Return VS. Returnless Fuel System...Which way to go?

[BadPiggy]

Last night BruceH made a comment in another thread and now I'm confused. I think I need a bit more education on this topic before I drop the coin.

I'd like to know the PROS/CONS of return VS. returnless fuel systems. I was under the impression to run E85, you have to run a return system.

When/where/why would I need a return system?
Which is the better, more dependable setup?
At what HP ranges do you go from single to double, or double to triple pumps?
Which pump is the best bang for your buck?
Is a return system needed to run E85?
Any other info you can offer up to educate me more on this, please include it.


Off topic, a bit.....
I also read that some injectors are better suited for E85 whereas others are not.
Mainly because of the injector innards.
Example...
ID2000's aren't good for E85 because they'll rust inside with prolonged downtime.
ID1300's are good for E85 because they have stainless innards.

I have ID1000's.
Are these compatible with E85?
Stainless innards?
No rust issues?

Thanks!

 

[NaS197]

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[dysan]

I think it all comes down to how much power you are looking to make. I am on the low side for a built set-up making 630rwhp/590rwtq, GT500 pumps, single 40A boost-a-pump, -8AN PTFE fuel line and stock fuel rails with the Bosch 1000cc injectors on E85.

On the dyno I was only at 74% duty cycle on my fuel pumps and that is at higher rpms than I run at the track so I'm probably only at 72% at the track. Paul(againstallodds1) has the GT500 pumps, FRPP 80lb injectors, upgraded fuel rails and the dual 20V competition boost-a-pump on E85 and has been 9.6x's at the track with a returnless system. I don't know what his duty cycle is though.

I would eventually like to go with a return system and a single large pump for the safety aspect that if the pump fails the car will just shut down...with a twin or triple system you run the risk of loosing a pump and the car will still run but you run lean and pop the engine.

 

[05moneypit]

I know I will get flamed for this but, a return system is much simpler to control from a tuning aspect.

Guys do make big power with the returnless but it takes a lot more work than just going the return route

 

[Department Of Boost]

I like return systems for over 600hp.

If I could do my fuel system all over.....which I may be doing I would do the following:

Aeromotive A1000 drop in pump

Aeromotive pump controller

-10 feed line PTFE

-10 to dual -8 Y block

-8 to each rail PTFE

ID1200-1300's

-8 from rails to regulator

Some sort of regulator

-10 return PTFE

 

[JoshK]

FWIW, I run a GT500 dual pump kit, KB Competiton Dual BAP, -8an fuel line with high flow filter, and ID1000 injectors. I have gone as high as 21lbs on my 11:1 engine on E85. Made 742whp and duty cycle is 86%.

I will be watching this though as I am considering the switch to return style

 

[sportinawoody]

Return style is going to be better for fuel temps which = power. The return style pumps running more amps @100% full time though. You can do gt500 return less to 800 easy with 1000's, -8 lines , rails and wire upgrade but you'll have higher fuel temps but if you run good gas that generally makes up for the temp. I mix 110 renegade with 93-95 non ethanol 50/50 and my car loves it on return less without a bap

 

[JoshK]

Dont you have the fuel temp thing backwards. I think I remember the return style heating the fuel up more since it is being circulated to the hot engine bay and back all the time and the pumps running full speed all the time. IIRC, Lito even did some testing with an in-line cooler on his return line to get temps down. I think JPC also did some testing with a cut open tank to monitor fuel temps. On a returnless the fuel cant heat up since it just stays in the tank until it is used.

 

[05yellowgt]

Yes, he has it backwards. Returnless systems have lower temps because the fuel isn't being heated and recirculated through the system as it is in a return system.

I ran a returnless setup on my car. on 27psi of boost I was running about 85% duty cycle with triple GT pumps and 80lb injectors. The injectors were near max so in order to keep up I had to up the base pressure to 55psi which put extra load on the pumps. if I had ID1000's or 13000's I would have been able to drop base pressure and been running a much lower duty cycle.

