How much MPG do you get?
Thread Starter
Pro
Joined: Jun 2001
Posts: 672
Likes: 0
From: Quebec
How much MPG do you get?
I am in the process of tuning my engine for MAX performance (L48) as I can get. Either for gas consuption or acceleration. The ignition is done; 34 degrees mecanical at 2500 RPM and 55 degrees total at the same RPM. The car runs great.
When I cruise in town with stop and go, I get around 12 MPG.
On the long trip I just did (a Corvette cruise), I got 17 MPG.
I have 3,07 rear end and a TH350 with a non-operational lock-up with a Quadrajet for carb.
I wonder if I could get better millage from playing with the carb; power piston spring, jets and rods.
Show me your numbers.
Stephan
When I cruise in town with stop and go, I get around 12 MPG.
On the long trip I just did (a Corvette cruise), I got 17 MPG.
I have 3,07 rear end and a TH350 with a non-operational lock-up with a Quadrajet for carb.
I wonder if I could get better millage from playing with the carb; power piston spring, jets and rods.
Show me your numbers.
Stephan
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Re: How much MPG do you get? (American Boy)
I get about 8mpg, but I've got a 4sp right now and no OD. I frequent the highway @ 3500+ rpm and I'm running rich.
I think stock for '81 C3s gets 12mpg.
I think stock for '81 C3s gets 12mpg.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: How much MPG do you get? (American Boy)
With a 460 cubic inch engine , a 8-71 blower, 2 850 double pumper carbs, 4.11 gears and overdrive transmission I get 12 mpg anytime around town without fouling plugs ever.
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Re: How much MPG do you get? (American Boy)
I used to get that same mileage with my '79 L82 with 3.55 gears and Trubo 350. I would expect you to get a little better with the 3.07 gears. The only real way to know for sure on your setup is to use a chasis dyno with an A/F ratio measurement. Dial in your mixture at part throttle highway speeds, perhaps evenas high as 16:1; but, make sure your full throttle ratio drops to between 13-14 to 1 when you ask for it.
Chuck
Chuck
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: How much MPG do you get? (American Boy)
0
Of course my speedo/odo aren't working. :)
I think 55 degrees total timing is a bit much, actual way to much. I believe your total timing should be betweeen 36 and 38 degrees. Check Lars' tuning paper for exact spec's.
Of course my speedo/odo aren't working. :)
I think 55 degrees total timing is a bit much, actual way to much. I believe your total timing should be betweeen 36 and 38 degrees. Check Lars' tuning paper for exact spec's.
Thread Starter
Pro
Joined: Jun 2001
Posts: 672
Likes: 0
From: Quebec
Re: How much MPG do you get? (Fevre)
Chuck
I'm going on a wheel dyno at the end of the month. I hope they have an A/F ratio thingy to check mine.
Fevre (I forgive you :D )
For others interested
The mecanical advance is only 34 degrees. When we speak of total advance, it include the mecanical and the vacuum. 55 degrees for the total was what I read somewhere on the forum and it's working great.
Stephan
[Modified by American Boy, 3:21 PM 5/7/2002]
I'm going on a wheel dyno at the end of the month. I hope they have an A/F ratio thingy to check mine.
Fevre (I forgive you :D )
For others interested
The mecanical advance is only 34 degrees. When we speak of total advance, it include the mecanical and the vacuum. 55 degrees for the total was what I read somewhere on the forum and it's working great.
Stephan
[Modified by American Boy, 3:21 PM 5/7/2002]
Safety Car
Joined: Jan 2000
Posts: 4,143
Likes: 0
Re: How much MPG do you get? (American Boy)
I'm running a Holley 3310 Vac. Sec. on a 427 B.B. with 'points' ignition.
My gas mileage :
On the highway ---> 14mpg on a good day (3:08 rearend) :D
In town -----------> 7-10mpg depending on traffic. :lol:
W.O.T. ------------> 3 mpg :eek:
Playing with timing & carb will help your gas mileage - but it's a trade-off. More power usually means less gas mileage unless you start 'swapping' parts on your motor to make it run more 'efficient'.
My friend's '82 crossfire averages a whopping 22mpg on the hwy. !!! :cheers:
My gas mileage :
On the highway ---> 14mpg on a good day (3:08 rearend) :D
In town -----------> 7-10mpg depending on traffic. :lol:
W.O.T. ------------> 3 mpg :eek:
Playing with timing & carb will help your gas mileage - but it's a trade-off. More power usually means less gas mileage unless you start 'swapping' parts on your motor to make it run more 'efficient'.
My friend's '82 crossfire averages a whopping 22mpg on the hwy. !!! :cheers:
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Le Mans Master
Joined: Apr 2002
Posts: 7,281
Likes: 5
From: Boston
Re: How much MPG do you get?
I get more like 15mpg with moderate driving in the city and 24 in highway, checked last year on trip to Seattle around 65mph.
