Moddoo

iTrader: (4)

NEW INFO?
here's some new info.
nobody really gives a rats *** about 1 more mpg!

Funny how some of us amateur tuners have gotten 25mpg+ out of ecsb 4x4s.

sorry, calling this mileage extreme is a joke.

AdioSS

iTrader: (2)

XFE is just a catchy looking badge that they will probably carry over to other Chevy vehicles.

However, it does get better fuel economy than any other V8 truck.

Just think what it could get after tuning

Look at what you get in the package.
* Soft tonneau cover (improves aerodynamics)
* Extended front lower air dam (improves aerodynamics)
* Lowered suspension and revised chassis tuning (improve aerodynamics)
* Aluminum lower control arms (reduce mass)
* Aluminum spare wheel (reduces mass)
* Seventeen-inch aluminum wheels (reduce mass)
* Automatic locking rear differential
* Trailering package
* Low rolling resistance tires
* 6L80E (Improves efficiency)

Less mass means a better power to weight ratio.
Better aerodynamic means that it takes less power to increase speed.

Too bad they aren't applying these improvements to the rest of the line. I have no doubt that the aluminum lower control arms and 6L80E will propagate to other trucks very soon though. Maybe even the lighter weight hood, seats, etc from the hybrid models?

If I were buying a full-size GM truck now, I would probably get an XFE. I really like the 09 Ram and the V8 Colorado though.

I do wonder which front end is more aerodynamic: Silverado or Tahoe/Suburban?

Leroy_454

I would guess the tahoe front end would be a bit more aerodynamic.

LawmanSS

iTrader: (19)

From these pics, it looks like they get a Denali-like slot in the front of the bumper, too (unless all 09s have it). Hmmm...a chrome version of the Denali bumper...that could look good on my 08...anyone have a part number?

cttandy

iTrader: (12)

Funny, I had an all stock 1987 GMC sierra Long bed standard cab, 305 TBI 700r4 2.73 rearend running 295/50R15's and regularly got 28 mpg on the highway. Even with 450,000 miles on the truck it still kept going. It lost it's transmission after about a year of pulling heavy trailers ( sometimes as much as 10,000 lbs). It was extremely far from fast, but descent enough, it could still smoke the wide tires, would run nearly 55mpg in first gear. It never gear hunted, although I never used the overdrive while pulling trailers. Pulling 5,000 lb trailers I got 20-21mpg hwy/interstate.

I miss that old truck. I kick myself everytime I see a red/tan 2 tone like it. This picture was taken when her second transmission gave up. Still had second gear, but with no muffler the police didn't like me driving it around. She only had a magnaflow convertor with a single straight pipe to the rear axle. It was geared so high it seldom saw much more then 2500 rpm, so it didn't matter. The new owner drove it home on the interstate with only 2nd, and he said he kept up with traffic. Thats a 4 hour drive.

zippy

The coin slot as I call it started out in the Chevy line in 07' if you got the Vortec Max and the NHT package. It was for extra air to get to the radiator. Now all of the 09's have it.


As for the flat nose getting 28mpg and 20-21 towing, . I've worked on many of that body style including a few with the 2.73 geared 305. Anything over 20mpg unloaded was possible, but rare and far between. Surely not towing and not 28mpg.

cttandy

iTrader: (12)

My dad didnt believe me either. So he descided to tag along one day. We stopped at the gas station and top the tank complete to the top of the filler neck. Then we set the GPS up on the dash and took off doing that days runs. At the end of the day, we went to the same gas station, same pump, and topped the tank to the top of the filler neck. It was exactly 21 mpg. That day we hauled the 3500 lb trailer and 2-3 compact cars. He was completely baffled at it. He had an identical truck with a carbed 350, and it maybe got 10-12 mpg on a good day, his was blue/white 2 tone.

I wasn't the only one that got good mileage out of the truck either. I was driving the truck one day and a guy flagged me down. He had owned the truck before me and he was the one that stripped all the chrome off as he was going to restore it. He said that he normally got 25 mpg out of it running around. He also told me he swapped the guages out in it. It showed 125,000 on the dash, he said it had more the 440,000 when he swapped out the dash the year before. He aslo said it had the original engine and transmission when he traded it in at the car lot. He thought the dash was messed up because it never showed oil pressure. But I put a mechanical guage on it, and it still showed nearly no oil pressure, it showed 5 lbs at idle, and 20 while driving.

