It's way too easy to make 500 hp these days. Let's look at the tested and true normally aspirated 383 small-block. This 3.75-inch stroke and 4.030-inch bore seems like a perfect combo to make large-caliber power. That's exactly what Terry Zupan Jr. of Zoops Products wanted for his '70 street terror Camaro. He wanted an edgy small-block that would take no heat from the bullies on the boulevard, a rogue small-block--a rapscallion.
The Buildup
Zupan contacted Beck Racing Engines in Phoenix, Arizona, which immediately started whittling on a new 350 block until everything was either perfectly round or square. Then Beck added a complete Scat rotating assembly using a 4340-steel 3.75-inch stroke crank and a set of Scat's 4340 forged-steel 5.7-inch I-beam connecting rods. The assembly also comes with a set of SRP forged pistons that are weight-matched to the crank assembly. This makes assembly really easy since you don't have to worry about knowing all that detail stuff that can trip up the first-time buyer.
Beck Racing then added a Moroso oil pump, pickup, and oil-pan kit that ensured proper lubrication for this wet-sump system. Once Beck Racing had clearance-checked all the parts and assembled the bottom end, it was time for cam shafting. The key to street performance is a balance between mega-horsepower and usable torque. Zupan wanted lots of horsepower, and Beck Racing knew that a solid 500hp number would be just the ticket. Given this, Beck spec'd a Crane mechanical-roller cam with just enough duration and lift to get the job done.
One aspect of the 383's longer stroke is its tendency to soften the torque loss of a big cam. Besides the additional stroke, Beck ensured that the engine had sufficient >> static compression (10.4:1) to support this longer-duration cam. Even with a set of aluminum heads, this engine is right on the edge of being pump-gas friendly. We ran this engine on 91-octane pump gas with no detonation problems however. With the cam in place, the next step was perhaps the easiest selection of the entire engine. When it comes to go-fast small-blocks, it's hard to get past the Dart Pro-1 215cc heads. These castings are a great deal and ideally suited to the 500hp target. The heads come with 2.05/1.60-inch stainless steel intake and exhaust valves and offer port-flow numbers that are downright awesome. Beck also ported these heads and came up with a stout 296-cfm flow for the intake at 0.600-inch lift.
To reach the 500-plus horsepower goal, Beck Racing decided to go with an Edelbrock Super Victor single-plane intake and a Barry Grant Race Demon 775-cfm carburetor. The combination boasts a short but generous port that's aimed at peak power above 6,000 rpm. For ignition, Beck spec'd a complete MSD ignition system including a billet aluminum MSD distributor, 8.5mm plug wires, an MSD 6-A ignition box, and a Blaster coil. On the exhaust side, we used a set of Hooker 13/4-inch headers on the dyno that were similar to those Zupan would use in the Camaro, and we capped the headers with a set of Flowmaster 21/2-inch mufflers.
Test Time
Once Beck Racing had completed the assembly, Zupan trucked the Mouse motor over to Westech Performance where dyno-master Steve Brule bolted everything up. Brule made a couple of quick pulls at 4,000 rpm to set the timing at 34 degrees and to ensure the air/fuel ratio was close. Beck Racing equipped the 383 with a 2-inch-tall spacer on top of the Super Victor. Our first runs with the tall spacer produced a peak of 525 hp at 6,200 rpm and 501 lb-ft of torque at 4,800 rpm, but we felt there was more left in the engine.
Our first experiment (Test 1) swapped in a shorter 1-inch spacer that cranked the horsepower up to 530 at 6,300 rpm and bumped the torque to 506 lb-ft at 4,900 rpm. That produced the best peak-power numbers, but we weren't done yet. Brule suggested we try an Edelbrock Performer RPM Air Gap intake just to see what we'd gain for torque. We figured the Air Gap would bump the torque while also pulling the peak-torque rpm point down. We also assumed this would cost us 10 hp or more.
