It IS from some other mystery! The stock manifold is tuned to produce
more power down low, the runners are tuned to fill the cylinders most
efficiently at low RPM's. The M1 on the other hand, is tuned for higher
RPM's. How does this effect pinging? Easy, there is less air making it
to the combustion chamber, which lowers cylinder pressure, which
lowers the tendancy to ping.
I don't know exactly where the M1 is tuned for, but I would listen for
pinging higher up (4000+). But then again by that time the stock heads
and cam are probably a bottleneck.
(This is purely speculation, I have no proof of anything!)
I'm still trying to figure out how nobody lost torque with the MPI.
<< Ok, since the MPI manifold my truck hasn't pinged one time!!!! Don't
get me wrong I'm NOT complaining.....
So the other day when I filled up I got curious. I filled up with 89
octane + 4 gallons of left over 93. This morning on the way to work I
laid into it and guess what.... NO PINGS, smooth as silk man! I'm
going to run one more tank of 89 so it's not diluted with any 93 stuff
and see how it does. If it passes that test, I'll try 87 and see what
happens. BTW, this is with the ac running full and outside temps in
the triple digits range.
Keep in mind I'm talking about the MP computer here, not the stock one.
Before the manifold it would ping with even 93. So what cured the
ping? Well, it could be the belly pan deletion, or the higher
flowing LA style thermostat, or perhaps some other mystery.....
--Mike www.mikesdakota.com >>
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