Yeah, a "lesser" cam might have lower peaks, but better numbers where you actually use the car. High peak HP and torque numbers are useless if they are at an RPM where you never, or almost never operate the engine. Unless you are building a race-only ride, you want an engine that works well with your car, in the low-end of the operating range. Where you are going to be is at low RPM, every damn time you pull off the line from having stopped the car. I see all of these "cam-shootouts" with results showing nice high numbers at 5000, 5500, 6000, 6500, and even higher.Īside from the 5-passes a month in the summer, and the occasional banzai run up an entrance ramp, when the hell are you going to be at those RPM's? Even then, you are going to only be there for a few seconds, total. The Thumpr (Cam C), on the other hand, clearly destroys the other two cams everywhere in the power and torque curve. That 45 hp difference is far greater than the 27hp gap posted by Cam B at peak power, proving once again that peak power is just part of the equation. By 6,300 rpm, Cam A is down to 415 hp, while Cam B is still making 460 hp. The Thumpr proved to be the most rev-happy as well, pulling hard to 6,600 rpm, while Cam B was out of breath by 6,200 rpmCam A and Cam B both produced peak horsepower in the 6,100- to 6,200-rpm range, but the smaller grind falls off a table after peak while the larger cam does not. Peak output aside, the Thumpr trounced the 232/240-at-.050 grind by a large margin in the area-under-the-curve department, holding a 10-15 hp advantage throughout the majority of the power curve. In fact, the Thumpr produced more torque down low than the smallest cam in the test, in addition to posting the highest peak output of 466 hp at 6,300 rpm.
059-inch of lift on the intake and exhaust valves, respectively. Cam C proved to be the most potent of them all despite giving up 5 degrees of intake duration to Cam B, and. While the SAM crew slid Cam C into the block, since its duration specs fell in between Cams A and B, we expected horsepower output to fall somewhere in the middle as well. After that point, Cam B pulls ahead big time, holding a 15-25hp advantage throughout the rest of the power curve.
Longer-duration cams typically sacrifice low-end torque for top end power, and predictably, Cam A held an advantage of 5 to 10 lb-ft of torque from 3,600 to 4,200 rpm. As expected, Cam B improved upon those figures dramatically, kicking out 464 hp at 6,200 rpm and 426 lb-ft of torque at 5,100 rpm. Cam A was good for 437 hp at 6,000 rpm, and 409 lb-ft of torque at 4,900 rpm. All three grinds idled well at 900 rpm, with the Thumpr providing a noticeably choppier disposition.īased on specs alone, Cam B would seem to have the advantage on paper since it packs the most duration and lift, but that’s not how things played out on the dyno. The wild card of the bunch was the 227/241-at-.050 Thumpr, which proved to be the best all-around performer in our 347. 050, and the latter with 232/240 degrees at. Both are Xtreme Energy grinds, the former measuring in at 224/232 degrees of duration at. Two of COMP Cams’ most popular SBF camshafts are PN 35-518-8 and PN 35-522-8. As one of COMP’s Thumpr grinds, Cam C was designed with a lopey, aggressive-sounding idle in mind, and as such, it has a tighter LSA and an earlier exhaust valve opening The wild card of the bunch is Cam C, which measures in at 227/241 degrees of duration at. 565/.574-inch lift, also with a 112-degree LSA. Cam B, the largest of the bunch, features 232/240 degrees of duration at. 555/.565-inch lift and a 112-degree lobe-separation angle. The smallest of the lot, which we’ll call Cam A for the sake of simplicity, is a 224/232-at-.050 unit with.
The challenge was picking three cams that were different enough to show a measurable difference on the dyno, yet similar enough to where variations in horsepower and torque output could be pinpointed to specific differences in their lobe profiles. I have a Sunbeam Tiger with a 347 stroker in it want to change cams was thinking about the small thumpr cam but hear a lot of mixed feelings about it Summit ,Jegs and comp cams themselves all say they make sound no power but according to this they make more power than the other ones so witch is it do they or don't they? A Tale of Three Cams hot rod networkĪs no surprise, a quick call to COMP Cams’ Trent Goodwin confirmed that the most popular grinds in the SBF catalog are relatively mild designs that offer a great balance between sub-6,500 rpm power and low-speed driveability.
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