Returnless Fuel Systems - what is the limit?

[Bugermass]

Why not use the stock feed as the return, and run a new feed?

[soxfan143]

Originally Posted by Bugermass

Why not use the stock feed as the return, and run a new feed?

Didn't some of the guys over on clubrsx have issue using the stock feed as the return? Besides it will be way cheaper to just keep the stock feed as the feed. I'll use a lot less fittings. Especially at the rail and trying to convert the feed to a return. Most of the fuel rails are setup to use the stock feed. So I'll save some cash there. All I would need fittings for are at the FPR and on the sending unit. Which my bud will more than likely have laying around the his shop.

Does anyone know if you can use any brand FPR on the AEM rail or do you have to run an AEM regulator?

[Str8JDM]

Originally Posted by soxfan143

Didn't some of the guys over on clubrsx have issue using the stock feed as the return? Besides it will be way cheaper to just keep the stock feed as the feed. I'll use a lot less fittings. Especially at the rail and trying to convert the feed to a return. Most of the fuel rails are setup to use the stock feed. So I'll save some cash there. All I would need fittings for are at the FPR and on the sending unit. Which my bud will more than likely have laying around the his shop.

Does anyone know if you can use any brand FPR on the AEM rail or do you have to run an AEM regulator?

i wouldnt use any regulator but the aeromotive. i had an aem one on my old b series and it didnt hold pressure for some reason at high boost, caused my motor to blow. one of my friends had similar expierence wit a B&M regulator but caught it before it caused damage.

[nycclaye]

good info....

[mitsukaiSI]

Awesome Info, subscribed for more reading later

[soxfan143]

I will probably use a fuelab FPR. My bud has them in stock. Plus they have those small ones. Sort of like a mini FPR. We've had good luck with them on the S2Ks we'e built.

[NitrousG35]

What an incredibly fascinating discussion going on here. With Geoff, Doug of Hondata and Mike-Soxfan143 discussing this vital issue, it will save a lot of headaches for others going F/I in the future [hopefully me].

This discussion is the same thing that went on at G35driver about 5 years ago when guys began S/C'ing and going Turbo. Infiniti uses a returnless fuel system as well. I should have paid more attention back then. LOL

[Str8JDM]

Originally Posted by soxfan143

I will probably use a fuelab FPR. My bud has them in stock. Plus they have those small ones. Sort of like a mini FPR. We've had good luck with them on the S2Ks we'e built.

ya i heard they good as well, same style as the aeromotive.


the style im talking about is this one. i would stay far away from it.

[wrecked]

Good info here!

[PanamaSi2007]

For some unkown reason, at least to me, some people dislike the walbro pump. I installed and recommend to go with Denso. More expensive but reliable specially if going into the search of plenty of horses.

[PanamaSi2007]

Originally Posted by Hondata

The Boost-A-Pump will not keep your fuel pressure constant in the stock Civic Si returnless fuel system. In the example of our supercharged Civic you lose 5 psi from the fuel pump to the connector on the outside of the tank and another 5 psi between the tank connector and fuel rail due to the friction of the high volume of fuel and the fuel lines.

The only way to minimize the 5 psi fuel pressure drop between tank connector and fuel rail is to run a larger diameter line.
Without further investigation I am not too sure whether the 5 psi drop from the fuel pump to the tank connector is due to the fuel pump or size of plastic fittings. As the fittings cannot be easily modified the only option is a bigger pump or Boost-A-Pump.

Realize that as the fuel pressure across the injector drops, the atomization deteriorates.

My suggested setup would be a return line system regulated 1:1 under boost with a Boost-A-Pump and stock fuel pump for moderate power and Walbro 255 high pressure pump for high power setups.

- A crushed FP regulator that increases FP by 10 psi would increase the fuel pressure differential across the injector in our Civic at the end of our run from 34 to 44 psi which provides about 14% more fuel.
- A return line system with stock FP regulator keeping the injector pressure differential constant at 55 psi would provide our Civic with 26% more fuel and better atomization.

Yes, we decided to installed a larger diameter line. Can't remember if -6AN or -8AN. My mechanic did the job.

[NitrousG35]

I made this a sticky because it is of such vital importance to so many people here. Thank God for the pioneers who have have learned by trial and error what works and what doesn't work so that others who follow will be spared the heartache.

[Supa Ninja]

Originally Posted by NitrousG35

I made this a sticky because it is of such vital importance to so many people here. Thank God for the pioneers who have have learned by trial and error what works and what doesn't work so that others who follow will be spared the heartache.

Thanks for sticking it, this us a very, very important aspect of boosting. Useful for both the TCs and the SCs. What's really interesting is all the top guys have very different opinions/methods and nobody is arguing about which one is better, but instead questioning and learning from each others experience. Great thread indeed.

[Full-Race Geoff]

thanks for all the discussion everyone - this proves there are many ways to get the job done!! some are easier than others, and some are more expensive than others, but the techniques outlined here will definitely give you ideas on what does and does not work.

FWIW i have not had good results with the fuel lab products. I use the aeromotive FPR now in 3 of my personal cars but that isnt great quality either... if i do it again some time soon I may us one of the SARD or HKS FPR's since they are very affordable, small/easy to fit and easy to use

[Full-Race Geoff]

Originally Posted by soxfan143

from what I've read on the Boost a pump it uses a vacuum reference to know when to up the voltage to the pump. So at idle the fuel pressure will remain at the stock pressure and once the boost a pump sees 5psi+ it will up the voltage accordingly. Now my question is how does it know how much voltage to add to keep the fuel pressure from spiking all over the place? Once 5psi hits does it increase voltage in increments or does it just jump right to the max 20v?

you dont have to use the hobbs switch, jeff evans told me he prefers to activate the boost-a-pump right from the ecu, to eliminate the possibility of the hobbs switch failing and causing the car to run lean if the extra voltage was not applied.

but yes, once the boost-a-pump is turned on it applies max voltage

[Bugermass]

The welden regulators are very good as well.

[Full-Race Geoff]

agreed!

[Radicalblackcivic]

This is great. Now I need to retune my setup because I was running 46psi at the fpr and now will turn up to 55psi. I am currently using walbro, aem fuel rail, aeromotive fpr and 650cc

[Supa Ninja]

Turn it up to 60 psi, it will give you a little more overhead. When do want do that DIY, I can write one up and email it to you, you can add to it or the other way around.

[white2010coupe]

I plan on using , walbro - id 1000cc - skunk2 rail - aem fpr.
Any insight on this setup pros , cons and if they will even work together?
When it comes to fuel setups I'm quite the noob so input from F/I pros appriciated.

This is for a FR gt30 kit