What this all comes down to is a great small-block. The peak horsepower rpm points were almost identical, yet the single plane managed 10 more horsepower and created a virtually identical average torque figure. The trade-off was torque, where the single-plane intake managed to still muster 418 lb-ft of torque at 5,000. What was more surprising was the 422 hp (a 10hp gain) at 5,700 rpm we saw over the dual plane. Not surprisingly, the 355 did sacrifice some power down low, but actually very little. We also experimented with reducing the timing to 32 degrees total instead of the previous tests 34 degrees.
After a few minor tweaks, the numbers looked very good, but we also decided to try adding a 1-inch spacer as well as an additional ½-inch spacer to simulate the nitrous plate. Generally, this is not a good trade for street engines, but Moore also plans to use nitrous on this engine and felt that the single-plane intake would work better with a plate nitrous system.Ĭhanging intakes was a snap, and once again we were working this small-block. We expected the single plane would trade power below peak torque for more power above peak torque. While these numbers are respectable, we also wanted to try the Edelbrock Super Victor single-plane intake for Vortec heads.
Peak horsepower came in at 412 at 5,600 rpm, creating a somewhat narrow powerband of only 1,200 rpm, but looking more closely at the numbers reveals the engine is punching out 400 lb-ft from 3,500 all the way through 5,300 rpm. Even at 2,500 rpm, the 350 managed 359 lb-ft of torque with a max torque of 423 lb-ft at 4,400. Once we had all eight cylinders firing with slightly leaner jets in the Demon carburetor, the 355 pulled up some impressive numbers. This required us to heat and dent the header to create enough air gap to protect the spark plugwire boot. 5 spark-plug boot was pushed too close to the header tube and melted. In the case of the Hooker headers, the No. Vortec heads are a straight-plug design that sometimes can cause header clearance problems. One reason the Vortec heads work so well is because of the superior chamber design and the fact that the engineers moved the spark plug closer to the exhaust side of the chamber. The first few pulls looked slightly rich, so Brulé pulled two jet sizes out of the carb, but first we had to do a minor tune-up on the driver-side header. The motor responded with an amazing 14 inches of manifold vacuum at 850 rpm, which means this could easily support vacuum-operated accessories like power brakes. The first thing we wanted to see was how well the engine idled. Finally, with a nice leak-free engine, we loaded up the fuel cell with 92-octane 76 gasoline and pulled the handle.įor this initial test, we used the GM Performance Parts dual-plane Vortec intake manifold. Moore set the total timing at 34 degrees and then allowed the engine a short 20-minute break-in session. Since this was a newly rebuilt engine, we pre-oiled the assembly and set the static timing to allow it to fire up immediately. For the final piece of the puzzle, we added a Barry Grant Speed Demon 750 mechanical-secondary carburetor to ensure that the carburetor would not restrict power. As for exhaust, we bolted on a set of Hooker 15/8-inch headers along with a 2½-inch exhaust system plumbed to a pair of Flowmaster mufflers. This gear is not cheap, but it does work. This also required a special melonized GM distributor gear to ensure the gear would live when used with the GM Performance Parts HOT hydraulic roller camshaft.
Moore elected to use an old Stinger electronic ignition distributor to trigger the MSD 6 box used on Westechs dyno. So we trucked this iron-headed small-block out to Westech Performance and let John Baechtel and Steve Brulé abuse this Mouse on their SuperFlow dyno. The best part is that we did all this for under $2,500.īut going in, we only guessed how much power this engine was going to crank out. By rebuilding a one-piece rear-main seal, hydraulic roller cam small-block using cast pistons and a stack of high-perf GM Performance Parts goodies, we estimated over 400 hp. In the previous story we introduced you to budget-buildup artist Tim Moores 355ci small-block featuring its stock Vortec iron heads, GM Performance Parts HOT cam, and 9.75:1 compression ratio. Now well show you how anybody can do it. Its tough to come up with an improvement on the wheel, and when it comes to small-block Chevy engines, it used to require considerable skill to make 400 hp with stock iron heads and a streetable camand all this on a budget.
0 kommentar(er)
