Peak Power: 357 lb-ft and 285 hp (4-hole)
Average Power: 301 lb-ft and 227 hp
Sometimes, no matter how much fuel- tuning comes into play, the perfect tune will more often than not elude you without the right combination of parts. One way to fine-tune an engine's air/fuel mixture is by trying different carburetor-to-intake manifold spacers. This time, we wanted to see what kind of gains could be had with a four-hole spacer, as opposed to an open-plenum design. Since Trans-Dapt Performance Products offers spacers in all shapes and sizes, we tested their 1-inch-tall Torque Swirl four-hole design against a 1-inch-tall open-plenum design. The spacers come with all the necessary installation hardware and can be bolted on in minutes. Our first test would run the four-hole setup and, hopefully, improve the engine's average power numbers. After warming the engine and stabilizing the test conditions, we ran the engine for more power. The Torque Swirl design amazed us, posting 357 lb-ft at 3,300 rpm and 285 hp at 5,200 rpm. The averages also took our breath away, breaking 301 lb-ft and 227 hp. With such great results already on the table, it was hard to imagine that the open-plenum design could do any better. We swapped the spacers and made our next pull, with slightly less torque at 349 lb-ft at 3,700 rpm and 289 hp at 5,900 rpm. The open design moved the rpm powerband up nearly 400 rpm, showing that more potential power could be gained on a higher-revving engine. While the four-hole Torque Swirl spacer may have been more ideal for our application, the open-plenum design did post higher peak horsepower numbers. Each spacer did amazingly well on the dyno, showing its strengths per application. What we could not show here was how effective the spacers are at diminishing heat transfer from the manifold to the carburetor. By touch, we can say that the manifold would burn our hands, while the carburetor base plate felt as cool as the room temperature. Since our mild small-block was set up for 5,500 rpm and under action, the four-hole Torque Swirl spacer went back onto the engine for the next test.
Peak Power: 357 lb-ft and 294 hp (4-hole)
Average Power: 298 lb-ft and 231 hp
The final test of the day consisted of swapping our stock 1.5:1-ratio rockers out for a set of roller-tipped, aluminum-body 1.5:1-ratio ProForm roller rockers. The camshaft inside the engine was initially chosen by SA Engine Design and turned out to be ideal for the application. This allowed us to test the benefits of the rockers without any complication, as their lightweight roller-tip construction would be put to the test. Once our engine's parameters were steadied, we spun the rollers to reap even more power than before with 357 lb-ft at 3,700 rpm and 294 hp at 5,900 rpm peak figures. Again we were pleased with our parts' performance, as the averages came in at 298 lb-ft and 231 hp, posting the highest net average of the day.
Our engine was now making 71 lb-ft and 67 hp over our baseline numbers, and Mr. Weinreb couldn't wait to get his Camaro back on the street. Saving money and avoiding hassles is the name of the game when you're trying to gain the best bang for the buck. And this time around, CHP (with the help of your real-world enthusiast) managed to show us all how to get the job done!
Behind the Scenes
A potent small-block can consume quite a bit of fuel during an upper-rpm pull. Our engine did not require very much fuel to make 294 rear-wheel horsepower at 6,000 rpm, but future upgrades will demand additional fuel as engine power increases. In order to make sure our fuel system would be capable of feeding a high-performance small-block, we installed a 130-gph mechanical fuel pump, an adjustable fuel pressure regulator, and a steel braided line kit from Holley. For complete install details, contact Earl's Performance Plumbing.