FW: Throttle Butterfly valve ramp
ssgacc at yahoo.com
Tue Dec 31 14:15:47 EST 2002
Right on brother. It's very similar to the stories of
my days of yore when guys would throw a 750 double
pumper carb and huge manifold on their unmodified SBC
and then wonder why it ran like sh*t. If you're going
to run track (4k rpm plus out to 7, 8 or 9k rpm, then
fine, go for it. But if you need to actually drive
it, low rpm, on and off throttle, it'll suck. I
couldn't agree more with your assesment of the
--- JShadzi at aol.com wrote:
> Mike, my recommendation is _not_ to mess with any of
> this stuff, having done it in Audi's and VW tuning
> business, for a street driven car in traffic
> There are some considerations however...in the
> smaller 2.2l I5 motors, messing with any of the
> wedges creates a really jerky low rpm throttle
> transition, I'd only recommend removing the wedge
> from an I5 TB on a full on track car, any kind of
> low speed, in the throttle off the throttle stuff
> will drive you crazy, and indirectly increase your
> neck muscle strength.
> The bigger, heavier breathing 2.8l VR6 can cope with
> the mod a little better, but even then, the bored
> out US VR6 throttle body makes for a very jerky car,
> max hp not withstanding, if you do any driving in
> traffic I don't recommend it. Frankly, if you want
> more airflow install a bigger TB (ie: Euro), but
> hogging out one of these will throw off the delicate
> low rpm, progressive considerations engineered into
> the TB. I'm running the stock VR6 TB on my car FYI,
> and I don't have any reason to change it as of yet,
> though its tempting to want "bigger thus better".
> The stock 20v and VR6 TB are 60mm straight from the
> factory, I can't imagine that they won't support
> 500+hp, if you did want to increase the size of
> either, I'd recommend modifying the throttle linkage
> for progression, or trying to re-engineer a wedge
> effect which wouldn't be too hard. Also, I believe
> the Sport Quattro has a bigger 65mm TB, I know the
> Trans Am and IMSA cars had really large close to
> 70mm TB's, not sure how the fit the 20v manifolds
> though, but that's easily modded with some welding.
> >-----Original Message-----
> >From: mlp qwest [mailto:mlped at qwest.net]
> >Sent: Monday, December 30, 2002 9:54 AM
> >To: s-car-list at audifans.com
> >Subject: Throttle Butterfly valve ramp
> >Some where, some time, some place out there, I no
> longer know where, on the
> >net there have been several threads debating the
> pros &/or cons of monkeying
> >with the butterfly ramp, i.e. a la:
> >"....The US throttle body has an air ramp right in
> front of the throttle
> >plate, restricting air flow. The upgrade (which is
> really the
> >European TBody from VW) does not have that ramp,
> and they claim that
> >the total package (chip + throttle + K&N filter)
> added 30 road Hps.
> >The throttle body is rather pricey (about US$ 300),
> and I
> >you can't take your existing tbody and mill that
> ramp out because there
> >is not enough material in the casting.
> >Another difference is that the Euro TBody has a
> progressive mechanism
> >to open the throttle valve while the US has a
> direct hoockup.
> >This makes the low end more controllable but also
> seemingly softer
> >The third difference is with the potentiometer. It
> is also different....."
> >Any one have a better line on this? As I vaguely
> recall, notwithstanding
> >the "Icelords" endorsement, this was otherwise not
> considered a "good thing"
> >to do.
> >Mike "still stumbling once & awhile, but it could
> have been the egg nog"
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