Comp Cams Phaser Limiters Install - Lockdown
Comp Cams limits the Three-Valve engine's variable cam timing for increased performance.
Navigating Comp's Line of Three-Valve Camshafts
OK, not everyone has a stroker with ported heads, so Comp designed many cams for all applications. If you want milder camshafts, Comp offers a variety under the XFI camshaft lineup. The first set is nicknamed NSR (No Spring Required). They're designed for blown or naturally aspirated engines, and best of all, you don't have to change springs, thus simplifying the install (not to mention saving you money, too). There are two stages each for N/A and blown combos, for a total of four different cams designed for mild applications. Neither N/A cam requires computer retuning, and each offers great idle manners. The Stage 2 NSR does require a looser torque converter and also a minimum of 3.73 gears. The Stage 1 NSR blower cam is designed for out-of-the-box boost levels, while Stage 2 is for higher boost output, a looser torque converter, and steeper gears.
The second family of Three-Valve cams is called VSR (Valve Springs Required). If you hadn't guessed it, the VSR cams are much more aggressive than the NSR cams. We've tested VSR cams several times in MM&FF over the years, with great success. Our testing has shown as much as 40hp gains over the stock cars, on stock engines. As with the NSR group, there are two naturally aspirated grinds and two blower stages. The VSR camshafts carry the same description as above but feature a rougher idle and definitely need custom computer tuning.
The third and final family of cams for the triple-valve mod motor are the SPR camshafts, which we tested in the Stage 3 version in this story. Six versions of the camshafts exist on the shelf at Comp. The SPR line is divided into three naturally aspirated grinds and three blower grinds, all broken down into Stage 1, Stage 2, and Stage 3. The first two stages are mild enough to be used with stock engines. Stage 1 can be used on a completely stock engine, while Stage 2 has a rougher idle and calls for taller gears and a better torque converter. Stage 3 is designed for built engines with better flowing heads, more compression, and high boost (in blower applications).
Comp Cams' Web site (www.compcams.com) has more information on each cam and its specific applications. Be sure to check it out to see which XFI camshaft is right for your Three-Valve engine.