Supercharged/Turbocharged The increase in air/fuel pressure above atmospheric pressure in the intake system caused by the action of a supercharger or turbocharger attached to an engine.

Dummy question(s) regarding FMU and Fuel Pump

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Old Dec 18, 2005 | 03:08 PM
  #1  
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Dummy question(s) regarding FMU and Fuel Pump

Here's the setup I'm building on my VE 5:

t3/t04e 60 trim, .63 ar blahblah
tial 38 mm wastegate
greddy ssqv bov

all the other normal goodies

I still need to get an FMU and fuel pump though

Looking at the Cartech FMU. My dummy question(s) are:

1) What's recommended.. the CAR 2025 or 2027 (1/8 NPT or 1/4 NPT)?

2) Is there a particular Walbro unit most of you guys are running?

I appreciate any input/suggestions
Old Dec 18, 2005 | 03:32 PM
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Can't help you on the fmu, I'm searching for that answer myself, but most people go with the walbro 255lph hp. It's in the stickies.
Old Dec 18, 2005 | 04:44 PM
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get an adjustable FPR insted of the FMU.
Old Dec 18, 2005 | 07:36 PM
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I believe the part no for the walbro is the GSS342

As for an fmu, I have the SFMU which is a static base fuel pressure regulator as well a boost based rising rate regulator. (thats a mouthful)

Basically, It and adjustable fuel pressure regulator and a FMU
Old Dec 18, 2005 | 07:48 PM
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whats your base FP? whats the rising rate set at? and finally how many psi are you running?
Old Dec 18, 2005 | 07:56 PM
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My base fp is set at 35, but since its hard to be stoich in closed loop (410cc injectors), I am going to drop it to 30 psi. The rising rate is about 1:3.5 is the best. I have not really tuned with the wideband that much. I am working on figuring out pressure v. voltage in my fuel pressure gauge. The datalogging on the wideband is now syncing with my laptop and am going to start more in depth tuning soon. If it ever gets above freezing, that is.
Old Dec 18, 2005 | 07:59 PM
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Oh yeah, but when I was on the afpr, it was set to 33 psi and had a 4:1 disc. I leaned it out to 13% with the safc2 from 2800-5400 rpm and have +4% from 6000-6600 rpms.

In 65-80 degree weather, this was between 11.7 and 12.0 on the Wideband.

I noticed that the 12.0 was during the shift.

I also had the nice experience to be able to tune with the manumatic. Since the auto has taller gears, there was more time to me to see the variation/rpm
Old Dec 19, 2005 | 05:14 AM
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I think I bought the 2027, but I'm not 100% positive. It shouldn't really matter, as long as you get the one for forced induction. haha
Old Dec 21, 2005 | 04:20 PM
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Slimer and JSutter

Isnt this what you guys are talking about?

http://www.cartech.net/fmu2020.htm

JSutter, what brand/unit are you running?

Here's some pics of my progress (if I can call it that)





Old Dec 21, 2005 | 04:47 PM
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James, your setup looks strangely familiar


Lookin good so far!
Old Dec 21, 2005 | 04:55 PM
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im not boosted but my close freind is. he has a g20 and im trying to get the bugs out of his car. im getting varied imput from people. he called cartech and they said to not use an AFPR with their FMU. its made to work with the stock frp. all the guys on sr20forum say dont use an FMU, its to crude of a tune. they say just buy a nismo AFPR. jwt recommends 720cc injectors and larger maf, and of course thier ecu. most of this tuning info has to do with maximas so im just trying to figure out whats best.

i think if you want to go with an fmu the CAR-2025 is most likely enough.

the walbro 255 is the one to get.
Old Dec 21, 2005 | 06:05 PM
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Originally Posted by Brad92SE
James, your setup looks strangely familiar

That's an understatement
Old Dec 21, 2005 | 07:07 PM
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Originally Posted by slimer
I believe the part no for the walbro is the GSS342
I'm finding the GSS-341 listed for the 3rd gen

