Bill Bowling

iTrader: (6)

Ditto... Muscle cars and real good gas mileage do not mix. I get about 13 miles per gallon around town. If I wanted good gas mileage I would get a 4 cylinder IMO. Just my 2-cents.

Bill

MrDude_1

iTrader: (4)

why not?
its that ignorant attitude of "v8s cant be gas efficent" and "4cyls are your only choice for milage" thats killing the v8 car.

i donno why your car is doing so shitty, (im willing to bet you dont tune it yourself) but mine gets honest mid to low 20s on every tank, with me playing around alot... and it gets low 30s on the hwy. btw, no. im not stock. but i did tune my car so i get MPG along with WOT fueling.


sure its not 40mpg, but whats the honest real world MPG of most 4bangers and v6s?... lol

ZL1Killa

iTrader: (17)

the point is if you tune it right and mod a little then ok you can get good gas mileage, sure go ahead.

all we are saying is your spending more than the saved gas money by supposedly modding the car to get the increased gas mileage and save money....which in the end you are not
lid$80~
bellow$40~
headers$800~
catback$400~
tune *from shop$200-400~
tuning software to tune $500+
.....

hell my slightly modded ws6 was getting 18 around town and 28 on the highway
but that was with 3.42 gears and me driving nice, at least sometimes
now i have 3.73 and a lot more power, also having more fun

hammertime

iTrader: (1)

I think we've overlooked the fast that the original poster already had some of these parts (possibly headers, definitley the software) so using them to a mileage advantage wouldn't necessarily mean they offset the savings.

MrDude_1 is right. People who say muscle cars and V8's are pigs and can't get good gas mileage are really missing the boat here. Sure an econobox can get 40+ on the highway, but at what cost?

There are three vehicles in our household. I'll list them for you from lowest to highest observed mpg on the same 300 mile highway trip from St. Louis to Joplin:

Buick Rendezvous, 3.4l v6, 24 mpg - windows up, no AC
Ford Taurus Wagon, 3.0l (12v)v6, 26 mpg - windows up, no AC
Chevrolet Camaro SS, 5.7l, 28+ mpg - t-tops out

Our two utilitarian vehicles get worse mileage than the muscle car. Run hard, the Camaro gets no worse mileage around town than either of the other two in average city driving.

ZL1Killa

iTrader: (17)

whats on the camaro ss 5.7l ?
its all speed dependent too

we have a :
01 Pontiac Trans am 5.7l 16 around town and about 26 highway(mods in sig)

99 chev venture 3.4l 18 around town 28 highway

2005 chev malibu LS v6 3.5l 24.5 around town and 35.6 highway @ 80mph (tested from Wilson, NC to PAlm Beach, Florida)

also tested on the malibu (Wilson, NC to Daytona Beach, Florida) 60mph and resulted in 39.8mpg


now wouldn't it be shitty if a malibu beat a v8 and got better gas mileage? but thats a different subject.

hammertime

iTrader: (1)

ZL1Killa

Mods also in the sig, lid, K&n, mandrel bent y and catback. Yes, it is all stock internally, so I would expect it to get stock fuel mileage.

As for driving conditions, I44 between STL and Joplin is a bit hilly through the ozarks. All three vehicles driven about 80 (give or take, with traffic). The main difference is the other vehicles are automatics, and a steep enough hill will either force a kickdown to 3rd. When that happens, the revs go to 3500 or so at highway speeds. I try my best when driving to feel impending kickdown, and when the converter unlocks, I back off the throttle a touch to conserve fuel.

In the SS, I just leave her in 6th, and it pulls all those hills just fine at 1700-1800 rpm without lugging the engine. If I must accelerate around another car going up a hill, dropping to 5th brings the revs up just enough to do the job without spinning a ton of rpms.

What I've learned? The more rpms you turn, the more fuel is required to sustain it, regardless of how light the load becomes. Keeping the converter locked in od without a kickdown gives the best results, even if it means slowing from 80 down to 72 or less.

