PowellSixO

I've been thinking a lot lately on how to improve gas mileage on my big tank of a truck, while possibly adding some more towing power (torque specifically). You can see my current mods in my signature. This truck was in no way built for gas mileage if you couldn't tell. Haha. I've got as low as 6.5 mpg, towing my 25 foot camp trailer. Lol. So any ways, my dad bought an eco boost a few months ago, and I've had the chance to drive it. I wasn't totally disgusted with it honestly. I was surprised how much torque it produced, and how it got half way decent fuel mileage. It got me thinking about building my own eco silverado. I just recently replaced the heads on my truck with brand new 243 heads, but my short block has 150K on it. I was thinking about finding a 4.8 silverado short block, replacing the rotating assembly with something a little more stout, and slapping my heads on it. Then putting a twin turbo setup on it, and dialing it in at roughly 400 rear wheel horse power, and rear wheel torque. Nothing too crazy, but enough to beat my measly low 300's I'm pushing right now. I know that I would have the possibility to burn MORE gas than before, but when I stay out of the pedal I should technically be able to burn LESS gas than before right? I'm not expecting 20+ mpg here. I'm thinking that 16-17 on the highway might be obtainable though. Right now I'm lucky to get 13-13.5 mpg on the highway. Towing numbers will likely be what they were before, but I'm ok with that. I'd really just like to get better cruising mpg on the highway if possible, and have more power when it's time to play. What say you guys? Can it be done?

arthursc2

iTrader: (5)

Adding turbos improves the VE of the motor at cruise speed. Tuning for target AFRs 15.5ish low load low rpm will help too. Driving slower will help. Aired up stock size tires will help. Gear vendors OD will help.

In the end, it will take you 3-5yrs to pay off the turbo setup in reduced fuel costs, if you achieved better numbers at all.

Turbo it for fun, not under the rouse that youre going to increase economy, but you might

150k aint ****. Hit that bitch. dont you have an LY6? 243s arent an improvement over the LS3 heads.

PowellSixO

Lol. Nope. I've got the LQ4. I have the 07' Classic. I replaced the 317's for the 243's. I might just turbo the lq4 for fun. It's all for fun really. I plan on running a turbo period for better towing torque. I just thought for pretty cheap I could throw a 4.8 short block under it all to make it run better mpgs when cruising.

FFDP

iTrader: (2)

The 4.8 would have to work way way harder to achieve any gains. The 6.0 makes gobs more torque everywhere compared to a 4.8. The torque is what gets you moving and if you had to add the turbo to a 4.8 it would consume twice as much fuel because you'd need boost to make it move. Even at cruise the 4.8 would be further into the throttle to maintain speed.

swathdiver

That camshaft don't look right. Did you put that in to work with the heads? My 5.3 makes 302 RWHP and all it has is a tune. The lift, tires and gears are your biggest mileage culprits. Unless you run a diesel, forget about mileage with all those mods.

smokeshow

iTrader: (16)

I might have to do a write-up on fuel economy and efficiency lol. Your main obstacle with a gas engine in improving fuel economy will be RPM. More revs means more friction which kills fuel economy. Next will be power enrichment. Knock limited engine/fuel combinations will need more fuel to keep things quiet, so that'll hurt you as well. Stay in the throttle too long and it becomes a thermal problem. It won't be enriching for power but also to keep temperatures down.

It IS possible to improve fuel economy with a smaller engine because less cylinder wall surface area inherently means less friction. And cruising at a higher load means there is less vacuum in the intake, so less pumping loss. But as the manufacturers have discovered, it is possible to go too small. With a 4.8 in a full size truck towing a 25 foot trailer, I doubt any realistic combination of parts will produce enough torque to prevent downshifts.

Without going too far into it, I'd recommend putting the turbo on the 6.0. Needs to be a small turbo so it can lean into boost easily to make torque without downshifting. It also needs to be calibrated to run fairly lean in boosted areas at low RPM - no richer than 0.9 lambda under 2500rpm or so. Spark would have to be monitored closely as would coolant and exhaust temperatures. Your compression is likely too high now with those heads to have any kind of thermal longevity, so the 243s would probably have to come back off.

There's a ton that goes into it. You really have to identify your goals to build a game plan. Don't expect a miracle with a truck that size on 35s.

swathdiver

For his platform the smaller motor would not be pleasing to him. Torque is what gets the load moving and keeps it moving steadily. More torque, more efficiency. Turbocharged engines are ideally set up fueling wise the opposite of naturally aspirated motors. We run them lean off the line and richen them up under boost.

PowellSixO

Thanks everyone for the input. Sounds like a turbo is going on the 6.0. Well after I get my motor sorted out. I've been letting my wife drive it lately while I use her car to commute to work. Yesterday she tells me that it's been "ticking" a lot lately, but it comes and goes. So I drove it yesterday afternoon, and it's definitely ticking from time to time. Ugggg. I have a lifter that is taking a **** on me. So I placed a small order with texas speed this morning to get her back into good working order. I ordered a new oil pump, timing set, lifter set, pushrod set, camshaft, rockers, and all of the assosiated gaskets needed for the job. I ordered them with 2 day shipping. So it looks like I'm going to be busy trying to get it back together this weekend. Pics to come for sure. Lol.

PowellSixO

I ordered the TSP Stage 3 216/220 low lift (.550"/.550") 112 lsa truck cam, for it this go around. We will see how it will perform. The cam I currently have is most likely pitted at the very least (due to the bad lifter), and like swathdiver mentioned, it is not a good match for my current configuration. I put it in just out of acquiring it cheaply. Lol. Wish me luck.

00pooterSS

iTrader: (40)

Real interested to see how this works out, lots of people talking about truck cams lately and not many can compare back to back like you'll be doing (going from aftermarket cam to aftermarket cam)