NewBeetle.org Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
566 Posts
Discussion Starter #1
Can anyone help me out with understanding fuel bar stuff. I've seen many sites regarding tuning my engine and they mention that you need to run at least a 3 bar set up and stuff like that. I've also seen a few of the members who list in their mods that they are running a 3 bar or 4 bar setup. It is to my understanding that these numbers are refuring to some sort of pressure system. But what does it all really mean?? Also what is stock?? When is it important to upgrade to more bars as they call it? Thanks for any info that mey help clear up this confusing jargin I keep reading about.
 

·
Premium Member
Joined
·
4,315 Posts
FPR = Fuel Pressure regulator

BAR = a measurement unit of pressure

A 3 bar FPR puts out roughly 44psi of Fuel pressure while a 4 bar FPR puts out roughly 59psi.

When you install an aftermarket chip in the APR 1.8T (99-mid 2001 model year) you need to upgrade the FPR from a 3 bar to a 4 bar unit to compensate for the smaller injectors.

I believe this is the only engine that you have to upgrade the FPR as the injectors and FPR are plenty big on subsequint models.

Tom aka Fowvay

PS.. check with your chip manufacturer for thier advice on upgrading the FPR.
 

·
my turbo is bigger!!!!!!!
Joined
·
502 Posts
i stuck a 5 bar in one time trying to make 240 seem kike their 440...lol not a good idea
 

·
Performance Freak
Joined
·
137 Posts
All NB 1.8Ts have 3bar stock.
Some of the aftermarket software requires using a 4bar FPR since they factored that into the tuning.
On the early 1.8T (APH with smaller injectors) APR requires the 4bar to allow the injectors to run less duty cycle time and deliver the same amount of fuel due to the higher fuel pressure.

I have a Revo Stage2 program which requires a 4bar FPR only because that is what they used when making the program since it is more agressive. They also have a 3bar program for a car with stock exhaust.
Basically with more mods like a larger exhaust or FMIC, they tune the programs more agressively and this can max out the stock injector duty cycle @3bar of fuel pressure. By increasing the fuel pressure, this allows the injectors to work a little less but deliver the same amount of fuel.

Some people put in 4bar FPRs as a bandaid fix since they may be running lean sometimes and increasing the fuel pressure may cure that.
 

·
Registered
Joined
·
566 Posts
Discussion Starter #7
This is great info to know.

Let me ask this. Since I am running with an APR chip on my AWV, would it be a good idea to move from the stock 3 bar to a 4 bar. If I do this what are the advantages as apposed to the old system of using the chip with a 3 bar? Would a mod like this even be worth doing. As of now I only have the chip but a new exhaust is coming soon. Thanks again for the knowledge on this subject.
 

·
Registered
Joined
·
5,793 Posts
-Since I am running with an APR chip on my AWV, would it be a good idea to move from the stock 3 bar to a 4 bar.
Nope. Call APR and ask, I'm pretty sure you're fine as is. APH motors are the only ones w/cripled injectors.

-If I do this what are the advantages as apposed to the old system of using the chip with a 3 bar?
The 'advantages' would be that if it were tuned for the 4bar, your injector wouldn't be open as long as normal. (good for high rpm when you don't have as much time to ... inject) On a car not tuned for this, the 'advantage' would be running rich all the time, wasting gas, ruining O2 sensors, and killing your CAT.

-Would a mod like this even be worth doing.
Based on the above 'advantages' and your specific car Photo... I would say no.


Heh... It doesn't hurt to try. :)

If you used limiwinks software, you could maybe use a wideband A/F sensor and adjust properly to take advantage of a 4bar FPR. But if you don't need it, I'd say don't bother. It may very well wear out fuel pumps faster running at a higher pressure.
 

·
Registered
Joined
·
566 Posts
Discussion Starter #9
Thanks noR. That was very well put. I just wanted to make sure I wasn't missing out on anything. When and if I ever go to a bigger turbo, I may look into the 4 bar more seriously. It sounds that it will be then, that I will need to upgrade.
 

·
beetle driver for life
Joined
·
1,151 Posts
Fowvay said:
FPR = Fuel Pressure regulator

BAR = a measurement unit of pressure

A 3 bar FPR puts out roughly 44psi of Fuel pressure while a 4 bar FPR puts out roughly 59psi.

When you install an aftermarket chip in the APR 1.8T (99-mid 2001 model year) you need to upgrade the FPR from a 3 bar to a 4 bar unit to compensate for the smaller injectors.

I believe this is the only engine that you have to upgrade the FPR as the injectors and FPR are plenty big on subsequint models.

Tom aka Fowvay

PS.. check with your chip manufacturer for thier advice on upgrading the FPR.
Fowvay please forgive me but did you mean to say APH instead of APR?
 

·
Premium Member
Joined
·
355 Posts
Bar

Bar is a measure of force as relating to (in this case)
fluid pressure.

1 bar
= .98692 atmosphere
= 1000 millibars
= 14.5038lbs.-force/sq.inch

(all at sea level)

The pounds per square inch value (14.5) is very close to
the common unit of atmospheric pressure (14.7)

So
3bar = 43.5 lbs/sq.inch
4bar = 58.01 lbs/sq. inch
 
1 - 12 of 12 Posts
Top