rock buggies with Toyota, GM Ecotec, and even Subaru engines that can crawl and still get jiggy across the sand and mud, but when tires get above 40 inches, a four-banger is getting worked.

1. Long-stroke engines are known for their torque, and when turning big tires off-road, you want torque. That's why we are always so concerned with going to lower gears for torque multiplication. The stroked ZZ383/425 engine package comes from GM Parts Performance (GMPP) with a modified four-bolt main engine block, a 3.80-inch stroke 4340 crankshaft, heavy-duty powdered metal rods, and the one-piece rear main seal. It is also ready for an automatic transmission with a 12.75-inch flexplate, and comes with stamped-steel valve covers that we replaced with Scoggin-Dickey's fabricated aluminum versions. It does not include a starter or front accessory drives.

The straight-six Jeep engine is a torquey little anchor and the GM or Toyota V-6 is great for almost any lightweight rig looking to haul a person or two around, plus it can be dialed in for serious smoke shows on steep rocky ledges.

Then there is the question: Why not go diesel? The 6.2 diesel V-8 in my '86 Chevy is fine, but isn't all that impressive, and the Cummins diesels are just too heavy. All the other diesels are either weaker than what I want, too heavy, or not offered in this country. I would love to explore them more down the road, but Fun Buggy needs some steak-and-potatoes power while keeping on the salad side of weight. So no four-cylinders, no diesels-maybe a V-6. But then again, why leave out those extra two cylinders? V-8s are cool-they are as American as mom, apple pie, and mud-wumpin'. They sound cool, can make big power and torque, and just seem right for a 4x4, especially one on big tires. So it had to be a V-8, but which one? The new Dodge Hemis and Toyota V-8s are hard to get-very cool, but hard to get-and there just isn't that much stuff for the Nissan V-8 yet. So old-school Dodge, Ford, or Chevy? Since Feature Editor Jerrod Jones is the Dodge guy, and a good buddy of mine is running a Ford, I started thinking Chevy. You gotta have something to argue about over the camp fire. Plus this is 2005, and 50 years ago some engineers at General Motors designed a V-8 engine that has stood the test of time. Yes, it's gonna be Old Faithful, a small-block Chevy.

Even when I decided on a small-block GM I still had choices to make. In my country-boy logic I saw 40-inch tires and 40-spline axleshafts (see last month's axle build), so I figured I needed 400 horses and even more torque. Of course, the junkyard or classified ads are the first stop for many folks looking for a good engine, but if I was going that route, I would be hard-pressed to come home with a 400hp rat motor. In fact, only two small-block Chevys ever came from the factory with over 400 horses, and both were in exotic Corvettes. If I was going to go with a junkyard engine, I would choose the late-model Gen III 6.0 like Tech Editor David Kennedy put in his Blazer (June '04 and June '05). What I ended up powering this tube car is not cheap, but it will make the tires turn and I'm trying to show the coolest dream parts I could get my hands on that are still anchored back to what the average guy could start with. I know many of you might think this means a big-block or an LS1 aluminum Gen III small-block. Sorry to disappoint, but I'm going with a GM Performance Parts ZZ383. The big-block is still too heavy, and though the LS1 is lightweight and an awesome performer, I decided to push the classic iron block. GM claims 425 horses and 449 lb-ft of torque, but that is based off of dyno tests using a carburetor, and I want fuel injection for steep climbs and off-camber wheeling. So further research brought me to Scoggin-Dickey Performance center in Lubbock, Texas, and its ZZ383EFI. Follow along as we build a crate small-block ready to scare old ladies and fat wallets. It ain't cheap, but it sure is sexy.

2. The difference between the ZZ383 and GM's entry-level stroker, the HT383, is the aluminum Fast Burn heads. The GM iron Vortec heads found on '96-'99 trucks have a reputation for great performance, and the aftermarket Fast Burn heads take that design and expand on it, getting even better flow out of slightly larger 2-inch intake valves and 1.55-inch exhaust valves. Plus, the intake runners are slightly larger as well. If you have a '55-'00 GM V-8 and want to go to an aluminum Vortec style head, you can get them through GMPP as well as many aftermarket companies such as Edelbrock, who offers similar E-Tec heads.

3. The two common styles of fuel injection are throttle body injection (TBI) and Tuned Port Injection (TPI). TBI is similar to a carburetor in that there are injectors (usually two) situated at the top of the intake manifold, and the fuel is atomized in and flows through the intake to each cylinder. But unlike a carburetor, the fuel is injected (duh!) under pressure and is more controlled. TPI (also referred to as multiport injection) usually has an injector for each cylinder and sprays fuel directly above the intake valve. This ensures that each cylinder receives a proper charge. I decided on the aftermarket ACCEL DFI Super Ram system that is designed like a TPI but offers many options for tuning. Since the engine is stroked, Scoggin-Dickey recommended 30-lb/hr injectors.

4. The ACCEL system is designed to replace carbureted engines or TPI engines, but none of these ever came with more desirable Vortec style heads. Instead the Vortec style heads only came in trucks with some goofy Central Port Injection (CPI) that utilizes eight injectors and tubes that run down to each intake valve. Luckily Scoggin-Dickey has developed this Vortec/TPI intake manifold to allow Vortec Fast Burn heads to be run on TPI engines, and since the ACCEL system is a TPI design it allows the better airflow characteristics of the Fast Burn heads without disturbing the optimum charge from the fuel injectors. The ACCEL system usually comes with a lower intake, but we requested a kit without it.

5. Another benefit of the Fast Burn heads is that they are equipped with 1.5:1 roller rocker arms, and when combined with hydraulic roller lifters and a 0.509/0.528 lift steel camshaft that equals 222/230 degrees of intake/exhaust duration measured at 0.050-inch lift. So what does all this mumbo jumbo mean? As the cam rotates (it's turned by the timing chain attached to the crankshaft), its lobes raise the lifters which in turn raise the pushrods that then pivot through the rockers and cause the intake or exhaust valves to open and close, and all this has to happen multiple times every second. The hydraulic roller lifters have less friction and can handle steeper cam lobes (more lift with less duration), which is good for allowing more air in or out. These lifters also require shorter pushrods, which are less likely to deflect so they are more stable and stronger. Then the 1.5:1 rocker arms multiply the movement of the pushrods even more to get longer duration of airflow into or out of the cylinder. Being roller rockers, the friction is again reduced.

6. One small issue we ran into was when the ACCEL Super Ram upper intake runners were bolted to the TPI/Vortec intake manifold, we had to clearance two bolt heads and runner tube slightly for a perfect fit. The crew at Scoggin-Dickey split the difference between the two to guard against any leaks.


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