Boost level with mods

[ridered74]

I got to the point where even the xdi35 began to taper to 2000 at 20 psi. Why I threw a little methanol at it lol. 2000 on stock hpfp I'd be all about haha! On the xdi that's like damn!

Ya my ajp tune on stock pump never dropped below 2100. The file torie told me to never again run when it was cold out dropped to 1100. Oof

 

[skyshadow07]

Here is those data points for me @15psi

 

[Jordan_R]

Here is those data points for me @15psiView attachment 13871

Yup. Looks like you're getting closer to the danger zone in fuel pressure. Anything less than 1500-1600 I'd say is getting dangerous. On a daily tune I wouldn't want less than 1800 personally.

It's the boost spikes on shift that usually drain fuel pressure horribly

 

[SM105K]

93 octane right?

 

[SM105K]

Yup. Looks like you're getting closer to the danger zone in fuel pressure. Anything less than 1500-1600 I'd say is getting dangerous. On a daily tune I wouldn't want less than 1800 personally.

It's the boost spikes on shift that usually drain fuel pressure horribly

I agree 1500 to 1600 is right at my limit...however if it recovers quickly then.....meh....

 

[Jordan_R]

When I went 11.76 on stock hpfp with no additional fueling I was on a very specific race fuel I picked out running 16-17psi. Like I said boost spikes suck the fuel... However... You can shut the throttle to mitigate that.

First off I'd like to say I ran that time on 16 and couldn't hook later in the day on 17 psi. Fuel pressure on 17psi didn't drop much with the lowest fuel pressure being 1800 psi. Something I want to go back to is the fuel was c20 which has a stoich ratio of 13.91:1. It's an unleaded and unoxygenated fuel meaning you can run more boost and keep fuel pressure higher.

If you don't want to go with an upgraded hpfp you can always pay a premium for a proper race fuel. However I will say with same mods and way more weight I ran 1 hundredth faster on a +3000da higher day with the hpfp which I attribute to being able to run even more boost than the race fuel. Sorry to write a novel.

 

[SM105K]

When I went 11.76 on stock hpfp with no additional fueling I was on a very specific race fuel I picked out running 16-17psi. Like I said boost spikes suck the fuel... However... You can shut the throttle to mitigate that.

First off I'd like to say I ran that time on 16 and couldn't hook later in the day on 17 psi. Fuel pressure on 17psi didn't drop much with the lowest fuel pressure being 1800 psi. Something I want to go back to is the fuel was c20 which has a stoich ratio of 13.91:1. It's an unleaded and unoxygenated fuel meaning you can run more boost and keep fuel pressure higher.

If you don't want to go with an upgraded hpfp you can always pay a premium for a proper race fuel. However I will say with same mods and way more weight I ran 1 hundredth faster on a +3000da higher day with the hpfp which I attribute to being able to run even more boost than the race fuel. Sorry to write a novel.

That is info a lot of people don't know about. My E30 tune does well in the fuel pressure department, however I can't push it anymore.