8AN, 1/2 inch fuel line

[greg schroeder]

Originally Posted by Jim Vander Wal

Greg,

I run a similar engine, RDI 427W (444 rwhp). I have an isolated system fuel pressure gauge in the cockpit and haven't seen any indication of fuel pressure falloff or starvation on the dyno, track or strip.

Mechanical pump, ProSystems 780cfm Holley HP, Vic Jr manifold and heads.

This combination runs to 155mph (checked via GPS), 11.8 / 120mph quarters and will hold 6k rpm w/o faltering.

I have also looked into 1/2" line but associates that know way more than I do don't think it's necessary.

Now that you have changed it was it difficult? Anything in particular that compelled you to make the change?

Jim
SPF 1855 in Grand Rapids, MI

For my Superformance 2040 as delivered with Roush 427R-095 everything was fine. I had the Roush supplied 750 CFM Double pumper on there, Superformance headers, side pipes, 1 inch tall oval air filter. Back then I took it to a load bearing Dyno at Dyno-Comp, www.dyno-comp.com , for a base line run. It came out corrected a touch over 400 rear wheel HP. I guess the number would be a little bit higher on a Dynojet. I then put on the different headers, 1000ish CFM carb from Pro-Systems, taller air filter and I eliminated the Superformance fuel filter noting improvement with each change. The car is faster from original to today. With the changes I had some fuel starvation issues in 4th gear full throttle around 140 mph at a track day for a club. Even though air fuel was fine at lower speed, less load, it still seemed to run out of fuel up top in 4th full throttle. Scary. I've been to the drag strip a few times. Trap speed would depend on density altitude, but corrected to sea level it's over 130 mph.

Once I put on the soon to arrive 3 inch internal side pipes with a performance type collector I'm thinking it will have potential to move more volume, potential for dangerous condition if I left the fuel components and lines as they were. There was a 90 degree cast elbow going into the fuel pump which looked dangerously restrictive. I might have been able to replace that one elbow and call it good, but I want to be safe knowing the fuel system is good for 700 HP and I'm never going to hit that. The hardest part about the job was deciding if I wanted to have the 1/2 inch line welded into the tank or use an 8AN part through a 3/4 inch hole. There was a bit of a research and learning curve, but the rest is pretty simple once you climb under there and blow a few hundred bucks on parts.

After I set this all up I'll force myself to pay the $ for a test with air fuel on the same Dyno that I started with. I'll post again after it's all done.

I'm leaning toward adding a little 50HP wet shot nitrous system some day for kicks. The larger line and new fuel pump will give me peace of mind if I pencil it out.