Gas mileage #'s

[turtlevette]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

 

[mrvette]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

What ever the speedo said, It was dead stock as far as gears were considered....they were unchanged since new, I never touched any of that until putting the 700 in there with this hotrod engine....down here in late '97....

and the miles indicated made sense overall with the known distances....

Still convinced this cam is killing off fuel economy....

got me curious enough now that I going factor ZZ4 cam shopping....12 years now, needs a chain anyway...gotta have 100k on it, easy....
Plus, I got a china wall oil leak in front anyway....maybe later this fall....

and on that speedo shit....ok 130 mph is more like it....guess the only way to do this right is take the garmin and build it in, or find out that in fact at a indicated 100 all of a sudden my speedo is 6 mph over, only really 94....

 

[SmokinBBC]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

Now that's some funny shit right there:rofl::rofl::rofl::rofl:

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

Yep, I am getting those kind of numbers. Checked my math many times. I get what I get.

Those numbers on the Mustang aren't bad. I only get 21 out of my G35 coupe. Hell, I only get 17 on the highway with my 2003 gas guzzling 5.4 V8 triton in the expedition.

 

[mrvette]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

Now that's some funny shit right there:rofl::rofl::rofl::rofl:

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

Yep, I am getting those kind of numbers. Checked my math many times. I get what I get.

Those numbers on the Mustang aren't bad. I only get 21 out of my G35 coupe. Hell, I only get 17 on the highway with my 2003 gas guzzling 5.4 V8 triton in the expedition.

Well that is what is disappointing to me, that I now with a damn similar drive train, same essential engine size, 60% or so of the frontal area, and then that Expedition gotta weigh 4800 lbs easy.... and I get the same 18 mpg....ethanol or not, that SUX.....and that's another factor come think of it.....12 years ago there was no 10% economy hit for the ethanol....but big deal that would make the car only 20 mpg at most....still off by 4 mpg.....

and still WAY the hell away from your performance, and I have MAF DPFI injection and lock up overdrive to boot....

comes down to cam and computer.....

:gurney:

 

[SmokinBBC]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

Now that's some funny shit right there:rofl::rofl::rofl::rofl:

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

Yep, I am getting those kind of numbers. Checked my math many times. I get what I get.

Those numbers on the Mustang aren't bad. I only get 21 out of my G35 coupe. Hell, I only get 17 on the highway with my 2003 gas guzzling 5.4 V8 triton in the expedition.

Well that is what is disappointing to me, that I now with a damn similar drive train, same essential engine size, 60% or so of the frontal area, and then that Expedition gotta weigh 4800 lbs easy.... and I get the same 18 mpg....ethanol or not, that SUX.....and that's another factor come think of it.....12 years ago there was no 10% economy hit for the ethanol....but big deal that would make the car only 20 mpg at most....still off by 4 mpg.....

and still WAY the hell away from your performance, and I have MAF DPFI injection and lock up overdrive to boot....

comes down to cam and computer.....

:gurney:

17 is highway....if it makes you feel any better, it gets 14 city driving.

 

[mrvette]

Yea, you also thought you were doing 150 with your top down too. What did that work out to.... maybe 110 after all the BS settled?

110/150 = .73 BS factor

.73 gene factor x 24mpg = 17.6 mpg

Now that's some funny shit right there:rofl::rofl::rofl::rofl:

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

Yep, I am getting those kind of numbers. Checked my math many times. I get what I get.

Those numbers on the Mustang aren't bad. I only get 21 out of my G35 coupe. Hell, I only get 17 on the highway with my 2003 gas guzzling 5.4 V8 triton in the expedition.

Well that is what is disappointing to me, that I now with a damn similar drive train, same essential engine size, 60% or so of the frontal area, and then that Expedition gotta weigh 4800 lbs easy.... and I get the same 18 mpg....ethanol or not, that SUX.....and that's another factor come think of it.....12 years ago there was no 10% economy hit for the ethanol....but big deal that would make the car only 20 mpg at most....still off by 4 mpg.....

and still WAY the hell away from your performance, and I have MAF DPFI injection and lock up overdrive to boot....

comes down to cam and computer.....

:gurney:

17 is highway....if it makes you feel any better, it gets 14 city driving.

about what I get now....

I come down to too much damn cam...makes no sense for a street car....idle is 850 rpm....should be 650.....

I already looking for a ZZ4 stock GM cam....

not even the hot one, just a ZZ4 mild street cam for roller engine....

 

[kwplot34]

You guy's crack me up with some of the crap you worry about :rofl::rofl:

 

[lars]

I drive my TPI 350 Vette 110 miles a day every day, so I have pretty solid mpg numbers on it:

With the headlights retracted, top on, and windows up, I get a no-BS 26 mpg on the highway with a combined city/highway of 24.

Aerodynamics make a noticable difference: Even running with the headlights in the "up" position will drop the 26 down to 25, and running with the top off will drop highway mileage down to 24. Running the car in the "clean" configuration, best mpg with the overdrive transmission occurs at 70 mph turning 1700 rpm. Running an A/F monitor shows cruise mixture to be dead on at 14.7:1 when best mileage is achieved.

