Thread: Msd 6al 6462
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356-930 356-930 is offline
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Join Date: Aug 2007
Location: Laguna Beach, CA
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Originally Posted by dsiegel360 View Post
356-930
I think full boost enrichment usually comes in at 6psi. (not sure). If so, should the MSD be set to begin retard at 6 psi and continue at either 1, 2, or 3 degrees per pound till 14.5 (1 bar)?

As you had mentioned, there is already a boost retard on the stock system, so, once we figure out how much, is it then just a simple equation or is the combo of the stock retard and the MSD retard a recipe for disaster?

Instead of idle at TDC as it is currently, if I set the idle timing to 3-5* ATDC, how will this affect non boost cruise at 3000 or 4000 rpm's? More power or might it miss?

When boost pressure kicks in, I've already got the stock retard. Is the only advantage to this system that at low rpm's timing can come in sooner, or does this system allow quicker timing on boost too? (I don't know if this question makes sense, but I tried.)

Thanks for your detailed answers.
Doug:
I don’t know where fuel enrichment occurs relative to boost on your engine. Perhaps a Porsche manual has that info but if not, a data logging system incorporated in your engine management system will reveal that data. In fact, if you don’t have a data logger giving you AFR v EGT, Boost and RPM, you’ll remain in the dark here.
Where the boost retard starts and at what rate is going to be determined by trial and error in your tuning efforts. A dyno is nice for adjusting but not necessary (provided you have a data logger and a ½ mile strip of asphalt without ingress/egress by other vehicles and not haunted by your local or state police).
If you’re significantly advanced at 3k-4k unloaded cruise, the engine will likely mis-fire (mine does) without load but the instant any load is applied, all is well.
Adding the MSD boost retard and employing it is not a recipe for disaster. Running excess timing without boost to get low end power/torque may cause EGT to rise a bit but it won’t result is detonation, the real enemy under load. If EGT gets above 1250, probably too much timing/advance.
The MSD boost retard system won’t allow timing to come in sooner, it allows one to run more initial timing – it’s in at all times until removed by the stock retard or the MSD’s electronics. Bottom line - adding a secondary boost retard system facilitates running greater initial timing as both the stock and MSD boost retard systems work independently to remove timing under boost. Where you may have had 8-10 degrees of retard under boost, with the addition of the MSD you will have 28-30 degrees of boost driven retard available.
Think of the MSD boost retard system as a safety valve to help prevent detonation that just happens to assist with low end performance. Whatever excess timing your engine needs to wake it up at low rpm and low manifold pressure can be removed under load/boost.
Lastly, if you really want to push the timing envelope for available power under boost, add a water/methanol injection system. There are several available. I run a Snow Performance unit (I don’t have room for an intercooler so it’s my “cooler”). You can learn what the system can do by studying info on Snow’s website http://www.snowperformance.net/
Chris
Old 04-15-2008, 08:37 PM
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