FW: Throttle Butterfly valve ramp
JShadzi at aol.com
JShadzi at aol.com
Mon Dec 30 14:03:14 EST 2002
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 especially.
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.
>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"
>Mike "still stumbling once & awhile, but it could have been the egg nog"
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