CamTom12

iTrader: (1)

You must either romp on it a lot or be running pig-rich...

my H/C car gets with average driving 17-18 city and 24-25 hwy

'JustDreamin'

There are a couple of pieces to the fuel economy puzzle.

1.) Power required to move car at speed:
Aerodynamic drag (wind resistance, function of velocity squared)
Rolling drag (tires, should be fairly linear with velocity)
Drivetrain drag (rear axle, transmission losses, not necessarily linear, automatics use much more power than manuals)
Power required to climb hills is mostly dependent upon vehicle weight.

2.) Mechanical efficiency of the engine: You've got to create the above power from the engine (and not any more). This typically means very small throttle openings on big motors, or bigger throttle openings on smaller motors (which is more efficient mechanically). A 98% closed throttle is a HUGE restriction and drives pumping losses way up.

3.) RPM you're creating the power at. It takes a certain amount of fuel just to bring the engine to a certain rpm. That amount of fuel is in addition to the required output power (above). Lower rpm is typically better, but there is a point at which you can't efficiently create the required power in a mechanically efficient manner.


One of the things I've seen suggested to raise the mechanical efficiency is to introduce fairly significant quantities of EGR, because it is chemically inert. But the key is to use cooled EGR, so that you don't put all that heat back into the motor, which causes all kinds of potential evils (detonation is the first that comes to mind). This strategy also requires high squish / swirl type combustion chambers to make sure the fuel and the oxygen are well mixed since there will be alot of exhaust gasses in the cylinder. Benefit is a much more open throttle setting, so greatly reduced pumping losses, without the drawback of introducting alot of oxygen, which would require alot of gasoline (even running at max economy AFR setting of somewhere around 17:1).


Somebody earlier had debated whether maximum economy is truely at 17:1 vs running at stoick of 14.7 (which is where the GM computer targets). I think it is a fairly well established fact that in the area of 17:1 AFR is peak economy. The piston aircraft community knows that fact pretty well because they all have a cockpit mixture adjustment to be able to go from max power (12 to 12.5:1) to max economy (16.5 to 17.5:1) while in the air (even on certificated aircraft).

'JustDreamin'

soundengineer

iTrader: (16)

heres the deal...

ANY Mod you do to the car that is considered a "performance mod" will hurt gas mileage ..as it is designed to increase airflow..so it needs more fuel..which means you burn more fuel....

you could try to find somebody near you that knows how to tune and you could do a lean cruise tune...either by having someone hack the stock OS to add lean cruise or just by creative tuning to get you some gas mileage in your going to work driving rpm's and load conditions...

increasing your timing down low wil help gain a little mileage...
keeping your foot out of it an accelerating lighter will gain you gas mileage...
purposely shifting a little low will get you into a higher gear and save you gas mileage(again not burrying your foot too deep while doing this)or in an auto making it shift into the next gear sooner will do the same..

just some basics.....

ringram

Not quite true, but a reasonable generalisation.

Increasing compression, optimising chamber design and swirl as well as quench is a win win. Optimal timing is a win win. Coatings on combustion surfaces, low friction rings etc are also win win.

I agree anything that put more air in will eat more fuel in general though.

Anything that increases thermodynamic efficiency, mechanical efficiency, friction reduction etc is a win win.

Rob

iTrader: (6)

The '04 GTO seems to be the only car over here that you can enable lean cruise by using the tables. I've been running it for over 1.5 years now. Its going to be terribly tough to get a tank average of 30mpg all the time. I've done it, but it was all highway doing about 70mph. Best was 33mpg but that also included a huge run of 50mph.

Problem with the goat is weight. In town cruising gets terrible gas mileage. Also, gearing comes into play. The goat is geared basically like a 3.90 geared F-Body, save for 4th of course.

I used to regularly get 28mpg in my cammed, 4.10 geared 96 WS6. Its just not as easy to get it in a goat. Too much drivetrain loss.

