To recirculate or not to recirculate? - Nissan Forums : Nissan Forum
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post #1 of 42 Old 10-29-2007, 09:54 PM Thread Starter
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To recirculate or not to recirculate?

heres the answer straight from the horses mouth, for those of you, like me, that are currently running a JWT program. this is in response to my email to Ben from JWT.

Hi Jay,
The Nissan control system was not designed to run a BOV to
atmosphere. There is no way to make the ECU work with this as the
amount of air flow in the system that is lost if an atmospheric BOV
opens is an unknown amount to the ECU. Once the air flow comes
across the MAF sensor, the ECU expects all that air to be in the
system and adds the fuel based on this amount. So if you do not want
to have the stalling when coming to a fast stop and/or the rich
conditions between shifts, we recommend you run a recirculation type
valve (also known as a compressor bypass valve). It might be
possible to convert your existing valve to the proper type. Check
with the company that made your BOV for this. Note that the air flow
when recirculated, should dump back to the inlet side of the turbo
and ideally aim at the compressor wheel in the turbo inlet. This
also helps keep the turbo more responsive between shifts.

Best regards,
Ben Pila (Technical and Sales Support)
Jim Wolf Technology, Inc.

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post #2 of 42 Old 10-29-2007, 10:26 PM
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disclaimer: i have no idea what i'm talking about.

what if the BOV were placed before the MAF? (if that is even possible) would it still matter?

1997.5 Altima GXE Ltd.
My first car, owned for 9 years and sold 09/2012

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post #3 of 42 Old 10-29-2007, 11:16 PM
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^yes its possible with a blow thru setup, but really, iirc the pressure spike at the MAF isnt good for it


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post #4 of 42 Old 10-30-2007, 12:53 AM
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Well dudes, there you have it. RECIRC. RECIRC, RECIRC.
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post #5 of 42 Old 10-30-2007, 02:34 AM
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AHHHHHHHH

This has been said like, i dunno a gazillion times.

DAMN


STICKY THIS SHIT BRIAN

Special-K
And the name is supposed to be vader3120. F*** IT!

1997 Altima KA24DE-T RIP
1991 SE-R SR20DE - For Sale
-Tranny Swap Done (JDM B13 VLSD & JGY LSD)
2004 Jetta 1.8T - Daily Driver
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post #6 of 42 Old 10-30-2007, 02:42 AM
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Yes, thats tru, for the setup most of us have with the stock maf pre-turbo and a JWT reprogramed Nissan ECU. I think if the MAF is after the turbo, it could work and i'm pretty sure i have seen it work. The MAF along with the ECU must be able to see and repsond to that boost pressure while in the boost path though. As dude described it, its the "Nissan control system" that cant run this setup, but a custom standalone i think can get away with it; an EMS or something. At least i think i'm sure about this. I mean almost anything is possible when you go standalone.

I was going through the KA-T forums for a few minutes looking at pictures of setups and not every 240 runs recirc. from what i can tell. By no means am i changing my setup, but i think i could be done.
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post #7 of 42 Old 10-30-2007, 02:44 AM
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if your running stand alone you better have an f****** MAP setup

And yeah not all of them have a recirc, but i can almost guarantee you that if you search their name and read through their posts, i bet at least half of them had issues or still do

Special-K
And the name is supposed to be vader3120. F*** IT!

1997 Altima KA24DE-T RIP
1991 SE-R SR20DE - For Sale
-Tranny Swap Done (JDM B13 VLSD & JGY LSD)
2004 Jetta 1.8T - Daily Driver
-FMIC, Turbo Inlet Pipe, 3" Turbo Back Exhaust

Last edited by vaser3120; 10-30-2007 at 02:46 AM.
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post #8 of 42 Old 10-30-2007, 02:50 AM
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yea, there may not be an issue-free approach. I'm not too keen on MAP setups but if we can run that with a standlone, thats sweet then. FastKA24 should go ahead and give that a go.

But all speculation aside, Yes, what Mr. JWT guy says absolutely correct.
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post #9 of 42 Old 10-30-2007, 05:18 AM
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Why no likey on the MAP setup, the only thing i dont like, is that the map im gong to use isnt a nice one like aem and only uses a barb type end. I would much rather be able to use press lock fittings rather then worm clamps.

Special-K
And the name is supposed to be vader3120. F*** IT!