It's possible to get a carbureted small block to run similar numbers, but you do need to play with the IFR sizing and low speed air bleeds in order to get the cruise mixture optimized for mileage: Primary jetting has little effect on cruise mixture, since most fuel at cruise is metered through the transition circuit, which is controlled by the IFR sizing and not the main metering jets. If you try to jet a carb down enough to lean out the cruise mixture to optimum, you tend to get severe stumbles and poor WOT performance. For this reason, few carbs are really mpg optimized for their specific application, making it appear that TPI is the only way to squeeze the mileage out of these cars. With a bit of work and a good A/F monitor, you can get very good cruise mileage numbers from a carbureted small block.

Lars

 

[mrvette]

I drive my TPI 350 Vette 110 miles a day every day, so I have pretty solid mpg numbers on it:

With the headlights retracted, top on, and windows up, I get a no-BS 26 mpg on the highway with a combined city/highway of 24.

Aerodynamics make a noticable difference: Even running with the headlights in the "up" position will drop the 26 down to 25, and running with the top off will drop highway mileage down to 24. Running the car in the "clean" configuration, best mpg with the overdrive transmission occurs at 70 mph turning 1700 rpm. Running an A/F monitor shows cruise mixture to be dead on at 14.7:1 when best mileage is achieved.

It's possible to get a carbureted small block to run similar numbers, but you do need to play with the IFR sizing and low speed air bleeds in order to get the cruise mixture optimized for mileage: Primary jetting has little effect on cruise mixture, since most fuel at cruise is metered through the transition circuit, which is controlled by the IFR sizing and not the main metering jets. If you try to jet a carb down enough to lean out the cruise mixture to optimum, you tend to get severe stumbles and poor WOT performance. For this reason, few carbs are really mpg optimized for their specific application, making it appear that TPI is the only way to squeeze the mileage out of these cars. With a bit of work and a good A/F monitor, you can get very good cruise mileage numbers from a carbureted small block.

Lars

:suicide: OK, fess up now, your exact cam, and rear end ratio....at 70 I"M closer to 2200 rpm .68/.70 o/drive 200 locked up.....336 rear....

I have a roller engine, so maybe you can recomend a good cam to go with??

I"m just shooting in the dark with my ZZ4 cam guess....looking at specs, only diff is slightly less duration, and lift...but it's not a whole lot....

:sos:

 

[BigBlockTank]

Really???

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

I don't do math, so my calculator is f'ed up, huh? 146 miles and I put in 9.8 gals of fuel. I don't see what is so hard about that simple math. It's actually over 14.8 but only by a bit.

And it would seem to me that a 700R4 trans with 3.08 gears would put you in a RPM range below what would be "most efficient", almost at the point of lugging it down. Just an observation.

Come on out, and I'll fill'er up and we'll go burn 150 miles and see what we get.


Tank

 

[turtlevette]

It's possible to get a carbureted small block to run similar numbers, but you do need to play with the IFR sizing and low speed air bleeds in order to get the cruise mixture optimized for mileage: Primary jetting has little effect on cruise mixture, since most fuel at cruise is metered through the transition circuit, which is controlled by the IFR sizing and not the main metering jets. If you try to jet a carb down enough to lean out the cruise mixture to optimum, you tend to get severe stumbles and poor WOT performance. For this reason, few carbs are really mpg optimized for their specific application, making it appear that TPI is the only way to squeeze the mileage out of these cars. With a bit of work and a good A/F monitor, you can get very good cruise mileage numbers from a carbureted small block.

Lars

I don't remember what IFR means. Your saying the idle screws determine the cruise mixture?

I thought it was impossible to get the cylinder to cylinder tuning the same since you can't control how the mixure disperses so you have to run much richer with a carb. Do you run with the exhaust crossover to better vaporize the fuel? I guess not. Sounds like you don't run a carbed engine.

 

[lars]

IFR is the Idle Fuel Restrictor, and it is the primary metering for fuel at cruise - most carbs run on the fuel metered through the transition slots and idle mixture screws at cruise because the throttle blade opening is not big enough at cruise, nor is air mass suffucient, to pull fuel out of the main discharge nozzles at light throttle settings. Proper tuning of the IFRs and low speed air bleeds can yield cruise fuel economy on a carb very close to TPI on a mildly built motor. The IFRs meter the fuel prior to both the idle mixture screws and the transition slots, and is the only fuel metering for the transition slots. At light cruise and high manifold vacuum settings, fuel is pulled additively from both the idle mixture discharge ports and from the transition slots. Since both of these discharge locations are in the throttle bore - and not in the venturi of the carb - fuel is metered from these locations when the throttle is only partially open and when manifold vacuum can "pull" the fuel from these locations (such as at light cruise). At moderate power settings and WOT, fuel is dicharged from the main discharge nozzles, and very little fuel is pulled through the IFR circuits.

