Small-Block Top-End Swap - Big Power For Little Cash

The mission: Take a purse of about $2,750, a willing 388ci small-block, and make over 500 hp by adding some of the industry's best top-end bolt-on performance parts. To fulfill this tall but doable order requires an exceptional set of cylinder heads, a well-thought-out camshaft design, and an intake manifold to supply the engine with sufficient airflow. As you already know, more air means more power.

Cylinder-head technology has advanced light-years from what was available only a generation ago. This is largely thanks to the combination of several key factors including lighter-weight components and flatter, more efficient valve angles formerly associated with high-end race stuff, producing the most efficient power measured under the curve.

Suffice to say, Air Flow Research (AFR) has been very busy staying ahead of the cylinder-head development curve, as evidenced by the recently released Eliminator series, an all-new cylinder head for street or competition that increases flow numbers significantly over any previous design. This new benchmark has been accomplished by completely redesigning the combustion chamber, ports, throat area, and valve job on a 23-degree head, creating a greatly improved cylinder head from top to bottom-with the flow numbers to prove it. At 0.500 inch lift this head flows an impressive 278 cfm on the intake side, which is a 17 cfm increase compared with the original design, which flowed less (though still respectable at 260 cfm). For even more power, you can expect a competition version by the time you read this.

Of course, when we first learned about the Eliminator heads, we had to see how well they would perform. Lucky for us, we're in pretty tight with AFR's cylinder-head guru, Tony Mamo, and we managed to bug him into letting us test a pair, but not just any pair; we actually got the very first pair. After describing our test mule, and at Mamo's recommendation, we opted to try out the larger 195 version over the 180s and set a date to meet him at the Westech Dyno facility, where we spent the entire day flogging his latest creation on our trusty small-block 388. A quick one-time pull wouldn't do anyone any justice, so we tested them in several configurations that included two Comp Cams camshafts (XE274H and XE284H), an Edelbrock Performer RPM Air Gap and an Edelbrock Victor Jr. intake, and two sets of Pro Magnum roller rockers (1.52 and 1.6 ratios). By the end of the day, we had made an unimaginable number of dyno runs and had our story. From mild to slightly wilder, we show two distinctly different combinations that both made incredible power; however, if you opt for the slightly more aggressive configuration shown here you can actually expect to save a cool $20. Check out the details, and be sure to e-mail us at chevyhi@sourceinterlink.com and let us know which combination is your favorite.

QUICK NOTES

What we did
Dyno-flog AFR's latest 195 Eliminator street heads, show the difference in gains between the Edelbrock RPM & Victor Jr. manifold, and push the limits with two camshaft grinds from Comp Cams.

What we did
Dyno-flog AFR's latest 195 Eliminator street heads, show the difference in gains between the Edelbrock RPM & Victor Jr. manifold, and push the limits with two camshaft grinds from Comp Cams.

Price (APPROX)
$2,750 in top-end parts (not including carb)

The new head is the result of intense research and development into the new Eliminator series. Mamo tells us that when he designs a new head like the 195 Eliminator, he begins at the combustion chamber, works his way up to the valve job, then tackles the ports. The combustion chamber's shape is critical to flow because it helps shape the umbrella of air coming off the intake valve, and helps direct the air into the exhaust port. The process of designing a performance cylinder head is largely rooted in old-fashioned trial-and-error, shaping almost everything by hand and using some epoxy. Only then is the finished product's final design digitally programmed so that it can be recreated to other cylinder heads on a CNC machine.

Eliminator 195 Street Head

THE CAMS

Tests 1-2
Comp Cams Xtreme Energy (XE274H ) flat-tappet hydraulic cam, PN 12-249-4
Intake/exhaust lift at cam lobe: 0.327 inch
Intake/exhaust lift w/1.52 rockers: 0.496 inch
Lobe separation angle: 110 degrees
Duration measured at 0.050: 230/236

Tests 3-6
Comp Cams Xtreme Energy (XE284H ) flat-tappet hydraulic cam, PN 12-250-3
Intake lift at cam lobe: 0.338 inch
Intake lift w/1.60 rockers: 0.540 inch
Exhaust lift at cam lobe: 0.340 inch
Exhaust lift w/1.60 rockers: 0.544 inch
Lobe separation angle: 110 degrees
Duration measured at 0.050: 240/246

Meet The Mule

HEADS
AFR 195 Eliminator street head (PN 1040)
195cc port, 65cc chamber (milled to 64 for the test)
2.055-inch intake/1.600-inch exhaust, 8mm valve-stem diameter with bead lock-style groove

SHORT-BLOCK
388ci small-block
Bore: 4.060 inches
Stroke: 3.750 inches
Block deck height: milled to 9.005 inches
Piston deck height: 0.000-0.003 inch
Piston dish: 6cc
Compression: 10.6:1 (approx.)
Rod length: 5.700 inches
Piston compression height: 1.430 inches
Piston-to-wall clearance: 0.005 inch
Main bearing clearance: 0.023-0.027 inch
Rod bearing clearance: 0.025-0.027 inch
Rod side clearance: 0.016-0.020 inch
Rod side-to-piston clearance: 0.125 inch
Ring end gap: 0.022/0.020/0.032 inch
Piston-to-head clearance: 0.041 inch
KB Forged pistons, PN UEM-KB-704

TEST ONE

For our baseline test we achieved the highest torque of the day, 490 lb-ft at 4,400 rpm. This is largely due to three reasons: The XE274H camshaft features less duration, the Air Gap intake is a dual-plane manifold, which helps produce a stronger intake signal, and the 750-cfm carburetor is comparatively smaller than the larger 850 we later used.

*750 Mighty Demon carburetor
*Edelbrock Performer RPM Air Gap
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 274 cam w/1.52:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78
*Timing: 37 total

TEST TWO

For this test we switched intakes from the Performer RPM Air Gap (dual-plane) to the Victor Jr. (single-plane) and recorded improved horsepower at a 200 higher engine rpm (488 hp at 5,900 rpm, compared with Test 1's 471 hp at 5,700 rpm). The peak torque number dropped to 475 lb-ft but at a slightly higher rpm.

*750 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator Cylinder Heads
*Comp Cams Xtreme Energy 274 cam w/1.52:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

TEST THREE

After a camshaft change to a bigger XE284H and 1.6:1 roller rockers we moved the horsepower number up considerably to 518. Peak torque stayed flat but was reached at a higher 5,200 rpm.

*750 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

TEST FOUR

Replacing the 750-cfm with an 850-cfm Mighty Demon produced almost no change. Our power numbers stayed very close to as before.

*850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

TEST FIVE

For this test we added a High Velocity Heads (HVH) 2-inch carb spacer and picked up a couple more horses at peak power, bringing the total to 521.

*850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Timing: 37.5 total
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78
*Carb spacer

TEST SIX

Finally, we added an S&B 4x15-inch air filter, fired up the dyno, and recorded 523 hp. A number of variables can account for the increase, but the point to drive home is that the filter certainly didn't hurt the performance.

*850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Air filter w/spacer
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78

The Prices