4.3L V-6 vs. 4.8L V-8.

My recent post regarding my bad experience with a series of early 1990's

4.3L V-6 engines has received replies from many others testifying that their newer 4.3L V-6's are great engines. Since the 4.3L V-6 is the standard engine in many GM vans and trucks, it would seem that the 4.3L V-6 would be a money-saving choice when only light duty performance is required. Yet, I'm not sure that this is actually the case.

According to the 2004 EPA Fuel Economy Guide, the 4.8L V-8 gets better gas mileage than the 4.3L V-6 when both Silverado trucks are equipped with an electronic 4-speed automatic transmission:

Model Trans. Engine MPG Average C1500 Silverado 2WD A-4 ..... 4.3/6 ..... 15/20 17.5 *** C1500 Silverado 2WD M-5 ..... 4.3/6 ..... 15/21 18.0 C1500 Silverado 2WD A-4 ..... 4.8/8 ..... 17/20 18.5 *** C1500 Silverado 2WD M-5 ..... 4.8/8 ..... 15/20 17.5

Of course, if you drive the 4.8L V-8 with the accelerator on the floor, you won't be able to tell the gas gauge from the speedometer. But maybe if you drive both the 4.3L V-6 and 4.8L V-8 gently, the 4.8L V-8 will downshift less and use less gas. However, the 4.8L V-8 will always have more power in reserve than the 4.3L V-6.

If the EPA figures are accurate, the 4.8L V-8 engine works out to be a free upgrade when it is paired with an automatic transmission. If a truck is purchased at the dealer invoice price, the $745 4.8L V-8 upgrade ends up costing around $670. If the 4.8L V-8 actually does use around 5% less gas than the 4.3L V-6, the savings in gas (figured at 15 thousand miles per year for 4 years, at $2.00 per gallon) would be at around $200. At trade in time, the truck with the 4.8L V-8 would be worth at least $500 more than an identical truck with a 4.3L V-6.

So, is the more powerful 4.8L V-8 really a free upgrade?

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Reply to
One-Shot Scot
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Just why, may I ask are you wasting our space with this meaningless drivel?

Doc

Reply to
"Doc"

I read virtually every post to atc, daily, and it appears that whether you intend it or not what you really appear to be promoting is a "bitch party" instead of a free exchange of comments on the 4.3L GMC engine through the years.

Perhaps you have had an extremely negative event in your life, or perhaps you are facing the onset of old age, or whatever....it appears that something has skewed your viewpoint...... hope you have a good day anyway.

You asked for comments, maybe this isn't what you wanted, but then that is life.

George

Reply to
George Vigneron

Man, are you over-thinking this.

Just buy the V-8 and be happy already!

Cheers - Jonathan

Reply to
Jonathan Race

Or buy the V-6 and be just as happy....

Reply to
vb

Is it meaningless drivel to announce that, with an automatic transmission, a Silverado with a 4.3L V-6 gets worse gas mileage than it would with a 4.8L V-8? I didn't know that until I read the 2004 EPA Fuel Economy Guide. The logical assumption is that the smaller V-6 gets better gas mileage than the larger V-8.

Apparently, the Federal government doesn't consider the 2004 EPA Fuel Economy Guide, as it pertains to Silverado trucks, to be meaningless drivel. There is a notation which says, "This label has been applied pursuant to Federal law prior to delivery to the ultimate purchaser." I am looking at the Monroni sticker from my truck and the EPA Fuel Economy Information occupies 30% of the area on this label.

While the line which says "TOTAL VEHICLE PRICE" has type which is less than 3/16ths of inch high, the CITY MPG and HIGHWAY MPG figures are 3/4 of an inch high and these MPG figures can be easily read from a distance of 30 feet. If the Monroni sticker were the front page of a newspaper, the EPA figures would be the headline.

At the bottom of the EPA section of the Monroni sticker, there is a reference to this website:

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The site discusses many fuel-related topics, including these:

Why is Fuel Economy Important? Protect the Environment Global Warming Oil Spills Air Pollution Reduce Oil Imports Conserve Resources for Future Generations Save Money

Each one of these subheadings is linked to detailed information on its subject. The "Save Money" section has a fuel cost calculator which will help knowledgeable shoppers make an educated choice when they are shopping for a vehicle.

Meaningless drivel? Not to me it isn't.

Reply to
One-Shot Scot

Last time I said, "Wow. I could have had a V-8!"

This time, I bought a V-8.

I will be happy if this truck delivers 100 thousand trouble-free miles.

Reply to
One-Shot Scot

Yes it's a dumbass question. Of COURSE a heavy FS truck will get better mileage with a slightly larger albeit more powerful engine. Put a 4.3 and

4.8 in vehicles of the SAME weight and let's see who gets the better mileage.

Doc

Reply to
"Doc"

So you're complaining about the V6, you calculated the V8 will save you $200/year in fuel costs and it will have a higher resale value. So buy the damn V8 already. No full size pick-up deserves a V6 anyway (my personal opinion). Help a poor salesman pay his bills, buy it NOW!

b
Reply to
Battleax

Are you aware that these mileage figures are extrapolated based on tailpipe measurements? And that they do not actually TEST the mileage? And that vehicle manufacturers are not allowed to advertise or tell you REAL mileage figures?