DVCrazyCamTAWs6

iTrader: (6)

has anyone mentioned a blower yet, that will help you through out the entire rpm range with MPG except going WOT. Just throw in a Vortech Kit and call it a day that should easily put you in the 30 range if your only at mid 20s which is pretty good for a heavy car.

Everything that adds Torque and better flow usually net better MPG.
But I'd Say the Most It's all in how you drive it, I drive my honda like i'm trying to make up for the acceleration i get in my trans am, flooring it on the freeway going WOT everytime i need to merge or switch lanes and not realizing that i'd be better off driving my TA and save more gas when it comes to mainly freeway driving. there not need to go WOT to merge , getting on the F.W. or changing lanes. the only thing the Honda was good for was driving up the street. I've gotten over 390 mpg to 11.5 gallons of gas with my cammed car in an automatic cruising at 90-100 half the time going to the track and back with another 3 gallons until E and 2 until EMPTY. thats not bad i was surprised myself.

and for 87 to high OCT. it's like less then 10-20cents in difference in a savings of like 1.50 to 2.50 every fill up. I really dont think of that much as a savings consider i used spend 20 bucks to fill the car now i spend over 40 to fill it, of course that could be 120 savings a year max. under the conditions you fill up everyweek.

saving of 5mpg is around 80more mpg to a 16g tank which @ 30mpg is 2.6 gallons saved which is $3.40 a gallon and 7 dollars saved every fill up.

so say you gain 5mpg you save anywhere from 120-336 a year depending on how much you drive of course. so buying something expensive to help with gas MPG depending on how much you do indeed drive could be worth it , but if you dont drive much a saving of 120 or less would take years to make up for in the cost spent to gain a mile or 2

2002_Z28_Six_Speed

iTrader: (19)

I don't know about slowly accelerating. I seem to get worse fuel milage while underdriving the car. I seem to get better fuel milage when I moderately accelerate, keep out of the gas, and skip shift like crazy.

RedWS6 00

What do you reckon on http://www.hydrogen-boost.com/index.html
They say its up to 50% beter gas mileage. Is this a hype like the 'Tornado' gizmo?

I'm not going to get either of them, just wondered on peoples opinions.

Rolemodel

i noticed better mpg when i did the same also

XRno1

I'm not sure it's relevant to this discussion, but in the Class 8 truck world (Tractor Trailers 80,000 lb. + GVW) the biggest rules of thumb for fuel mileage are go slower, turn as few RPMs as possible, and stay in top gear as much as possible. Supposedly every MPH above 55 results in a reduction of 0.1 MPG, which may not sound like much, but that's a big percentage in a truck that gets 5.5 MPG. This may not affect a car like a GTO or Camaro as much where they are much more aerodynamic, but I'm sure it does affect them to some degree. I would also say it is better to lug the engine in 6th rather than downshift to 5th and ease out of the accelerator. My car has done as well as 27 MPG on the highway, but never does worse than 21 or 22 around town. My 2004 Sierra with the 5.3 averages about 14 around town and can do as well as 18 to 19 on the highway.

BJM

iTrader: (1)

I took measurements tonight for fun, driving in different gears and at different speeds using the cruise control. I wound up getting gas mileage as shown in the picture. I have perhaps 20 samples at each data point. The weather was 87% humid and 26 C and raining. I had the roof up and the AC on.

P Mack

iTrader: (6)

How'd you get those numbers? A scanning program?

GuitsBoy

iTrader: (4)

Wind resistance really does play a hige role... Ill get 25 MPG driving at 80 MPH highway only. On heavy traffic days where im limited to 60 MPH or so, I would probably see closer to 28 MPH if it wernt for all the stop and go traffic that usually accompanies it.

BJM

iTrader: (1)

I used HpTuners and post-processed the values into instantaneous mpg on a graph in Excel. I then pick out the values where I have stabilized at a given condition (gear and speed).