Small Block Chevy Cast Iron Intake Manifold Dyno Charts

Can You Use Some Extra Horsepower?

A stock cast iron intake is the most restrictive item on a small-block Chevy racing engine. Let's face facts: Stock cast iron intake manifolds were designed for passenger cars where the engine never sees 3,500 rpm. In a race application, the engine is never under 3,500 rpm. We have seen lap times reduced a couple tenths of a second with a Brzezinski Racing Products Modified Cast Iron Intake Manifold.

2 Barrel Cast Iron Intake Comparison

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2 Barrel Intake Manifold Compairson
TORQUE INFORMATION (ft.-lbs.)
RPM Stock
 
Acid
Intake
 Stage  1 
 Fully
Modified  
4000 358 360 363 368
4500 326 339 347 354
5000 315 326 330 336
5500 299 310 313 322
6000 257 268 280 286
6500 220 230 240 247
7000 181 194 204 211

Volumetric Efficiency
Stock 2 Barrel 84.3%
Acid Intake Part #201XXXX 86.1%
"Stage 1" 2 Barrel 87.1%
Fully Modified 2 Barrel 88.7%

TEST ENGINE: 355, Stock ’492 heads, flat top pistons, flat tappet cam, headers and stock 500 Holley 2 barrel carb. NOTE: The intake manifolds were the only components changed.


"If you are running Hobby Stock, Limited Late Model, or Sportsman, you couldn't miss hearing about Brzezinski because he is the prime exponent of having the stock cast iron intakes and heads pull more air than ever before.  He has learned all the good part numbers and the ways to make them respond."

-- Alex Walordy, "Cast-Iron Creativity" - Circle Track Magazine. 

Q-Jet 4 Cast Iron 4 Barrel Intake Manifold Compairson

Q-Jet Modified Intake Dyno

 Q-Jet 4 Barrel Intake Manifold Compairson
TORQUE INFORMATION (ft.-lbs.)
RPM Stock
Q-Jet
Stage 1
Q-Jet
Fully
Modified
Q-Jet
4000 375 379 388
4500 356 367 385
5000 344 355 371
5500 323 339 357
6000 285 307 327
6500 251 266 289
7000 221 235 259

Volumetric Efficiency
Stock 4 Barrel 90.7%
"Stage 1" Q-Jet 92.8%
Fully Modified Q-Jet 97.2%
TEST ENGINE: 355, Stock ’492 heads, flat top pistons, flat tappet cam, headers and 750 Holley 4 barrel carb. NOTE: The intake manifolds were the only components changed.

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