Increasing towing performance

[schwarze_crewcab]

Looking to see if anyone has ideas to make my truck actually tow worth a crap. I pulled an empty horse trailer 180 miles today, and I averaged 11.3 mpg. Trip was in the rolling ills of southern Iowa. Truck and trailer together weigh in right at 9000 lbs. This thing is a pooch and downshifts on basically every incline, no matter if I am going 60 or 70. I came from a 6.7 Cummins, so I realize I may be asking more than what this thing is capable of. I sold the Dodge because we bought a house, and I figured a gasser would be enough truck for me. I am staring to seriously regret it, and thinking this thing may go down the road real soon.

Thanks in advance.

 

[cabodiver]

do you have it out of overdrive when on the hills?

 

[schwarze_crewcab]

If I know it will downshift I do. Otherwise on the flats I leave it in OD.

 

[SilveradoGuy85]

I'd be happy as hell to get 11.3 mpg towing about 3-4,000 lbs. I get 11.5 mpg in town in the summer so be glad you're getting the mileage you're getting. As for the shifting, I've towed a dual axle U-haul trailer completely full from top to bottom, front to back and with a fridge and other stuff in the bed and it towed it all just fine and most of the driving was in the country. I didn't notice any unnecessary shifting. I have a 5.7 with the 4L60e and 3.73 gears so the only difference in the trucks in the driveline is the trans. Not sure about the difference other than the 80e being more "heavy duty" so the gear ratios are probably a little different, but not sure. I was thinking about switching out my 4L60e with a 4L80e and I've seen where the 4L60e is better, especially when upgrading it a little.

 

[96Z71ECSB]

A 5.7L in your particular truck is not enough for what your pulling. It will do it, but not as well as the 7.4L.
Your dealing with more power loss through the drivetrain than us half ton guys with the same 5.7L engine. Not to mention the added weight of the crew cab.
I have the same basic setup as silveradoguy85 but in a GMC package. I regularly pull 5500+lbs., get 12.5 mpg at 75 to 80mph, but I stay out of overdrive completely unless on flat or downhill grades.
My truck never slows down even at a 6% grade. I also have the disadvantage of the Colorado altitude (this might explain the better fuel mileage).

The Vortec 5.7L power band is between 2500rpm and 4000rpm. In my truck, leaving the trans in third at 75 mph, my tach reads 3000rpm. I actually use less throttle to keep the rig rolling than I would using overdrive at the same speed.

As far as adding more power to your rig, the Black Bear tune will help. So will a Volant CIA, long tube headers, high flow cats, and a proper dual exhaust. A supercharger would be the biggest power adder but they are hard to find.
Then there's engine swaps. You can drop in an HT383E, an LS engine, a big block, or a cummins. Maybe even a Duramax. The skies the limit.

I would suggest starting with a Volant CIA, then a proper dual exhaust, then the Black Bear tune.
Then see what you think.

 

[SilveradoGuy85]

A 5.7L in your particular truck is not enough for what your pulling. It will do it, but not as well as the 7.4L.
Your dealing with more power loss through the drivetrain than us half ton guys with the same 5.7L engine. Not to mention the added weight of the crew cab.
I have the same basic setup as silveradoguy85 but in a GMC package. I regularly pull 5500+lbs., get 12.5 mpg at 75 to 80mph, but I stay out of overdrive completely unless on flat or downhill grades.
My truck never slows down even at a 6% grade. I also have the disadvantage of the Colorado altitude (this might explain the better fuel mileage).

The Vortec 5.7L power band is between 2500rpm and 4000rpm. In my truck, leaving the trans in third at 75 mph, my tach reads 3000rpm. I actually use less throttle to keep the rig rolling than I would using overdrive at the same speed.

As far as adding more power to your rig, the Black Bear tune will help. So will a Volant CIA, long tube headers, high flow cats, and a proper dual exhaust. A supercharger would be the biggest power adder but they are hard to find.
Then there's engine swaps. You can drop in an HT383E, an LS engine, a big block, or a cummins. Maybe even a Duramax. The skies the limit.

I would suggest starting with a Volant CIA, then a proper dual exhaust, then the Black Bear tune.
Then see what you think.

So is that power loss on his truck because of the 4L80e since the rest is the same as ours other than the cab? If so then I was right, sometimes I over complicate explanations lol. My trans needs to be rebuilt and when I looked up possibly swapping it out with a 4L80e since it's more HD I read that it would actually be worse in a 1/2 ton. I guess because of what you said that it doesn't work as well with a 5.7 than if it was a big block or diesel. I can only assume it's the gear ratios in the 80e.

I also figure that sure crew cab weighs more than ext cab, but I don't think it's enough of a difference to make it feel like it doesn't have as much performance. I could be wrong, but my 1/2 ton roughly weighs about 5,500 lbs I think. That's mainly because of all of the I have in my toolbox lol.

