Question:
– Pacifism – The theory that if they’d fed Jeffrey Dahmer enough human flesh, he’d have become a vegan.
– Hide quoted text — Show quoted text -> inline > > that’s why you’re getting such lousy mileage. ethanol blends > don’t have > > nearly the energy in them as straight gasoline. less energy in > the fuel, > > the more you need to go a mile. > Do you know the BTU/Gallon of ethonal blend as compared to a > non-ethonal octane blend or can you point us to a reference on > that? > no I can’t, but logic should bear out that if there is a set amount of btu’s > required for an act (i.e. climb a hill) then a fuel with a higher btu > content will allow less fuel to be used for said act. higher BTU content is > a big factor in why a diesel engine will get better mileage than a gasser (a > more efficient design helps too) > I always thought in the case of modern internal combustion > engines, slight differences in the latent heats of combustion > between a certain octane gasoline using ethanol or some other > knock supressant would be negligible. > If I buy gas in Maine (where I live) it is oxygenated with MTBE, I get about > 2mpg less than if I drive 15 miles across the border to NH and purchase > non-oxgenated gasoline. my dad used to have a 3 cyl metro that would get > about 15mpg LESS with oxygenated fuel (learned this when MTBE gas was forced > on us by the EPA 7 or 8 years ago). > The higher the octane rating of the fuel, the slower burning the > fuel is. The higher the pressure in the combustion chamber, the > greater thermal efficiency. The higher the pressure, the faster > the gasoline burns. If it burns too fast it causes "knock". > knocking is the gasoline exploding rather than burning in a controlled > fashion. > That > is why we boost the octane rating of the gasoline with something > like ethonal or MTB. The higher the octane rating, the slower the > fuel burns. Do you know what a Carnot cycle is? > no clue on the carnot cycle, but ethanol and MTBE are oxgenators, they > aren’t there for the octane rating. putting more latent oxygen in the fuel > helps with CO and hydrocarbon emissions.
http://www.nesea.org/greencarclub/factsheets_ethanol.pdf Gasohol: A blend of finished motor gasoline containing alcohol (generally ethanol but sometimes methanol) at a concentration of 10 percent or less by volume. Data on gasohol that has at least 2.7 percent oxygen, by weight, and is intended for sale inside carbon monoxide nonattainment areas are included in data on oxygenated gasoline. See Oxygenates. Oxygenates: Substances which, when added to gasoline, increase the amount of oxygen in that gasoline blend. Ethanol, Methyl Tertiary Butyl Ether (MTBE), Ethyl Tertiary Butyl Ether (ETBE), and methanol are common oxygenates. —–= Posted via Newsfeeds.Com, Uncensored Usenet News =—– http://www.newsfeeds.com – The #1 Newsgroup Service in the World! —–== Over 80,000 Newsgroups – 16 Different Servers! =—–
Response:
>I use only the cheapest unleaded regular on my 5.3 liter 1/2 ton >extended cab truck and always have. If I am driving the >interstate, I set my cruise on 82 and consistently get 16 to 17. >If I am driving two lane, I set the cruise on 72 and very >consistently get 17 to 18.5. I have drove with the cruise at >60-65 and got over 20. I have 3.73 gears, which is probably what >that guy has in his Tahoe. My truck dry weighed 4700lbs and I >carry a large tool box. That tahoe dry probably weighs >4300-4400lbs. Something is wrong with his Tahoe or driving if he >can’t get over 13.5mpg on the highway.
<snip> Ok, I can tell you this: A) I only have about 5,000 miles on my Tahoe now, so perhaps it’s too early to think of 13.5mpg a problem? Perhaps it will still increase? The 13.5 is *average total* btw, not just highway. I do mostly highway, 60+ miles per hour, but not all. How arcurate can the "average mpg current trip really be anyhow? The numbers just keep fluctuating as you are driving… B) I have the regular, smaller tires NOT the off-road tires. They are inflated to about 35 psi I believe C) I Don’t cary any major weight or tools, and only occasionally "floor it" to get around a slowpoke. D) I did verify, my sticker says 14mpg/city and 18mpg/highway. What does the stickers say on you people claiming 18-20mpg?? I’d really like to know if your stickers say 18-20, and if not, then how could you be getting *better* mpg that the sticker says? Usually you get LOWER numbers than what the stickers say, even if just slightly lower-but certainly never higher. E) As I said before, I do use cruise control quite a bit on highways. I also have yet to use the A/C, so we can rule that out.
