Lacking Power
I purchased a 1998 Gulf Stream Sun Voyager today. It has a 5.9 liter Cummins Diesel with Allison 4 speed transmission. The test drive the owner took me on was about 20 miles, since I didn't drive I...
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1998 was when the 5.9 switched from 12 valves to 24 and both were produced that year. It sounds like you probably have the 12v version which topped out at a little over 200hp I believe when in perfect condition. The 24v would have been at a little over 230hp in 1998. The 12v were known to be extremely reliable engines. What were the RPMs when you were chugging up the hills? It may have been in the power band in 4th and didn't need to downshift. Diesels don't rev to produce max power like Gassers do.
It would be a great Idea to take it by a Cummins authorized service center for a checkup and they may be able to suggest upgrades for more HP.
There is always:
Banks Power
It would be a great Idea to take it by a Cummins authorized service center for a checkup and they may be able to suggest upgrades for more HP.
There is always:
Banks Power
