My current fuel system consists of stock 3/8 line, a mechanical carter fuel pump, and a 780vs holley. Last year my car went 13.1-13.2@101-102MPH with a non slipping 1.8x 60'. Does this look like a fuel starvation problem due to the low mph? this years combo should be hitting mid-high 12's plus an additional 150hp N20.

I'm doubting my current fuel sytem will be enough to supply both engine and bottle, so what steps should I take to keep both happy?

You should be OK with a 3/8" line, IMO. I'm also running a 400, but with a 304* cam, 12.5:1 CR, and a single plane. I run mid-high 11's, and I also use a 3/8" line. But there have been people who have had a motor similair to mine and gained 1 MPH when they switched to a larger fuel system, but the car never "laid down" at the top end of the track. So, it still is possible you need a larger line.

Low MPH numbers can be ignition related also. As well as converter slippage, low HP but high torque, restrictive intake system (air filter, etc), and a few others.

Your mph is inline with your e.t. I ran low 12's in a 68 Camaro,,,and high 11's on nitrous with the stock fuel lines....running high 11's low 12's now with a stock 3/8" fuel line...carter mechanical pump,added a Mallory Comp140 back at the tank this fall with no improvement.

I ran 117 mph (11.40's) consistently with a Carter 172, stock 3/8 fuel line through the stock pickup, 32 year old fuel sock out of the stock tank.

You are right in line with 101-102 at your ET.

if you want, try a 172 Carter, keep good records and report back on what happens.

Good luck

so you guys think I'd be safe to run a moderate amount of nitrous (100-150) on my current system without leaning out the nitrous side?

I have never used juice, but most I know who do have a separate system for the nitrous system. Someone with experience will chime in here.

What does the Nos manufacturer recommend?

Hey Tom,I can type fast when I'm mad...my Rams got beat today...LOL...I ran the stock fuel system with a NOS 125hp shot...just ran a seperate regulator for the Nitrous so it wouldnt fall below 5 psi fuel pressure...now a 150hp shot, I don't know if you need a seperate fuel system for that or not :confused:

EDIT: I ran nitrous 20 yrs ago,,,havent touched the stuff since :D