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inline
> that’s why you’re getting such lousy mileage. ethanol blends > don’t have > nearly the energy in them as straight gasoline. less energy in > the fuel, > the more you need to go a mile. > Do you know the BTU/Gallon of ethonal blend as compared to a > non-ethonal octane blend or can you point us to a reference on > that?
no I can’t, but logic should bear out that if there is a set amount of btu’s required for an act (i.e. climb a hill) then a fuel with a higher btu content will allow less fuel to be used for said act. higher BTU content is a big factor in why a diesel engine will get better mileage than a gasser (a more efficient design helps too) I always thought in the case of modern internal combustion > engines, slight differences in the latent heats of combustion > between a certain octane gasoline using ethanol or some other > knock supressant would be negligible.
If I buy gas in Maine (where I live) it is oxygenated with MTBE, I get about 2mpg less than if I drive 15 miles across the border to NH and purchase non-oxgenated gasoline. my dad used to have a 3 cyl metro that would get about 15mpg LESS with oxygenated fuel (learned this when MTBE gas was forced on us by the EPA 7 or 8 years ago). > The higher the octane rating of the fuel, the slower burning the > fuel is. The higher the pressure in the combustion chamber, the > greater thermal efficiency. The higher the pressure, the faster > the gasoline burns. If it burns too fast it causes "knock".
knocking is the gasoline exploding rather than burning in a controlled fashion. That > is why we boost the octane rating of the gasoline with something > like ethonal or MTB. The higher the octane rating, the slower the > fuel burns. Do you know what a Carnot cycle is?
no clue on the carnot cycle, but ethanol and MTBE are oxgenators, they aren’t there for the octane rating. putting more latent oxygen in the fuel helps with CO and hydrocarbon emissions.
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sorry, I thought the guy geting 13.5 was using that ethanol blended crap.
– Hide quoted text — Show quoted text -> that’s why you’re getting such lousy mileage. ethanol blends don’t have > nearly the energy in them as straight gasoline. less energy in the fuel, > the more you need to go a mile. > 18 to 23 mpg with a full sized ext cab 4×4 w/ 5.3 is lousy? Please read the > posts before replying to them. > Dave
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>I only use mid grade or better. >I’m not concerned with the price of fuel too much. Good fuel and good oil >are the key to long life and optimum performance. I’ll only tank up with >Panther piss if I have to. >IMO if you can’t afford another few bucks to fill up your driving the wrong >vehicle, a Metro would be a better choice. Spending 40K for a truck and >skimping on fuel isn’t worth it. >At 4-5 miles per gallon difference using better fuels to me is a no >brainer. What are we talking about saving? Not that much, and I would >rather not have the knock sensor working overtime to save a few bucks in my >expensive truck.
This is all of course, if you even buy into the whole "fuel grade" thing in the first place. Many people have said there is little difference. Still further, the manual I believe, reccomends 87 octane.
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>sorry, I thought the guy geting 13.5 was using that ethanol blended crap.
That would be me, and no, I have never used ethanol yet. Stright 87 octane.
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there are differences in the fuel grades, however, you most likely won’t see any difference running a normal compression (9.5:1 and lower) and normal rpm (5000rpm and lower) engine. you will see a big differance with higher comp. ratio’s and high rpms. the 4AGE in my MR2 is ~10.5:1 CR and has a 7500RPM rev limit and you definately can tell a difference above 4500RPM, with 87octane it pings like crazy, bump up to 93 no pings and a bunch more power. so in short, a truck engine most likely won’t benefit from anything higher than 87octane, but a ‘67 Camaro Z28 w/ the solid lifter 302 won’t hardly run on anything less than 93. – Hide quoted text — Show quoted text -> This is all of course, if you even buy into the whole "fuel grade" > thing in the first place. Many people have said there is little > difference. Still further, the manual I believe, reccomends 87 octane.
Response:
> there are differences in the fuel grades, however, you most likely won’t >see any difference running a normal compression (9.5:1 and lower) and normal >rpm (5000rpm and lower) engine. you will see a big differance with higher >comp. ratio’s and high rpms. the 4AGE in my MR2 is ~10.5:1 CR and has a >7500RPM rev limit and you definately can tell a difference above 4500RPM, >with 87octane it pings like crazy, bump up to 93 no pings and a bunch more >power. so in short, a truck engine most likely won’t benefit from anything >higher than 87octane, but a ‘67 Camaro Z28 w/ the solid lifter 302 won’t >hardly run on anything less than 93.
Ok, so this would explian why the Tahoe and some other SUV manuals I have read recently call for 87 octane. In any case I’ll likely (for the sake of curiosity) try 93 octane for a while and see if my 13.5 MPG magically starts to rise…As far as pinging, I have never had any pinging in recent SUV’s I’ve owned or been in. – Hide quoted text — Show quoted text -> This is all of course, if you even buy into the whole "fuel grade" > thing in the first place. Many people have said there is little > difference. Still further, the manual I believe, reccomends 87 octane.
