Bolt On Parts - Dyno Proven Bolt-ons - Tech
Bolt On Parts - Dyno Proven Bolt-ons - Tech
http://images.chevyhiperformance.com..._bolt_ons+.jpgCan there be any doubt that bolt-ons are the lifeblood of our hobby? Granted, parts that take a bit more time to install-things such as pistons, camshafts, and stroker cranks-can lead to big power gains. But you show us a guy who meticulously builds the perfect, tire-shredding powerplant for his classic Chevy, and we'll show you a guy who still can't resist the urge to bolt on a few more horsepower. The attraction is easy to understand: You buy a part for your application, spend a few hours in the garage bolting said part on, and you make more power. That's the way it's supposed to work, anyway.
And that's the shape of this month's dyno thrash. In a nutshell, we picked out a bunch of bolt-ons, then produced dyno numbers to document actual power gains.
Our methodology for this project was pretty straightforward. For any given part, we had to have before and after dyno sheets in hand to report on that piece's effectiveness. It was as simple as that. No approximations, no unsubstantiated claims. As a gearhead-minded Joe Friday might have said, "Just the facts, man." Much of the data we've collected here came from the test archives of respected dyno facilities, places such as Westech Performance and Vrbancic Bros. Racing. The rest of the info, lest you think we didn't get our hands dirty during this investigation, is the result of a punishing, two-day dyno thrash at Granatelli Motorsports. J.R. Granatelli and his staff, specifically Morgan, Ralph, Martin, and Jeremiah, ran cars on and off the dyno, wrenched when needed, and put in some substantial overtime to make this report possible. When these guys take on a project, they take it on all the way.
In choosing our mules, we tried to pick combos that span the performance spectrum, focusing mainly on traditional small-block performance. We won't claim to be all things to all people, but we think everybody can find some useful information here. Speaking of useful info, we've listed peak power numbers, of course, but note that we've also included average numbers to help you evaluate how a given bolt-on affected performance throughout the powerband. In one case, we were even able to record an increase in gas mileage to go along with our power increase, which was certainly a bonus.
As for the numbers, for the most part, we're gonna let them speak for themselves. Some of the results aren't all that surprising; others, however, were unexpected. All of them are dyno proven, and our hope is that the info here will make your next bolt-on purchase that much easier.
Carburetor
The bolt-on
Our 383ci stroker test bed was fitted with a 650-cfm Speed Demon carb (70/78 jets); we stepped it up to a 750-cfm Mighty Demon mixer (75/83 jets). $550
The mule
'69 Nova with a 383ci small-block stroker running 10.5:1 compression, ported Dart Iron Eagle heads, and a Tremec TKO 600 five-speed trans, with an Edelbrock RPM Air Gap intake manifold and a 650-cfm Speed Demon carb. Power measured at the rear wheels.
Our take
The bigger mixer freed up some upper-rpm power without sacrificing torque, which is right in line with this ride's street/strip mission.
Before
Max torque: 363 lb-ft @ 3,700 rpmMax power: 314 hp @ 5,900 rpmAverage torque: 333 lb-ftAverage power: 278 hp
After
Max torque: 364 lb-ft @ 3,700 rpmMax power: 324 hp @ 5,800 rpmAverage torque: 340 lb-ftAverage power: 285 hp
Difference
+1 lb-ft+10 hp
Intake Manifold
The bolt-on
After outfitting our 383ci whipping boy with a bigger carb, we followed up by replacing the dual-plane Edelbrock RPM Air Gap intake with a single-plane Victor Jr. $196
The mule
The Nova with an Edelbrock RPM Air Gap intake manifold and a 750-cfm Mighty Demon carb.
Our take
As you might expect, the single-plane intake increased top-end horsepower at the expense of low-end grunt.
Before
Max torque: 364 lb-ft @ 3,700 rpmMax power: 324 hp @ 5,800 rpmAverage torque: 340 lb-ftAverage power: 285 hp
After
Max torque: 361 lb-ft @ 3,900 rpmMax power: 335 hp @ 5,800 rpmAverage torque: 361 lb-ftAverage power: 274 hp
Difference
-3 lb-ft+11 hp
Electric Water Pump
The bolt-on
A Meziere WP 321 electric water pump in place of a standard mechanical unit. $550
The mule
The Nova with Edelbrock Victor Jr. intake manifold and a 750-cfm Mighty Demon carb.
Our take
We were impressed with the amount of power gained, and our mule's coolant temperature never broke 190 degrees.
Before
Max torque: 361 lb-ft @ 3,900 rpmMax power: 335 hp @ 5,800 rpmAverage torque: 361 lb-ftAverage power: 274 hp
After
Max torque: 391 lb-ft @ 3,900 rpmMax power: 358 hp @ 5,900 rpmAverage torque: 341 lb-ftAverage power: 293 hp
Difference
+30 lb-ft+23 hp
Underdrive Pulleys
The bolt-on
March serpentine conversion kit with underdrive pulleys: crank, water pump, alternator, and power-steering pump. $476
The mule
The Nova with an Edelbrock Victor Jr. intake manifold and a 750-cfm Mighty Demon carb.
