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Old 06-21-2011, 05:43 PM
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eric32 asked me to run a sim on his motor on a PM. I thought I may as well post it on here for everyone to see. This is a very mild 355 with 9.1:1 static compression ratio, low-rise intake manifold, 600 carb, ZZ4 cam installed straight up. He didn't tell me about the exhaust system, but I'm assuming 1 5/8" long-tube headers. Heads are RHS 180's which I factored down to 95%.
1500 109 382
2000 155 406
2500 193 405
3000 230 402
3500 275 412
4000 302 396
4500 316 369
5000 313 329
5500 290 276
Peak volumetric efficiency 86.3% @3500
Peak BMEP 174.8 @ 3500
Motor makes 400+ ft/lbs of torque from 1800 to 3800, right in the street driving range and should operate detonation-free on cat pea pump gas. Low-rise intake is a power killer. A change to a high-rise, dual-plane intake would add 51 horsepower and 24 ft/lbs of torque according to the DynoSim software.

There's just no getting around it, you have to get the carburetor up off the motor in order to make power. The over and under runner system on a low-rise, dual-plane intake just doesn't work well. On some motors, like the big 472 and 500 Cadillac, the runners were so screwed up that the mixture went uphill to get to the head ports. You can get around it with a single plane intake, but then you are stepping into another rev range for the motor (4000-8000), whereas the dual-plane works well from idle to 6000.

Last edited by techinspector1; 06-21-2011 at 05:53 PM.
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