Hello.
I'm looking to get a tuner for performance BUT I'd like to start with one that might give me a couple of miles per gallon. I've got a 2003 LQ4, bone stock except for shorty headers. It runs as it should(no codes, no issues). The truck has 4.10s and a 4l80e.
Any suggestions? I've used Smartys on my diesel for this purpose, but have been back in the gassers for quite some time.
Thanks
Jeff
2003 2500hd silverado, long bed single cab, 256K. Rebuild trans and transfer case.

 

If you have to run Premium, try mixing mid grade 89 50/50 with some 93 octane Premium. In some states, 91 octane Premium is all there is, no 93 octane in some states. If 91 is all you do have, never mind previous statements. If you aren't supposed to run Premium, DON'T!! Best mileage in that case will happen running Regular gas, as long as the PCM isnt pulling timing due to spark knock......

 

Thanks for the reply. Currently, I do not have to use premium. I believe the stock CR is 9.15 to 9.5. I don't seem to have any spark knock.
jeff

 

LS engines up to 10:1 compression use regular 87 octane. Many Gen IV 5.3 in trucks are made that way,and no knock in sight.

 

it has a 6.0, a 4l80 and 4.10's.....

 

Your LQ4 stock compression is 9.46:1. Bolting a set of 243/799 heads will take it up to 10.07:1 with no other changes. Plus you get more efficiency and better breathing.

 

LOL. Point taken. Only played with smallblocks before.
jf

 

Thanks for the info. I have a set of 799s I was saving for the 6.0 block I'm building.
jeff

 

Lol, so what are you trying to say?

 

Oops, didn't put in context. I was responding to Liljayv10. He pointed out that this is a 6 liter, 4.10, and a 4L80. Not friendly to gas mileage in general.
jeff

 

I have a 02 4x4 crew cab with 4.10's and 33" mud tires, 799 heads "Truck Norris" cam and longtubes it gets 13-14mpg unloaded with mostly highway driving in the 60-65mph range, Ive tuned it to get the best mileage I can and thats all I got out of it lol.
Before the cam and tune it was around 12-13ish... so really only have gained a consistent 1MPG but does have quite a bit more power now.
Loaded It gets 9 every single time weather im towing my 3000lb car or my 8000lb tractor, or my 14,000lb 5th wheel, no idea how that is.

This is just for reference

 

ive spent quite a bit of time playing with trying to get economy in a ls2 s10, turbo 4.8 s10, twin turbo 4.8 and 5.3 in a awd silverado and what ive learned is the platform is the biggest driver of economy. tune wise, ive had the best luck running 15.0-15.2 afr, much leaner and you lose too much power so you end up driving around at much higher map. my truck ran fine 15.6-7 but it killed too much power i got worse economy than when i ran 15.0. also throw a lot of timing at it in cruse. if im remembering right id cruise my 5.3 around at 44-45 degrees.

 

@jfulford1

There's not a whole lot that can be done. Do you have a tuning software yourself (hptuners or whatever)?

I have a 2000 Silverado 2500. Mine is a stick shift with 3.73s, so I get way better mileage than the autos with the 4l80 and 4.11s as is (I average around 18 mpg, but have it setup in an efficiency trim), but there are a couple things that can make a small difference in the tune that TrendSetter mentioned. You want more timing in your cruise cells.
Running 93 octane definitely helps, ONLY when you have the timing to do so (aka a lot more than stock. The 6.0s were tuned even more anemically than the 5.3 and 4.8).

With the stock compression (9.5ish) and running high octane, you can run 41 degrees of timing from no load (<30kpa on the MAP) to about 60kpa (medium load) from 1600rpms up. With 87 octane maybe only up to 50kpa (I never bother running 87 anymore. More power and mileage on 93 with proper timing). Just this alone made it drive way snappier.

Otherwise, the biggest differences in gains mileage will come from 1: Run fully inflated stock size (245/75 r16) highway/road tread tires instead of oversized off-road tires on aluminum rims, 2: Factory ride height, 3: E-fan swap, 4: Front end alignment, 5: Stick to the speed limit/drive like a grandpa, 6: Bed Cover.

The first 5 will make more difference than the tune. However, if you do get a tune while doing those, it should help even more. I did those 6 and tuned my engine for 93 octane. Took me from 15 mpg average to 17 mpg average. Got solid 19/19.5 mpg on the highway on a road trip (cruise always set at 65).

If you REALLY want a project, bumping the compression up will help. I put on some 241 heads with a 3 angle valve job done to bump my compression to about 10.0:1. That got me to 17.5 mpg average.
I also installed the Cam Motion Titan 1 truck cam (208/214 110+4). It makes the truck feel like it has all the torque in the world, but it actually improved my mileage to about 18.5 mpg.

