20% + increase in fuel mileage!

[Frankenchevy]

Well, the 8.1 is a notorious gas hog too.. it's hard to find the same aftermarket parts and they are way pricier than the older BBC stuff. Hopefully being able to tune everything myself and having improved parts helps out. There's a bunch of people that have done the 0411 conversion on factory GMT-400 454/4L80e combo's and had good results into the 14mpg range.

That’s pretty dang good

 

[jake wells]

I usually get 5 days out of my square driving it to work and back it has a 16 gallon tank it is a bone 350 2bbl with a th350.
round trip to and from work is around 40 miles.

 

[Doppleganger]

So I take it you like the Pro Flo 4? Thats the setup I have - going on when the new motor goes in this Spring.

 

[rt66paul]

Another factor is the traffic factor. Was there more traffic before the Covid crisis? Being able to cruise at speed without the stop and go(or slowing down and up to speed), does make a difference in fuel mileage.

 

[davisw73]

I think the combo of both helped you out equally and it doesn't sound far fetched. I had much the same results.
Mine had a TH400 w/4.56 rear end and stepped it down to 3.42. That increased me from 13mpg screaming at 55mph to 15mpg screaming at 70mph, lol. When I could keep the mph down to 55 I could get 17 (stock 31in tires).
A few months ago I converted to a NV4500 and now I'm cruising at 70mph getting 20 (it's a 6.2l diesel with a banks turbo).
The key is to maximize your mpg gains by staying in the right RPM range. For my diesel that is 1700-1900rpm. My combo of tires, gears, OD, and desired mph put me right in the sweet spot. Not sure what it is for your combo, but if you find out you could use an online rpm calculator to figure out what the best gear ratio would be for you...unless you want/need the 4.56 for towing/off-roading. Of course I only had one axle to change so it was cheaper.

 

[DoubleDingo]

I think the combo of both helped you out equally and it doesn't sound far fetched. I had much the same results.
Mine had a TH400 w/4.56 rear end and stepped it down to 3.42. That increased me from 13mpg screaming at 55mph to 15mpg screaming at 70mph, lol. When I could keep the mph down to 55 I could get 17 (stock 31in tires).
A few months ago I converted to a NV4500 and now I'm cruising at 70mph getting 20 (it's a 6.2l diesel with a banks turbo).
The key is to maximize your mpg gains by staying in the right RPM range. For my diesel that is 1700-1900rpm. My combo of tires, gears, OD, and desired mph put me right in the sweet spot. Not sure what it is for your combo, but if you find out you could use an online rpm calculator to figure out what the best gear ratio would be for you...unless you want/need the 4.56 for towing/off-roading. Of course I only had one axle to change so it was cheaper.

Yep, maximum vacuum at cruise will require minimum pedal to keep rolling, because the engine is working effortlessly.

 

[SquareRoot]

So I take it you like the Pro Flo 4? Thats the setup I have - going on when the new motor goes in this Spring.

Pro-Flo was the single best thing I've done to the truck. Maybe the Vintage Air Surefit....wait maybe the Dakota Digital VHX dash...wait maybe the NV4500....it's so confusing!

 

[Swearbody]

Pro-Flo was the single best thing I've done to the truck. Maybe the Vintage Air Surefit....wait maybe the Dakota Digital VHX dash...wait maybe the NV4500....it's so confusing!

I thought I wanted a Sniper unit until I realized the Pro Flow comes with the ability to control timing and is boost referenced right out the box. Just add the 60 or 80lb injectors and you can make 800hp+. The Sniper requires a separate timing controller and special distributor BOTH SOLD SEPERATLY for around another 5-600. In the end both are really close on price but I think the fuel rail/throttle body combo is more accurate per cylinder and especially when adding boost or N2O. Just my 2cents.

 

[DoubleDingo]

Pro-Flo was the single best thing I've done to the truck. Maybe the Vintage Air Surefit....wait maybe the Dakota Digital VHX dash...wait maybe the NV4500....it's so confusing!

All of the above?

 

[SquareRoot]

I thought I wanted a Sniper unit until I realized the Pro Flow comes with the ability to control timing and is boost referenced right out the box. Just add the 60 or 80lb injectors and you can make 800hp+. The Sniper requires a separate timing controller and special distributor BOTH SOLD SEPERATLY for around another 5-600. In the end both are really close on price but I think the fuel rail/throttle body combo is more accurate per cylinder and especially when adding boost or N2O. Just my 2cents.

Sniper is a wet manifold whereas PF4 is a dry manifold. There's a BIG difference in drivability and efficiency. I'm not convinced that mounting the ECU on top of a hot, vibrating engine makes sense for durability. I immediately regretted the TBI (Sniper) system all because I wanted to save a few bucks. It took less than 2 months before I sold it for half what I paid for it. Live and learn.

 

[RecklessWOT]

Another factor is the traffic factor. Was there more traffic before the Covid crisis? Being able to cruise at speed without the stop and go(or slowing down and up to speed), does make a difference in fuel mileage.

lol covid had the exact opposite effect on my mileage. Being forced to cruise at 60-70 on a good day got me reasonable mileage. But with next to no traffic on the road I can comfortably go 80-90 everywhere (with bursts of full on pedal to the floor driving on particularly empty stretches of highway), even when I borrow the wife's little fuel sipper I'm barely north of 20mpg, I don't want to know what I'm getting out of the 2500. I do know I have to fill it at least twice a week...

Though I will say it's almost worth spending the extra money in gas for a much shorter and less stressful commute

 

[Swearbody]

Sniper is a wet manifold whereas PF4 is a dry manifold. There's a BIG difference in drivability and efficiency. I'm not convinced that mounting the ECU on top of a hot, vibrating engine makes sense for durability. I immediately regretted the TBI (Sniper) system all because I wanted to save a few bucks. It took less than 2 months before I sold it for half what I paid for it. Live and learn.

Thats what ive gathered as well. I thought I saw you selling a sniper not too long ago...thats why I wanted your opinion. Im not as concerned with mpg as I am with having a proper stoichiometric mixture. I know from having ran carbs with N2O that wet intake setups do not atomize the fuel nearly as well as having injectors firing more directly into the cylinder. Since I do plan to add forced induction or N2O eventually, I want something that renders itself to that mo betta. Looks like proflow is the way to go.

 

[Green79Scottsdale]

Back in the day... the year 1999... a co-worker bought a brand new 1500HD with a 350 and 3.42 gears. He managed 12mpg. After about 6 months of ownership he was quite disappointed because another co-worker had a 1998 2500 with a 454 and 4.10 combo, and he was getting 14mpg.