Engine/Transmission (1998.5 - 2002) 1999 with 8 Speed wants Larger Turbo

[JMHodge]

I would like to put a larger Turbo on to get more power and maybe cut down on some of the smoking at cruise. However I need power at the low-end since my Cummins is happily idling down the road at the speed limit. Can anyone recommend a Turbo and another chip to stack on top my Superchip. I would like to shoot for a Max of 400 to 450 hp. But I don't want my EGT's to go through the roof at the low RPMs I currently run the engine at.

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I have a 1999 5-speed with the Gear Vendors 2 speed installed. I'm running BFGoodrich 315's with a 6 inch longarm lift and a 3. 54 rear end. The engine has a Superchip, Volant high-performance intake, and a four-inch stainless steel exhaust. I installed 5 in. Bull Horn stacks and welded up a custom light bar for six Black Magic's. My Ram-zilla has a massive Trail-Ready front bumper with Brush guard (half cowcatcher and half basket ball goal) and 12,000 lb. WARN, I fabricated my plate back bumper with swing out tire carrier. So she is pretty heavy and pretty dirty aerodynamically, a lot like pushing a locomotive down the road…. at least it looks like one. People are all kind now and don’t pull out in front of me anymore. With the Turbo wine and the throaty 5 in. stacks it sounds like a Kenworth and I'm loving it. Right now it averages 20 to 21mpg with 23 nursing it… with a tailwind.

The engine idles at 900 but in double overdrive (8th) will do 50mph at 1000 rpm. I don't run it in double over at such low rpm but do run 65 mph at 1250 rpm and 75 mph at 1500 rpm…. so 3000rpm would-be 150mph and we don’t want to go there with my BFGoodrich Mud Terrains. My EGT’s average between 800F and 1000F (1100F max) with beautiful contrails. Dodge in all their brilliance controls the cruise control with the computer and the computer looks at my speed and my RPMs and has decided that there is no way that the truck to be going that fast and the engine going that slow so it refuses to engage in 8th. I asked one of my local Dodge dealers if they could reprogram my computer so it would engage in double over. To no avail they can’t reprogram it so I'll have to put an aftermarket cruise control on the RAM. However that's not my question at this time, I currently have the problem solved and started a Redneck Urban Legend with an EASTON cruise control.

Mike

 

[bmoeller]

At those RPMs, a larger turbo WILL smoke worse than what is currently on the truck. They take more RPMs to spool.



"65 mph at 1250 rpm and 75 mph at 1500 rpm" The RPMs are really lower than they should be. 1500 at 55 would be better.



Is the thermocouple pre, or post turbo? If post, 1100* is pretty hot. Really should drop a gear, or 2, to bring the RPMs back a little (and to drop the EGTs). 1100* (post) would be 1400*+, depending on the temp differential.

 

[DHayden]

Those rpms are low, it's been shown that you will actually get better mileage keeping the engine in the sweet spot of torque rather than lowering the rpm's. I would try to stay around 1700/1800rpm's for the best mileage. JMO

 

[JMHodge]

The thermocouple is pre and at 55 it is running 500-800F actually I drop back a gear where the engine seems happy. In 8th 65 is 800-900F 1000F on hills. If it starts to lug I downshift to 7th (old 5th). Thanks Mike



When I was running the old setup I got my best milage at 1450 since I have all the lights that make a air dam out of the light bar... the faster I go the drag really increases. But I'll try the 1700-1800 range in 5th (old 4th) and in 6th (old 4th over) which is about 200RPM greater than the 7th (old 5th) and let you know what it does.

Thanks Mike