Chevy Big Block Zex Nitrous Perimeter Plate Install - The Big Squeeze

Adding Power With A Zex Nitrous Perimeter Plate

Sean Haggai Dec 1, 2009 0 Comment(s)

If you recall from our November '08 issue ("A Monster is Born"), Steve Brulé of Westech Performance built a superb naturally aspirated 12:1 496ci big-block. We made good use of its internals too with a solid rotating assembly starting with a Lunati 4.125-inch stroker crank and 6.385-inch I-beam rods. The bores were then plugged with 48cc domed Wiseco pistons and topped with a heavy breathing pair of cylinder heads from AFR to create 12 points of compression. The AFR 325 as-cast lungs we installed flowed 385 cfm on the intake and 285 cfm on the exhaust at 0.700 inch of lift. At the center, we chose a high-lift Comp piece to deliver 274/280 intake/exhaust degrees of duration at 0.050 inch of lift and pulled out a matching set of solid roller Comp lifters. When all was said and done, we planted the mule on Westech's 902 SuperFlow dyno for testing. The bored and stroked combination churned out 780 hp and 658 lb-ft worth of stump-pulling force without even breaking a sweat.

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Fast forward to the present and Brulé was itching for even more power to wring out of the Monster. When the phone rang he presented an idea we couldn't pass up-nitrous, and a whole lot of it, through Zex's Dominator flange nitrous perimeter plate system. What better way than to add more go without shelling out loads of cash. While some builders stay away from it, others like Brulé let it rain down in full force, literally. For the money, you can't deny the simple fact that a blast of nitrous through the intake plenum is the best instant power adder, hands down. When used safely, the amount of horsepower you get per dollar can't be matched by anything else out there. Plus, it's easily adaptable to most engine combinations. The added power from nitrous is obvious, but why is it so potent? To put it simply, nitrous oxide is laden with oxygen. When nitrous is fed down the intake, it's also mixed with extra fuel. By the time it reaches the combustion chamber and ignites with fuel from the carburetor, the extra oxygen from the nitrous is then released, creating massive cylinder pressure.

To prove Brulé wasn't all talk, we were back at Westech's facility to strap the 496ci back down and shoot it full of juice. To back up our previous findings we laid down a base run to 6,600 rpm in which case we were spot on at 779 hp. When Brulé pulled out the Zex perimeter plate, he wasn't messing around and loaded it up with the 250hp pills. How much was the nitrous worth on the dyno? Let's just say the visual chart doesn't do it justice; the beast leaped towards us and produced quadruple digit power figures-yes, it's that easy!

Quick Notes
What We Did
Westech's 496 big-block receives a Zex nitrous perimeter plate with a 250 shot

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Bottom Line
We gain an extra 311 hp with a simple bolt-on and prove it on the dyno

Cost (Approx)
$680

Zex Jets Precision-machined jets are used for adjusting both nitrous and fuel flow. They feature a special internal taper to minimize turbulence resulting in very consistent flow and power. Zex offers jets at $3.50 each.

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