We bolted the dual-plane intake in place and added the 1-inch spacer. Generally, dual-plane intakes don't like open spacers, but in this case, the 383 cranked its best numbers with the spacer. After a few jetting and timing adjustments, we settled on 34 degrees of lead with 85 primary and 89 secondary jets. This produced a stout 512 lb-ft of torque at 4,700 and an impressive 524 hp at 6,200. This equated an excellent 1,500-rpm powerband between 4,700 and 6,200 rpm.
Conclusion
While it's true that we did lose 6 hp, you can see that the dual plane was worth as much as 30 lb-ft of torque in two places and the average torque increased by an impressive 9 lb-ft. These numbers illustrate why it's so important to look at the entire curve and not just the peak values when evaluating a power curve. Ironically, we dialed both power curves into the RSA Quarter program to evaluate just how much that average 9 lb-ft of torque was worth in the 1,320 and both combos ran within 0.01 second! We used our typical simulated 3,600-pound street machine with a 3.55 rear, 26-inch-tall sticky tires, and a TH350 trans with a 3,000-rpm converter. The 383 was worth a solid 11.20 at 124.20 mph.
Clearly, either combination is plenty stout and would easily bring a smile to your face. It did for Terry Zupan. Now all he has to do is figure out how to hook up his newfound power so he can push that Camaro into the 11s. We should all have those kinds of problems, right?
The Beck Racing-built street stroker started with a Scat rotating assembly that matched a 4340-steel 3.75-inch crank with a set of 5.7-inch-long Scat I-beam 4340-steel rods floating on a set of SRP pistons. |
Power is all about airflow, so Beck Racing Engines spec'd a set of Dart Pro 1 heads that measure up with 215cc intake ports using 2.05/1.60-inch stainless steel valves. These heads rock. |
Beck next matched up a Crane mechanical-roller cam with the airflow potential of these heads. The Crane bumps the valves to 0.543/0.561-inch intake and exhaust lift with 240/248 degrees of duration at 0.050. |
Zupan had built a previous engine using this Crane stud girdle, so it went in with the rest of the pieces even though this 6,500-rpm engine probably doesn't need it. Beck Racing used Fel-Pro gaskets throughout the engine to seal it up. |
The assembly included a Moroso oil pump and pan system, and the induction system consisted of an Edelbrock 2925 Super Victor single-plane, a 2-inch spacer, and a Barry Grant 775-cfm Race Demon carburetor. |
With the engine fully assembled, we bolted it to Westech's SuperFlow dyno along with a set of Hooker 1-3/4-inch headers plumbed into a pair of 2-1/2-inch Flowmaster mufflers. The first power numbers were impressive, but we thought the engine could do better. |
The first thing we did was replace the 2-inch spacer with a 1-incher that would fit better under Zupan's '70 Camaro hood. The torque increase led us to consider a big dual-plane intake. |
We ran several intake combinations across the dyno in a relatively short period of time with Westech's Steve Brule at the controls. |
Despite the big cam and heads, we decided to try an Edelbrock Performer RPM Air Gap dual-plane to see the difference. Torque improved as we expected, but the combo lost only 6 hp at the top, which was surprising. |
Bolting the engine in the car, Zupan naturally outfitted it with a complete Zoops serpentine accessory drive system. The system drives the water pump, downsized power-steering pump, and alternator all with a single belt. The best part is it looks great doing it. |
Zupan originally spec'd the engine with the single-plane, so for now it's back on the engine. But we've proven the RPM dual-plane can still crank out the power and deliver even more torque to boot! |
Parts List |
Cam Specs |
Test 1 Equipped the 383 with an Edelbrock Victor intake manifold with a 1-inch spacer underneath the Barry Grant 750-cfm Race Demon. Timing was set at 34 degrees. This is the best overall pull with this combination after several jetting and timing changes.
+ Test 2 Tested an out-of-the-box Edelbrock Performer RPM Air Gap with a 1-inch open-plenum spacer under the same Barry Grant 750 Race Demon carburetor. |