Response:
> >13.5 is pretty lousy, my ‘99 Yukon w/5.7 gets 17-18 mpg on cruise at 70 mph >with the AC on. > One question: are you using high grade fuel? because if you are of > course, you are loosing the benefit of higher miles-per-gallon in the > cost of the fuel, which is pointless. The whole idea is to save money. > Ok, maybe it’s nice to not have to fill up as often too, but I think > money is number 1.
I use only the cheapest unleaded regular on my 5.3 liter 1/2 ton extended cab truck and always have. If I am driving the interstate, I set my cruise on 82 and consistently get 16 to 17. If I am driving two lane, I set the cruise on 72 and very consistently get 17 to 18.5. I have drove with the cruise at 60-65 and got over 20. I have 3.73 gears, which is probably what that guy has in his Tahoe. My truck dry weighed 4700lbs and I carry a large tool box. That tahoe dry probably weighs 4300-4400lbs. Something is wrong with his Tahoe or driving if he can’t get over 13.5mpg on the highway. In all 35,000 miles of driving my truck, which includes a lot of idling time (hundreds of hours) in the winter on cold remote Rocky Mountain locations and a lot of driving on really bad dirt and gravel roads and city driving, I have overall averaged 14.1mpg. I’m running 265×16 Toyo 8 ply rated tires, which are off road tires with a fairly agressive tread. I run them with 35psi. I’m sure I’d get better milage with 245’s with a highway tread, as is the case for most Tahoes. I’ve never felt that Toyos were very good for gas milage, but they quite good demanding conditions out in the boonies where I work at least 100 days a year. Tires, type and tire size and the pressures you run them at can make a difference. The larger tire you run the less gas milage you are going to get. Larger lower pressure tires can have a much higher coefficient of friction. Narrower higher pressure, harder rubber compound tires will have a lower coefficient of friction and can get quite a bit better gas milage on the same vehicle, especially if the gearing on your vehicle was designed for the smaller tires. If you stuck some over size softer rubber tires on your Tahoe, you can count on getting less gas milage. We all like larger fatter tires, but we pay for it in more way than just what they cost us to buy and have mounted and balanced. I have kept meticulous records of every drop of gas, oil, and other maintaince of every vehicle I have drove since 1982. That includes blazers, 1/2 ton trucks and a host of automobiles. Curiously I used to manage a fleet of some 150-200 oil field trucks. 99% of the the cost per mile and milage had -nothing- to do with whether they were fords or chevys or how often the oil was changed and whether it was synthetic oil or not, and -everything- to do with the idiot behind the wheel. Even in the best maintained trucks, there are drivers who can drive the same road with the same vehicle and get 2-5mpg less and tear that vehicle up in 1/3 of the time. Never give a ford man a chevy and never give a chevy man a ford….expecially if they are YOUNG men (Ages 30 and under). Young men are the hardest people there on any vehicle and especially hard on trucks. My guess is that if a person can’t even get the EPA rated milage his tahoe, he is a young man and/or put oversize tires on it. – Hide quoted text — Show quoted text -> A tad less on winter blend fuels. This winter I had to tow >a friends Exploder that blew a head gasket back home (300 miles) on a dolly >and got 11.5 mpg running 65 mph with all that crap hanging off the back >end. >A 5.3 getting 18-20 is totally realistic on the freeway IMO > The sticker, last I remember, states 13-18, and rarely in my > experience have I ever seen the maximum numbers on the window sticker > (in this case the 18) reached by any vehicle. I suspect that it will > top out around 15 or maybe 16 eventually. Incidentally I do use cruise > quite a bit too, and mine is a 5.3 also, for the record.
Are you running a bug smasher and a rear air foil? Believe it or not an ill designed bug smasher can affect your milage. The old flat ones were really bad. On a stock truck, unless I put oversized tires on it, I’ve always been able to get more than the sticker rating starting with the first truck I had that had a sticker rating (1982 Silverado 4×4 305-16epa vs 17-20 hwy actual, 1983 305 blazer 4×4, 17 EPA, 18-21 on highway-both had 3:03 gears) and I’m a crochety old guy that has had lot’s of 4wd trucks and full size SUV’s over the last 30 years. I keep meticulous records, both on personal and company vehicles. But as I said, 99% of it is the driver, not the vehicle. Do you drive like an impatient young man? <chuckle>. One thing I have noticed with new body style Chev/GMC is that gas tanks can be quite erratic to fill depending on how I am parked when I fill up and how impatient I am to get the tank completely full and how the pump shut off itself is set. Take your truck on a long trip that takes 3 or more fillups, use the cruise and keep your foot off the gas and the brake. If you the disgruntled Tahoe driver does that, I will be amazed if he averages less than 18mpg.
