Best way to run FPR?
 

What's the best way to run the Fuel Pressure Regulator?

I've switching out the stock rails, etc. Is it better to run fuel feed into regulator, then hit the back of both rails or hit both rails FIRST and regulator after that ? Thought about running it the first way and capping the front off the rails off.

Rails first then to the regulator.

I had it ran this way and it worked fine but the problem with running it that way is IF your regulator fails in such a way that prevents fuel flow than you will lean out. The though process behind running the regulator after the rails is simply the opposite of what I just said. If the regulator fails you will get whatever pressure your pump is putting out.

Best way to set it up IMO is to have the pump feeding both rails (T) and then (T) them back into the regulator after the rails or use the regulator as your (T)

The general thought is that you want the regulator to compensate for the pressure loss across the rails. By placing it after the rails, you should have no less than what you have it set at at all times. Both ways have been shown to work though

I thought this out to, since I was plumbing mine and ordering fittings
some said to tee into one end of the rails, tee out the other end to the reg
some said just go in one rail, cross over on the other end, and back out to the reg-it seemed to me you could starve the far side injs. by feeding one side first, but I guess there's enough vol. it doesn't happen
If you look at a Nascar engine, they just go in one end, cross over, then out the other end to a reg-so that's what I settled on, lol

I think it depends on rail size and crossover line. If I was running a real small rail and crossover line I would probably feed into both rails and then out from both into regulator. But if you have a large high capacity rail and crossover. I will feel comfortable just going into one across to other and the regulator.
Just my thoughts
Kerry

in an fbody? you can just do a regulator and then feed the stock rails
we are over 700whp on stock rails

https://cimg2.ibsrv.net/gimg/ls1tech...d536f15c4b.jpg


Stuck mine here after the rails. -8 feed, y-block to both rails with -6. -6 crossover and return.

Best way to do it

I'm not building a wild 1k hp car here. Any real harm in going into regulator, feed back of both rails and cap off the fronts?

It's already been explained. There isn't a whole lot of different ways to do this. Pick which ever one your comfortable with

Im not building a 1khp car either, But I made this mistake and put my regulator pre fuel rails and I had issues with my injectors not being able to flow properly. I am boosted and run a boost reference regulator, under boost I am running 72psi to compensate for the regulator being improperly placed and the injector duty cycle maxing out at lower pressure. This winter I am going to fix that problem to get the pressure lower and hopefully get more out of it.

Cliff notes yes you can do it, but there is adverse affects and its not hard to hook it up post rails and do it properly.

I have the reg before a stock rail and am almost at 700rwhp with zero fuel pressure issues. Works great so why change it