Is standard fuel pump good enough for 550 an 2,5l engine
 

TEsted today. Standard fuel pressure is 2,5bar at idle, 3,0bar under load. Maximum fuel pressure 4,5 bar. Is it good enough for 550 injectors and 2,5l USDM engine?

No! OK, I can't say for sure - but why would you fit bigger injectors (requiring more fuel to suply) and expect all to be OK when it's even recommended to swap the pump on stock injectors/pressure?

Also, I thought stock pressure at atmospheric pressure should be 3 bar. ARe you reaslly getting 2,5 bar, or is this the reading with the vacuum applied to the manifold?

Are you remapng IDC's too? I sincerely hope so :D

Richard

Yes 2,5 bar was with the vacuum in manifold.
Somebody suggest me Audi 80 fuel pump- (7,5bars) or Kadett GSi.

Next question is what i can get if I switch fuel pressure to 4 bars. Injector flow will be increased around 10%? (more, less?)
Its important for me because my injector duty cycle is now about 85% at 1,2 bars.

what is IDC?

IDC - Injector Duty Cycle ;)

Based on the info you've given, the figures don't quite add up.

2.5bar at idle.
3 bar at atmospheric (?)

4.5bar on boost (1.2bar)

Theoretically, your max fuel pressure should be the total of fuel pressure at "atmospheric + max boost". So based on your info, 4.2bar.

What fuel reg' are you using. If it's the stock one, it would look like it's struggling to return the fuel, and increasing pressure a little.

Fuel supply ISN'T just about fuel pressure. As you increase fuel pressure, you REDUCE fuel flow, and you need to make sure that you have enough fuel flow, at the max boost you want to run.

The other issue, is that the stock pumps can deteriate very quickly, if they are driven very hard. I remember in the early days, Bob having a fuel supply issue, and discovering that his stock pump could supply a MAX of 3.6bar !!!!!! Good for only .6bar of boost at 3bar fuel pressure, at atmospheric.

Mark.