I DO want the 255 lph HP and not just the 255 lph, correct?
Old Dec 22, 2005 | 05:37 AM
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Originally Posted by JSutter
im not boosted but my close freind is. he has a g20 and im trying to get the bugs out of his car. im getting varied imput from people. he called cartech and they said to not use an AFPR with their FMU. its made to work with the stock frp. all the guys on sr20forum say dont use an FMU, its to crude of a tune. they say just buy a nismo AFPR. jwt recommends 720cc injectors and larger maf, and of course thier ecu. most of this tuning info has to do with maximas so im just trying to figure out whats best.

i think if you want to go with an fmu the CAR-2025 is most likely enough.

the walbro 255 is the one to get.
I hope your friends are saying just buy a nismo AFPR AND larger injectors (and preferably, an ecu or piggyback programmed to drive the larger injectors).

The fmu is indeed somewhat crude, but it and an air flow converter will get the job done along with some dynotuning time with a WB O2.
Old Dec 22, 2005 | 09:23 AM
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he has 370's already, along with walbro 255 and safc.
Old Dec 22, 2005 | 10:21 AM
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Originally Posted by James92SE
I'm finding the GSS-341 listed for the 3rd gen

I DO want the 255 lph HP and not just the 255 lph, correct?
Thats the one. How much boost are you planning on running to start with?
Old Dec 22, 2005 | 11:36 PM
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make sure you get an afpr while your at it youll need it to get stock fuel pressure back after instaling the 255 or youll run rich everywhere except boost
Old Dec 23, 2005 | 06:24 PM
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Originally Posted by subs1000w
make sure you get an afpr while your at it youll need it to get stock fuel pressure back after instaling the 255 or youll run rich everywhere except boost
I guess I'm confused then

I thought the Cartech FMU allowed you to do that?

And Brad I'm planning on running 6-7 psi initially. I guess I'll have to take some time off work or else I'll never get this thing finished
Old Dec 23, 2005 | 06:59 PM
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the people at cartech said not to use thier fmu with an adjustable regulator. its made to be used with the stock one. theirs must have a base adjustment.
Old Dec 24, 2005 | 06:49 AM
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Originally Posted by James92SE
I guess I'm confused then

I thought the Cartech FMU allowed you to do that?

And Brad I'm planning on running 6-7 psi initially. I guess I'll have to take some time off work or else I'll never get this thing finished
The Cartech only allows for adjustment at the onset of boost and during boost. To set your base fuel pressure you will need to get another adjustable fuel pressure regulator. I'm using the Nismo one for a SR20, courtesy sells em. I would recommend getting that one as it mounts nicely in the stock location, and your engine bay will get very cluttered as-is, and having to mount something else would just be a pain.
Old Dec 24, 2005 | 10:43 AM
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Originally Posted by Brad92SE
The Cartech only allows for adjustment at the onset of boost and during boost. To set your base fuel pressure you will need to get another adjustable fuel pressure regulator. I'm using the Nismo one for a SR20, courtesy sells em. I would recommend getting that one as it mounts nicely in the stock location, and your engine bay will get very cluttered as-is, and having to mount something else would just be a pain.

Does that Nismo SR20 AFPR fit in the stock 4th gen location too?
Old Dec 24, 2005 | 02:53 PM
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Originally Posted by ewuzh
Does that Nismo SR20 AFPR fit in the stock 4th gen location too?
To be honest, I'm not sure. I think it will mount up (it has the fuel passage in the middle, which inserts into the fuel rail and has two screw holes on either side of it) but I think I remember someone saying that there was an issue with hooking up the fuel return line to it.
Old Dec 24, 2005 | 03:39 PM
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there are a few different manifolds for the sr20. the USDM are high port and low port. they both have different rails, and the newest sr's have top feed injectors, possibly a different reg. i have both regulators to the usdm hiport & loport so i could check for you. i know they have some funny bends in them.
Old Dec 25, 2005 | 12:39 AM
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It will not fit the 4th gen. there is not enough clearance. I have tested a nismo fpr and the pigtail gets in the way. it is also hard to adjust where its situated.
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