i read this in the ramtruck mailing list: enjoy!. im going to try this
possibly this weekend!.
Several have asked for info on any "home-brew" attempts at modifying the
factory throttle body on their magnum's (for increased airflow I
presume).
Well - I have successfully done some grinding with my Dremel tool after
discovering a large restriction from the throttle plates upward. Let me
explain:
I have been following several vendor's & magazine's results of throttle
body modifications. There are several Stages (if you will) to the
modifications. I say stages because modifications in different areas
have differing results (presumably). I have seen several vendors
selling 'upgrades' to your factory Throttle Body (TB) which consists of
you sending them your original TB and they send you someone else's core
that has been modified in one or more ways.
After deciding that I could do SOME good by opening up my Indy Ram's
breating capability - I bravely removed my TB and brought it in the
house for assessment. (When my wife caught me in the floor with my
Dremel and aluminum filings flying out of our ONLY daily driver's TB -
she about lost it!)
I immediately noticed a large ridge that was located above the throttle
blades. (Later I discover that in my Indy's option list - it says that
a 'progressive' TB was optioned? Say what?) I first thought that any
modification that would remove this ridge would be detrimental to the
idle/part throttle portion of its performance. Started doing
measurements now - Find that the bore & blades are 52mm (from memory?)
but from about half inch above the blades to a little below the top of
bore was a progression which led (in center) to a restricted bore of
48mm. Thats right - looking down into your engine (from the top of TB)
your engine sees 48mm. But the blades and from blades down are 52mm.
Comparing these results to vendor's claims showed bore sizes going up to
80mm (dont think this will work using OEM/Holley TB) This combined with
an article about doing the Dremel work on the TB coming from someone
named Kukukooter on the Dakota List 8-) made me decide to whip out the
ole Dremel. I kept reminding myself that I wanted to replace the
OEM/Holley two-barrel TB with a Holley ProJection-style four-barrel type
(including manifold swap) OR could just buy another OEM TB for around
$200?
So I'm grinding now (using the little sand-paper-wrapped barrel-type
attachment) - just working on the 48mm ridge for now. Decided to take
out throttle blades and shaft so I could get at it from both sides
(Mistake - I dont recommend this as it was a $%&@$# to get back together
- screws didnt want to grab original threads)
Anyway, I removed about half of the 48mm ridge (giving me approx. 50mm
above the blades) and decided to put the thing back together and try it
on the truck for any noticible improvements 8-)
A few minutes later - cranking the truck now / truck starts / kinda
rough idling like it wants to go dead so I kill the ignition / MIL
(Malfunction Indicator Lamp) lights immediately! Big frown now! Was my
wife right? (Your gonna screw up our ONLY driver!)
Kukukooter fails to mention this (in fact - everyone fails to mention
this!) They just say that after the mods - you have to drive around for
'awhile' for the computer to re-learn its fuel-trim. I crank up again
(MIL still burning brighter than ever 8-) I go driving - still kinda
rough around idle. Off-idle seems punchy (dreaming?) so I play with it
giving it big gulps of air - performance seems slightly different each
time I goose it. Altogether seems to have lots more low-end pulling
power.
I jotted down the key-on-key-off MIL flashing codes (still havent
decoded them yet 8-) and it was a good thing because within about 25
miles the MIL went away!! Thats right - the computer learned its new
fuel trim and now (several thousand miles later) I have never gotten
another MIL since!
Wide-Open Throttle (WOT) seems only marginally better (breathing wise)
but the pep-factor (torqueiness?) has definately improved. I decided to
test this theory with a standing start (first stopped - then WOT) and
was pleasantly surprised that I had to let off the throttle QUICKLY
(before going all the way down to the floor - maybe 80%) as my 17-inch
meats (Eagle GT-III's no less) were smoking!
This was a big surprise since before the TB mod - they wouldnt break
loose under almost any condition! (straight line only - turning not
included)
Wheelspin was never a problem before but definately is now! I wanted to
jump back in with the Dremel and remove the other half of the ridge
(leaving 52mm throughout entire bore length) as well as the large
nodules (to help place that sick black-box breather thingy I presume)
but will save this for later as I would like to assess the
fuel-consumption properties since the last modification. Mileage seems
just a tad bit less than before - will probably not make this
determination until later since I cant keep my foot out of it!
To all of you contemplating this modification - I say 'go for it' as we
all stand to gain information as a result (as long as you all share!)
Some drawbacks worth noting are:
- not too much boring or you will be off the computer's fuel map
- questions: What are the limits? Does MP Computer extend them?
- Obviously more air = more fuel = more power =? less economy?
- Illuminating Malfunction Indicators
- questions: Supposedly exceeding x% (x=4??) airflow will trip MIL?
After re-learn is the last MIL stored for tech to
retrieve later?
- Removing blades/shaft - be carefull as mine didnt want to thread-align
the screws
would prefer all new shaft/low-restriction screws & new threads
Implications?
Any comments Jules?
Would love to hear some more results 8-)
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