Plugs

[Lyndon S.]

[Michael W.]

100% hype

How the gas/air mixture becomes lit is irrelevant, whether it be from superunobtanium-tipped hypertestosterone megaplugs or by clever squirrels throwing burning matches down the carb throat.

The same people that believe in spark plug miracles also believe that the taste of a grilled steak will change depending on how your light the flame on a grill.

[Duke W.]

Re: Plugs

All these different spark plug designs are just marketing hype. Use the correct geometry design heat range "5" AC plug or equivalent "two dollar" basic spark plug from any other manufacturer.

I view your report of 31 MPG from a '83 Caprice with some skepticism.

Accurate fuel mileage can only be determined once the odometer accuracy is known. It can vary due to installed tire size, and various mechanical factors.

Then accurate recording of the amount of fuel required to fill the tank and the odometer readings over a period of time will yield a fairly accurate average for your mix of driving, and the observed readings should be corrected based on observed odometer error.

You can research EPA fuel mileage ratings back to mid-eighties models at:

http://www.fueleconomy.gov

These ratings have recently been "adjusted" to estimate the mileage based on the new test that went into effect for 2008, which incorporates more rapid acceleration, higher speeds, and use of the air conditioner. This brings the fuel economy numbers more in line with real world consumer experience.

My daily drivers are a 2700 pound 2.2L 4-cyl. sports car and a 2900 pound 2.6L 6-cyl. sedan, both with manual transmissions. They both average odometer corrected low twenties in my normal around town driving and high 20s on road trips, which is right in line with their orignal EPA mileage ratings. They handily beat the new "adjusted" ratings because my normal driving habits include several techniques to reduce fuel consumption.

The mid-eighties Caprice new "adjusted" ratings with a gasoline V-8 engine/auto trans are mid teens/low twenties, city/highway.

Duke

[Dave Morris]

Re: Plugs

If I had an 83 Caprice that got 31 mpg I wouldn't change anthing on it. Maybe apply for Guiness Book of world records though.

[Lyndon S.]

[Richard T.]

Very Hard To Believe NM* *NM*

[Joe C.]

I Know How You do That!

Remember when Car and Driver Mag usta run mileage contests in the seventies? One technique was applying throttle while traveling DOWNHILL rather than uphill, and backing off as much as possible while going uphill. I never actually tried that, but I DO practice most of the other tricks (when I'm in the "conservative" mode). I can usually boost the mileage by a few MPG, or so. But 31 mpg sounds like a stretch. What's your final drive ratio in that thing? 200R4 is about.67:1 in 4th with locked converter. Are you using a special rear axle ratio, like 2.00:1?

If you usta read C/D mag, do you remember the illustrius "balloonfoot" Bedard?

C/D's tech editor at the time, Don Sherman used to drive with a raw egg between his foot and the "go" pedal. That would help increase mileage, too.

[Lyndon S.]

Re: I Know How You do That!

That is some of the things that I do like you said on the hill. Mostly just drive like a 90 year old and you would be surprised at the mileage one can achieve. I am not sure what that gear is in the car I am sure it is a 308 or higher. I know that trans will lock up at around 35mph.

Kelly

[Joe L.]

Re: I Know How You do That!

Kelly-----

I think that there's some gross error in your calculation methodology or error in the data you're using to do the calculation.

I seriously doubt that an 83 Caprice would achieve 31 MPG on a straight highway drive at a cruise-controlled 50 MPH, let alone in any other sort of driving.

[Lyndon S.]

[Joe L.]

Re: I Know How You do That!

Kelly------

I never said that you were "doing 50". What I said was that I seriously doubt that you'd get 31 mpg IF you were doing 50 MPH in a cruise-controlled condition. 50 MPH in a cruise-controlled condition on a level highway is going to deliver about the MAXIMUM fuel economy that a car is going to get. So, if a car cannot deliver a certain miles per gallon at 50 MPH in a steady-state cruised-controlled condition on the highway, it's not going to deliver better fuel economy under any other conditions. In fact, it will be worse under any other conditions.

The MAJOR factor in vehicle fuel economy is vehicle WEIGHT. A 1983 Caprice is a HEAVY vehicle. On top of that, the 80's were especially bad years for fuel economy. It's NOT going to get economy car-like fuel economy.

[Duke W.]

Re: I Know How You do That!

On a car with converter lockup at 35 MPH, the best steady speed fuel economy on a level road is probaby about 35-40 MPH, but this is strictly a "laboratory experiment" type number since this type of real world driving condition is rare.

In addition to the "downsized" (compared to the previous 1976 whale) Caprice being relatively heavy, it also has a high drag coefficient compared to modern sedans - probably no better than about 0.45 compared to the typical 0.30 for a modern sedan.

On top of this, mid-eighties GM engines were nowhere near as efficient as modern engines. In particular, the requirment to meet emission control standards severely compromises the spark advance map compared to one that would provide the highest thermal efficiency at normal road load, and idle fuel comsumption is high due to both higher than pre-emission idle speeds and ported vacuum advance.

Duke

[Lyndon S.]

Re: I Know How You do That!

So a car with a 150hp V8 and computer controlled Rochester 4 barrel carburetor can not get 27-31 mpg. Well dang it I am doing it. And yes weight is a factor, and so or a lot of other things that one can do to maximize the mpg.
Believe me I know that your skeptical. All I am asking is that check out the stuff on achieving hyper mileage and try it and see what you can do with your own car and mpg.
oh and the car is not that HEAVY as you would think.

Kelly

[Lyndon S.]

Re: I Know How You do That!

Aerodynamics typically do not come into play on a automobile until around 60mph. So that is not really a factor.

[Lyndon S.]

Re: I Know How You do That!

Has anyone here ever looked at a large frame on a full size Chevrolet car from the eighties? It is not what you would think, it is a very light weight frame. And will bend quite easy. The whole car weighs in at 3402. And a new 2007 ZO6 weighs in at 3902. A lot of the older cars are actually lighter than modern cars. There was a article a few months back in one of the major magazines about just that how the cars weigh more than cars from the fifties, and you would think with all that metal it would be that the new cars would weigh less. It just is not so. And no I am not driving around with all the seats out of the car either.
But hey that is a thought and I might get rid of another 100lbs

Kelly