L89 427 Big-Block Engine Build - L89, Version 2.0

We Recreate The Iconic L89 427 With Aftermarket Parts And Make A Lot More Power.

The idea was to recreate the L89 427 with all aftermarket parts just to see if we could best the GM power numbers. What we didn't know until we chucked the motor on a dyno is we built a little 427 that is knocking on the door of the race-only L88. Not only did we build a pretty healthy engine, we did it without pushing everything to the limits. If we want to expand our pump-gas 427-or we should say our 0.030-over 427 (433ci)-it can be built up into the 600ci range because we used an aftermarket block. Funny how we are calling a 427 small-man, how things have changed.

Sucp_1101_19 L89_427_big_block_engine_build Dyno_testing 1/20

Last month, we covered how to blueprint an engine using this engine as the guinea pig. This story will cover the parts recipe and dyno tuning of the rev-happy Rat. Instead of trying to find a clean block out of the junkyard or swap meet, we decided to start with something better. Dart's Big M iron block will be the foundation for the build. Inside the block, we used an Eagle forged 4340 chromoly-steel crankshaft, Eagle I-beam rods, and forged JE 30cc domed pistons.

To make sure this 427 sounded as nasty as possible, we ordered up a Big Mutha' Thumpr cam from Comp. Let us tell you, this cam does thump. Again, instead of trying to find a factory set of painfully expensive, rare aluminum heads, we grabbed a set of Darts new 275cc Pro 1 oval port castings. These heads have many cool features that make them better than factory, but we will get into that later. To cap off the top end, we picked up a Weiand Stealth dual-plane intake manifold and a Holley 750 CFM Street HP carburetor. Providing spark is a digital E-Curve distributor from MSD. It's a billet aluminum small body distributor that has a digital module inside so you can set the timing curve with two rotary dials.

Now that you have an idea of the components we used to build our version of the L89, let's get into the good stuff. Jeff Strech from Speed-O-Motive took time out of his busy schedule to finish assembling our long block and tune it on the dyno.

DYNO NUMBERS

RPM Power Torque
3,000 227 398
3,100 228 386
3,200 234 385
3,300 249 397
3,400 263 406
3,500 281 422
3,600 298 435
3,700 280 398
3,800 304 421
3,900 324 436
4,000 339 446
RPM Power Torque
3,500 290 436
3,600 306 447
3,700 320 454
3,800 332 459
3,900 343 462
4,000 355 466
4,100 365 468
4,200 372 466
4,300 378 461
4,400 383 457
4,500 390 456
4,600 398 455
4,700 408 456
4,800 417 456
4,900 427 458
5,000 437 459
5,100 449 463
5,200 461 466
5,300 470 465
5,400 478 465
5,500 481 459
RPM Power Torque
3,500 302 453
3,600 316 461
3,700 328 466
3,800 338 467
3,900 348 469
4,000 357 469
4,100 367 471
4,200 374 468
4,300 379 463
4,400 386 461
4,500 393 459
4,600 401 458
4,700 410 458
RPM Power Torque
4,800 420 460
4,900 430 461
5,000 440 462
5,100 452 466
5,200 464 469
5,300 472 467
5,400 480 467
5,500 484 462
5,600 490 459
5,700 495 456
5,800 500 453
5,900 504 449
6,000 507 444
RPM Power Torque
3,500 302 454
3,600 317 463
3,700 328 466
3,800 340 470
3,900 350 472
4,000 361 474
4,100 370 474
4,200 377 471
4,300 384 469
4,400 390 465
4,500 395 461
4,600 402 459
4,700 411 459
4,800 419 459
4,900 429 460
5,000 441 463
5,100 452 465
5,200 464 469
5,300 474 470
5,400 483 470
5,500 487 465
5,600 492 462
5,700 499 459
5,800 506 458
5,900 510 454
6,000 515 451

Sources

Comp Cams
Memphis, TN 38118
800-999-0853
http://www.compcams.com
ATI Performance Products
Baltimore, MD 21207
877-298-5039
www.atiracing.com
Dart Machinery
Troy, MI 48084
248-362-1188
www.dartheads.com
JE Pistons
Huntington Beach, CA 92649
714-898-9763
www.jepistons.com
Eagle Specialty Products, Inc.
Southaven, MS 38671
662-796-7373
www.eaglerod.com
Speed-O-Motive
West Covina, CA 91790
626-869-0270
www.speedomotive.com
Ansen
Torrance, CA 90505
310-534-1837
www.ansenusa.com
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