One of the really cool things about magazine engines is that we continually get to "revisit" them and monitor their progress. One such project was first seen in our June '01 issue, called "A Stroke of Genius." It involved the buildup of a 391-cid small-block using an effective, yet unconventional, offset-ground crankshaft and rods with the small 327 journal size to yield the extra cubic inches. We followed the buildup over the next two issues and finished with a dyno flogging at Vrbancic Brothers Racing Engines in the August '01 issue.
Then, we revisited the 391 once again in the November '01 issue where we abused it on the dyno in an attempt to see just how much nitrous we could pump into a street motor before it blew up. That test revealed some interesting results. The most important thing we got out of it was that nitrous motors really need some high-octane race gas to live with anything above a 150hp shot. Due to our insistence on running only 91-octane fuel, the engine broke and was summarily shelved for several months until we could figure out a cool approach for its next story. That begins now.
We pitched the idea of setting up the "Genius" stroker to test some Holley street EFI equipment to its original builder, Hye-Tech Performance in La Puente, California. They agreed that it would be a cool idea and began rebuilding the engine near to its original, pre-nitrous-destruction specs. That means a new set of 10.4:1 JE pistons were hung off the original C.A.T. Power 5.7-inch rods with a new Total Seal gapless ring set replacing the damaged pieces. Clevite supplied some new rod and main bearings, and the bottom end was complete.
Hye-Tech Performance rebuilt the long-block using all the same components as before, inclu
Since EFI is currently the hot ticket when it comes to making everyday-reliable street power, we thought we'd add a new Holley Stealth Ram to this stroker to see what it's made of. One thing that had to be changed to work best with the new EFI system was the cam because the solid nitrous grind we had in it before just wouldn't do. So a call was made to Lunati for one of their hydraulic roller EFI grinds, since that'd be a cool way to cruise. With the new cam in the block we tackled installing the Holley Stealth Ram kit. After reading the Holley instruction manual, figuring out where each of the multitude of wires plugged in was fairly simple. Then, to see what this thing could do, we trucked it back over to Vrbancic Brothers Racing and bolted it onto the DTS dyno for its third flogging.
There's another benefit to building magazine test engines. When the people that make the parts we're testing, Holley in this case, want to be sure that we get the best results possible, they'll send a representative out to "supervise" our test sessions. We love that because it means we've got another more-experienced soul in the dyno cell to bounce questions and ideas off of, and if we run into problems, they'll have a much better chance of getting them corrected back at the shop than we would on our own.
For this test, Holley's Doug Flynn came armed with his mighty laptop and was able to tune some impressive figures from our otherwise docile Mouse. The thing to remember with the Stealth Ram kit is that it's not designed to make gobs of power. Rather, its sole purpose is to give its owner smooth cruising, reasonable economy, and easy tunability, all in a package that anyone with a toolbox and a laptop could install and tune. Don't get us wrong; at first this thing was a bit hard to figure out, but once we got all the wires plugged into their correct spots and fired it up, Doug showed us that dialing it in was a piece of cake.
Installing the Stealth Ram intake manifold was no more difficult than installing a regular
The injectors get pushed into the cast-in bungs on the intake manifold, and the fuel rails
The plenum box sits on top of the runners and needs to have this vacuum hole plugged if yo
This is the power we made using a relatively small hydraulic roller cam with 1.6:1-ratio r
The twin throttle body gets bolted onto the plenum next and the Idle Air Control Valve (IA
Note how the horsepower smoothly kept climbing until it peaked and, even then, just barely