This is a story of wanton destruction. At least it started out that way. A year or so ago, when I was the editor of Chevy High Performance, we decided to see how much nitrous a stock, junkyard small-block Chevy could take before it grenaded. So we rounded up a high-mileage 350 out of a '75 Chevy from our friends at Memory Lane, a recycling yard that specializes in '73-and-earlier vehicles.
In short order, we bolted in a Comp Cams nitrous camshaft to give the little Chevy some real power potential along with new valvesprings (so it wouldn't float the valves at 4,500 rpm) and a single-plane intake to accommodate the nitrous plate. We also bolted in new Fel-Pro head gaskets in the hope the nitrous wouldn't push the gasket out before it blew up. The horsepower came in a big yellow bottle from Barry Grant's Nitrousworks in the form of a dual-stage plate kit. The maximum power we could add was 425 hp, and we figured that would be enough.
Before we could bolt the engine on the dyno, Westech's dyno man Steve Brule wanted a signed statement stating that we'd clean up the mess after the Mouse motor expired. We had a feeling that it was going to be less spectacular than that, but we humored him. After breaking in the new cam, we loaded the engine with a normally aspirated test first just to ensure the engine was going to be OK. Our paltry performer surprised us with an impressive 310 hp peak at 5,200 and 344 lb-ft of torque.
We quickly hit the engine with a one-two punch of 100hp and then 200hp nitrous hits that the engine handled without a whimper. With the 200hp kit, our mighty Mouse was steamin' at 521 hp with 587 lb-ft of torque! Next, we hit it with 300hp and saw the power shoot up to 599 hp and 655 lb-ft of torque. When we re-baselined the normally aspirated combo, our little hero small-block stepped up with 325 hp, an increase of 15 hp over the previous baseline. We attributed this to better ring seal after the nitrous knocked the carbon off the rings! Now we were ready for the big squeeze!
At this point we loaded all the nitrous the small kit would push (a 400hp shot) and got ready to really thump on this junkyard jewel. Not thinking too clearly, we also decided to internally purge the system at idle. Even just flicking the nitrous button was enough to rock the little engine almost right off the stand. Unfortunately, this little trick also knocked the ring lands off three of the cast pistons on the right bank--our day was done.
The autopsy later revealed that except for three broken pistons, the engine survived remarkably well. This is when replays of the TV show The Six-Million Dollar Man began playing in our heads: "We can make him better--we have the technology." The cylinder walls were basically undamaged, so we dumped the ailing motor at Ed Taylor's doorstep and said, "Fix it." Now that's a dangerous thing to say to our resident torque-wrench spinner, so we quickly put limits on what Ed could do our boneyard-beater.
The limits came down to adding a set of Federal-Mogul flat-top forged pistons, new 5/64-inch rings, and a set of Federal-Mogul rod and main bearings. We didn't even allow Ed to use the Sunnen machine to hone the cylinders. Instead, we forced him to use one of those bottle-brush hones. Ed added new Fel-Pro head gaskets mainly because we wanted to put as much pressure on the pistons as possible. To give the head gaskets a fighting chance against the nitrous onslaught, we also used a set of ARP head bolts and told Ed to crank down on the torque to really squeeze the gaskets. There was talk of welding the heads on, but we passed on that idea only because it sounded a bit over the top.
We decided to reuse the Comp Cams NX268 cam, 1.5 stamped rockers, and the stock heads since they survived the first flogging unscathed, as did the single-plane intake and Demon 750-cfm carburetor. From our prior experience, we figured the original dual-stage 450hp Nitrousworks kit we used the first time around would still be enough. If need be, we could always step up to one of Nitrousworks' Magnum "X" Dual Stage Systems. This system can flow up to 550 hp on the second stage, which suited us just fine.