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> that’s why you’re getting such lousy mileage. ethanol blends don’t have > nearly the energy in them as straight gasoline. less energy in the fuel, > the more you need to go a mile.
Do you know the BTU/Gallon of ethonal blend as compared to a non-ethonal octane blend or can you point us to a reference on that? I always thought in the case of modern internal combustion engines, slight differences in the latent heats of combustion between a certain octane gasoline using ethanol or some other knock supressant would be negligible. The higher the octane rating of the fuel, the slower burning the fuel is. The higher the pressure in the combustion chamber, the greater thermal efficiency. The higher the pressure, the faster the gasoline burns. If it burns too fast it causes "knock". That is why we boost the octane rating of the gasoline with something like ethonal or MTB. The higher the octane rating, the slower the fuel burns. Do you know what a Carnot cycle is? No doubt I’m a bit rusty on the various thermodynmic considerations in an internal combustion engine, but my gut feel is that worrying about slight difference in the heats of combustion of a 10% ethonal mixture as compared to using some other octane booster thermodynically just isn’t going to make a smattering of difference. But I’ve not studied the Carnot Cycle as it pertains to internal combustion engines in a long LONG time. Check it out: – Hide quoted text — Show quoted text – message > > >> I am considering buying a Tahoe with the 5.3 liter engine and am > wondering > > >> what can be expected for freeway (70mph) gas mileage? > > >> Anyone with experience? > > >My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway > at > 70 > > >mph, but 18-20 is much more common. > > >Dave > > What kind of fuel? (See my other post) > I always use the lowest priced gasoline I can find. Usually a mid grade > ethanol blend. Here in Iowa, it’s usually a couple of cents cheaper than > regular. > Dave
Response:
> that’s why you’re getting such lousy mileage. ethanol blends don’t have > nearly the energy in them as straight gasoline. less energy in the fuel, > the more you need to go a mile.
18 to 23 mpg with a full sized ext cab 4×4 w/ 5.3 is lousy? Please read the posts before replying to them. Dave – Hide quoted text — Show quoted text -> > >> I am considering buying a Tahoe with the 5.3 liter engine and am > wondering > > >> what can be expected for freeway (70mph) gas mileage? > > >> Anyone with experience? > > >My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway > at > 70 > > >mph, but 18-20 is much more common. > > >Dave > > What kind of fuel? (See my other post) > I always use the lowest priced gasoline I can find. Usually a mid grade > ethanol blend. Here in Iowa, it’s usually a couple of cents cheaper than > regular. > Dave
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> I am considering buying a Tahoe with the 5.3 liter engine and am wondering > what can be expected for freeway (70mph) gas mileage? > Anyone with experience?
My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway at 70 mph, but 18-20 is much more common. Dave
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>13.5 is pretty lousy, my ‘99 Yukon w/5.7 gets 17-18 mpg on cruise at 70 mph >with the AC on.
One question: are you using high grade fuel? because if you are of course, you are loosing the benefit of higher miles-per-gallon in the cost of the fuel, which is pointless. The whole idea is to save money. Ok, maybe it’s nice to not have to fill up as often too, but I think money is number 1. > A tad less on winter blend fuels. This winter I had to tow >a friends Exploder that blew a head gasket back home (300 miles) on a dolly >and got 11.5 mpg running 65 mph with all that crap hanging off the back >end. >A 5.3 getting 18-20 is totally realistic on the freeway IMO
The sticker, last I remember, states 13-18, and rarely in my experience have I ever seen the maximum numbers on the window sticker (in this case the 18) reached by any vehicle. I suspect that it will top out around 15 or maybe 16 eventually. Incidentally I do use cruise quite a bit too, and mine is a 5.3 also, for the record.
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– Hide quoted text — Show quoted text -> I am considering buying a Tahoe with the 5.3 liter engine and am wondering > what can be expected for freeway (70mph) gas mileage? > Anyone with experience? >My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway at 70 >mph, but 18-20 is much more common. >Dave
What kind of fuel? (See my other post)
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– Hide quoted text — Show quoted text ->> I am considering buying a Tahoe with the 5.3 liter engine and am wondering >> what can be expected for freeway (70mph) gas mileage? >> Anyone with experience? >My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway at 70 >mph, but 18-20 is much more common. >Dave > What kind of fuel? (See my other post)
I always use the lowest priced gasoline I can find. Usually a mid grade ethanol blend. Here in Iowa, it’s usually a couple of cents cheaper than regular. Dave
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that’s why you’re getting such lousy mileage. ethanol blends don’t have nearly the energy in them as straight gasoline. less energy in the fuel, the more you need to go a mile.
