One of the many great things about the small-block Chevy is its versatility. Think about it for a minute: the same basic powerplant has been used to power everything from a heavy-hauling farm truck that rarely sees the high side of 30 mph to a production-bodied, land-speed record holder exceeding 300 miles per hour. The needs of most Super Chevy readers fall somewhere between these two extremes, but that still leaves a lot of room for individuality when it comes time to choose motivation for your favorite muscle car, street rod, or even daily driver. At Super Chevy we recognize the fact that not every enthusiast wants or needs an 8-second street machine, but few stick to stone stock.
In an effort to appease as many of the small-block faithful as possible and to demonstrate the versatility of our magnificent little Mouse, we decided that a minimum of three different engine combinations were in order. Technically, it was four if you count the stock baseline combination, but whether your tastes run from mild to wild, check out what it takes to add, 100, 200, or even as much as 300 horsepower to a typical 350.
At the local wrecking yard, we snatched what we thought was an L65 350 from the engine bay of a 1/2-ton truck, a most basic small-block right down to the 2G, two-barrel carburetor. Though we were tempted to plop it right on the dyno and hope for the best, we decided that the tired little Mouse deserved a little TLC before subjecting it to a triple layer of abuse. It was disassembled, cleaned, and machined (0.030-overbore) to accept new forged rods, JE flat-top pistons (with adequate valve reliefs), and Total Seal rings. The stock crank was deemed worthy and given a quick polishing, while the 882 heads received a fresh valve job. New bearings were installed as was a set of Fel-Pro heads gaskets and ARP head bolts. The stock cam looked fine but we replaced the old lifters. Our intention was to run the original 2G carb that came with the engine, but were forced to substitute a Sean Murphy unit supplied by Westech Performance.
When all was said and done, we had was a stone-stock, two-barrel 355 with a stock cam that eventually produced 246 hp at 4,500 rpm and 364 lb-ft of torque at 3,000 rpm with headers and an MSD distributor.
Phase 1: 100 hp
Obviously, coaxing more power out of a two-barrel 355 isn’t particularly difficult, especially given the vast array of performance products available. The first 100 hp is the easiest since every component on the stock two-barrel engine is restrictive, starting with the diminutive carburetor. Replacing the 2G with a Q-Jet and intake alone can be worth 25-30 hp. Toss in a mild cam and cylinder head upgrade and the power gains really start to add up. Though this power level would easily be served by a set of ported stock or Vortec heads, we stepped up to a set of as-cast Pro Action aluminum heads from RHS. Working with the 180cc RHS heads was a mild Comp High Energy 252H cam that offered 0.425-inch lift, 206-degrees of duration (@ 0.050) and 110-degree LSA. Topping the as-cast RHS heads and RV cam was a Speedmaster dual-plane intake and Holley 650 HP carb. The mildly modified Mouse pumped out 347 hp at 5,400 rpm and 399 lb-ft of torque at 3,700 rpm. Note that the engine produced peak power and torque higher in the rpm range compared to the two-barrel configuration. This trend continued with each successive step up in power.
Phase 2: 200 hp
The first 100hp increase was easy, but each successive jump in power becomes more and more difficult. Though we could get away with using the as-cast RHS heads at this power level, we decided to try a whole new combination. Off came the 100hp upgrade parts and on went a new set of heads and induction system. The basic short-block remained the same, but the 355 received a new set of AFR 195 Eliminator heads. For this application there was no need to step up to the Competition package, but the Eliminator heads featured 65cc chambers, a 2.05/1.60 valve package, and flow numbers to support over 550 hp. The same dual-plane intake and a Holley 750 HP carburetor topped the AFR heads. A good portion of the extra power came from the cam upgrade, a Comp Cams XR276HR hydraulic roller cam. The XR276HR offered a 0.502/0.510-inch lift split, a 224/230-degree duration split, and 110-degree LSA. In addition to the cam, Comp Cams also supplied the necessary lifters, pushrods, and stainless roller rockers. After installation of the new components, the 355 produced 449 hp at 5,900 rpm and 446 lb-ft of torque at 4,600 rpm.
Phase 3: 300 hp
The final upgrade netted nearly 300 additional horsepower over our baseline, but know that this combination certainly reduced driveability compared to the previous two. This combination was skewed much more to the strip end of a street/strip buildup. Exceeding 540 horsepower from 355 cubic inches required a healthy cam profile, and the Comp 300BR-16 cam certainly fit the bill. Though it was possible to produce this power with a hydraulic roller cam, we stepped up to a solid roller. It had 0.630-inch lift, a 264/270-degree duration split, and a tight 106-degree LSA. The aggressive roller cam was teamed with a set of as-cast Dragon Slayer 225 heads from Brodix. As indicated by the name, the Brodix heads featured 225cc intake ports, and flow over 300 cfm (enough to support over 600 hp). To maintain the static compression, we took the liberty of milling the Brodix heads to reduce the chamber size from 68 cc down to 65 cc. Feeding the impressive Brodix heads was a single-plane Power Plus intake. Completing the induction system was a Holley 950 HP carburetor teamed with an MSD billet distributor. After tuning, the new combination belted out 543 hp at 6,900 rpm and 463 lb-ft of torque at 5,300 rpm.