Our take
Reducing accessory-belt drag paid off with big power gains.
Before
Max torque: 361 lb-ft @ 3,900 rpmMax power: 335 hp @ 5,800 rpmAverage torque: 361 lb-ftAverage power: 274 hp
After
Max torque: 391 lb-ft @ 4,000 rpmMax power: 360 hp @ 5,900 rpmAverage torque: 355 lb-ftAverage power: 289 hp
Difference
+30 lb-ft+25 hp
Nitrous
The bolt-on
An NOS Super Powershot carbureted plate nitrous system spraying a 125hp shot. $440
The mule
The Nova with an Edelbrock Victor Jr. intake manifold and a 750-cfm Mighty Demon carb.
Our take
Even a fairly mild motor can put up big numbers on the juice.
Before
Max torque: 361 lb-ft @ 3,900 rpmMax power: 335 hp @ 5,800 rpmAverage torque: 361 lb-ftAverage power: 274 hp
After
Max torque: 559 lb-ft @ 3,500 rpmMax power: 429 hp @ 5,200 rpmAverage torque: 463 lb-ftAverage power: 392 hp
Difference
+198 lb-ft+94 hp
Bonus Nitrous
The bolt-on
We couldn't resist the urge to place a bonus pull, especially after seeing the results. Check out what a 250hp shot from a Zex Perimeter Plate nitrous system for Dominator-style intake manifolds can do. $907
The mule
A 588ci big-block running 12.5:1 compression, Brodix rectangular-port heads, an Edelbrock Super Victor BBC EFI manifold, and FAST XFI fuel-injection with a High Flow 4500-style throttle body flowing 2,000 cfm. Power measured at the rear wheels.
Our take
It's a big engine taking a big nitrous shot, and it made big power.
Before
Max torque: 564 lb-ft @ 5,000 rpmMax power: 602 hp @ 6,000 rpmAverage torque: 429 lb-ftAverage power: 446 hp
After
Max torque: 797 lb-ft @ 5,300 rpmMax power: 813 hp @ 5,800 rpmAverage torque: 654 lb-ftAverage power: 675 hp
Difference
+233 lb-ft+211 hp
Mass Airflow Sensor
The bolt-on
Granatelli Motorsports' Mass Airflow Sensor with cold-air tuning. $300
The mule
'02 Camaro SS fitted with a Volant cold-air kit and SLP Loud Mouth exhaust. Power measured at the rear wheels.
Our take
The increased airflow and performance calibration provided by Granatelli's MAFs improve power and throttle response.
Before
Max torque: 285 lb-ft @ 4,700 rpmMax power: 276 hp @ 5,400 rpmAverage torque: 243 lb-ftAverage power: 198 hp
After
Max torque: 302 @ 4,500 rpmMax power: 288 @ 5,450 rpmAverage torque: 277 lb-ftAverage power: 208 hp
Difference
+17 lb-ft+12 hp
Throttle Body
The bolt-on
A BBK 80mm LS1 PerformanceThrottle Body. $380
The mule
The Camaro with a Granatelli Mass Airflow Sensor.
Our take
You get more air in, you make more power.
Before
Max torque: 302 lb-ft @ 4,500 rpmMax power: 288 hp @ 5,450 rpmAverage torque: 277 lb-ftAverage power: 208 hp
After
Max torque: 317 lb-ft @ 4,450 rpmMax power: 304 hp @ 5,300 rpmAverage torque: 290 lb-ftAverage power: 218 hp
Difference
+15 lb-ft+16 hp
Performance Programmer
The bolt-on
A DiabloSport Predator flash programmer. $400
The mule
The Camaro with a Granatelli Mass Airflow Sensor and a BBK LS1 Performance Throttle Body.
Our take
The Predator allows custom tuning, which allowed us to dial in the Camaro's computer to work with other bolt-ons.
Before
Max torque: 317 @ 4,450 rpmMax power: 304 @ 5,300 rpmAverage torque: 290 lb-ftAverage power: 218 hp
After
Max torque: 325 lb-ft @ 4,600 rpmMax power: 316 hp @ 5,400 rpmAverage torque: 303 lb-ftAverage power: 226 hp
Difference
+8 lb-ft+12 hp
Performance Chip
The bolt-on
A Jet Performance Products GM Stage 2 chip. $130
The mule
A bone-stock '91 Silverado TBI 350 transplanted into an '84 El Camino. Power measured at the rear wheels.
Our take
The car's owner reports vastly improved performance throughout the rpm range; economy improved by 2 mpg.
