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CPR-E FLOW NUMBERS This chart compares the stock 243 LS1 cathedral port head with CPR-E’s CNC-ported, 227cc version with 2.02/ 2.160-inch valves, a CPR-E valve job and some minor hand blending. The E/I column is the exhaust-to-intake flow relationship. Generally, a higher percentage of exhaust flow compared to the intake requires less additional exhaust lobe duration to help the engine make horsepower. Valve Lift

Stock Intake Stock Exh.

0.100 0.200 0.300 0.400 0.500 0.600 0.625

64 139 193 215 228 236 —

CPR-E Intake

CPR-E Exh.

E/I

68 131 193 243 279 302 304

61 114 161 193 219 230 —

90% 87% 83% 79% 78% 76% —

55 102 138 175 189 199 —

Camshaft

Dur. at 0.050” lift

Valve Lift (in.)

Lobe Sep. Angle

Stock ’02 LS1 Intake Stock LS1 Exhaust COMP LSr Intake COMP LSr Exhaust

196 201 219 227

0.479 0.467 0.607 0.614

116 --112 ---

RPM 3,000 3,200 3,400 3,600 3,800 4,000 4,200 4,400 4,600 4,800 5,000 5,200 5,400 5,600 5,800 6,000 6,200 6,400 Peak Avg.

TQ1 446 464 477 486 494 495 499 507 513 516 514 508 500 490 477 463 448 429 516 484.8

HP1 255 282 308 333 358 377 399 425 449 472 490 503 514 523 527 529 528 523 529 433.1

TQ2 456 471 483 494 502 504 510 519 526 528 525 522 519 512 498 485 471 454 528 498.8

HP2 260 287 312 339 363 384 408 435 461 483 500 517 534 546 550 554 556 553 556 446.8

TQ + 10 7 6 8 8 9 11 12 13 12 11 14 19 22 21 22 23 25 12 14.0

HP + 5 5 4 6 5 7 9 10 12 11 10 14 20 23 23 25 28 30 27 13.7

For more charts, including the dyno results, search “Real World” at PPNDigital.com.

With the FAST manifold and larger throttle body bolted on, the 383 again pushed through the power curve and after a little WOT-tuning on the stock ECU, the numbers surged. the entire rpm span from 3,000 to 6,400 rpm. There aren’t too many aftermarket parts that can pull off that kind of broad power magic across a 3,400-rpm span. As for the specific numbers — the most important really isn’t the peak torque at 528 lb-ft at 4,800 or even the 556 peak horsepower number. The most impressive number is the average 14 lb-ft improvement across the entire power curve. Add to this a minimum of 500-plus lb-ft from 3,800 rpm to 5,600 rpm and the fact that the torque never dropped below 450 lb-ft over the entire curve, and those are some outstanding numbers. True, all this comes at a price. The induction package comes to more than $2,000 for the manifold, throttle body, fuel rails, and injectors. But short of a supercharger or nitrous, it’s hard to come up with something that can add power across such a broad power band. That means this engine will deliver excellent drivability and fantastic acceleration while still delivering near-stock idle characteristics. This engine should also be able to pass a California emissions test even with the LSXr manifold in place since it has a California Executive Order (E.O.) number, making it a legal manifold with the smog police. Owner Livezey is currently hunting for a set of headers that also offer the same E.O. clemency. Of course, there’s bound to be a minor power loss when the engine is bolted in the car since it will have to breathe through the Corvette’s street exhaust system, but that should present only a minor decrease. Frankly, the torque will probably suffer the least, and that’s exactly what Livezey intends to rely on the most. As we said,

After baselining the 383 with the stock LS6 intake, CRP-E bolted on the FAST LSX-r intake along with a 102mm Big-Mouth FAST throttle body and pulled the handle again. Just changing to the FAST intake and throttle body was worth 30 more horsepower at the top and a generous torque increase everywhere. Those are the kind of changes that will put a smile on your face.

Livezey is an autocross racer, so you can expect to see his ’04 Corvette at more than its share of local Los Angeles autocross challenges. Be prepared to discover he is quick behind the wheel!  Sources: COMP Cams; compcams.com; Custom Performance Racing Engines (CPR-E), cprengines.com; Fuel Air Spark Technology (FAST), fuelairspark.com; King Bearings, kingbearings.com; Melling Automotive Products, melling.com; PAC Racing Springs, racingsprings.com; RaceTec Pistons (Auto-Tec), racetec.com; Racing Parts Maximum (RPM), racingpartsmaximum.com; Scat Enterprises, scatenterprises.com; SI Valves, sivalves.com PPNDigital.com 35

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Power & Performance News Spring 2016  

Built upon a Resto Mod theme, this issue of Power & Performance News is packed full of DIY performance projects, car features and hardcore t...

Power & Performance News Spring 2016  

Built upon a Resto Mod theme, this issue of Power & Performance News is packed full of DIY performance projects, car features and hardcore t...

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