Fuel Pressure Regulator

[bichmgnt]

I'm going to upgrade the manifold, do the Big Six AFM upgrade, and put bigger injectors on my 91 325iC and I figure I need an adjustable FPR. Does anyone know about these guys and is this a good deal? FPR and gauge in one package.

http://www.cosmoracing.com/productinfo.asp?cid=117&pid=324

Steve

 

[Rukus]

an adjustable FPR is really only needed if you are applying some sort of forced induction (turbo, super) to your car. you shouldn't need to upgrade your FPR at all.

I'll look into it tonight and let you know for sure.

 

[bichmgnt]

Check out Dave Adams' article on his AFM/ injector upgrade on his site

http://www.davelength.net/

You'll have to navigate in to the article yourself but it is easy to find. In particular, the last paragraph when he dynos the car he says he got an extra 2 hp by increasing the pressure from 3.0 to 4.0 bar.

BavAuto has a 'rising rate' adjustable FPR which increases the pressure faster than a stock FPR at low vacuum conditions (open throttle). That one is nice since it has the stock mounting bracket but it is also $200 and no gauge.

Anyway, I think it is a good idea to have one and I was really wondering if anyone knew of these guys and their products.

Steve

 

[Rukus]

Here's what a friend of mine, who is very indepth on the technicalities of engines thinks:


normally, when doing basic upgrades such as slightly larger injectors, air filter, exhaust, there is no need for an adjustable fuel pressure regulator to be installed.
only when bigger and better upgrades are done may it be necessary in most circumstances. if you are making a big jump on injector size, or other fuel modifications, which are usually only made when change to forced induction or nitrous, then you may need to upgrade it.
so it can be needed on an NA, but nto usually when just BPU mods are done (this is a term coined by supra guys meansing Basic Performance Upgrades - or easily bolt on stuff)
so exhaust, intake, fuel system, maybe an ecu chip

 

[bichmgnt]

Your friend is probably right in that it is not essential but I think it will be beneficial. Did you check out the link I posted? The pertinent article is in the white cars section on ugrades under Fuel injector/AFM upgrade.

Steve

 

[Rukus]

This is what my friend had to say:

That page is very good and imformative, and for all intensive purposes correct. i would also recommend (it's pretty much necessary) getting an adj. FPR when making a jump of 149cc injectors to 200cc.

air/fuel ratio gauges on their own are usless, and EGT gauge is what really tells you what's going on. the only usefull air/fuel ratio reading you can tune by is available via a wideband 02 sensor, which is well worht the money

 

[bichmgnt]

EGT = exhaust gas temperature?

The wideband O2 sensor - would that work with the EFI in these cars? Where do you get one?

I know you need to keep the output of the O2 sensor at about 0.4-0.5 volts for everything to be working right. I was planning on putting in a new sensor before doing all this to make sure it was good and then driving around in various conditions to make sure the readings were consistent over the range. But I don't know about wideband O2 sensors. Can you expound a bit?

Steve

 

[Rukus]

this is what my freind replied with:

Yes, EGT = Exhaust Gas Temperature
It should be noted you want to locate the probe close to the engine's exhaust ports. Also, make sure the probe is no more than 1/3 the way into the piping. Contrary to old beliefs, it is actually the exhaust pulses that destroy probes, not the temperatures.

Wideband Oxygen Sensors
Cost is about 300-1000 US
Here are a few sources off hand...
http://www.innovatemotorsports.com - $329 w/ the Bosch Sensor
http://www.techedge.com.au - $398 w/o the Bosch sensor
You can buy a Bosch sensor from www.1stvwparts.com for only $28

A wideband oxygen sensor can be used on any EFI system, but it is rare for it to be able to work with a stock ECU.
If it is possible to work with a stock ECU, then to make it able to work, you need to do a few tricks...
The output of a wideband box is usually 0-5v, sometimes linearized, sometimes not. However, some WB boxes have a separate 0-1v signal that can be fed to a stock ECU (and is there just for that purpose).
Otherwise, you need to run two sensors (one WB, one NB) if you want to give the ECU a narrow band signal.

A wideband lets you know how rich/lean you are. With a standard O2 sensor, you're either rich, lean, or just right. You don't know by how much. With a wb, you immediately know how much to adjust by, because you know just how off you are.

A stock 02 sensor is constantly varying the fuel to get better fuel economy during different conditions and types of engine load, and is called the lean run mode.
At WOT (wide open throttle) or high loads, the ECU defaults to the maps and does use the O2 for feedback and fuel economy. The wideband gives you better resolution concering HOW rich or lean you are.

The output of a standard O2 sensor varies dramatically with temp, so because of the wildly varying exhaust gas temp on a car it's only accurate within a small window of operation, namely light load cruise. The wideband sensor's control unit use sophisticated compensation software to calculate an accurate reading.