Supercharged Nytro AFR differences with hood off

[Krummy]

I went up for the first time this year thinking I had cured my fuel issues from last year with a new inline pump and FPR. After taking it out at 8.5 psi, I am still seeing 12.7-13 AFR at WOT. I then went to adjust my blow off valve and kept the hood off during testing. I took it out and started getting cruise AFR in the 9's which had never happened before. I then took it out for a blast with the same boost and saw AFR's in the 11.5-11.8 range WOT. I then put my hood back on and my WOT AFR's went right back to the upper 12's to 13. I am at a loss as to why the AFR's would be drastically lower with the hood off rather than with the hood on. Does anyone have any thoughts on this? Ultimately I am thinking I will need to upgrade to PCV-PTI with 430cc injectors but I am still confused why it ran so well with the hood off and why the numbers were so different.

 

[YukonMP]

Maybe the intake air flow is smoother with the hood on, turbulent and therefore less efficient with it off. Be warned this is a complete guess by a total novice.

No charge.

 

[Krummy]

Haha, yeah it just doesnt make any sense to me. It is a supercharger with a cold air intake over the clutch gaurd. I am wondering if one of my boost reference lines for the fpr, gems, or koso gauge is getting kinked by the hood and if that would change these numbers

 

[peppahillcustom]

Do you have a fuel pressure gauge inline after the pump? Your fuel pump can change pressure flow slightly from the heat under the hood, on my setup I see a 2 to 3 lb difference from when I start it cold to running at idle warmed up. The pump can heat soak. I always set my fuel pressure on a warm motor

 

[yamadoo]

I’m with Yukonmp in both theory and expertise, I suspect with hood off there is a significant difference in air flow direction and pressure
Again no charge for this opinion based on old physics and pulmonary (lung) air flow training. LOL