Area of the 65mm TB is 3318 sq mm and The Shaft is 10mm x 65mm = 650mm
Area of the 68mm TB is 3631 sq mm and The Shaft is 10mm x 68mm = 680mm
That's aprox 10 percent more area for the larger TB
If you trim the shaft down to 5.5mm you pick up about 300 sq mm.
So you could get 3937 sq mm on the 68mm modified.
That takes up to aprox 15 percent more area over a stock 65mm TB.
Patrick O'Day
2000 Dakota 4x4, 4.7L, CC
Ztube w/9 inch big mouth filter
68 MM TB Ported and Polished
Rancho 9000 Shocks
Robert Shaw 755 180F Thermostat
Mobil 1
----- Original Message -----
From: "John Clawson" <johnc@asltg.com>
To: "dmllist" <dakota-truck@buffnet.net>
Sent: Friday, February 09, 2001 11:30 AM
Subject: DML: 68mm 4.7l tb
> I guess, in a sense, they might have as a result of more than one change
> in specs. I understand that all '01 4.7's have precats(not all 00's
> did). Also the new tb. Possibly more?, Don't know.
>
> I guess the reason I'm asking is because I don't have a feel for the
> difference in air flow(cfm or whatever) for a 3mm difference in tb
> throat size. Doesn't seem like much.
>
> FWIW, its only an interim step anyway as I've got my eye's on Bruce B's
> billet tb along with matched injectors, etc. If nothing else it will
> make cleaning stock tb's a little easier(install a clean one and take
> your time soaking and cleaning another one)
>
> Just curious.
>
> jc
> 00 Sport,cc,4.7,4X4,auto,3.92sg,
> Quickd air,Flowmaster,180 tstat,Jet II
>
> > Shouldn't the horsepower/torque specifications for
> > the 2001 model year truck increase due to the larger throttle body?
> >
> >
>
>
>
>
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