Vortec 7.4 MPG vs 5.7 on lifted truck

[kylenautique]

1. You're wasting time, money, effort, and enthusiasm converting to electric fans. Likely creating problems you wouldn't have with a properly-functioning stock fan system.

2. Removing torque management is a great way to screw-up a transmission.

3. I can't comment on the rest of the "Black Bear Tune".

4. Explain again, if fuel economy is important, what is the reason you're running lifted trucks. Seems to me that you're not in such a serious "off-road" situation that a lift is doing anything positive for you, but adds extra friction and wind-resistance, and makes life harder on the U-joints.

ok, I will answer your questions..

Electric fans are not a waste at all. They free up quite a bit of HP especially around town driving or climbing a hill when its really hot outside. Its not expensive and there is a reason lots of newer GM trucks use them. Mine are ECM controlled, and use a Trinary switch for the A/C and I'm using a stock GM fan off a 2006 tahoe. Fits perfectly, keeps the A/C cooler and it cost me $180 to install the whole thing, and it performs like GM factory.

Yes, removing 100% of torque management on a stock high mileage transmission might not be favorable, but it depends on how you drive it. My transmission has abuse mode turned off which removes TQ management from 0-2400 RPMs, then after 2400, I've left 15%, so if I have to stomp on it, it goes. No delay, but it still cuts a little timing to make the up or down shift less abrupt. I drive like a grandpa, and my 4L60e was just rebuilt and improved. Also, changing your shift points to offset different tire sizes makes a world of difference in how the rig performs.

Black Bear tunes are great. My only gripe with them is the turn around time between tunes. It was a fun process for me because I've done some tuning myself in the past with a previous truck and boats that I have converted to fuel injection. Justin is very good at what he does and all he does is GM stuff.

For fuel economy, I created this post because I'm very curious to see what people are getting with these 7.4 trucks. Yes, a lift and larger tires puts you in the wrong direction fuel economy wise, but, an ECM tune really can make a huge difference to bring it closer to stock numbers, plus the engine gets woken up. I have a lift on my truck because I go into the mountains a lot and will encounter lots of snow. Ground clearance is nice to have, and I even have the torsion bar relocators, so I actually have all the ground clearance created by the lift. I drive around on lots of beat up forest roads too, so again, the clearance is nice to have. I'm not rock crawling it, but I do go have fun with it. Its not a pavement princess.

Hopefully, that clears up things for you.

 

[kylenautique]

I wouldn't touch a Black Bear tune with a 100 mile pole.

Electric fans are also a waste.

I think the 454 will perform better than the 350 towing. 8-lug truck has a much beefier driveline, better brakes, etc.

The black bear tune was great. The turn around time was not. They need to figure out a better way to get a person with Justin's knowledge on the phone instead of the sales guy that can't really answer technical questions. I think they are a small shop and are experiencing growing pains. But, overall, the tune is fantastic. I'm sorry you had a bad experience with them. I think they are very good at what they do.

I disagree on the fans. See my post to Schurkey. But hey.. different strokes for different folks!

I agree with you 100% on the towing aspect. That's why the vortec 7.4 intrigues me.

 

[L31MaxExpress]

The black bear tune was great. The turn around time was not. They need to figure out a better way to get a person with Justin's knowledge on the phone instead of the sales guy that can't really answer technical questions. I think they are a small shop and are experiencing growing pains. But, overall, the tune is fantastic. I'm sorry you had a bad experience with them. I think they are very good at what they do.

I disagree on the fans. See my post to Schurkey. But hey.. different strokes for different folks!

I agree with you 100% on the towing aspect. That's why the vortec 7.4 intrigues me.

I saw your post to Shurkey. I too used the Tahoe fans and had a massive overheating issue towing both at slower speeds in stop and go as well as on long uphill pulls. To add insult to injury, my AC is colder with a mechanical fan than electrics. The electrics are just too weak to keep my setup cool especially under load. The power loss from a mechanical fan is minimal unless the cooling is needed. Climbing a grade with a heavy trailer at 60 mph the mechanical fan will engage and actually keep the engine cool. There is a reason GM does not use electric fans on heavier GVW 8-lug trucks or even a 4.3L powered Express van. The electrics simply cannot keep up with the cooling demands.

I never let Justin touch anything of mine. That being said I have fixed 3 different tunes local that Justin butchered. Mostly torque management caused transmission failures and horrible MPG. One poor guy went through 3 different 4L60Es behind a stock 350 in his K1500. Anybody that blindly deletes abuse mode and reduces torque management torque cut is asking for trouble. Abuse mode helps smooth the torque output before the line pressure has had time to increase. Shift torque reduction makes the transmission shift more quickly by reducing clutch/band slippage. One guy on here had 2 or 3 failures of his 4L60E behind a 4.3L that was tuned by Justin. As weak as the 4L65E is, I have tuned one running behind an 8.1L in a H2. Stock transmission has 150K on it, 50K behind the 8.1L. Some of making that pile of junk trans live is in the tune. That 4L65E has a shift kit and Billet 2nd and 4th gear servos but otherwise stock.

