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383 Chevy Small Block LS1 Engine Build - LS Resurrection

Building A Carbureted 383 Gen III Stroker With Turn Key Engine Supply

John Nelson Dec 1, 2008

As the old saying goes, "The end of one man's garage space is the start of another man's project." OK, we made that up. Nevertheless, it's true for so many of us-we tenaciously hang onto parts or engines or even entire cars, certain that sometime in the future we'll actually make something of our cache of go-fast goodies. Often, however, that future happens for the next guy-the one who gets a smokin' deal when all that stuff just finally has to go. In this case, the treasure to be had was a complete LS1 engine with a spun bearing, minus coil packs, available for a ridiculously low $250 when the previous owner just had to get it out of his garage. You can be sure we'll be putting this bargain find to good use, starting with its re-creation by Turn Key Engine Supply into a stout-and carbureted-383 stroker.

The decision to add some capacity to this LS1 ended up being something of a no-brainer. The motor had to come apart, and the damage caused by the spun bearing was severe enough to require a new crankshaft. Therefore it made sense to increase the stroke and add some displacement to our Gen III creation. In fact, this is really the only practical way to gain more cubes with the aluminum LS1 block, since bore increases are limited with the factory pressed-in cast-iron liners. A very minimal overbore-0.005 inch to 3.905 inches-along with an increase in stroke from 3.62 to 4.00 inches, yielded that magic Chevy stroker number: 383 ci.

As for component choice in the lower end, we plan to lean on this thing pretty hard, so we wanted to create a bulletproof short-block. The factory six-bolt main configuration is a more-than-solid foundation. Once it was filled it with a 4340 forged-steel Lunati crank and 4340 rods (6.125 inches long, a hair longer than the factory 6.098 pieces) along with JE Forged Side Relief (FSR) pistons that brought us in at a pump-gas-friendly 10.3:1 compression ratio, we knew we'd devised a bottom end that could handle anything we threw at it. And by "anything," we mean forced induction. But that's another story.

When it came to our heads and cam combo, we were primarily focused on making high-rpm horsepower, hopefully without totally sacrificing lower-end grunt. We went for the bottom-of-the-page choice and picked out a Comp Cams XER287HR. It's a big cam for an LS motor. According to Comp's Billy Godbold, the engine's basic architecture incorporates a very stiff valvetrain (thanks in part to the cam's 55mm core size). What does this all mean? The lobes are quicker, for one, getting the valves open further, faster. It also means that less duration is lost to valvetrain deflection, so they stay open longer. In short, the engine gets every bit of lift and duration promised on the cam card.

We teamed the big 'stick with AFR's 205cc LS1 Mongoose heads, which enabled us to kill two birds with one stone. On the one hand, these heads flow extremely well and are designed to accommodate LS1, LS2, or LS6 powerplants displacing as much as 408 ci, so they lend themselves to the high-rpm power we were seeking. On the other hand, the 205cc intake openings are designed to maintain high port velocity, which helps out with bottom-end power. "At low speeds, smaller ports do a better job of filling the cylinders," says AFR's Tony Mamo. "They really shine in the real world, making the engine more responsive at in everyday, part-throttle situations. These types of gains are rarely measured on a dyno, as most testing is done at WOT."


1. We topped our Victor Jr. LS1 manifold with a Holley 750 Street HP carb; best power numbers were obtained with a Wilson Manifolds 1-inch tapered combo spacer in place.

2. MSD's 6LS ignition controller is a real plug-and-play deal. You can use preprogrammed timing curve modules or program it with a laptop if desired.

3. MSD coil packs and Super Conductor wires provide higher-energy sparks for hi-po setups.

4. AFR 205cc LS1 Mongoose cylinder heads flow big numbers with high port velocity-the Holy Grail of head design.

5. This bargain-find Gen III block is filled with bulletproof internals from Lunati, JE, and Comp.

6. Need a little bling on your LS? The chrome balancer and bolt from Turn Key runs $225.

7. QTP makes this trick two-piece timing cover, allowing cam changes without disturbing the crank pulley.

Although most of Turn Key's Gen X engines are fuel injected-and we intend to try out EFI on this particular engine-we decided to go carbureted for this project. "We'll cater," said Turn Key's Kory Enger, so we bolted up an Edelbrock Victor Jr. LS1 manifold and teamed it with an MSD 6LS ignition controller. While we were looking to save a few bucks compared to the cost of an EFI system, the setup we used had one big advantage: simplicity. And sure, we're saying that installing the manifold, slapping on a carb, and dialing it in was simple. But the same thing goes for the MSD ignition controller-it truly is plug-and-play, especially if you go with one of the preprogrammed timing curve modules. How simple was it? This writer actually hooked most of the harness up, minus the power and ground wires. With that done, all that was left was to fire her up and have at it.

When all was said and done, it was hard to be disappointed with the results: 560 hp at 6,500 rpm, along with 505 lb-ft of torque at 5,100 rpm. And despite our emphasis on the upper end, we still managed a pretty broad torque band, maintaining 400-plus lb-ft from 3,300 rpm all the way to the end of the run at 7,000. They're good numbers, especially when you consider that we're dealing with only 383 ci and 10.3:1 compression. There's more in store for this thrown-away LS, but we're off to a good start. Check it out.

Quick Notes
What we did
Turned a cast-off LS1 into a potent stroker motor

Bottom line
We got big-block horsepower numbers from an aluminum small-block

Cost (approx)


Air Flow Research
Valencia, CA 91355



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