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ZZP throttle body turndown?

the good news is that you can control certain 90 millimeter drive by wire throttle bodies with our TAC
at least then your throttle body is larger than the blower inlet.
 


Turbocharged400sbc said:
well to start there is a 10 millimeter thick shaft running through the middle of the smallest part of the bore...
then onthe DBW there is also the airflow shelf that is riveted to the blade so that at throttle openings less than 15 pct, only one half of the throttle blade is effectively changing the airflow volume.
even then it does not allow for very fine changes in idle control...it works well enough though
Click to expand...

I not arguing that this effects the effective diameter. Everything above sounds like a guess. 10mm shaft sounds really big.
Trying to determine what you think versus what you know.

I know the gen 5 supercharger has a inlet hole that is 75mm or bigger.

I know that the ZZP inlet turn down is closer to 70mm inner diameter.
 
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sseilmnop said:
I not arguing that this effects the effective diameter. Everything above sounds like a guess. 10mm shaft sounds really big.
Trying to determine what you think versus what you know.

I know the gen 5 supercharger has a inlet hole that is 75mm or bigger.

I know that the ZZP inlet turn down is closer to 70mm inner diameter.
Click to expand...

since i was out here i grabbed one of my dbw tb's out of the dbw tb bucket and stuck a caliper on it.

center of shaft is at .390, the end near the bearing is at .393, 9.98 mm
the tb bore is offset, it is not a straight through venturi design, it is a butterfly inside a sphere with an increasing radius, this allows the throttle blade to mave at each individual stepper position but the bore/airflow path doesnt change but a hair, once the blade is at about 12-15* those spherical ramps disapear and the straight section of the bore is presented to the blade. early tb's had a spherical shelf riveted onto the bottom of the blade (leading edge) to do this with a straight bore. you can remove the shelf from these early ones for much better flow but it will have the notchiest idle youve ever experienced.

the later ones would probably have a had time passing a 70mm od shaft straight through the bore axis centerline due to the spherical offset at the blade pivot centerline.

so yeah its a 75mm on paper, but it aint. tis why i played around with the 90mm dbw with our external TAC
 
The turndown hit my cross over when I was not intercooler. Had to grind it down to get it to fit... Then I went IC and it didn't matter any more.
 
Turbocharged400sbc said:
since i was out here i grabbed one of my dbw tb's out of the dbw tb bucket and stuck a caliper on it.

center of shaft is at .390, the end near the bearing is at .393, 9.98 mm
the tb bore is offset, it is not a straight through venturi design, it is a butterfly inside a sphere with an increasing radius, this allows the throttle blade to mave at each individual stepper position but the bore/airflow path doesnt change but a hair, once the blade is at about 12-15* those spherical ramps disapear and the straight section of the bore is presented to the blade. early tb's had a spherical shelf riveted onto the bottom of the blade (leading edge) to do this with a straight bore. you can remove the shelf from these early ones for much better flow but it will have the notchiest idle youve ever experienced.

the later ones would probably have a had time passing a 70mm od shaft straight through the bore axis centerline due to the spherical offset at the blade pivot centerline.

so yeah its a 75mm on paper, but it aint. tis why i played around with the 90mm dbw with our external TAC
Click to expand...

That is definitely factual! I would not of expected a 15 percent reduction in area.
 


sseilmnop said:
That is definitely factual! I would not of expected a 15 percent reduction in area.
Click to expand...

yeah, but keep in mind dbw was "cheaper" it still is 75mm across the bore where the 10mm dia shaft sits lol

but yeah N*/LS1 75mm > DBW 75mm

id go as far to say that i believe thats why gen5 builds on average seem to make more power on cable drive cars over the dbw
 
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