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Forced Induction Superchargers | Turbochargers | Intercoolers

TH400 vacuum modulator????

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Old Apr 28, 2008 | 06:17 AM
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Default TH400 vacuum modulator????
Something I never put much thought into, but what are you guys using for this on a turbo application? Any schematics or diagrams would be appreciated. What about the electric kickdown, I wonder if I can trigger that through the big stuff 3 via TPS, non trans control version.
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Old Apr 28, 2008 | 09:12 AM
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You could run the downshift off the wire for the second fuel pump, that is adjusted by tps. The vac thing I am not sure what you would need to do, but you can't have pressure on the trans. Probably need a one way check valve in the line with a controlled leak.

Kurt
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Old Apr 28, 2008 | 09:46 AM
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I'm curious about this as well, because I'll be running a Th350 with a VM too.

I hope someone chimes in. I've never thought of that either.
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Old Apr 29, 2008 | 01:27 PM
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Originally Posted by 427
You could run the downshift off the wire for the second fuel pump, that is adjusted by tps. The vac thing I am not sure what you would need to do, but you can't have pressure on the trans. Probably need a one way check valve in the line with a controlled leak.

Kurt


Transgo makes a kit just for turbo/supercharger vacum to boost, it does have a check ball. However you can set the modulator just right and run it with no vacum it will work great.
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Old Apr 29, 2008 | 01:52 PM
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Just put a T in the vac supply to the modulator and put a checkvalve (like for a/c or cruise) on one port so it closes under vacuumand opens under pressure. Or you could just buy one on ebay Ive seen them on there.
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Old Apr 29, 2008 | 01:58 PM
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Or you could just buy one on ebay Ive seen them on there

Are you talking about the previously mentioned TransGo kit?
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Old Sep 20, 2008 | 07:02 AM
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any part numbers?
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Old Sep 20, 2008 | 10:18 AM
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Originally Posted by 427
You could run the downshift off the wire for the second fuel pump, that is adjusted by tps. The vac thing I am not sure what you would need to do, but you can't have pressure on the trans. Probably need a one way check valve in the line with a controlled leak.

Kurt
could you not run that vacume line to the pre turbo for vacume?
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Old Sep 20, 2008 | 11:13 AM
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Originally Posted by daniel6718
could you not run that vacume line to the pre turbo for vacume?
Not enough vac there, is there? I just went with a full manual valve body with a hammer shifter. I think it's great.
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Old Sep 20, 2008 | 12:01 PM
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Originally Posted by 1dirtyZ
any part numbers?
VBP-VAC

It's been recommended to me to run two in series at high boost levels to make sure all the boost is being vented.
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Old Dec 8, 2008 | 07:43 AM
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I just picked up the Transgo VBP-VAC, pretty simple check valve, but when it goes under boost, the check valve will close, and it vents the boost out one of the ports on the "t", so it does not go on to the modulator. My question is, does that create a boost leak? It just goes to atmosphere. Anyone using one of these?
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Old Dec 8, 2008 | 11:54 AM
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Here is a diagram.
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Old Dec 8, 2008 | 06:18 PM
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I'm using one, I guess it is a boost leak, but it must not be big enough to make a difference b/c my car makes the boost it should.
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Old Dec 8, 2008 | 06:23 PM
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Originally Posted by veee8
My question is, does that create a boost leak? It just goes to atmosphere. Anyone using one of these?
Technically yes, but as long as you put it at the transmission, it should be fine.
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