1997 Altima KA24DE-T RIP
1991 SE-R SR20DE - For Sale
-Tranny Swap Done (JDM B13 VLSD & JGY LSD)
2004 Jetta 1.8T - Daily Driver
-FMIC, Turbo Inlet Pipe, 3" Turbo Back Exhaust
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post #10 of 42 Old 10-30-2007, 08:16 PM
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oh no, i meant i dont know much about the subject, MAP setups and all. but if it works, thats cool. FastKA has been talking about it and he's running EMS so he should go for it. Or you if you are going standalone. So this is an actual sensor that reads the pressure right at the intake manifold? and you custom install this? what sensor do you use, something aftermarket or from another nissan like the twin turbo Z or SR-T?
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post #11 of 42 Old 10-30-2007, 08:40 PM
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Well the sensor itself does not have to be directly attached to the manifold. As long as the sensor is reading Manifold Absolute Pressure. (Check out Ultimatuc's pics, and you can see his AEM MAP sensor attached to a vacuum manifold)

That is prob the easiest way to do the setup.

You can buy MAP sensors from quite a few places now, most use the GM 3 Bar MAP sensor, this is good for like 33+psi.

I myself am going to try something else, im going to use the sensor that mega squirt uses, or a similar one.

Special-K
And the name is supposed to be vader3120. F*** IT!

1997 Altima KA24DE-T RIP
1991 SE-R SR20DE - For Sale
-Tranny Swap Done (JDM B13 VLSD & JGY LSD)
2004 Jetta 1.8T - Daily Driver
-FMIC, Turbo Inlet Pipe, 3" Turbo Back Exhaust
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post #12 of 42 Old 10-30-2007, 09:34 PM
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^why not just use the gm 3bar like everyone else? lol... MAP sensor eliminate the NEED for a recircing bov *typically*


basically it works like this:
if you have a MAF, it needs to sense ALL air traffic going into your engine. however, if you place the BOV somewhere between the MAF and the TB, what will happen is this:
when you close the TB (like to shift or let off the gas or something of that nature) the turbo still pushes air against the TB creating a boost in pressure inside the intake tubing. the reason for a BOV is to vent out this excess pressure and prevent turbo damage (i forget what the term is, but basically where your turbine gets interrupted). a BOV must be located between the compressor and the TB. if your BOV is between the MAF and the TB, what happens is that the ECU reads x amount of air that it expects in the engine. when you close the TB, the BOV opens and releases air, meaning, less air in the engine than the ECU had already calculated for. when the ecu thinks it has alot x amount of air coming in, it will up the fuel to avoid running lean. however, if your BOV vents some of this air out, then your car will run rich, because the ECU does not know that the BOV has expelled some of this air.
with a blow-thru MAF setup, you can get away with this setup:
TURBO => BOV => MAF => TB
basically, in this case, when the TB closes, the BOV vents air BEFORE it ever reaches the MAF. however, the increase in pressure can still throw off the MAF, but not nearly as much as if you just dumped the air without the MAF sensing the loss of air.

in a pull-thru setup, it works like this:
MAF => TURBO => BOV => TB
and the BOV just has to vent in between the MAF and the TURBO. that way, all the air that the MAF tells the ecu is still there and the turbo is still happy.

in conclusion, the best way to run atmos. bov is to use a MAP sensor and the best thing to do with a MAF is a pull-thru, recirc. bov.


1994 Altima GXE - Auto
Sold 9-15-07
2003 Toyota Echo 2dr - Auto
Given away 8-20-09
1998 Subaru Legacy GT Sedan - 5spd
2.2L Motor Swap
New 2.5 5spd Transmission
Outback Front Bumper Swap
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post #13 of 42 Old 10-30-2007, 09:39 PM
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Cause what im going to use is about the size of a quarter and can work with the software i want to use, not to mention its about $14.00

Special-K
And the name is supposed to be vader3120. F*** IT!

1997 Altima KA24DE-T RIP
1991 SE-R SR20DE - For Sale
-Tranny Swap Done (JDM B13 VLSD & JGY LSD)
2004 Jetta 1.8T - Daily Driver
-FMIC, Turbo Inlet Pipe, 3" Turbo Back Exhaust
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post #14 of 42 Old 10-31-2007, 12:14 AM
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^lol whatever is cheap and works the best for your setup


1994 Altima GXE - Auto
Sold 9-15-07
2003 Toyota Echo 2dr - Auto
Given away 8-20-09
1998 Subaru Legacy GT Sedan - 5spd
2.2L Motor Swap
New 2.5 5spd Transmission
Outback Front Bumper Swap
2002 Legacy GT Black Leather Front Seats
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post #15 of 42 Old 10-31-2007, 02:58 PM
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Thanks for the explanation, Dark. That really cleared up a lot of what was on my mind about the different types of setup for the intake.



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