01. Making big power from a recycled 350 Chevy is as easy as ...
02. After removal from the wrecking yard, the block was bored 0.030-over, honed, and decked in preparation for assembly.
03. The stock cast crank was in good shape, needing only a quick polish before balancing. The stock crank was combined with forged rods and JE flat-top pistons prior to assembly.
04. Hardly the cream of the performance crop, the 882 iron heads were cleaned and given a fresh valve job prior to installation for the baseline. We even drilled and tapped the heads to replace the prone-to-pulling press-in rocker studs.
05. Run with a stock cam and two-barrel Rochester carb, the mild 350 produced 246 hp and 364 lb-ft of torque. The stock exhaust manifolds were ditched in favor of a set of Hooker headers.
06. Off came the stock heads, cam, and intake to make room for a set of RHS Pro Action heads.
07. The as-cast, aluminum RHS heads featured 180cc intake ports that flowed considerably better than the stock 882 iron heads.
08. Exhaust flow is a critical element in power production and the RHS heads offered considerably more exhaust flow than the 882s.
09. Along with the airflow, the static compression increased thanks to a drop in combustion chamber size from 72 cc (on the 882 heads) to 64 cc. The RHS heads also featured a 2.02/1.60 stainless steel valve package.
10. The stock cam was replaced with a slightly more aggressive hydraulic flat-tappet cam from Comp Cams. The High Energy 252H cam stepped things up with 0.425-inch lift, 206-degrees of duration at 0.050 (both intake and exhaust), and 110-degree LSA.
11. The cast-iron, two-barrel setup was replaced with a Holley 750 HP carb and Speedmaster dual-plane intake. The new combo increased the power output from 246 hp and 364 lb-ft to 347 hp and 399 lb-ft of torque.
12. Though the RHS heads had more to offer with wilder cam timing, the 200hp upgrade relied on a set of CNC-ported AFR 195 heads. Even without the Competition porting, the AFR heads were capable of supporting over 550 hp.
13. We chose the 64cc chambers for our test, but the AFR 195s were also available with larger 72cc chambers. The CNC-ported heads featured a lightweight (8mm stem) 2.05/1.60 valve package.
14. To take better advantage of the airflow offered by the AFR 195s, we stepped up slightly in cam profile. Once more from Comp, the (still mild) XR276HR hydraulic roller cam offered a 0.502/0.510-inch lift split, a 224/230-degree duration split, and 110-degree LSA.
15. The Comp 1.5-ratio roller rockers were carried over from the 100hp combo. Note the titanium retainers and ARP hardware used to secure the AFR heads.
16. Run on the dyno with a Holley 750 HP carb and Speedmaster dual-plane intake, the modified 355 produced 449 hp at 5,900 rpm and 446 lb-ft of torque at 4,600 rpm.
17. Knowing the last 100 hp would be much more difficult than the first, we stepped way up in cam timing. The Comp drag-race-oriented solid roller featured a healthy 0.630-inch lift combined with a 264/270-degree duration split, and tight 106-degree LSA. A powerful roller cam to be sure, the Comp piece was necessary on an engine sporting just 355 inches.
18. The JE forged pistons featured sufficient valve reliefs to allow for the radical roller cam specs.
19. Brodix supplied a set of its new, aluminum Dragon Slayer heads. Though as-cast, the Dragon Slayer heads flowed over 300 cfm, enough to support well over 600 hp. What we liked was the fact that the flow curves exceeded 300 cfm even down at 0.600-inch lift, making them ideal for our 0.630-lift roller cam.
20. The CNC’d combustion chambers were actually slightly larger than our previous two tests, but we had them milled from 68 cc down to 65. The heads were assembled with a 2.08/1.60 valve package.
21. The exhaust flow numbers were equally impressive, topping out at 210 cfm at 0.700-inch lift.
22. Since the cam and heads were designed to push power production higher in the rev range, we needed a suitable intake manifold. This single-plane, high-rise was ideal for our application. We also ditched the stainless rockers for a set of (lighter) Comp Cams Gold aluminum rockers.
23. To ensure adequate fuel and air flow to the new combination, the intake was topped off with a slightly larger Holley 950 HP carburetor.
24. Once again we relied on an MSD billet distributor and wires to provide adequate spark energy for our 355.