The guy was really ticked off I wouldn't sell it back to him.

95 bright teal

did you calculate for the different tire size? was your speedo correct? i had a 305 in a caprice and was lucky to get 18mpg

eallanboggs

iTrader: (1)

The PCM for the Flex Fuel motor uses an algorithm to "try" to figure out how much ethanol and how much gasoline you have in your tank at any given time. The fuel and spark tables are adjusted accordingly. It's really a guess at best. If the PCM takes a dump and needs to be replaced you have to remove the gas tank(or in this case gas/ethanol tank) and dump the fuel IF there is any ethanol it the tank when the PCM is replaced.. That's because you have to start out with 100% gasoline to baseline the new PCM or the algorithm will never be able to figure out the correct ratio of gas to ethanol.
As far as the 3.08 ring gear is concerned the ring and pinion is part of all the ratio calculations, not just low gear or overdrive or in this case both overdrives(6L80E has two overdrives). It's not going to launch hard because a 3.08 just isn't going to give you the kind of torque a 4.10 does on the start line. In overdrive you don't have the torque you need to pull a trailer up a hill. This doesn't just apply to the 3.08 ring and pinion when coupled with the 6L80E. Just ask anyone who does a lot of towing. You'll find that overdrive is seldom if ever used while towing, but that doesn't mean you can't drive down the interstate with the family in the truck at 70 miles per hour and stay in overdrive using a 3.08 ring and pinion unless you start going up a steep hill or a mountain. From what I've learned so far the 6L80E is state of the art and should NOT "seek" the correct gear as other less ran transmissions have been known to do when going up a slight grade.
I do have to agree that 1 mph is NOT worth it as has already been mentioned. For all the supposed "upgrades" you see on this truck you would expect a much greater advantage over a run of the mill Silverado, but it just isn't there. For my money I'm going to buy a 5.3 with the 6L80E and the towing package that goes with it in a crew cab. I plan to low ball the price BIG TIME and once I get them to give me the truck at a ridiculous price I'll whip out my GM credit card and tell them to take off another $1,700.00 in rebate I have accumulated. I've already done that twice. Then when they ask who will be doing the financing I'll say your looking at him as I pull my checkbook from my hip pocket.

cttandy

iTrader: (12)

Notice I said we took a GPS along to verify the results. The speedo was dead on. The 295/60R15 was very close to the factory height tire, but just a tad shorter and nearly 2 times as wide. A shorter tire would have actually made it read faster, but according to the GPS and the radar signs, it was dead on.

I have owned multiple trucks with similiar setups. I currently have an 89 GMC K1500 350 TBI 4x4 3.42's, it has never done better then 18 mpg. I have owned 2 s-10's one automatic and one manual, both with 2.8L's and 2.73 gears, neither got better then 20mpg. I have owned 2 4.3L blazers, one 89 4x4 and one 96 2wd, that I played with and got into the mid-20's. There was something wierd about the truck and I don't know what it was.

It's the only 87 TBI truck I have had, so I don't know if this is normal or not, but I couldn't find any other computers like what was in it. I worked at a salvage yard, looked up the interchange for that year truck and none were the same. It had a GM part number on it but I don't know if it was the original one to the truck. The owner before me restored old boats and built performance boats. He said he played around with it but I could never find anything done to it, other then the wierd computer. The only modification I could find that he said he did was the bullet hole in the passenger door from the inside out.

I was given a performance chip for the computer, when I got ready to put it in I noticed that it was different. When I got a different computer that the chip would fit in, it would plug into the truck, but the truck wouldn't run. Like I said never could figure it out. The TBI setup appeared identical to the 89 4x4 I have now. Neither truck have any smog pump setup on them at all.


Oh, it's also worth mentioning that on the trip that I got 28 mpg, I filled it up at the interstate, drove up to my sisters house in the country, and back home. There was no stop and go traffic, no city driving. It was a constant 60-65 mph the entire trip.