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Re: RE: [T3] engine internal stuff

Hey Toby-

> Wow, great information!

Thanks :-)

> Hmm, you mean me and Leon are the ONLY two people who push our gas pedals
> like they were a light switch? ;)

Nah... currently, I have an upright T4 2.0L (with air conditioning!) in my
'71 Ghia (I'm converting it back to pancake, still with A/C, and putting it
in my '72 Fasty and building a T4 2594cc for my Ghia :-).  And,
unfortunately, I have carbs on it.  Anyway, my highway mileage is typically
24-28mpg or so.  However, between the insensitive throttle and a slighty
(yah, right) "digital gas pedal," my city mileage is typically 16-20mpg :-)

> Right after I bought my (used) Jetta from the stealership I replaced
> and tranny oils with synthetic and realized an increase of 5hp (average)
> .5 second off my 0-60mph timing.  I'm a firm believer of synthetic
> lubricants...right volks? :)  See the bottom of this page on how I
> my results:  http://www.icbm.org/erkson/personal/mycars/jettastats.htm

That's quite a bit!  I'm a firm believer, too, but they're not all equal.
That's the only trick!

> What does "IR" mean for your carb calculation?

Independent Runner.  It means you have one independent carb throat per
cylinder.  It's common for VW guys, but V8 muscle car guys drool at the
thought of IR carbs on their toys...

> I read a small portion of the dynamic compression thread but it's honestly
> too, too long and someone should condense it.  I'd like to know more about
> the theory, sounds quite interesting and applicable to all cars (hmmm,
> about rotaries? ;)

I don't have time now, but perhaps I can make a longer one.  It should
actually be much easier to understand since I skipped several things in the
shorter one...

Take care,

> Thanks for the info!!
>    Toby Erkson
>    air_cooled_nut@pobox.com
>    '72 VW Squareback 1.6L bored and stroked to 2.0L, Berg five-speed
>    '95 VW Jetta III GL 2.0L, P-Chipped, Jamex sport suspension
>    Portland, Oregon, http://www.icbm.org/
> >-----Original Message-----
> >...
> >And, heck, you aren't riding at WOT all the time, which is all
> >that plot is good for...
> >Here's one I use for a rough IR carburetion calculation:
> >VenturiMM=SQRT(RPM*CylCC/2800).  For a 2332cc engine (583cc
> >cylinder) at
> >6000rpm, that's about 35.33mm.  From what I've seen, typically
> >VW people tend
> >to stay on the liberal side of this estimate.
> >
> >Then, as for throat size, you have a catch 22.  Big throat
> >size for the same
> >venturi size means better atomization on the main circuit, but
> >an overly
> >sensitive throttle response at your foot (can you say gas
> >mileage killer?  :-)
> >and poorer atomization on the idle and progressive circuits.
> >Smaller throat
> >size for the same venturi size means the opposite of above.
> >Keeping the ratio
> >of venturi area to throat area (VenturiMM/ThroatMM)^2 around
> >65-80% is good
> >enough.
> >
> >Now, Weber 44IDFs come out of the box with 36mm venturis.
> >Sounds good to me!
> >
> >As a sidenote, Weber 48IDFs come with a 40mm venturi.  But,
> >Weber 40IDFs come
> >with a 28mm venturi.  Too small!!!
> >...
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