On the 40-minute ride to SLP, we noticed the idle and drivability was similar, but once it hit over 5,000 rpm, it pulled much stronger, right to the 6,600-rpm chip in the MSD rev limiter. Once the car was strapped to SLP's rollers, would the new roller cam prove its worth, or would it fail miserably? After the first blast, we noticed peak power was coming in at a higher 6,250 rpm. Now the 440 was revving and making power way beyond the hydraulic cam, which previously encountered valve float at 6,150 rpm. We were pleased to gain 22 hp at peak, but noticed the efficient roller was running too rich with black smoke belching out. This only meant the 440 would need a leaner mixture.
With limited dyno time, we reached into the jet box and changed the secondary jets on the 850 Demon from 88s to 84s. The jet swap netted us 4 hp, and then we checked the timing and found it to be at 35 degrees total. We bumped that up to 40 degrees, and picked up another 4 hp. That gave us a 30hp gain. We still had some unsightly black smoke, so we once again changed the secondary jets to a leaner set of 82s and picked up 2 more horsepower. We were now out of dyno time, but very pleased to gain a total of 32 hp with a cam swap.
When testing this Indy-headed 440 with the hydraulic cam, we benefited from more dyno-tuning time. We knew there was more power available from the more efficient roller cam, and we'll give the new combo a strip-tune at a later date. With power up significantly at 700 higher rpm, to get the most from this cam, a higher-stall converter will become part of the program. The 11-inch converter (2,800 rated stall) will be removed in favor of a Dynamic 10-inch converter (3,500 rated stall). The higher stall converter will enable the wedge to use its new higher and broader power range more effectively.
We needed a more stable and efficient cam combination that matched the high-flow/rpm capabilities the Indy heads have to offer. The Comp Cams Xtreme Energy Street Roller delivered the extra power we wanted. The roller/Indy combination outperformed the flat-tappet/906 combination by a total of 134 rwhp at 6,100 rpm-a big-time gain. There's no need to custom-order a cam when there's a good selection in the catalog. When looking through the catalog or Comp Cams web site, there are recommendations about which cam will work for the engine combination, converter, and gearing you have. If you are still undecided about what you need, Comp Cams has a CamHelp Hotline [(800) 999-0853] to help you make the right cam choice. Flat-tappet cams are definitely the cheaper way to go, but if your willing to pay for that extra power, a roller cam is the way to get there.
Chassis Dyno Results
SuperFlow SF840 SAE-corrected rear-wheel horsepower and torque at SLP Performance Parts and Engineering Center.
|Baseline ||906 w/hyd ||Indy w/hyd ||Indy w/roller |
|Max hp ||366 @ 5,600 ||433 @ 5,600 ||465 @ 6,200 |
|Max tqe ||427 @ 4,200 ||435 @ 4,700 ||426 @ 5,100 |
|Avg hp 5,000-6,000* || 358 || 420 || 421 |
|Avg tqe 4,500-5,500* || 372 || 421 || 418 |
*Average horsepower readings were from 5,000-6,000 rpm due to valve float at 6,150 with the hydraulic cam-an unfair average to the solid roller. Peak roller horsepower was at 6,250, and it pulled well beyond 6,500 rpm (we ended each pull at 6,500).