I don't run a carbed engine? The engine referenced in my initial post response is a TPI engine as stated in my post: "I drive my TPI 350 Vette 110 miles a day." I also have 5 cars with carbs and another 3 with TPI.

Lars

 

[Ozzy]

A lot of these claims just don't add up. The brakes on these things drag like crazy. The coefficient of drag is not good. I'm sure there are other intrinsic reasons why these cars will never achieve some of the numbers being claimed here. You can't change the laws of physics. If you have a big block with carb and you're getting 17 mpg in town, you better check your math! I think most of you need to check your math.

My brand new mustang V6 gets around 25-28 on the hwy. There's no way guys....your getting these kinds of numbers.

I had a 283 in mine at one time and drove back and forth to work on back roads at approx 45mph which is about the most efficient speed for mileage and i got 17 mpg. The carb was running lean too. Oh, yea with the 700r4 and 3.08 gears.

I did not locate the drag cofficient for the chrome bumper C3's,here are a few others to compare:

80 coupe .443
87 coupe .33
02 coupe .29

Stock 1987 A4.L98 C4 coupe, drivers window up or down, varied with the outside temps, Las Vegas to Spokane 69 mph indicated on speedo of Vette and 95 Camaro I was travelling with. 28.6 ave mpg for the trip.

Stock '02 LS1.A4 Coupe, windows up w/ ac running if needed.
Spokane-Vegas-Spokane speeds of legal to 20% above at various times. 26.4 ave mpg round trip.

Both cars get low 16's around town.

 

[AJ77]

Last time I checked mine was last year going to Eureka Springs Arkansas and back from Ft. Worth Tx. I drive the speed limit and have a 383 with aftermarket TPI, a 700R-4 and 3.70 rear gears. I filled up a total of 5 times over the 4 day trip and averaged 22.6 MPG. On the fuel economy run I got 24.6.

 

[DeeVeeEight]

Some of these numbers are awesome and after reading Lars' responses it makes me want to take the Holley off and fine tune it.

:drink:

 

[Bee Jay]

I've got 3.55 gears and a 700r4 trans. I run a Summit 1105 cam, 224/234 duration at .050, AFR 195 heads, and Holley Throttle Body Injection. I drive 200 miles and I fill up with 20 gallons. I have a heavy foot, but 10mpg gets old when it's $5 a gallon. I hope to improve my gas mileage significantly by switching to a milder LT4 Hot Cam hydrualic roller,218.228 duration at .050. Rollers are supposed to have less friction, right? Less friction, less duration, better gas mileage right? My 1500HD Crew Cap with a 6.0 liter LS engine gets 14mph on the road. I should get at least that with my 3200 lb Corvette, right? Maybe I shouldn't give a damn like kwplot.

 

[mrvette]

I've got 3.55 gears and a 700r4 trans. I run a Summit 1105 cam, 224/234 duration at .050, AFR 195 heads, and Holley Throttle Body Injection. I drive 200 miles and I fill up with 20 gallons. I have a heavy foot, but 10mpg gets old when it's $5 a gallon. I hope to improve my gas mileage significantly by switching to a milder LT4 Hot Cam hydrualic roller,218.228 duration at .050. Rollers are supposed to have less friction, right? Less friction, less duration, better gas mileage right? My 1500HD Crew Cap with a 6.0 liter LS engine gets 14mph on the road. I should get at least that with my 3200 lb Corvette, right? Maybe I shouldn't give a damn like kwplot.

All I know is that with my old rebuilt by PO L48 engine, muncie tranny 336 gears, I got 24 mpg on I95 crusing here looking for a house...Feb 97, TPI was installed ..so NO overdrive,

but living here I went '89 truck roller engine and overdrive, and have ruined the fuel economy....lucky to see 20 on the freeways now....

I don't understand it.....the cam is nearly a ZZ4 hot spec.....decent idle went from 650 to 850, I had thought the overdrive would bring back any engine losses....guess not....

:crap:

 

[AJ77]

My cam is somewhat radical. It's a Crane retrofit roller with 112* lobe separation, 222, 236 duration @ .50 and .518", .539" lift with 1.5 Crane roller rockers. The car idles @ 850 rpm and is jumping up and down. I need to find time to get my tuner to take a ride with me so he can tweek the system with his laptop. I think I might be running a little lean. I think my mileage has dropped since I had the tranny rebuilt. It shifts at higher speeds now so that will eat up some mileage. Oh well, if I have to worry about that, I don't need the car--right?

 

[4 SPEED]

I have been averaging 18-20 per gal with windows up or down or tops on or off.
I have a 700dp Holley, M20 4 speed and a 3:08 rear.
Total hp around 400

When I get heavy on the pedal forget about it.


Schoon

 

[mrvette]

I have been averaging 18-20 per gal with windows up or down or tops on or off.
I have a 700dp Holley, M20 4 speed and a 3:08 rear.
Total hp around 400

When I get heavy on the pedal forget about it.


Schoon

A HOLLEY and no overdrive, and you getting same as me, 10% more gear in my car, but overdrive, .70.....got FI, closed loop even....

my cam sux gas and ass.....

:goodnight::flash: