RHS Head Swap - LQ=HP

A Bumpstick Swap and a Set of RHS’ New Heads Make a Truck Motor Really Haul.

John Nelson Dec 28, 2011 0 Comment(s)
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For our final test, we bolted on a set of RHS’ new Pro Action cathedral-port heads for LS applications. These new lungs, which use Clean Cast Technology to maintain more precise tolerances than are normally found in an “as cast head”, bumped our engine’s compression ratio up to 11.41:1 (due to its 62cc combustion chamber) and added a 225cc intake runner. The extra air and bump in compression allowed our transformed truck engine to really take off, recording 521 hp at 6,300 rpm, along with 476 lb-ft of torque at 5,000 rpm. If the engine is turned on, it’s making more than 400 lb-ft. That’s a total increase of 105 hp more than the carbureted stock long-block version, along with an extra 37 lb-ft of torque at the peak of a much fatter torque band. It’s also a 16 lb-ft and 26hp improvement over the stock lungs. This rejuvenated truck lump makes lots of useful torque throughout the powerband, and it now has a great top end. It should make for one snappy, fun-to-drive Chevelle. We’ll let you know.

1202chp 07 O  Rhs Head Swap Pistons 2/15

LQ9 Shopping List

PN Description Price
ARP 134-3609 High Performance Series cylinder head bolts $170
134-2001 carburetor studs 18
130-2001 intake manifold bolts 31
COMP Cams 26918-16 valvesprings 188
7795-16 Hi-Tech pushrods, 7.375 inches 136
54-428-11 XR281HR camshaft 370
Edelbrock 41183 coil covers 215
71187 LS1 Performer RPM 266
Fel-Pro 1161L/1161R MLS head gaskets 192
1312-3 intake manifold gaskets 26
Holley 0-86770BK Ultra Street Avenger Carburetor 500
302-1 LS Retro-Fit oil pan 400
MSD Ignition 6010 LS6 Timing Control Module 320
RHS 54302-05TS Pro Action 225cc cathedral port heads (assembled) 1,470
TCI 399753 LS1 168-tooth flywheel 215
TOTAL $4,517

Baseline

Holley 770-cfm Ultra Street Avenger
Jets: 73/81 primary/secondary
Headers: 13/4 Kooks long tubes with 18-inch extensions
Fuel: 91-octane unleaded
Advance: 33 degrees
RPM LB-FT HP
3,100 421 248
3,200 419 256
3,300 422 265
3,400 426 276
3,500 429 286
3,600 431 295
3,700 433 305
3,800 435 314
3,900 436 324
4,000 438 334
4,100 439 343
4,200 438 351
4,300 437 358
4,400 437 366
4,500 436 374
4,600 434 380
4,700 431 386
4,800 429 392
4,900 425 397
5,000 422 402
5,100 418 406
5,200 413 409
5,300 408 412
5,400 402 414
5,500 396 414
5,600 390 416
5,700 384 416
5,800 377 416
5,900 370 416
6,000 363 415
Average Torque 418
Average Power 360

Stuff to make it fit

Looking ahead, we had many of the pieces that we’ll need when this mill takes up its new residence under the hood of a ’66 Chevelle. One of these is Holley’s new LS Retro-Fit oil pan. According to Holley, this slick casting provides maximum chassis clearance for GM rear-wheel-drive applications, small-block or big-block, as long as it came with a rear sump oil pan. It also comes with a sump baffle, pickup tube, sump plug, oil filter stud, and an oil passage cover.

1202chp 08 O  Rhs Head Swap Oil Pan 6/15

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