When do stock fuel hardlines become a limitation at standard pressures?
 

What is the maximum HP achievable on stock fuel hardlines (from tank to engine bay) at a standard pressure?

What are you thoughts on upgrading the lines if they need to be replaced?

The bottleneck is the output nipples from the pump bracket even if I replace the hardlines, I know people have replaced these with –AN fittings.

Any suggestions from people that have tested, and can recommend a upgrade path if needed at all?

Thanks

check my thread, i did some testing on fuel flow through stock lines and stock fuel regs. Im currently running 1.6bar boost with T-64 compressor and using stock fuel line.

https://www.rx7club.com/showthread.p...2&page=1&pp=15

Hey bobybeach thanks for the timely response, I was afraid no one had interest in what I thought should be an important issue when thinking about a fuel system.

I have a question you say your lines ID is 3/16” =0.1875 ~4.75mm this seems small to me is this an accurate number for what I assume to be a metric line? Considering the pic that you posted appears larger?

My fuel hardline is for an FD and is ~7mm which is roughly 9/32”

also wondering if anyone has run over 450-500hp on stock hardline at standard pressures?

https://www.rx7club.com/attachment.p...6&d=1144979073
https://www.rx7club.com/attachment.p...5&d=1144978998

Sorry yes your rite, I just checked my fuel hose is 5/16" ID. So stock fuel line must be around 8mm OD with perhaps 4/16" ID or 6mm ID.

not sure if this helps but Ari told me he ran his FD back in the day on stock hard lines to 600+rwhp.

I believe it, but usually they use a non standard base pressure allowing them to flow much more through the same cross sectional area or even use a rising rate FPR. Not that I couldn’t jack up the pressure, but it just helps to have a very standard setup to make comparisons with other cars easier and valid based on the setup parameters.

I was told by my tuner that I need to flow more, but I don’t know where I need to look considering I have -6 run in parallel from the stock hardline that comes from the tank to the engine bay and have replaced the stock filter with a high flow Aeromotive as well as an aero FPR. Also running a very high flow bosch pump, so I am not sure really what to look for at the moment in terms of restriction?

The least cross sectional area is the stock hardline and the pump bracket tubing, so I am hoping a few people will chime in with there ideas on what the stock hardlines are easily capable of supporting at a stock or standard pressure?

Bobybeach, thanks for the info BTW very helpful. What is the max number you have attained with the stock lines and at what pressure?

Increasing the fuel pressure will reduce the flow of the pump. The only reason you should be increasing the fuel pressure is to overcome the boost increase. But your stock rising rate reg should already cater for that.

The benefit increased fuel pressure has is providing better injector spray pattern or slight increase in capable injector flow however the flow capability and endurance of the pump reduces with the increased fuel pressure.

Bottom line is...If your running out of duty cycle you would be better of using larger injectors and larger pump with stock base fuel pressure.