("Before and after" dyno pulls)
Above is a comparison of the stock manifold and the MPI on a '97 Dakota with a 318 and an automatic transmission. Mods to this particular truck include an open element air cleaner, Mopar Performance headers, cat-back dual exhaust, Mopar Performance R/T cam and Mopar Performance valvetrain. At the time of this dyno run, the truck was using a computer calibrated for a blown Ram with 30lb injectors.
The top graph is the dyno run. The graph below it shows the torque and horsepower gain (or loss) of the MPI vs the stocker. Positive numbers indicate the MPI making more HP or torque than the stocker, negative numbers indicate the MPI making less HP or torque than the stock intake.
As you can see, from about 3400-4100rpm, the stock intake is actually making more power than the MPI. We still are not sure whether this is a characteristic of the MPI or whether it is a problem with this particular truck. (I don't have enough data to make a valid comparison.) However, even if we take a "worst case scenario" perspective and assume that the MPI will exhibit this characteristic on all engines it is installed on, I think the data is still quite favorable for the MPI. Except for that ~700rpm window, the MPI averages about 10hp more than the stocker across the entire powerband. And check out those numbers around 2000rpm; a 40lb-ft advantage for the MPI! You can also see the MPI showing off its superior ability to breathe at the top end with over 30hp and a solid 35lb-ft advantage over the beer barrel when the run was shut down. Notice also that the power and torque growth was increasing in a linear fashion, with no indication of slowing down! Its fairly apparent that the MPI would love to rev to 6000rpm and beyond. If you have an engine that is capable of doing so, you should see some MAJOR gains by switching to the MPI!
This is the same truck as above, but using the stock computer instead of the blower PCM. As you can see, the mid-rpm power shift is present here as well, but outside of that RPM range, the MPI showed similar gains as before. The advantage of the MPI at low and high RPMs is evident here as well. (Though the gains aren't quite as large as with the more agressive PCM.) Even so, take a look at the lower RPM gains... 20-25 more foot-lbs than the stocker at around 1300-1700rpm. So much for the theory that the single plane MPI will take away your low RPM torque! If there is one thing I've learned about intake manifolds, its that there are so many variables involved that there are no pat answers. Single plane does not always mean poor low RPM torque, just as dual plane does not always mean poor high end HP. The only way to know for sure is to try it!
(Dyno pulls of trucks with MPIs installed; no "before" data available)
226hp and 332lb-ft at the rear wheels
This is the same '97 318 as above, but using a 1996 Mopar Performance PCM.
235hp and 293lb-ft at the rear wheels
This is my 1996 Dakota with a 318 5-speed. Mods to this truck include an open element air cleaner, ported throttle body, MPI intake, JBA headers, 2.5"->3" y-pipe, 3" exhaust with no cat, 3" Gibson cat-back, and a Mopar Performance PCM.
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