hybrid hydraulic rollers:

There’s a lot of internet chat about running solid-roller lifters on a hydraulic roller cam to gain some power and rpm potential. I’ve never been a big fan of the idea, because to me, the one thing a hydraulic cam can do very well is keep things quiet. Once you drop solid rollers on it, you might as well get a “real” solid-roller cam and make serious power. But we had a perfect opportunity to test the idea and see what would happen. We pulled the intake and installed a set of Crane solid-roller lifters on the hydraulic roller cam. We used the same springs, but we needed to change to another combo of the Trend pushrods to keep the valvetrain geometry intact. We lashed the valves at .002 inch and made some hard pulls. We picked up about 3 lbs-ft throughout the lower ranges. At 5,800 rpm, we started seeing the advantage of the solid lifter not experiencing the normal lifter collapse that any hydraulic lifter will exhibit at high rpm. We were up 10hp to 771.1 at 6,300 rpm, and at 6,500 rpm, we were up about 18hp. From that point on, the solid-roller lifters continued to prove their ability to rev, and there were no issues spinning past 7,000 rpm. We didn’t gain any more peak horsepower since the cam was relatively small in duration for a “solid roller” in a 555-inch motor, but the power didn’t fall off like the previous hydraulic lifters did on the same cam. This is another option where the hybrid hydraulic roller cam/solid-roller lifter combo could match rpm with the solid flat tappet and have improved low-speed manners. This series of lobes would be gentler on the valvetrain than the typical race solid-roller and not have the worries of solid flat tappet wear. But remember, this is not an ultimate combination. A purpose-designed solid “street roller” would do even better overall. We didn’t run the Edelbrock Super Victor intake and Dominator on the hydraulic roller cam combinations due to time constraints, but since the rpm range is the same, I have no doubt you would see similar increases as we did on the solid flat-tappet platform.

Along with the three camshaft swaps, we tested four intakes, an Edelbrock Victor Jr, Edelbrock Super Victor, Edelbrock CNC Victor 454-R and a Edelbrock C-454 dual plane. We also used several different carb configurations, depending on what intake was used.

going solid:

We installed the big solid-roller cam with the same Wilson-modified Edelbrock Vic Jr. and the Holley HP 1000 carb used in the previous tests. We knew that was going to be our end-game combination on top of the motor when the dust settled. Speculation was running rampant during this phase. Judson had been keeping an eye on our results and was very impressed with what we had pulled from the solid flat tappet. His words were, “Don’t be surprised if the solid-roller doesn’t pick up as much as you think.” He’s been around awhile and knows what solid flat tappets can do in circle track applications, so we were figuring we must have hit that flat-tappet cam selection pretty close.

Once again, we removed the cam through the Jesel belt drive, changed all the valvesprings and installed a new pushrod setup. Now you’re starting to see why we did all the mock-ups and test assembly work. There is no way we could have done all this in two days if I hadn’t worked out all the bugs ahead of time.

If you’ve never run a solid-roller cam on the street, you don’t know what you’re missing. Even though they make incredible power and will rev forever, they can have some of the best street manners, too. The lobes operate the valves so much faster that you end up with much less advertised duration than the hydraulic rollers and the solid flat tappets. This is where the good manners come from. It actually “acts” like a much smaller cam at low speeds, but really gets with the program as rpm builds. This custom Crane cam did all that and more. It idled very nicely under 1,000 rpm, and when you punched the throttle, it was instant.

There didn’t turn out to be much tuning needed. The Holley HP 1000 was delivering the goods, regardless of what combination we bolted it to. We bumped the timing one half of a degree to see if it liked it. The increase didn’t hurt anything, so we left it there for the rest of the tests. We were now at 790.9hp at 6,500 rpm, and it was still making 773hp at 7,200 rpm! Peak torque was down to only 690 lbs-ft and still at the same 5,000 rpm where many of the combos peaked. Comparing the solid-roller cam to the hybrid hyd/solid version at peak horsepower, you can see we are only up 15-20hp so far. But again, look at what happens after peak horsepower … remember, that’s the premise of this buildup. With the super strong parts, along with careful assembly, you could shift this thing at 7,000-7,200 rpm (or higher!) and just fly!

horsepower in a bottle:

Now, we were ready for another fun and easy test. You’ve heard it before … synthetic oils can make more power, right? We purposely waited until we were in the 800hp range to change out the excellent regular 10/30wt oil we had been using through all the tests, to Royal Purple’s Synthetic XPR 5/30wt. We wanted to see if all the claims could be verified right before our eyes. After dumping the oil and changing the filter, we made three pulls to stabilize the oil and water temps to be identical to the previous runs and then recorded the results. All I can say is that the stories you’ve heard were true. The Royal Purple change picked up 10hp even down at lower rpm, but where it really paid off was when we let Bruiser scream. At 7,200 rpm, we were up just under 20hp! All through the midranges, it was 13-15hp better consistently. Interestingly the oil pressure was actually higher at peak rpm with the slightly thinner Royal Purple. Faster return to the pan and less aeration are the likely reasons. Just as a side note about oil pressure, I noted previously that I like oil pressure in my street motors. The SAM guys were lining up to tell me how much more horsepower we could make if I would drop oil pressure from the 70-78 psi we were seeing. That’s OK. I’ll give up a few horsepower for some peace of mind on a 100-degree Texas afternoon! Another item that stood out during all this high-rpm flogging was that we made the right oil pan choice with the Milodon stepped drag race pen. The oil pressure never waivered throughout the 30+ dyno pulls and surely kept Doug’s motor in one piece! This pan is the real deal, and it just fits in a ’Vette!