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05 Silverado Return or Returnless Fuel system? v6 to v8 5.3
Hello,
I have a 05 Silverado with stock base tune 5.3L 5 speed manual that I did a v6 to v8 swap and I'm hoping to run a cam and eventually turbo it next year.
Currently has a Returnless set up that I just simply want to replace because its feed line is about 6 inches to long that kinks to the feed line at manifold.
That being said, there is a braided steel line kit I can swap in and call it a day for under $200 but not sure if they coincide to my application.
From reading online, Return fuel is best when running more than 400 whp due to continuous fuel being sent and filtered.
So IF Return is the best option for modded configurations, I plan to swap pump with e85 compatible lines and a pressure regulator.
Anyone that has done any fuel swaps is greatly appreciated for their input. TIA!
Id say 600hp is a more reasonable threshold. Theres nothing inherently wrong with a returnless setup, it is just generally easier to use a higher flow fuel system with it being return style. The nomenclature can be confusing, both styles use a regulator that functions by bleeding off flow to maintain pressure. With a "return" system this regulator is on the fuel rail so both the feed and return run the length of the truck back to the tank. In a "returnless" system the regulator is in the tank so you dont see the return line even though its there, you only see the feed.
There is a power threshold is mainly for 2 reasons. In a returnless system all of the fuel flow has to go through the regulator since it is not on the rail, and the regulator being so far away is generally not pressure referenced so it cant adjust rail pressure for boost. This latter reason means your injectors effectively get smaller with more boost.
I see. Makes sense! Thank you!
Going to order BTR stage 2 cam and run it N/A for the time being just gonna swap injectors and fix feed line. Ideally id want 400+. Which i think is reasonable to achieve.
keep in mind: unless you want to cam it twice, using a N/A cam for a turbo build will typically leave some on the table regarding turbo efficiency. superchargers are a different story & can run much better on a N/A cam.
another pro tip to keep in your back pocket: your nv3500 may or may not last... it all depends on how you drive it & what you do with it. being a little 2wd, you should be fine with the power so long as you ain't trying to tow more than 6000lb or so. Ed from forever ago on here ran a 454 & then a boosted 8.1 in his RCSB with the stock 5 speed. a built T56 is an option - look for the M12 gearset out of a CTS-V or GTO. you'll want 4.88s or so in the diff, though, and won't be able to tow at all.
another option if you do plan to tow is an nv4500 - which is almost a direct bolt-in swap. in that case, you could easily plan for 3.42 or even 3.23 gears. the other hidden gem that i didn't think about until after i'd already 4500-swapped mine is grabbing a late-model GMT400 nv3500 from a v8 truck, which had the M50 gearset. they've got closer ratios and not as low of a 1st gear.
Yes, very true. For the time being ill run N/A. Buying 50 lbs/hr Fuel Injectors GM 12613412 with Delphi to EV6 adapters keeping the stock 05 truck intake manifold followed with a Walbro 255 LPH. Next week or two I should have them in.
I'm seeing Tick Performance sells a T56 Magnum in gear ratios 2.66, 1.78 and/or 2.97, 2.10 first & second gear ratios. Looking to get the 2.97, 2.10 gear ratio since its longer. Steep price but don't want to be limited in the future.
I am taking my time with this truck. I do occasionally haul but no more than 4,000 lbs if that, truckload of fire wood and a small double jet skis plus trailer is mainly what gets hauled when I do use it which is every fall/winter.
My 05 Silverado currently has a GU5 code which says has 3.23 open diff. I want an 'LSD Posi', 3.73 gear ratio with a Trutrac Posi.
for them T56s: the M12 gearing i mentioned earlier is that 2.97 option, and MM6 is the 2.66 version. for a truck application, your weight will appreciate the M12 ratios. to go along with that, you'll want at least a 4.56 rear end (4.88 minimum if you get MM6); otherwise, 1st gear will be miserable on your clutch and 6th will be useless. Truetrac is a good mechanical street LSD option; mine worked great.
also, plenty of guys have burnt up T56s in ECSBs & Suburbans just due to their weight alone, so i wouldn't recommend trying to tow 4000lb behind one. it's less about the internals being 'strengthened for the extra power' and more about the small physical size & limited fluid capacity getting hot from the strain of the weight (just like our 5000lb H3 Hummer literally coming with a Pontiac Solstice 5speed [the AR5] and being capped at 3500lb towing). if you're serious about 3.73 rear + light towing, i'd strongly suggest an M50 NV3500 out of a mid-90s Silverado.
it's your truck, and you're more than welcome to proceed however you see fit. i'm just speaking from 15yrs of researching these very options, burning up one NV3500 (not from my cammed 5.3 swap but from towing 7000lb in 5th... even with 4.30s), and ultimately doing an NV4500 conversion in my last RCSB. take that for what you will.
Last question,
Will a Walbro 255lph fit the v6 fuel pump module assembly? I'm reading all tanks that have a 24 gal capacity are the same, just curious if ill have issues retrofitting the 255 pump to the v6 Delphi module.
i was under the impression they ran the same fuel pumps in v6 & v8 (at least in my 99 NBS).
the e85 flex trucks might've had a bigger pump (definitely bigger injectors)
when my stock pump gave up the ghost at 210k, i asked the shop about upgrading to a 6.0 truck's pump and was told they pulled the same part numbers.
07-22-2024, 08:29 PM
05 Silverado Return or Returnless Fuel system? v6 to v8 5.3
