DPF Delete question
Fleet Mechanic
Joined: Oct 2011
Posts: 1,778
Likes: 287
From: Down SOUTH
I was getting 14.6mpg stock with 4x4 SRW cc long bed 3.73 axle.
I completely removed both egr coolers, cat & DPF.
Installed aftermarket intake elbow with the Gearbox Z -
I now can barely squeeze 16.3mpg empty - hand calculated, all highway staying under 2,000rpms at "ALL Times ".
Your right, on the skinny pedal. Mpg loss is getting these heavy trucks from a stop, Up to Hwy speed
I completely removed both egr coolers, cat & DPF.
Installed aftermarket intake elbow with the Gearbox Z -
I now can barely squeeze 16.3mpg empty - hand calculated, all highway staying under 2,000rpms at "ALL Times ".
Your right, on the skinny pedal. Mpg loss is getting these heavy trucks from a stop, Up to Hwy speed
Lead Driver
Joined: Jan 2006
Posts: 6,267
Likes: 5
I was getting 14.6mpg stock with 4x4 SRW cc long bed 3.73 axle.
I completely removed both egr coolers, cat & DPF.
Installed aftermarket intake elbow with the Gearbox Z -
I now can barely squeeze 16.3mpg empty - hand calculated, all highway staying under 2,000rpms at "ALL Times ".
Your right, on the skinny pedal. Mpg loss is getting these heavy trucks from a stop, Up to Hwy speed
I completely removed both egr coolers, cat & DPF.
Installed aftermarket intake elbow with the Gearbox Z -
I now can barely squeeze 16.3mpg empty - hand calculated, all highway staying under 2,000rpms at "ALL Times ".
Your right, on the skinny pedal. Mpg loss is getting these heavy trucks from a stop, Up to Hwy speed
Fleet Mechanic
Joined: Oct 2011
Posts: 1,778
Likes: 287
From: Down SOUTH
It's a lot more than stock was 
I'm Guessing 15lbs, but I'm not real sure as I don't drive the truck much.
I've often wondered if the extra boost sucks more Fuel.
I'm Guessing 15lbs, but I'm not real sure as I don't drive the truck much.
I've often wondered if the extra boost sucks more Fuel.
Postmaster
Joined: Jul 2008
Posts: 2,565
Likes: 2
Extra boost does use more fuel. My mileage got its best after the 3rd or 4th full fuel load and all highway. The boost on mine on flat ground generally runs under 10lbs. but does go up to 15-20 lbs. My 1st tank on the highway after the mod netted me a gain of 1.8 mpg. It got better on the next few tankfuls. I get 3.5-4 mpg better now than I got stock.
Lead Driver
Joined: Jan 2006
Posts: 6,267
Likes: 5
I find that my best mileage has been with the VVT wire pulled. It runs about 3-5 psi down the highway empty at about 60 mph or 100 km/h.
EGT's fine. Running tow tune with defuel EGT safety on it.
Pulling the wire off isn't ideal as it gets laggy as heck, but I think it proves that the computer demands way too much boost than is needed. Guaranteed for emissions.
My 7.3 only made a little bit of boost on flat highway, why would my 6.4 need 10-20 psi for doing the same job, with better combustion?
The truth is that it doesn't.
Your boost should be high enough to clear up smoke and keep EGT's good. More than that, and you're just wasting energy and stressing parts more. Higher boost means higher back pressure, which makes it harder to push the exhaust out, and also leaves more exhaust in the cylinder for the intake stroke.
EGT's fine. Running tow tune with defuel EGT safety on it.
Pulling the wire off isn't ideal as it gets laggy as heck, but I think it proves that the computer demands way too much boost than is needed. Guaranteed for emissions.
My 7.3 only made a little bit of boost on flat highway, why would my 6.4 need 10-20 psi for doing the same job, with better combustion?
The truth is that it doesn't.