Before
Max torque: 230 lb-ft @ 3,700 rpmMax power: 167 hp @ 4,100 rpmAverage torque: 191 lb-ftAverage power: 152 hp
After
Max torque: 245 lb-ft @ 3,300 rpmMax power: 169 hp @ 4,200 rpmAverage torque: 193 lb-ftAverage power: 152 hp
Difference
+15 lb-ft+2 hp
Centrifugal Supercharger
The bolt-on
ATI Procharger's Street Rod blow-through kit, using a C-2 compressor running 8 psi boost. $3,296
The mule
355 small-block, 8.2:1 compression, Pro Topline heads, and a Carb Shop 650-cfm blow-through carb.
Our take
This compact setup with a relatively small compressor produces impressive power gains.
Before
Max torque: 410 lb-ft @ 4,300 rpmMax power: 390 hp @ 5,400 rpmAverage torque: 305 lb-ftAverage power: 247 hp
After
Max torque: 507 lb-ft @ 4,200 rpmMax power: 506 hp @ 5,800 rpmAverage torque: 478 lb-ftAverage power: 381 hp
Difference
+97 lb-ft+116 hp
Headers
The bolt-on
Stainless Works 2-inch primary long-tube header kit with converters. $1,941
The mule
A bone-stock, LS7-powered '06 Z06. Power measured at the rear wheels.
Our take
Even modern, high-performance exhaust manifolds can be improved upon.
Before
Max torque: 430 lb-ft @ 4,950 rpmMax power: 473 hp @ 6,450 rpmAverage torque: 404 lb-ftAverage power: 383 hp
After
Max torque: 438 lb-ft @ 4,900 rpmMax power: 481 hp @ 6,500 rpmAverage torque: 417 lb-ftAverage power: 391 hp
Difference
+8 lb-ft+8 hp
Cylinder Heads
The bolt-on
We swapped out a set of factory iron cylinder heads for a pair of Holley's aluminum small-block heads, which have 184cc intake runners, 68cc chambers, and 2.02/1.60 valves. $1,226
The mule
355 small-block, 8.3:1 compression, GM production iron heads, 650-cfm Carb Shop-built Holley.
Our take
Even a mild, low-compression small-block can benefit from a good set of high-flow cylinder heads.
Before
Max torque: 365 lb-ft @ 3,500 rpmMax power: 307 hp @ 4,900 rpmAverage torque: 342Average hp: 258
After
Max torque: 407 lb-ft @ 4,200 rpmMax power: 375 hp @ 5,500 rpmAverage torque: 389Average hp: 296
Difference
+42 lb-ft+68 hp
Exhaust
The bolt-on
We replaced a compression-bent, 2 1/2-inch exhaust with a 2-inch balance pipe and big-block Chevelle mufflers in favor of a Flowmaster 2 1/2-inch, mandrel-bent A-body dual exhaust kit with Super 44 mufflers. $386
The mule
355 small-block, 9.5:1 compression, ported L98 heads, Edelbrock Performer RPM intake, 750-cfm Holley carb. Power measured at the flywheel.
Our take
Even with identical pipe diameters, the mandrel-bent system with Flowmaster's new Super 44 mufflers freed up double-digit power gains.
Before
Max torque: 405 lb-ft @ 4,300 rpmMax power: 393 hp @ 5,700 rpmAverage torque: 385 lb-ftAverage power: 334 hp
After
Max torque: 418 lb-ft @ 4,600 rpmMax power: 413 hp @ 5,700 rpmAverage torque: 400Average power: 352
Difference
+13 lb-ft+20 hp
Roller Rocker Arms
The bolt-on
Comp Cams Pro Magnum roller rocker arms, 1.6:1 intake and 1.52:1 exhaust. $276
The mule
An out-of-the-crate ZZ4 350ci small-block: 10:1 compression, GM dual-plane intake and aluminum 58cc heads, and a Holley 770-cfm carburetor. Power measured at the flywheel.
Our take
The mildly cammed ZZ4 responded to this rocker arm upgrade; if you have one, this mod's a no-brainer.
Before
Max torque: 390 lb-ft @ 4,200 rpmMax power: 344 hp @ 5,200 rpmAverage torque: 371 lb-ftAverage power: 287 hp
After
Max torque: 407 lb-ft @ 4,200Max power: 366 hp @ 5,400 rpmAverage torque: 386 lb-ftAverage power: 302 hp
Difference
+17 lb-ft+22 hp
High-Flow Air Filter
The bolt on
A K&N high-flow air filter. $40
The mule
A 406ci stroker small-block running 11.1:1 compression, Dart Pro 1 227 CNC heads, a Victor Jr. port-matched manifold, and a 750-cfm Mighty Demon carb. Power measured at the flywheel.
Our take
Running a good, high-flow air filter doesn't hurt performance compared to running an open carb.
Before
Max torque: 533 lb-ft @ 5,000 rpmMax power: 583 hp @ 6,300 rpmAverage torque: 485 lb-ftAverage power: 431 hp
After
Max torque: 536 lb-ft @ 5,000 rpmMax power: 582 hp @ 6,300 rpmAverage torque: 488 lb-ftAverage power: 433 hp
Difference
+3 lb-ft-1 hp
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