as above. I have few 4.0bar regulators but i have notice that most of modded coupes (~340bhp) was equipped with 3.8bar fpr. is there any reason for that ? fuel pump cant feed enough fuel? injectors cant cope with the pressure ?

Thank you.

I'm sure it's because a 4 bar fpr Simply isn't needed for -340 bhp, im currently making 343 bhp at just over 1.05 bar using a standard pump, 3.8 bar fpr and standard injectors and my fueling is absolutely spot on.

However to push the standard injectors further to get into 350+bhp territory, I would need to upgrade the pump and fit a 4 bar fpr, but I'm just switching to 440 injectors, upgraging the pump anyway and just not pushing them as hard.

I guess at 340+ bhp, using a 4 bar fpr, it would be more down to starvation from the pump, rather than the injectors not coping

Mate a 3.8 bar is fine I'm running gt2871r 440cc injectors and a 3.8 .. Standard injectors will max out at 380bhp full duty

thanks guys ;-)

Sorry to hijack thread. Thats a nice low boost figure for that power. What is the spec of your setup?

You don't really want to be running injectors at 100% duty if you can avoid it, though plenty of people do. 75% is ideal.

Thanks Craig, surprisingly not that much to be honest...
I'll keep it blunt to avoid going much further off topic:

Torque italia fully re-worked stage 2 head
Gt2860rs .64 A/R
Mitsubishi evo 9 FMIC (TI shortened pipe work)
Custom free flowing 3" down pipe
Full 3" stealth system (decat) from the down pipe back
Ported exhaust manifold
Slightly milled out throttle body
Fuel pump wiring mod
Bailey dv30 re-circ DV
Gizzmo ms-ibc controller

The only real difference between mine and the many other's running the exact same set-up, is the stage 2 head, and by a country mile it's played the biggest factor in not only completely transforming the car but achieving that performance at low boost, whilst making the car more economical!! It's not just the HP but it also made 334 ft-lb's at that level of boost, and the turbo's barley being tickled.

I'll post the results in the new year, when the car's mapped on a DTA, with increased boost after a few fueling modifications, And a clutch!

And in the mean time, anybody considering head work, should most certainly go for it! Most only go for head work when going forged for big power, but it would transform even the most basic set-up! Yes it's alot of money but the transformation it makes to the car on the road (figures aside) at partial throttle, 3/4 throttle, full throttle etc makes it worth every penny.

And with the fuel I save, it will pay for itself in a couple of years!

Anyway.... Back on topic

Very interesting. What sort of mpg do you get? Mine has dropped from an average of 27 to 24 lately

Depends what mood im in

Nipping around town, I'll get anywhere between 25 and 30mpg, depending on traffic and lights etc. I usually get mid to high 30's cruising at the speed limits, and well over 40mpg on a run taking it easy, the 6 speed box helps alot too mind!

Best get back on topic...

I run a 3.8 bar fpr into 630cc injectors - copes fine with nearly 500bhp

I'm sure Leighton will be along in a minute, but from memory, the fuel pressure is more about spray pattern and atomisation than it is about the volume of fuel delivery

On that note Nigel. I thought most injectors were designed for 3 bar pressure?

Increasing the fuel pressure is a good way of getting more flow from standard injectors, or the injectors you already have.

What is the reason for increasing the fuel pressure when upgrading the injectors?

I am currently running 3.8 bar with standard injectors running around 340bhp.

For example the Bosch 440's are designed for 3.8 Bar operating pressure. ;-)

Thats good to know. All i have seen have beeb rated at 3 bar.

I guess I could have reverted to the 3 bar FPR when I changed from 440cc to 630cc (I was maxxed out on the 440s, hence continuing to use the 3.8 bar) but Leighton didn't mention it, so I assumed it would be OK

Thats fair enough Nigel. The 3.8 bar wont cause a problem. Was just curious if there was a specific reason people used them with after market injectors.