 

[schwarze_crewcab]

What kind of gains can I get out of the black bear tune? I've heard a lot of people recommend them, but haven't seen any numbers. I like that it shuts the egr off and makes it so you can gut the cats.

I was under the impression that a single exit exhaust was actually better for low and mid range power. Has I known that wasn't the case, I probably would've put duals on it.

I guess I should mention that it has 265s on it. I bought it that way, so I doubt the speedo has been recalibrated. Will they even throw it off?

I have let it run in od on the flats because I figured it would get better mileage. If it would actually get better mileage in drive, I guess I will try that.

I would also like it a lot better if this thing actually had an appropriately sized fuel tank. But, I can't say I'm going to be spending that kind of money on this thing.

 

[Crummins]

I was under the impression that a single exit exhaust was actually better for low and mid range power. Has I known that wasn't the case, I probably would've put duals on it.

A properly sized single exhaust produces more torque than true duals. I don't know the science behind it but I have talked to make exhaust companies and they all agree on this fact, some even had dyno numbers to show it was true. If you want the look of duals, go into a single muffler with dual outs.

 

[96Z71ECSB]

So is that power loss on his truck because of the 4L80e since the rest is the same as ours other than the cab? If so then I was right, sometimes I over complicate explanations lol. My trans needs to be rebuilt and when I looked up possibly swapping it out with a 4L80e since it's more HD I read that it would actually be worse in a 1/2 ton. I guess because of what you said that it doesn't work as well with a 5.7 than if it was a big block or diesel. I can only assume it's the gear ratios in the 80e.

I also figure that sure crew cab weighs more than ext cab, but I don't think it's enough of a difference to make it feel like it doesn't have as much performance. I could be wrong, but my 1/2 ton roughly weighs about 5,500 lbs I think. That's mainly because of all of the I have in my toolbox lol.

Yes. The 4L80E will consume more power from your engine. It's called frictional loss. The 4L80E is heavier, has more rotating mass, more clutch drag, compared to the 4L60E. That's what makes the 4L80E a stronger trans.
The same applies to the bigger differentials that are installed in HD trucks. You get frictional loss due to the bigger, heavier internal parts in the differentials.
The heavy duty trucks are not the same as our half tons. They have longer heavier frames, larger heavier differentials, larger heavier suspensions, and, with a crew cab, a longer cab.
It takes more power from the engine to get these trucks moving.

 

[96Z71ECSB]

What kind of gains can I get out of the black bear tune? I've heard a lot of people recommend them, but haven't seen any numbers. I like that it shuts the egr off and makes it so you can gut the cats.

I was under the impression that a single exit exhaust was actually better for low and mid range power. Has I known that wasn't the case, I probably would've put duals on it.

I guess I should mention that it has 265s on it. I bought it that way, so I doubt the speedo has been recalibrated. Will they even throw it off.


I have let it run in od on the flats because I figured it would get better mileage. If it would actually get better mileage in drive, I guess I will try that.

I would also like it a lot better if this thing actually had an appropriately sized fuel tank. But, I can't say I'm going to be spending that kind of money on this thing.

I can't give you any info on the BB tune because I don't run one. There is a few guys here that do run a BB tune so maybe they will chime in. From what I've read, a BB tune will give it a little better mpg and power.

As far as the single vs dual exhaust controversy, I have my own opinions on that subject. The scavenging effect created by the "Y" pipe in a single exhaust, only works if it's close to the engine. It works for 5.7L TBI trucks ("95 and older) because the factory "Y" pipe is before the single catalytic converter. It's close to the engine so you get a certain amount of cylinder scavenging. Installing headers defeats the need for a "Y" pipe on TBI or any other engine.
Vortec 5.7L heads/engines are a different animal. The head design is far superior to the older TBI heads so Vortecs won't benefit from a "Y" pipe close to the engine. The exhaust flow is far better than the TBI heads. This is one of the reasons for the stock Vortec trucks having dual cats and pipes clear back to the muffler. Installing headers will also help Vortecs.

Unlike 5.7L TBI engines, Vortec 5.7L engines make it's power from the mid to high rpm's. Your exhaust system should be built to enhance power in this power band. It's my opinion and experience that single exhaust systems don't achieve this.
I started with the stock exhaust on my '96, to a Flowmaster American Thunder, Single Side Exit exhaust, to a proper dual exhaust with a Flowmaster dual in/dual out 50 series muffler.
My truck pulls harder now than it ever did.

I do use OD on the flats and downhill but Colorado rarely has it's flat spots so I rarely go into OD when towing. Staying out of OD also gives me some engine braking.

If you went from 245's to 265's, then yes, your speedo probably reads a little slow (example:actual 57mph, speedo reads 55). That is, if it was accurate in the first place. Mine reads fast (actual 54mph, speedo reads 55).