– Hide quoted text — Show quoted text -> >> I am considering buying a Tahoe with the 5.3 liter engine and am > wondering > >> what can be expected for freeway (70mph) gas mileage? > >> Anyone with experience? > >My ‘99 Sierra ext-cab 4×4 w/5.3 has gotten nearly 23mpg on the freeway at > 70 > >mph, but 18-20 is much more common. > >Dave > What kind of fuel? (See my other post) > I always use the lowest priced gasoline I can find. Usually a mid grade > ethanol blend. Here in Iowa, it’s usually a couple of cents cheaper than > regular. > Dave
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I only use mid grade or better. I’m not concerned with the price of fuel too much. Good fuel and good oil are the key to long life and optimum performance. I’ll only tank up with Panther piss if I have to. IMO if you can’t afford another few bucks to fill up your driving the wrong vehicle, a Metro would be a better choice. Spending 40K for a truck and skimping on fuel isn’t worth it. At 4-5 miles per gallon difference using better fuels to me is a no brainer. What are we talking about saving? Not that much, and I would rather not have the knock sensor working overtime to save a few bucks in my expensive truck. — John "Some suffer from insanity, I choose to enjoy it" – Hide quoted text — Show quoted text ->13.5 is pretty lousy, my ‘99 Yukon w/5.7 gets 17-18 mpg on cruise at 70 mph >with the AC on. > One question: are you using high grade fuel? because if you are of > course, you are loosing the benefit of higher miles-per-gallon in the > cost of the fuel, which is pointless. The whole idea is to save money. > Ok, maybe it’s nice to not have to fill up as often too, but I think > money is number 1. > A tad less on winter blend fuels. This winter I had to tow >a friends Exploder that blew a head gasket back home (300 miles) on a dolly >and got 11.5 mpg running 65 mph with all that crap hanging off the back >end. >A 5.3 getting 18-20 is totally realistic on the freeway IMO > The sticker, last I remember, states 13-18, and rarely in my > experience have I ever seen the maximum numbers on the window sticker > (in this case the 18) reached by any vehicle. I suspect that it will > top out around 15 or maybe 16 eventually. Incidentally I do use cruise > quite a bit too, and mine is a 5.3 also, for the record.
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I am considering buying a Tahoe with the 5.3 liter engine and am wondering what can be expected for freeway (70mph) gas mileage? Anyone with experience?
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18-20
– Hide quoted text — Show quoted text -> I am considering buying a Tahoe with the 5.3 liter engine and am wondering > what can be expected for freeway (70mph) gas mileage? > Anyone with experience?
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>18-20
I’d like to see that somewhere in reality. My 2003 Tahoe LT is up tp 13.5 after about 4 months, of mostly 60-70 mph. The Tahoe is a big truck, and expecting it to get 18-20 miles per gallon is not realistic. I love the truck and was fully aware of what kind of gas mileage to expect when I bought it, and I have not been surprised thus far at all. – Hide quoted text — Show quoted text -> I am considering buying a Tahoe with the 5.3 liter engine and am wondering > what can be expected for freeway (70mph) gas mileage? > Anyone with experience?
Response:
13.5 is pretty lousy, my ‘99 Yukon w/5.7 gets 17-18 mpg on cruise at 70 mph with the AC on. A tad less on winter blend fuels. This winter I had to tow a friends Exploder that blew a head gasket back home (300 miles) on a dolly and got 11.5 mpg running 65 mph with all that crap hanging off the back end. A 5.3 getting 18-20 is totally realistic on the freeway IMO — John "Some suffer from insanity, I choose to enjoy it" – Hide quoted text — Show quoted text ->18-20 > I’d like to see that somewhere in reality. My 2003 Tahoe LT is up tp > 13.5 after about 4 months, of mostly 60-70 mph. The Tahoe is a big > truck, and expecting it to get 18-20 miles per gallon is not > realistic. I love the truck and was fully aware of what kind of gas > mileage to expect when I bought it, and I have not been surprised thus > far at all. >> I am considering buying a Tahoe with the 5.3 liter engine and am wondering >> what can be expected for freeway (70mph) gas mileage? >> Anyone with experience?
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> That tank got better mileage than my teensy little S10 blazer, too. > (But doesn’t everything?) 