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

Adding Power With A Zex Nitrous Perimeter Plate

Sean Haggai Dec 1, 2009

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.

chp_01_z Chevy_big_block_zex_nitrous_perimeter_plate_install Aftermarket_power_adder 2/16

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

chp_02_z Chevy_big_block_zex_nitrous_perimeter_plate_install Intake_manifold_spacer 3/16

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

Cost (Approx)

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.

ZEX Nitrous perimeter plate 82048 $680

Zex Jets
NS6501I 0.014
NS6501J 0.016
NS6500M 0.017
NS6500N 0.019
NS6500O 0.021
NS6501H 0.024
NS6501K 0.025
NS6500P 0.026
NS6501G 0.028
NS6500Q 0.030
NS6500A 0.032
NS6501F 0.033
NS6500B 0.034
NS6500C 0.035
NS6500D 0.036
NS6500E 0.038
NS6500F 0.040
NS6500G 0.043
NS6500H 0.046
NS6500I 0.052
NS6500S 0.053
NS6500R 0.054
NS6501E 0.056
NS6501D 0.057
NS6500T 0.062
NS6500U 0.064
NS6501C 0.067
NS6500V 0.072
NS6500J 0.073
NS6500W 0.074
NS6501B 0.076
NS6500K 0.078
NS6500L 0.082
NS6500X 0.083
NS6500Y 0.088
NS6501A 0.105
NS6500Z 0.125


Westech Performance Group
Mira Loma, CA
Memphis, TN 38118



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