Your boost should be high enough to clear up smoke and keep EGT's good. More than that, and you're just wasting energy and stressing parts more. Higher boost means higher back pressure, which makes it harder to push the exhaust out, and also leaves more exhaust in the cylinder for the intake stroke.
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Senior User
Joined: Dec 2008
Posts: 192
Likes: 0
From: Canada
That is not entirely true.
While the transmission might have a stock calibration, the line pressures and shift information is based on several inputs from the PCM. Since the tuning for the engine is now new, the transmission will be getting slightly different information to base it's shifting from.
Chances are, it will figure itself out, as the transmission "learns" as you drive. There are some ways to make it learn faster, like wide open throttle runs.
The factory system adjusts itself for clutch pack wear, driving style, etc. Chances are that all will be fine just after driving a bit.
Is it just a shift flare? Like when it doesn't shift fast enough, or is it binding and stumbling?
While the transmission might have a stock calibration, the line pressures and shift information is based on several inputs from the PCM. Since the tuning for the engine is now new, the transmission will be getting slightly different information to base it's shifting from.
Chances are, it will figure itself out, as the transmission "learns" as you drive. There are some ways to make it learn faster, like wide open throttle runs.
The factory system adjusts itself for clutch pack wear, driving style, etc. Chances are that all will be fine just after driving a bit.
Is it just a shift flare? Like when it doesn't shift fast enough, or is it binding and stumbling?
Fleet Mechanic
Joined: Oct 2011
Posts: 1,778
Likes: 287
From: Down SOUTH
I finally got my truck out into daylight the other day & drove it 
It runs 9lbs of Boost now deleted at 60mph empty on flat ground with 3.73 axle.
Both egr coolers are removed, aftermarket intake elbow & STOCK programming from GearBox Z DPF-R
How does this compare to others out there ?
It runs 9lbs of Boost now deleted at 60mph empty on flat ground with 3.73 axle.
Both egr coolers are removed, aftermarket intake elbow & STOCK programming from GearBox Z DPF-R
How does this compare to others out there ?
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Lead Driver
Joined: Jan 2006
Posts: 6,267
Likes: 5
I finally got my truck out into daylight the other day & drove it
It runs 9lbs of Boost now deleted at 60mph empty on flat ground with 3.73 axle.
Both egr coolers are removed, aftermarket intake elbow & STOCK programming from GearBox Z DPF-R
How does this compare to others out there ?
It runs 9lbs of Boost now deleted at 60mph empty on flat ground with 3.73 axle.
Both egr coolers are removed, aftermarket intake elbow & STOCK programming from GearBox Z DPF-R
How does this compare to others out there ?
9 PSI sounds decent.
Mine with the spartan tuning ran about there, but just mild throttle it would raise to 20 or more.
Fleet Mechanic
Joined: Oct 2011
Posts: 1,778
Likes: 287
From: Down SOUTH
I'm Ol' School
I like my GBZ very well. It's Plain & Simple = No bells & Whistles
I'm NOT a fan of Tuners, monitors, programmers etc
I only wanted to quit dumping the NASTY SOOT into my intake & improve MPG.
I'm NOT a fan of Tuners, monitors, programmers etc
I only wanted to quit dumping the NASTY SOOT into my intake & improve MPG.
Cargo Master
Joined: Dec 2003
Posts: 2,022
Likes: 4
From: Redford, Mi.
I have an old H&S (before the EPA hit), just went deer hunting up north, 442 mile drive, going either 70MPH or 60 MPH depending on the road. It ran from 4 to 10 LB's of boost depending on the terrain. My average from Detroit to the Big Mac on 75 was 21.88 MPG(on performance tune, 300 HP)MINE IS ONLY 2 WD!
On the way back pulling my trailer with 2,000 LBs of 4 wheeler I averaged 11.87 MPG running the stock setting. I was seeing boost from 10 to 30 LB of boost.
On the way back pulling my trailer with 2,000 LBs of 4 wheeler I averaged 11.87 MPG running the stock setting. I was seeing boost from 10 to 30 LB of boost.
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