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Old 02-07-2020, 10:39 PM   #1
xXforgotenxX
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Default 102mm ls throttle body to subaru intake manifold

I was wondering if anyone sees a problem doing this
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Old 02-08-2020, 04:33 PM   #2
Barge
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Besides it being massive?

I'm running an 80mm Hemi throttle body and it's massive compared to stock.

102mm throttle body you're looking at a 4" inlet. I'm all for giving things a shot but 102 seems a bit excessive. My 80 is probably excessive.
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Old 02-09-2020, 12:03 PM   #3
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Besides it being massive?

I'm running an 80mm Hemi throttle body and it's massive compared to stock.

102mm throttle body you're looking at a 4" inlet. I'm all for giving things a shot but 102 seems a bit excessive. My 80 is probably excessive.
Haha yeah probably is excessive I found 1 for $40 so that's why I was curious
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Old 02-13-2020, 04:58 PM   #4
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We did a Q45 TB on the TIC time attack car and that 90mm TB was more than enough for our GTX3582R at 32 PSI.
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Old 02-24-2020, 06:51 PM   #5
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Not worth it IMO. Pretty common to see turbo LS motors running the factory intake manifolds and throttle bodies (86-90mm IIRC).

Guess you could build a manifold to fit the flange then guess correct upper plenum volume, plenum floor height, and runner dimensions. If you're that good, I'd convert to a 4150 style throttle with delayed secondary butterfly.
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Old 02-25-2020, 01:30 PM   #6
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Just for comparison this is the flange for my Hemi TB overtop of a stock size TB inlet.

I added several rods of filler behind the new flange to fill in thin area or completely ground away holes to get it ported out to size.

It would be interesting to see some differential pressure changes across throttle bodies. I have too many other projects I need to get done first though.
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Old 02-25-2020, 03:09 PM   #7
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I'd be interested to see how individual cylinder cfm is affected. Uneven flow between cylinders is more dangerous than total flow restriction.
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Old 02-25-2020, 04:29 PM   #8
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Originally Posted by imma_stocker View Post
I'd be interested to see how individual cylinder cfm is affected. Uneven flow between cylinders is more dangerous than total flow restriction.
I was pretty careful keeping it aligned on center and making sure the plate opens the same direction as stock. I also attached my new flange to the stock flange to at least give it some area flow into the plenum.

These NA manifolds seem to have pretty equal flow based on what tests I've seen and hopefully I maintained that.

Without individual widebands or EGT I don't really have a good way to say for sure that they're balanced though.
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Old 02-26-2020, 06:32 PM   #9
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Oh didn't realize you're modifying the NA manifold. That would also be my pick for this project. Got anyone local with a flow bench?
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Old 02-27-2020, 04:41 PM   #10
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Oh didn't realize you're modifying the NA manifold. That would also be my pick for this project. Got anyone local with a flow bench?
I'm sure someone in the Detroit area has a flowbench. Really need to run it with the TB on for true numbers in my opinion. Also be nice to run it with different TB opening percentages.

I only have an 80mm though... 102 is way too big hah.

I doubt I'll do any flow work on the NA manifold. I've got some ideas to build a custom one so when I get around to that for sure. As said.. runner balance is pretty critical.

I recall in the old intake manifold flow comparison some of the high flowing aftermarkets manifolds had pretty terrible runner to runner variation.
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