How to Degree a Cam: Introduction
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Introduction
02.43
| 00:00 | - In this worked example, we're going to be looking at degreeing the cams on our Nissan SR20 DET that's had a P11 Primera VVL cylinder head fitted to it. |
| 00:10 | This is commonly referred to as an SR20 VE. |
| 00:15 | The P11 Primera cylinder head has some significant advantages over a stock SR20 DE or DET cylinder head. |
| 00:23 | Primarily because it features Nissan's take on Honda's VTEC mechanism. |
| 00:29 | In other words, each cylinder or each set of valves has both low RPM cam profiles and high RPM cam profiles. |
| 00:37 | And this allows the cam profiles to be tailored more accurately to the RPM range under which they're going to be operating. |
| 00:44 | In plain English, this means that we can have a cam profile that gives good low RPM performance, good idle quality and good fuel economy. |
| 00:53 | But at higher RPM when switch to the larger lobe which offers more lift and more duration, we can have a cam profile optimised for high RPM performance. |
| 01:03 | Now while we will be focusing here on the VE cylinder head, this worked example is still going to be valuable to anyone using a conventional SR20 DET cylinder head. |
| 01:16 | Obviously there's going to be some aspects with the switchable cam system that won't relate but the general gist of this worked example will still be 100% applicable. |
| 01:28 | For this particular engine build, we've selected a set of Kelford aftermarket cams that are suited towards a turbocharged application using the P11 Primera cylinder head. |
| 01:39 | These are actually a slightly more conservative grind that the stock P11 cams as the stock cams are designed around a naturally aspirated engine. |
| 01:48 | The cams we've selected offer 246 degrees of duration at one millimetre of lift and they offer 10.6 millimetres of valve lift on both the inlet and the exhaust side. |
| 02:00 | Now in order for us to be able to degree these cams, it is essential that we lock the VVL mechanism into operating only on the high lobe profile. |
| 02:10 | There's a variety of ways that this can be done, including dissasembling the rocker assembly and mechanically fixing it into the high lobe operation mode. |
| 02:19 | However in this instance what we've done is simply used cable ties temporarily to lock the VVL mechanism in. |
| 02:27 | Obviously it's going to be essential to remove those cable ties after the cam degreeing has been performed. |
| 02:34 | So with an introduction to our project here, let's move on with the first step of our process. |
