4 bar fpr and fuel pump

[s4mmie]

I can't find much info on the subject.

Some tuners say bigger injectors, 310cc or so, others say 4 bar fpr...
I get the theory behind more pressure, squeeze more in for a given time.
Bigger injectors will obviously inject more fuel for a given pulse as well.

I guess it's finding that balance between too big for decent low speed atomisation and too small for required power.
I punched some power figures into an injector calculator and it comes back with 480-550cc at 4 bar to support 280 crank horsepower!


Does anyone have any personal experience with injectors they run?
Just putting my order in at ECS and want to get it all in one go.

[Redliner]

I can't find much info on the subject.

Some tuners say bigger injectors, 310cc or so, others say 4 bar fpr...
I get the theory behind more pressure, squeeze more in for a given time.
Bigger injectors will obviously inject more fuel for a given pulse as well.

I guess it's finding that balance between too big for decent low speed atomisation and too small for required power.
I punched some power figures into an injector calculator and it comes back with 480-550cc at 4 bar to support 280 crank horsepower!


Does anyone have any personal experience with injectors they run?
Just putting my order in at ECS and want to get it all in one go.

There is some basic info on this page:
VWVortex.com - My Stock turbo tuning guide

[noone]

For stock turbo?

[s4mmie]

No, trying to future proof for my turbo upgrade but I think I might leave the injectors until I confirm the exact turbo.
I think I should be right with the 4 bar fpr and pump on my current tune.
I just found it interesting that the calculator thinks 480-550cc on 4 bar are the right size for something like a JBS04. That's a lot bigger than what most spec for their turbo upgrades, are they maxing out the injectors??

[h100vw]

What you have to take into account is that the fuel pressure is over 5.5 BAR when you are running at max boost. Manifold pressure gets added to the FPR pressure as it rises the 4BAR difference is maintained. Different story for NA.

Re-do your calculations with that in mind Sam.

The TT/S3 225 injectors are 386cc from memory. Although a bit pricey they are a known quantity, you can get software to run pretty much whatever you want to fit but as you say, you have to consider what it'll run like around town as well.

I personally like the idea of a better pump, no doubt you can get away with running a new car at 4 BAR but with 70-80000 ks up can it still cope?

The horrors of finding it can't would keep me awake.

Gavin

No, trying to future proof for my turbo upgrade but I think I might leave the injectors until I confirm the exact turbo.
I think I should be right with the 4 bar fpr and pump on my current tune.
I just found it interesting that the calculator thinks 480-550cc on 4 bar are the right size for something like a JBS04. That's a lot bigger than what most spec for their turbo upgrades, are they maxing out the injectors??

[s4mmie]

No worries, thanks Gav.
I'll more than likely be running either the JBS04 or a similar hybrid to what Ant has on the way. It'll def be one of the two, I'm just waiting to see the results of his ball-bearing jobby and how the price of the unit compares.
I'll be coming over to Custom Code for the tuning.
So you reckon I'll be right with the 386cc injectors, 4 bar FPR and pump?

ECS has these:
Volkswagen Golf IV 1.8T > Engine > Fuel > Injectors > ES#2919 386cc Fuel Injectors - Set Of Four - 06A906031J TT

Or these 440cc:
http://www.ecstuning.com/Volkswagen-...ors/ES1866540/

If low speed drive-ability won't be affected too much with the bigger 440cc's and CC can tune it nicely I think I'd go the 440cc.. more than happy to go with your recommendation though as you know the software.

[whiteVR6]

You dont need anything bigger than 380s out of a KO4 . 440s will work but its overkill . Then you need a bigger MAF as well

[h100vw]

Those TT ones are the wrong ones. You need the ones without the extension bit. Ant has some 'green giants' I think they are. A bit over 400 cc IIRC.

The TTs are big enough for the JBS04, expecting that the other injectors will cope with the ball bearing blower.

OE Audi Gas Engine Part Fuel Injector Nozzle TT Quattro | eBay

Gavin

[s4mmie]

From what I've been reading the 440's are getting on a bit and there's more advanced injectors out there that are better suited to multi-valve engines.


The 386cc injectors seem to have a good rep.

I ran some numbers and running the 386cc injectors on 4 bar will effectively make them run at 446cc (assuming they are rated 386cc at 3 bar) When the fuel pressure rises with the added boost pressure as you mentioned, they'll effectively be flowing 525cc at ~5.5bar.

Then using this formula:
Inj size (lb/hr) x 80% duty cycle / .60 Brake Specific Fuel Consumption
49.8lb/hr(525cc) x 80% / .60 = 66.4hp per injector x 4 = 265bhp

So running the TT injectors at 4 bar will support 265 crank horsepower at 22psi if I've done my maths right.
Which means I'll have to be pushing well over 180kw at the wheels before I need bigger injectors.

[h100vw]

I am not a maths teacher Sam. So won't be able to check your homework LOL

No one changes the injectors on chipped S3s that I am aware of, unless the turbo is changed, so essentially they should be good for anything you can wring from the Polo.

APR don't change them as I am sure you know, when fitting a K04. No idea how much duty they are running but APR aren't in the habit of blowing engines up.

Gavin

From what I've been reading the 440's are getting on a bit and there's more advanced injectors out there that are better suited to multi-valve engines.


The 386cc injectors seem to have a good rep.

I ran some numbers and running the 386cc injectors on 4 bar will effectively make them run at 446cc (assuming they are rated 386cc at 3 bar) When the fuel pressure rises with the added boost pressure as you mentioned, they'll effectively be flowing 525cc at ~5.5bar.

Then using this formula:
Inj size (lb/hr) x 80% duty cycle / .60 Brake Specific Fuel Consumption
49.8lb/hr(525cc) x 80% / .60 = 66.4hp per injector x 4 = 265bhp

So running the TT injectors at 4 bar will support 265 crank horsepower at 22psi if I've done my maths right.
Which means I'll have to be pushing well over 180kw at the wheels before I need bigger injectors.