Being that I am a novice when it comes to Dakotas, as I've
been told...
Gutting the cat is one reason you lost your low end.
Here's a little info on the R/T (and other 5.2/5.9L Magnum
powered vehicles).
The cam is setup for torque-- towing power (even though we
all know the story about the R/T and towing). Your torque
curve comes on around 1400 rpm and climbs steady up to
around 3800 where it starts to curve back down (and
steeper). You horsepower doesn't really start to build
until around 3500 rpm (150 or so at the wheels)... and
peaks around 4600 rpm. By 'gutting' the cat for
horsepower, you've killed your torque. I bet the truck is
a dog (to me at least) until about 2500 rpm, when it starts
to get going... Your power curve would fall into a small
window of about 2500-4600 rpm. That's only 2100 rpm worth.
If you had a high reving cam, then the horsepower window
would be much wider, as it most likely wouldn't be gear
towards torque. What to do? Well.. start from where you
did- headers. Shortie headers are great for torque, and
offer some increases in horsepower (JBAs w/ stock y pipes).
The R/T already has tons of torque down low, so you might
want to (if you haven't already) look at replacing the
stock Y pipe with larger (JBA Y pipe, or Mopar Performance
complete Header setup). This arrangement will lower torque
values a little on the low end, but horsepower gains will
help, as well as higher torque values farther into the rpm
range. Now you've got that done, you need to run with a
CAT. A stock cat is already a good flowing setup. Go too
big, against a too low back pressure exhaust, and you lose
all the perf. gains the headers gave you. A good
compromise is to open a stock cat to 3" in/3"out. This
helps to gain a little more flow, without killing your low
end. From there-- don't over do the exhaust. 3" is plenty
big w/flowmaster, Borla, etc. A bullet or ultraflo
straight through design is good, but lowers your torque
some (vehicles vary-- but you need to keep a balance on the
backpressure-- ever drive a car with a bad exhaust leak??--
no power). If you go duals out of the muffler, 2.5x2 on
flowmaster, borla, etc. If you go with a ultraflo or
bullet style-- 2.25x2 will work wonders. Put bigger tips
on the end to get the look, but the setup works. Adding
horsepower usually causes a traction problem, and thus, a
higher 60' time. Adding traction devices to gain traction,
might give you too much traction, and slow your
acceleration-- higher 1/4 mi times. Welcome to physics!
You now must balance all of this to lower your e.t. One
item you might not have thought about-- adding headers
creates enormous amounts of heat under the hood, and that
affects the way the truck runs (air intake, TB, intake
manifold heat, etc.)
The problem with your check eng/abs, etc. should be checked
at the dealer. You could have a bad O2 sensor (you
mentioned headers), or a fault PCM.
Sam '00 RT RC (237.5 hp/327 ft.lbs.- My wifes truck)
'99 4x4RT CC(205 hp/289 ft.lbs. - My work truck)
'99 RT RC (209 hp/310 ft. lbs. -buyback)
'95 SLT CC (217 hp/315ft. lbs. -sold to my brother)
'99 RT CC (? hp / ? ft. lbs.- ran a 15.1 stock-
buyback)
'91 LE CC (145 hp / 260 ft. lbs.- traded in on the
'95!)
Been there-- Done that.
=====
Sam '00 RT
(14.667@93 mph)
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This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:53:38 EDT