Project Excursion Killer, Part 1

Put your ARCA rockcrawler on the trailer and forget about your 200:1 gear reduction, because it's time to go fast! Seems like everyone these days has got it in their minds that four-wheel drive is only for going slow, so we wanted to show you how much fun it is to travel at lethal speeds when you build a vehicle that can handle it.

Consider this phase one of a three-part story where we'll show you how we built a street-legal pre-runner out of a '01 Chevrolet Suburban. Some of the things we'll do with this truck will be more race than street, and others will be more street than race. Don't feel left out if you don't own a late-model GM (or if you don't own a GM at all) because secretly we positioned a '73 GM truck chassis under the late-model Sub's sheetmetal.

To make sure this buildup came together before they outlaw the internal combustion engine, we enlisted the talents of Maurice Rozo and the staff of Off Road Unlimited in Burbank, California, to help us with the project. We knew ORU would be up to the task of building this kind of high-end project because they helped us two years ago with the buildup of our 4xQuad project Dakota (Mar., Apr., May, and June 2000 issues).

We begin this month by tackling an engine swap no one has ever shown you before. Working closely with Chevrolet we scored a new 8.1L Vortec engine from a '01 3500 truck. We were psyched to find out that this is more of a bolt-in than we would have ever dreamed. The toughest part of the swap will be making the factory fuel injection work in another chassis, but since this is 4-Wheel and Off-Road we've got that covered too.

Next month we'll show you how the slick suspension went together with coilover and bypass shocks. We'll walk you through the plumbing and electrical, and give you a look at the tricks desert racers use to cool 800hp engines in 100-degree heat. We'll wrap it all up in July with a shakedown run on the open desert to show you what this thing can do. See you at the finish line.

The foundation for our '01-bodied...        read full caption The foundation for our '01-bodied Suburban is actually a '73 Chevy pickup truck frame that's been reinforced with a cage made of 0.135-wall chromoly tubing. We chose this frame so the truck could be registered as a pre-smog vehicle in order to run the new 8.1L engine we wanted. Off Road Unlimited knew early on that the stock frame would need a lot of work to mount the engine and suspension we wanted. So they chopped off the rear half of the frame and added a new C-notch frame section made from 4x4 square tubing to give the heavily gusseted 14-bolt room to travel.	Unless you work at the Tonawanda,...        read full caption Unless you work at the Tonawanda, New York, assembly plant, this is probably the first time you've ever seen the new Vortec 8.1L (that's 496 very nasty cubic inches) big-block on an engine hoist. This one came to us directly from Chevrolet, but it's rumored a GEN VI crate engine from GM Performance Parts is in the works. In the factory HD truck trim these mills produce 340 hp and 455 lb-ft, but in our nonemissions marine trim (no smog pump, no EGR, a set of headers, and a trick new EFI controller) it puts out an estimated 420 hp and 505 lb-ft of torque. Here you can see how we routed the original serpentine belt to work without the A/C compressor or smog pump.	ORU fabricated this engine...        read full caption ORU fabricated this engine plate to mount the 8.1L lower and farther back in the chassis than stock for better weight distribution. When installed in our pre-runner the top of the 8.1L will sit beneath the level of the driver's thigh for a snake-belly-low center of gravity. Sharp-eyed readers will notice that GM hasn't changed the traditional Chevy 90-degree V-8 bellhousing pattern on its new Vortec engines. That meant we could bolt up the 8.1L to a JET-prepped TH400 and stall converter instead of the Allison 1000 or 4L80E that the factory uses.
More good news. The 8.1L is...        read full caption More good news. The 8.1L is internally balanced and will accept the old 14-inch, 168-tooth, neutral balance flexplate from a 396 or 427. Just don't try to run an externally balanced (weighted) flexplate from a 454 as it will damage the 8.1L's reciprocating assembly. Taking all this information to the next step tells us that an Allison 1000 transmission will bolt up to any internally balanced Chevy V-8!	It gets even better. Even...        read full caption It gets even better. Even though GM has adopted a new engine-mount location on the new Silverado chassis, the old GM engine-mount pad is still cast into the 8.1L blocks. Want to bolt an 8.1L in where a 454 came out? No problem. For our pre-runner ORU fabricated these solid front engine mounts to work with the rear engine plate to make sure it stays put no matter how high we sky it.	We wanted to run a mechanical...        read full caption We wanted to run a mechanical throttle cable but all 8.1L engines use a drive-by-wire electronic throttle, which means we would have to use the factory engine control module (ECM). We didn't want to so we contacted BBK and had the comany send us one of its 80mm throttle bodies for an LS1, engine and it bolted right on.
Headers make more power than...        read full caption Headers make more power than factory exhaust manifolds, but no one makes a full-length tube header for the 8.1L yet. We had Morse Muffler in Burbank, California, TIG-weld us a set of tubes from mandrel-bent 304 stainless with 1/2-inch-thick flanges. These pieces were beautifully crafted to awaken the Rat-bread power from an otherwise stock engine. The headers flow to dual 21/2 stainless Borla mufflers that exit in front of the rear wheels with a ferocious pro-stock exhaust sound.	We knew we were going to run...        read full caption We knew we were going to run an external Fluidyne oil cooler mounted at the rear of the Suburban, so we asked System 1 to build us a prototype oil pump to make sure we could move the oil over 13 feet through the system. The best thing about this pump is that the oil pressure is externally adjustable with an Allen wrench when you remove the access plug ORU added to the aluminum oil pan.	We'll just tease you a little...        read full caption We'll just tease you a little this month with a parting shot of the ORU-designed front A-arm suspension. That's right, the company that pioneered the late-model GM solid-axle swap has gone to the dark side with its first ever solid-axle-to-IFS swap. The trick thing about ORU's design is that it uses a Dana centersection and CV joints to spin 35-spline Dana 60 outer stub shafts. Don't expect to see this IFS ever offered in kit form because it took them weeks to get the geometry right and everything was custom fabricated from the arms to the knuckles.