We first teamed up with Brian Hafliger of IMM Engines in Indio, California, in our June ’10 issue. We documented his build of a stout 408ci 360 stroker that made 485 hp with cast-iron RHS cylinder heads. In the months since, we kicked around the idea of investing a little more, going bigger with the cylinder heads and cam specs, and shooting for 600 hp with the same 360-based engine. After several months of gathering parts, we drove back out to the Coachella Valley to watch this version come together and run on IMM’s DTS dyno. We were thrilled to see the horsepower numbers soar past our goal of 600, with the needle finally indicating 621 hp at a thundering 6,800 rpm. Torque numbers weighed in at an equally impressive 541 lb-ft at 5,100 rpm. In a 3,500-pound Duster, this engine will do low 10s at the dragstrip all day long and sound awesome doing it. Interested in how IMM pulled this off? Let’s get to the build.
Cylinder Head Flow
Stock Edelbrock IMM Ported Combustion chamber 64 72 Intake runner 171 195 Intake valve 2.02 2.08 Exhaust valve 1.60 1.60
Stock Edelbrock Intake Stock Edelbrock Exhaust IMM Ported Intake IMM Ported Exhaust 0.200 129 108 154 112 0.300 188 142 224 151 0.400 232 171 272 190 0.500 249 183 295 205 0.600 251 190 299 218 0.700 N/A N/A 305 224
On the Dyno
Test 1: Check out the numbers from IMM’s DTS Dynamometer. Right out of the gate, IMM’s 414 nailed our 600hp goal. The Holley 1000HP was untouched with 82/90 jets, and Hafliger set the timing to 32 degrees total. The headers are from TTi with 17⁄8 primaries and 3-inch collectors.
Test 2: Adding a 1-inch open spacer increased torque everywhere and netted a notable gain in peak horsepower.
Test 3: Real Ultimate Power came when Hafliger plopped on the 1050 Dominator and headers with slightly larger 31⁄2-inch collectors.
Test 1 Test 2 Test 3 RPM HP TQ HP TQ HP TQ 4,000 331 434 334 438 324 426 4,100 349 447 348 446 344 441 4,200 366 457 367 458 367 458 4,300 384 469 384 469 387 472 4,400 400 477 402 479 409 487 4,500 415 485 419 488 429 501 4,600 433 495 435 497 449 513 4,700 450 503 453 506 467 522 4,800 467 511 469 514 484 529 4,900 481 516 485 519 499 535 5,000 491 516 499 524 514 540 5,100 509 524 508 523 525 541 5,200 519 524 515 520 534 539 5,300 523 519 529 524 540 535 5,400 526 512 531 517 547 532 5,500 535 511 544 520 553 528 5,600 544 510 552 518 560 525 5,700 548 505 560 516 561 517 5,800 561 508 567 514 577 523 5,900 567 505 567 505 578 515 6,000 564 494 574 502 586 513 6,100 566 487 578 497 593 510 6,200 584 495 582 493 600 508 6,300 587 489 586 488 608 507 6,400 590 484 603 494 614 504 6,500 605 489 600 484 613 495 6,600 605 481 613 487 621 494 6,700 602 471 615 482 619 485 6,800 602 465 621 480
Parts List
Description PN Source Price Dodge 360 block N/A eBay $125.00 Block prep and machining N/A IMM Engines 650.00 Scat 360 stroker kit 9-360-4000-6123 IMM Engines 1,600.00 Harmonic damper 301 Innovators West 375.00 Master gasket kit 95-3343-VR Victor Reinz 120.00 Oil pump MEL-M72 Summit Racing 25.95 Oil pump drive MEL-IS-72 Summit Racing 39.95 Viton rear main seal 9360 Superformance Products 40.00 Cylinder heads, bare 60769 Edelbrock 1,199.00 Cylinder head porting and assembly NA IMM Engines 1,600.00 Intake valves 11558-8 Manley 134.95 Exhaust valves 11863-8 Manley 115.95 Valvesprings 917-6 Comp 179.00 Retainers 23657-16TI Manley 249.00 Locks 13194-16 Manley 29.00 T&D rocker arms 8008 T&D Machine 1,095.00 Cylinder head gaskets C5622-040 Cometic 90.47 Pushrods 502 Manton 245.00 Lash caps 42104-16 Manley 32.95 Camshaft Custom IMM grind—ask for it Comp 375.00 Cloyes billet steel timing set CLO-9-3503X9 Summit Racing 99.95 Lifters 8043-16 Comp 598.75 Super Victor intake manifold 2815 Edelbrock 339.95 Intake manifold gaskets 169104P SCE 24.00 Intake manifold porting N/A IMM Engines 450.00 4150 HP carburetor, 1,000 cfm 0-80514-1 Holley 785.95 Plastic, 1-inch open carb spacer 8710 Edelbrock 30.95 Pro-Billet Distributor 8534 MSD 204.95 Distributor drive P3690874 Mopar Performance 214.95 Ignition wires 32749 MSD 84.95 NGK R5672 A-8 7173 IMM Engines 21.52 Ceramic coated 17⁄8 headers with 31⁄2-inch collectors TTI340BE178-C4 TTI 776.00 TOTAL $11,953.14