However, that's mostly because this is a very mild cam made for trucks, I drive like a grandpa, and my commute doesn't have much stop and go.

Edit: I forgot about DFCO (Deceleration fuel cut-off). This will completely cut-off fuel injectors if you meet the criteria in the tune.
Not sure if this will help automatics as much as a stick shift, but tweak the dfco so it will activate in your normal driving deceleration conditions.

Even when completely stock, I got better mileage towing through the mountains than I did on the plains because any time I'd be descending a mountain, I'd hit the cut-off criteria and get infinity mpg using no gas until I got to the bottom of the mountain and needed throttle to keep speed.

 

.
.
. You'll get 13 to 14 miles per gallon- MAXIMUM, unloaded, flat ground, driving miss daisy. The book of physics will NOT give you 15% more fuel economy.

 

To really get more fuel economy you need more compression, lower drag tranny, and less rear gear. That and a light hammer foot will get more mileage.
Tuning will sharpen things up a bit, but only improve mileage incrementally

 

i think i got 16-17 in my RCSB, TT5.3, 4l80, np149 awd full weight truck. but that was after months of tweaking the tune and doing all kinds of stupid data analysis on map vs timing vs afr. plus the truck was lowered to about stock 2wd height and had car wheels and tires.

 

Hello.
I haven't purchased a tuner yet; any suggestions? Last time I did this I was burning eproms......

Thanks for the tips, especially the cam. I'm trying to currently build a 6 liter between 450 and 500 hp, making power before 5500.
Would love to have a stick--practically non-existent these days.
I do have 799 heads I was saving for the engine I'm building. Little afraid of putting them on now, basically hurrying the bottom end of my currently engine to wear out(257K).
jeff

 

I have HP Tuners. It's definitely a learning process, but there a lot of info out there on how to tune Gen 3 LS engines.

If you want 450-500 at the crank on a 6.0 you're gonna need to rev to at least 6000 rpm with either rec port heads (i.e. not the stock heads or 799 heads) or have a whole lot more cam that's wont drive as nice (i.e. less gas mileage, rough idle) in a big heavy truck. Also gonna want the TBSS/NBSS intake and good exhaust of course.

425hp with just as much torque at low rpms is a heck of a lot more fun to drive in a truck that is used as a truck than 450-500 that takes until 3000 rpms to get into the power.
Now if is being used as a hot rod/cruiser, then go for a big cam and higher stall converter. Otherwise, those things don't make for practical truck usage.

If your engine has good oil pressure, doesn't burn oil, and the bottom end doesn't knock, it should fine for a mild builds. Definitely go with the 799 heads.
You will need 93 octane with compression nearing 10.5 to 1. You could run 87 with a lot of timing pulled, but trust me, the engine will run better on 93 with a proper tune instead of a lethargic "keep it alive" tune for 87.

These heavy trucks put a lot more load on engines than light cars, so you would definitely want high octane if you towed with the 799 heads.

 

So, I need to stay under 450HP? Cam recommendations for this 6 liter with 799 heads and flattop pistons?
jeff

 

You can do whatever you want with your truck. There's just some give and take when swapping cams.
More power = wilder cam

450hp at the crank isn't super hard to get on a 6.0. It just happens in the 5500-6000 range (pretty close, right?). If you want that much power and more below 5500 (i.e. a LOT more torque) you need more cubic inches or boost.
There are a lot of cams that will get you in the 450hp ballpark, it really comes down to personal preference.

I recommend the Cam Motion Titan 1 Truck cam because I just threw that in my truck. Behaves like stock, but with a lot more power. ~430hp
There's the truck norris cam from btr, this one definitely has some chop. Makes idle a bit harder to tune if you are DIY, but it's do-able. ~440hp
Summit has a bunch of good truck cams from nearly stock to mild to wild. Summit Racing™ Pro LS Vortec Truck Swap Camshafts - Free Shipping on Orders Over $99 at Summit Racing
Cam Motion also has the Lil' Lope. Lil' Lope LS Camshaft (216/224-108+3) - Cam Motion Their dyno shows 450hp with a 6.0.
Cam Motion also has the Little Chopper. Their dyno has it around 465hp, but this would really have a choppy idle and NEED a non-stock torque converter.

Anything more than that starts to become a race cam because the power starts shifting to higher rpms and you lose power from idle to 3000.

Give the folks at Cam Motion a call. They can give their expert advice that will be way more detailed than what you'll get in one place online.