At WOT I can see the gas neddle move
FroDaddy>>The 1981 R&T mag, had 16mpg on the L-81 4-speed i'll post a pic later today
norvalwilhelm>> 12 mpg's:confused: how come. I'm thinking more like 12 gallons per mile :lol:
Paul
At WOT I can see the gas neddle move
FroDaddy>>The 1981 R&T mag, had 16mpg on the L-81 4-speed i'll post a pic later today
norvalwilhelm>> 12 mpg's:confused: how come. I'm thinking more like 12 gallons per mile :lol:
Paul
Instructor
Joined: Apr 2002
Posts: 115
Likes: 0
From: Pg county MD
Re: How much MPG do you get? (American Boy)
For pete's sake.......your driving a Corvette. Your not suposed to care about gas milage. It's the journey that counts. On a more serious note, I can't figure what kind oF milage I get because:
1. Haven't gotten though a whole tank yet
2. Haven't driven it without mashing the gas at least once (usually more)
3. If I had to estimate, I would say I'm going to get around 12 MPG (including the foot to the floorboard driving) Man do I love this car!! :chevy
1. Haven't gotten though a whole tank yet
2. Haven't driven it without mashing the gas at least once (usually more)
3. If I had to estimate, I would say I'm going to get around 12 MPG (including the foot to the floorboard driving) Man do I love this car!! :chevy
Drifting
Joined: Apr 2002
Posts: 1,736
Likes: 37
From: Stockton Ca
Re: How much MPG do you get? (American Boy)
I have followed this subject before. A strong SB w/o OD can get 17-18 mpg depending. To get much more than that will require OD. This is not to say that very careful driving won't do better, but REAL WORLD " reasonable take off,cruising over limit" driving it's hard to beat the 17-18 and 22-24 w/OD. It all comes down to how hard do you put your foot into it! I want to join the 12 sec 20 mpg club. This will not happen w/o 5 speed trans.
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
Re: How much MPG do you get? (American Boy)
I'm getting about 15 MPG and that's cruising at 80 to 95 most of the time, with 3.73 gears and a 4 spd. It's interesting, everytime someone brings up the subject somebody else pipes up about "who cares about gas mileage". Mileage is just another performance parameter to measure. So the point is "is it in tune", not "I don't care". I always check my mileage but when it comes to performance decisions, more power is the only way to go.
Team Owner
Joined: Jun 2001
Posts: 43,136
Likes: 155
From: Thomson Georgia
Re: How much MPG do you get? (Taijutsu)
before the mods I was getting around 19 on the highway and 13 around town..I expect to be around 13hwy and 9 around town with everything i have changed...but who cares it will be FAST :smash: :cheers:
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: How much MPG do you get? (burners)
burners
you must be reving abut 4000+ rpm's all the time with that set up. :eek:
I get scared at about 3500 on the highway, can just see a rod shooting out the hood/oil pan
you must be reving abut 4000+ rpm's all the time with that set up. :eek:
I get scared at about 3500 on the highway, can just see a rod shooting out the hood/oil pan
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Re: How much MPG do you get? (American Boy)
When I set up my 69 L46 lean, I was getting 22-24 mpg at a steady 70 mph cruise with 3.36 gears and 4 speed. The secondaries realy need to be rich to bring the mixture back down when you open them for power.
Chuck
Chuck
Racer
Joined: Apr 2000
Posts: 499
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From: Kristiansand
Re: How much MPG do you get? (American Boy)
Fixing the lockup will improve milage and make the trans run cooler.
With the TH350C I got 15mpg town, 17 freeway.
The new 700R4 is 18 town, 23 freeway (55mph).
This is with very careful driving of course.
The gas prices over here makes you try to increase milage, this is what I have done to my stock L48:
Removed all emission equipment. (egr, canister, pvc, air etc)
Adjusted the Qjet piston to the bottom position (as per Lars' instructions).
Removed AC compressor (no need for it here..)
Electric fan.
K&N filter.
Dynomax headers with 2 1/2 true dual freeflow exhaust, no cats.
Fixed all vacuum leaks.
Next is TPI...
With the TH350C I got 15mpg town, 17 freeway.
The new 700R4 is 18 town, 23 freeway (55mph).
This is with very careful driving of course.
The gas prices over here makes you try to increase milage, this is what I have done to my stock L48:
Removed all emission equipment. (egr, canister, pvc, air etc)
Adjusted the Qjet piston to the bottom position (as per Lars' instructions).
Removed AC compressor (no need for it here..)
Electric fan.
K&N filter.
Dynomax headers with 2 1/2 true dual freeflow exhaust, no cats.
Fixed all vacuum leaks.
Next is TPI...
Melting Slicks
Joined: May 2001
Posts: 2,700
Likes: 3
From: Lebanon KY
Re: How much MPG do you get? (American Boy)
I have 3,07 rear end and a TH350 with a non-operational lock-up with a Quadrajet for carb.
Drifting
Joined: Oct 2000
Posts: 1,824
Likes: 55
From: Shawano WI
Re: How much MPG do you get? (challenger818)
For pete's sake.......your driving a Corvette.
I get 16 on the highway and absolutely terrible around town. But then again I like to hear the sound of the sidepipes echo off the buildings around town, That might have something to do with it.
[Modified by Pete79L82, 4:31 PM 5/7/2002]
