Join Date: Nov 2004
Location: Pacific Northwest
Sure, a person can learn something on these forums, at times on the order of an epiphany of sorts no less. I regularly browse this and dozens of other forums in an ongoing search for knowlege, much more than it would seem from my limited posts. I just tend to refrain from chiming in unless I feel that what I have to say has some basis in my own personal validated experience. I do appreciate however that there is a lot of traffic in basic conceptualizing, I just usually don't have the time to participate here and would rather do my testing in real life in the shop and at the track.
Having said that, in my opinion there is far too much opinion based on anecdote given as fact, particularly on this forum for some reason. A typical question is followed by a response endorsing a method or product with no rationale beyond the fact that the person making the endorsement uses that particular method or product, therefore it's the best. Of course that must be the case, because otherwise I made a bad decision. It's a self- supporting argument, and by definition has little to no real value.
How does this translate, and why did I respond the way I did?
Early 930 engines don't have any engine management electronics that act as a buffer for conditions that can instantly cause terminal damage. They don't tolerate experimentation with fueling and ignition. I think many people fail, and continue to fail to appreciate just how quickly things can go very bad, from seemingly innocent actions, and then suddenly you have a pile of junk and no one to blame but yourself.
Posting queries on a forum about subjects like ignition timing, when someone is looking for suggestions beyond the factory specifications for ordinary stock builds, need to include a comprehensive list of data points before any real judgements can be made. Especially for boosted air cooled engines with no electronic management systems that will step in to prevent excessive settings. Things beyond the usual build specs, in particular the cam profile type, lift/duration/LSA, and the cam timing setting, which all determine but only in part when the peak cylinder pressures will be present. Other things play into this; the intake design, the turbo map, fueling system configuration and ignition system type also play critical roles. The only real way to know what the timing value should be is to run the engine on a dyno, preferably an engine dyno with full instrumentation including an EGT monitor, begin with conservative settings, and sneak up on the optimum setting which should present itself as peak torque with proper EGTs and AFRs.
If a person doesn't have access to this equipment, the budget to support the testing, or possibly the intelllectual capacity or motivation to build the intellectual capacity then my recommendation of leaving things to the professionals only makes sense.
So from a practical perspective, in reality there is nothing to be gained from doing a survey about timing settings, except possibly just knowing you're in the ballpark and NOT using that range to experiment with. On the other hand, there is a lot to lose if a person chooses to assume that a committee style consensus validates a range of timing values.
The same can be said of many subjects, although the risks are far less when choosing a torsion bar size or tire size, to the point where it's probably O.K. to proceed with some information gathering and part selection, since worst case you simply won't care for the outcome, rather than taking a $20K (typical 930 rebuild) hit in the wallet.
Finally, I don't care for the personality conflicts that add nothing to the discussion, that usually have a basis in some emotional response, and that don't account for both sides of a story. It's not relevant and adds nothing to the discussion.
Last edited by Randy Blaylock; 11-21-2006 at 06:04 AM..