We also saw a new best at the upper end of the test range, recording 325.1 horsepower at 5,400 rpm.An older member of the COMP Cams grind family, the Magnum series of camshafts offers excellent performance gains over stock without the added wear and tear associated with more aggressive camshafts. We have heard from numerous sources that a narrower lobe separation makes for a narrower torque curve, but we saw a wider curve during this test. Even though the torque was similar to the Magnum camshaft through the middle of the rpm range, we were pleased to see a new best of 370.2 lb-ft at 27,-2,800 rpm.
The power numbers we received with the Thumper cam were a little surprising. The vacuum at 850 rpm did drop to 8.25 inches. After the break in period was completed and the idle speed was set, we could tell that this engine definitely had some "bark" to the idle, as compared to what we had previously heard. We installed this cam with the intake at 102 degrees, per Comp Cams' recommendation. The larger exhaust duration combined with the narrower lobe separation of 107 degrees is where the radical exhaust sound comes from. The lift was also split with this camshaft, with nominal figures of. 050-inch duration was 227 degrees on the intake, and 241 degrees on the exhaust. This camshaft features an advertised duration of 279 degrees on the intake, and 296 degrees on the exhaust. We then moved on to the Thumper cam, which looks quite a bit larger in regards of duration on paper, but is still rated for the same basic rpm range. The peaks of 363.3 lb-ft of torque at 2,900 rpm, and 301.3 horsepower at 5,300 rpm are pretty comparable to several crate engines on the market using similar combinations, so we felt we would not see huge gains within our test range. The engine responded with a nice torque curve, and produced relatively decent horsepower for the compression ratio involved. After a few easy pulls to dial in the ignition timing and check the air/fuel mixture, we set the dyno's load control to make a sweep from 1,800 to 5,800 rpm. We also noticed just enough of a performance idle to know all was not stock. The dyno's vacuum gauge showed 9.5 inches. After the initial break in and leak checks were performed, we set the idle to 850 rpm and recorded the engine vacuum for comparison later. We installed this camshaft with the intake lobe at 106 degrees. 464-inch on both lobes, and a lobe separation of 110 degrees. 050-inch duration is 222 intake, and 226 exhaust with nominal lift figures of. This camshaft features an advertised duration of 268 degrees on the intake side, 276 degrees on the exhaust side. We started our tests with the 268 camshaft.
0 kommentar(er)
