FW: Throttle Butterfly valve ramp

Jim Green jeg1976 at yahoo.com
Mon Dec 30 15:58:30 EST 2002

--- 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
> 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.
> HTH,
> Javad

Having just switched to a Ford V8 TB at 65mm, no
wedge, I can say it is a little different.  It takes
some getting used to, but it's been fine so far.  I
did have to add another spring to it to make the pedal
stiffer, and that helps enormously with modulation.
Stop and go traffic was easy.  The one area where it
was real jumpy was at 80-85 mph.  One little crack of
the throttle and you're in triple digits before you
know it.  I was going to play with some different cams
that I had, but they didn't fit to well.


Jim Green
'89 90tq 034EFI, Haltech IG5

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