GE8 big bore throttle body question

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#21

07-29-2010, 11:51 PM

555sexydrive

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Join Date: Oct 2009

Location: ATL, Jorja

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Quote:

Originally Posted by mkchiu

It's more like 107% assuming that 44mm air filter box opening is the smallest cross section. Assuming those Neon TB restriction results are the same as on the USDM Fit (that is same area shaft and blade), then 44mm allows about 193 cfm.

1.5L ~= 91.5 ci
@100%: 6800*91.5*0.5/1728=180 cfm
@110%: 180*1.1=198 cfm

193/180 ~= 107%

Or more like 228% at the opening if the USDM GE8 Fit TB is 63mm (~2.5in). Although there are posts indicating 2.75 in. Assuming those Neon TB restriction results are the same as on the USDM Fit (that is same area shaft and blade), then 63mm allows about 410 cfm.

410/180 ~= 228%

I'm not using the stock airbox so that 44mm opening doesn't come into play.

Also the GE in the US is using a bigger TB than the JDM model? I ask because J's bored throttle body is 60mm ID at the opening and 52mm at the butterfly and I believe stock is 49 or 50mm butterfly and 57 or 58 at the opening. I should go find some calipers and measure the TB opening or just crudely do it with a metric ruler.

#22

07-30-2010, 05:00 PM

apexanimal

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does all of this assume that the intake air is at the atmospheric pressure the car is at? that is that there isn't a pressure drop or increase from where the air is being ducted from?

#23

07-30-2010, 08:12 PM

mkchiu

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Location: CA

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Quote:

Originally Posted by 555sexydrive

I'm not using the stock airbox so that 44mm opening doesn't come into play.

I've seen multiple posts here that say 2.5 & 2.75 in (outer diameter maybe?), but I just opened my USDM GE8. Without taking out the battery to get the the air filter housing, etc out, I measured about 57mm with my calipers. So butterfly is likely the equivalent for USDM and JDM.