OK My friend and I were discussing making a fuel return kit and diffrent ways to do it since his car his a greddy tt running stock boost ( soon to be built motor) and my car is currently getting fully built so we are both going to need a return fuel setup, his goal is around 440rwhp and mine is around 520rwhp. Before many greddy cars were making over 400whp and up to 450whp on the stock fuel system. and it seemed to work fine.

The question:

Since we are only looking at 50 or so whp more cant we just mount the FPR in the tank area instead of in the engine comparment to elimate running another line ( how the PE kit and APS kits do it ) and then modifie the stock fuel rails to flow better by removing the 1/4in hard line and changine that to a larger line and drilling out the centers to make them flow better. This would give us the constant 51-53psi and shouldnt loss and pressure that would make a diffrence. Again im a looking for non biased opinions on if this would work safely. Thanks for taking the time to read and respond.

-George

 

yeah. there is a thread on here somewhere that shows how to make a decent fuel return system out of the stock rails. Try searching...pretty sure there is the same thread on motoring too.

 

Cool, thanks for the reply

 

I really never understood why people think the stock rails are that bad. There are a bunch of guys running 500-550 HP with the stock rails and the APS fuel return. The APS return uses the stock fuel line and stock rails. Who much HP are you looking for?

 

Thats is exactly what me and my friend beleive, that these return systems arent really need unless 600 + WHP is desired. I just want to make SURE that the stock rails are SAFE for 520whp, i know they will work just want to make sure they are safe!

 

there are restrictions in the stock fuel rail inlets that block almost half the diameter of the rail. these can be drilled out pretty easily then they will be a consistent dia. all the way through. if you weld fittings to the ends of the rails you can run a nice Y and feed both rails equally.
the reason to run the fpr in the engine compartment is to get a very fast reacting fuel pressure raise or change in vacuum/boost.
i think i have done 2-3 threads on how i did mine.

 

500whp its certainly doable. Your approach is the same one used by APS, and several other members did the tank mounted FPR/return prior to the APS kits coming to market. I dont see a problem with it, but for max fuel VOLUME...not just pressure, I would upgrade to the full system at 500whp+.

Also keep in mind, that mounting a rising rate FPR at the tank has its drawbacks. Namely, the fuel presure is being set prior to the injectors sucking down their fuel requirments. In a proper and complete return system, the FPR is placed after the fuel rail, not prior.

Again, probably not a problem at 500whp, but less than ideal beyond that.

A lot of people purchase the return fuel systems, for ease and completeness, but the DIY's could certainly make their own.

 

no one can tell you yet if the stock rails are safe or not, because no one has done proper R&D on the stock rails.

just because its been done, doesnt mean its safe.

If you want to know for sure, you will need to datalog fuel pressure on both the inlet and the outlet side of the fuel rail. Dont be surprised if you start to see a variance on the top end... which = not as safe as you might have thought... or maybe its perfect?

Things can work for a long time before causing a problem. Ultra conservative tuning can make up for it also. But if you really want to know if aftermarket rails have a benefit or not, you need to perform this test.... and it also depends on how you use the stock rails.

You can use stock feed lines all the way to the rails, and return back at the tank. You could weld fittings on the front of the rails and return off them... or you could weld fittings on both ends of the rails and use all AN lines... or you could dual feed the rails on both sides and outlet in the middle. Lots of different variables here.

 

I couldnt agree more...I should add that to my sig.

 

OK so the FPR should be placed after the rails on the way back to the tank, and i should drill out the stock rails to get better flow, and the reason to mount in the engine compartment is to get a fast reacting boost/vacuum to the FPR.

Also what do you guys think of adding a second fuel pump on the drivers side tank, just getting another fuel pump assembly and dropping it in the drivers side tank and modifying the secondary fuel level sending unit to work with it. Would i just run both pump lines to one big 3/8 line? Thanks again for all the input.

-George

 

will be testing it next week, lol.

 

testing it or using it? big difference

 

been using it for quite some time now. this is not my first try at building a fuel system though. i have made many full fuel systems for my vettes and others. from building the fuel rails from 1/2" stock to the pickup assemblies. to bad there isn't the room under the plenum to just use standard rail stock on the Z though as that would make it even easier. i have been using this set up on the Z to 14 psi for 1000 miles so far with no fuel probs at all. but will be heading for the dyno to test other things and crank the boost way up and the fuel system will get a full flogging in the process. as posted earlier, there are alot of ways to achieve the same outcome, lol. this is my way, lol.

 

Cool, let me know how that goes What do you guys think about the twin pump idea?

 

I think phunk is coming out with a twin pump setup. IMO I thinnk YOU need it for your HP goal.

 

Yea i am looking into make my kit a twin pump kit to produce a safe 520whp with about the same trq

 

you dont need twin pumps for 520whp... a customer of mine just made about 675rwhp with a single... given that is on the edge, but 520 is no problem for a single.

twin pumps is far more complex in this vehicle then you probably know... which is why no one has yet released a kit for it. Much easier said then done.

 

550whp is where we see the signle 255 begin to loose pressure at higher RPM. Anything beyond that is heading into the unsafe territory.

 

Ok, I just wanted to make sure i will be safe at 520whp and and return fuel system i will be good.

My next question is what is the diffrence in effeciency betweening feeding the lines with a Y or just going in and out of the rails. ( in one side out the other with a U at the end to connect on of the ends)

Thanks again!

-George

 

it will not gain you much as far as cost. plus it will again help to make sure all the injectors are working with the same pressure, especially on a fast mashing on the accelerater. i used an aeroquip Y. it is not a cheap piece (about $30) but about the best Y you can use for good flow and distribution.
if you decide to go this route, be sure to drill the feed ends (the rear) out or you will have a serious bottle neck. running new feed and return lines also gives you the ability to run them down the trans tunnel and away from the exhaust like it is stock.