Tuning the fuel system took a bit of time, but I had someone who understood how to do it right tuning the car so that wasn't a problem. Flowing as much fuel as 3 GT pumps can and not having the adaptive fuel tuning dialed in can and will result in a bunch of popped FRPS's due to wild swings in pressure.

If I did it over again I think I would have just gone to a return system and called it a day though.

 

[sportinawoody]

Typo,,,

 

[dugstang]

so say someones goal is just 600-650? would you bother going return style?

 

[05yellowgt]

On corn you should be able to add a BAP and call it a day, so long as you are using injectors that don't require you to up the base pressure too much. I also depends on how much boost it takes to hit that number.

 

[dugstang]

so to switch to corn...which would make my goal easier and safer to achieve, i would need to step up injectors and pump? I currently have 39lb with stock gt pump on a BAP. Going forged very soon and want to do all this at the same time.

 

[05yellowgt]

so to switch to corn...which would make my goal easier and safer to achieve, i would need to step up injectors and pump? I currently have 39lb with stock gt pump on a BAP. Going forged very soon and want to do all this at the same time.

Yes you would have to upgrade both. 39lb injectors are good to around 500-525 or so and you need about 30% more capacity for E85 as a very general rule of thumb. I'd go for ID1000's or their rough equivalent and a GT500 setup with BAP if you want to stay returnless.

 

[Department Of Boost]

so say someones goal is just 600-650? would you bother going return style?

I wouldn't.

Yes, he has it backwards. Returnless systems have lower temps because the fuel isn't being heated and recirculated through the system as it is in a return system.

But if you run something like the Aeromotive pump controller it's like having a returnless system. The Aeromotive pump slows the pump down (3v I think) while cruising, etc and kicks it into high gear when it sees boost. The best of both worlds.

 

[05yellowgt]

But if you run something like the Aeromotive pump controller it's like having a returnless system. The Aeromotive pump slows the pump down (3v I think) while cruising, etc and kicks it into high gear when it sees boost. The best of both worlds.

Yep, there is that.

 

[dugstang]

gt500 pump setup, keep current BAP and id1000s then I can cornhole it to my goal. Sounds good to me. Roughly $1500 to stay returnless and $2000 to switch to return. Im working on a rough estimate on numbers for my complete build

 

[BruceH]

IMO returnless is a better way to go. It lets you adjust fuel pressure in the tune and on the fly. What I mean by that is you can run 39psi for lower loads and command a higher psi for higher loads. This lets the injectors run a longer and more accurate pulse width at lower loads like in town driving.

The max I've run on e85 was 699rwhp uncorrected -meaning that it was actual power the pumps were supplying. This was done with gt500 pumps, bosch injectors that were rated 970cc at 3 bar and 1300cc at 4 bar, and a single 40 amp bap. It was powered with an 8 gauge wire.

Max duty cycle was 86%.

Someone might correct me on this but all a return style really does is make it easier for the tuner. Set the regulator and that's it. The downfall is at lower power levels because that 5 bar needed to run wot is still there for normal driving. This means very short pulse widths are needed to run the motor at low loads.

Ready for someone to explain it differently.

 

[skwerl]

I took the same approach as Bruce and think his explanation is spot on. GT500 pumps with a wiring upgrade and BAP will supply more than enough fuel for 99% of the builds on this forum and pretty much anything that is expected to remain a viable street car. If you're building a track only car then by all means go for it, but if you are expecting to drive it around town on a regular basis then you can get all the fuel you'll ever need with a returnless setup.

 

[19COBRA93]

I've made some pretty big numbers on stock lines, GT500 pumps, dual BAP, and ID1000's. It's a relatively cheap setup, and drives like stock. I would recommend sticking with that as long as you can.

With that said, I'm about to go return style, because I have much higher HP goals that the returnless just won't support.