What size Bypass jet do you recommend for a 70 shot NOS n2o system?
I have the stock .042? bypass jet and I'm getting about 80-90FPSI. So basically I'm way way too rich. Do I go up in size to lower the PSI? I want to be around 60psi from what I remember reading. I have a SARD FPR and Walbro255lph pump.

 

You have to go smaller. I would try in the 34-36 range but its trial and error to get it precise.

 

Actually with NOS, you probably need to go bigger. I was running a .055 bypass with a .042 jet, but it's really going to depend on your car. You also want to keep the fuel pressure a little higher than that, you should be around 70psi+ with a 70 shot. I tried going with a smaller jet, down to a .032, and my fuel pressure didn't get any lower, it wasn't until I tried a bigger jet that I got my fuel pressure to go down, and this was using the 255lph fuel pump. Good luck.

 

You are right, I was looking at the wrong column in my chart. Sorry SLCI30t.

 

I know that we've used the 70 psi with our cars to match the EGT temps with typical driving. After doing a dyno I noticed our cars run very rich, thats why I was going to try to pull the PSI down to try to lean the car out a little.