And minimizing the visibility of the price while trying to sell a vehicle says exactly what about anything else? Nothing. If you were selling a vehicle, would you be drawing attention to features or price? honest answer now...

You need to educate yourself further. Tailpipe measurements say nothing about what you will experience with YOUR driving habits in YOUR climate over the typical terrain YOU drive with YOUR typical load. A government website will NOT tell you that.

Reply to
Commentator

No, I was unaware of the tailpipe measurements. According to the EPA site, this is how the tests are done:

*** *** ***

How are fuel economy estimates obtained?

The fuel economy estimates are based on results of tests required by the U.S. Environmental Protection Agency (EPA). These tests are used to certify that vehicles meet the Federal emissions and fuel economy standards. Manufacturers test pre-production prototypes of the new vehicle models and submit the test results to EPA. EPA re-tests about

10% of vehicle models to confirm manufacturer's results. The vehicles are driven by a professional driver under controlled laboratory conditions, on an instrument similar to a treadmill. These procedures ensure that each vehicle is tested under identical conditions; therefore, the results can be compared with confidence.

There are two different fuel economy estimates for each vehicle in the Fuel Economy Guide, one for city driving and one for highway driving. To generate these two estimates, separate tests are used to represent typical everyday driving in a city and in a rural setting. Two kinds of engine starts are used: the cold start, which is similar to starting a car in the morning after it has been parked all night; and the hot start, similar to restarting a vehicle after it has been warmed up, driven, and stopped for a short time.

The test used to determine the city fuel economy estimate simulates an

11-mile, stop-and-go trip with an average speed of 20 miles per hour (mph). The trip takes 31 minutes and has 23 stops. About 18 percent of the time is spent idling, as in waiting at traffic lights or in rush hour traffic. The maximum speed is 56 mph. The engine is initially started after being parked overnight. Vehicles are tested at 68 F to 86 F ambient temperature.

The test to determine the highway fuel economy estimate represents a mixture of "non-city" driving. Segments corresponding to different kinds of rural roads and interstate highways are included. The test simulates a 10-mile trip and averages 48 mph. The maximum speed is 60 mph. The test is run with the engine warmed up and has little idling time and no stops (except at the end of the test).

NOTE: To make the numbers in the Fuel Economy Guide more useful for consumers, EPA adjusts these laboratory test results to account for the difference between controlled laboratory conditions and actual driving on the road. The laboratory fuel economy results are adjusted downward to arrive at the estimates in the Fuel Economy Guide and on the labels seen on new cars, light trucks, and vans. The city estimate is lowered by 10% and the highway estimate by 22% from the laboratory test results. Experience has proven that these adjustments make the mileage estimates in the Fuel Economy Guide correspond more closely to the actual fuel economy realized by the average driver.

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Reply to
One-Shot Scot

yeah congrats on the V8 be sure to post at 100,000 miles your experiences! til then - happy trails

Reply to
ricky_d

Don't worry about those bunch of grumpy old codgers. I could ascertain their combined intellectual might doesn't approach 1/10th of what ye possesses.

There are times when the smaller engine gets more mpg and times the larger gets the better mpg. In this case, it appears the small 4.8 V8 gets a wee bit better mileage. But, doesn't the 4.8 have sequential feul injection while the 4.6 has the mfi type? That might account for the difference.

Recently, on flat ground with no load with 50% freeway driving between 60-70 mph and 50% 2-lane highway with a few stops, some 35 mph, 45 mph... etc etc. In other words, a cross-section of driving conditions the 4.8/auto 4x4 long bed pure stock driven in an average manner obtained 19.5 mpg. Not bad for a full-size pick-em-up truck.

Sumpthin', just a gut feeling, tells me the V6 would do better in city driving while the V8 will do a little better on the open road.

Reply to
Obbop

According to the Chevrolet Silverado literature, all 2004 Vortec engines have sequential fuel injection.

I am unable to do an accurate comparison between my two full-size Chevrolet trucks: The 1990 4.3 V-6 vs. the 2004 4.8 V-8. There are too many differences, for example:

My 1990 4.3 V-6 truck had a 5-speed manual transmission, 15-inch wheels and a 3.08 rear end. This truck averaged between 16.5 and 17 miles per gallon city and around 22 MPG highway. The highway mileage was probably the result of a 0.83 gear ratio of the 5th gear. When timed to operate on 87 octane fuel, without pinging, the 4.3 V-6 truck performed as though it were pulling a trailer. In order to get any performance at all, advanced the timing and used 91 octane premium. This performance enhancement added 10% to the cost of gas.

My 2004 4.8 V-8 truck has a 4-speed automatic transmission, 16-inch wheels and a 3.42 rear end. The higher rear end ratio combined with larger tires still works out to a 5% increased gear ratio, and a 5% increase in engine RPMs, over the rear end and tire combination of the

1990 truck. After 4968 miles, the 2004 Silverado has used 305.51 gallons of regular gas, which works out to 16.26 MPG. So far, I have not been able to take the truck out on an extended highway trip, where it would probably deliver its rated 20 MPG.
Reply to
One-Shot Scot

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