 

[L31MaxExpress]

Just FYI, abuse mode and torque reduction do not make these trucks any slower. In the tune I created, my brothers suburban had the abuse mode set to coincide with the S10 converters ~2,800 rpm flash stall and the shifts had 40% torque reduction for 0.250s at WOT. Stock transmission shifted quick and it lived. It ran 9.20s @ 74 mph in the 1/8 in near 3,000 DA. Stock 4 bolt main L31 from a work van that had previously been rebuilt, bored 0.020" over, stock 906 heads, stock 96 F-Car LT1 cam, 1.6 roller rockers, long tubes and 2.25" duals with a Volant intake.

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[kylenautique]

I saw your post to Shurkey. I too used the Tahoe fans and had a massive overheating issue towing both at slower speeds in stop and go as well as on long uphill pulls. To add insult to injury, my AC is colder with a mechanical fan than electrics. The electrics are just too weak to keep my setup cool especially under load. The power loss from a mechanical fan is minimal unless the cooling is needed. Climbing a grade with a heavy trailer at 60 mph the mechanical fan will engage and actually keep the engine cool. There is a reason GM does not use electric fans on heavier GVW 8-lug trucks or even a 4.3L powered Express van. The electrics simply cannot keep up with the cooling demands.

I never let Justin touch anything of mine. That being said I have fixed 3 different tunes local that Justin butchered. Mostly torque management caused transmission failures and horrible MPG. One poor guy went through 3 different 4L60Es behind a stock 350 in his K1500. Anybody that blindly deletes abuse mode and reduces torque management torque cut is asking for trouble. Abuse mode helps smooth the torque output before the line pressure has had time to increase. Shift torque reduction makes the transmission shift more quickly by reducing clutch/band slippage. One guy on here had 2 or 3 failures of his 4L60E behind a 4.3L that was tuned by Justin. As weak as the 4L65E is, I have tuned one running behind an 8.1L in a H2. Stock transmission has 150K on it, 50K behind the 8.1L. Some of making that pile of junk trans live is in the tune. That 4L65E has a shift kit and Billet 2nd and 4th gear servos but otherwise stock.

That's interesting you had issues with electric fans. I have mine set to come on at 205 and off at 197. My trinary switch controls them for A/C so I never have a situation where the A/C compressor kicks on at the same time with the fans. Towing my 5000lbs boat, plus camping gear and my whole family in 100deg weather up and down big grades, my temp gauge never moves. I upgraded my alternator to the NBS alternator, only because the stock one failed, and the NBS alternator was the same price. I use 10 awg wire on my relays and I use high quality Hella weatherproof relays with maxi fuses.

Idk on the tuning issues. I'm happy with mine. The transmission works perfectly. 93-95 4L60e transmissions only had abuse mode and zero tq management controls after that, and they seemed to work fine. All comes down to how you drive it. If the trans has high mileage, you drive it like you stole it... stock settings might be better. Mine is built and improved, and I service it often. Plus, it has a huge cooler on it. It made it to 218k before it slipped one time. I take care of my stuff.

Not trying to get in to a keyboard cowboy match on this. To each their own! I just wanted to see, do people only get 8mpg with a vortec 7.4 crew cab short bed 2500, or is 13-14 freeway mpg somewhat common with a lift, 33or 35" tires and a tune.

 

[Spareparts]

Can't exactly answer your question but my 1998 Suburban, 7.4L, 4L80E, 265/70/16, 4:10
I get 13.5 highway not towing and 10ish in town.
Last weekend Swapped to the 0411 and a Black Bear tune. Still working on the tune a little but i can say so far it is the best thing i have done so far to the truck.
Have not checked mileage yet after the swap/tune but i think it is slightly better judging by the gas gauge during my normal weekly drive to work and back.
I can say for sure that it has more power and shifts firmer under half/full throttle. Part throttle it feels pretty much the same as before tune/swap. I'm very happy with the way it now drives.

 

[BNielsen]

One of my favorite mods I've done to my truck is the 0411 swap, if you go that route you can invest in HPTuners or EFILive and do your own tuning.
E-fans are kind of a hot topic; I was toying around with the idea of using the Flex-A-Lite 295 fans for a Duramax truck; rated at 6600 CFM I think, and a Flex-A-Lite 238 in place of the factory e-fan; a fully aluminum rad, FlowKooler water pump, 180 T-stat, and running Shell Rotella ELC coolant with some sort of additive like Amsoil Coolant Boost or RedLine Water Wetter.

But also, from my direct experience; an S10 fan, a severe service fan clutch, and an AC Delco water pump will bring my truck from 215 to almost 170 in minutes with the fan clutch locked in under throttle. It'll slow the truck down when it kicks in.

 

[df2x4]

One guy on here had 2 or 3 failures of his 4L60E behind a 4.3L that was tuned by Justin.

That was me. To be fair though, that was my fault. Justin at Black Bear advised me that removing torque management from a 4L60E was a bad idea and I asked him to do it anyway. No regrets in the long run as it led me to the 4L80E swap, and I'm really happy with how that turned out.

EDIT - The second 60E that died in that truck was brand new and significantly beefed up. Billet servos, beast sunshell, TransGo HD2 kit, etc. Don't think just because you've upgraded hard parts that you can ignore the warnings about removing torque management...

I've been very happy with everything else Black Bear has done for me on that truck though. I wouldn't hesitate to use them again.

Agreed on the torque management, at least on the 4L60E platform. I'm convinced they need every bit of it to stay alive.