What kind of mileage do you get on the highway with your motor/trans/gear combo?
09-27-2011, 12:29 AM
#22
Safety Car
Approx 400 H.P. L-46 SB with a Ford WC T-5 Trans and 3.08 gear and a Lars tuned Q-Jet. Stock/Rebuilt heads and Performer intake W/sidepipes. Dual Spals and no PS/PB or air cond.
I made it to Pittsburgh from about an hour North of Detroit(330 miles) in a torrential rainstorm, on 14 gals. of fuel. 70 mph at approx. 2000 rpm's. I figure thats about 23 mpg. I was quite surprised!
In the city you can probably cut the mileage in half.
I made it to Pittsburgh from about an hour North of Detroit(330 miles) in a torrential rainstorm, on 14 gals. of fuel. 70 mph at approx. 2000 rpm's. I figure thats about 23 mpg. I was quite surprised!
In the city you can probably cut the mileage in half.
09-27-2011, 01:31 AM
#23
Race Director
'72 stock 350/200 HP TH400, 3.08, 18 MPG at 55-60, 16 MPG at ~75 MPH, 15 MPG at ~90 MPH
'61 Corvette, 427 SB, EFI, 440 RWHP, DNE 5 speed, 3.08 22-24 MPG at 55 MPH, 17 MPG at ~75 MPH, 14 MPG at ~90 MPH, about 11-12 at 100 MPH. AFR at cruise is running about 15:1.
The C3 is slicker moving through the air at higher speeds.
Doug
'61 Corvette, 427 SB, EFI, 440 RWHP, DNE 5 speed, 3.08 22-24 MPG at 55 MPH, 17 MPG at ~75 MPH, 14 MPG at ~90 MPH, about 11-12 at 100 MPH. AFR at cruise is running about 15:1.
The C3 is slicker moving through the air at higher speeds.
Doug
09-27-2011, 07:05 AM
#24
Le Mans Master
78 L82 4 speed 3.73 gears, holley 4175 spreadbore, no pollution control, 2.5 inch duals w/ shorty headers-16 mpg @ 70 mph (3,500 rpm). The biggest gas mileage killer by far are the revs of the motor! A steep overdrive would give me 20-21 mpg with no other changes, droppingvtge Revs to 1,800-1,900 @ 70.
09-27-2011, 09:29 AM
#25
Melting Slicks
Member Since: Aug 2008
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302 cubes, header/sidepipes, Holley 4776, Vertex magneto set at 50 degrees total advance, Muncie M21, 3.70:1 rear gears, speedo checked against my GPS...15mpg at 70-75mph interstate speeds. I never drive it in commuter traffic.
As jb78L-82 said, it's all those rev's that kill mileage. But I still get as good mileage as my 6 cylinder GMC with overdrive auto, and have more fun doing so.
As jb78L-82 said, it's all those rev's that kill mileage. But I still get as good mileage as my 6 cylinder GMC with overdrive auto, and have more fun doing so.
09-27-2011, 11:51 AM
#26
Team Owner
I bought my '72 vert, L48 rebuilt engine by p/o and Muncie with 336 gearset.....almost immediately I put on a L98 injection and the idle was lke 600 rpm....so not much cam....with the stock rams horn pipes, it got 24mpg cruising from DC to Florida on I95 at typical speeds of 75-80 indicated..... this was in '97, before GPS etc was common/cheep.... the town mileage went from 12 to an easy 18 mpg.....
now the car has a roller 355 engine, 200 4r o/drive auto....same 336 gears..driven silly round town for maybe 2-4 miles round trip, poor thing gets 10 mpg....go figger.....but on the road at 45-70 mph it gets 22 mpg.....that what a larger cam and 850 rpm idle will do to you....Roller engine or not....thinking of going to an L98 cam and have done with it....
I think injection is wonderful, but not for any 1800 bux.....that's severely overpriced when you can get L98 setups off ebay/craigslist and DIY .....
now the car has a roller 355 engine, 200 4r o/drive auto....same 336 gears..driven silly round town for maybe 2-4 miles round trip, poor thing gets 10 mpg....go figger.....but on the road at 45-70 mph it gets 22 mpg.....that what a larger cam and 850 rpm idle will do to you....Roller engine or not....thinking of going to an L98 cam and have done with it....
I think injection is wonderful, but not for any 1800 bux.....that's severely overpriced when you can get L98 setups off ebay/craigslist and DIY .....
09-27-2011, 12:19 PM
#27
Race Director
when my '82 was bone-stock (CFI, 700R4, 2.87:1 gears), it took exactly 10 gallons to cover 236 miles, mostly highway/Interstate, A/C blowing ice-cubes, at 70+ MPH (filled to the gills both before, and after, at the same SUNOCO station)
a swap to 3.73 gears dropped that to a respectable 17+ MPG over the same trip
4 years later, the CFI was yanked by a friend, replaced with a 650 carb & old intake lying around, resulting in 14.0-second @ 95 MPH performance in the 1/4 mile:
a quick check over 90 miles (equal-parts highway & city driving through Orlando) showed the same 17+ MPG
a swap to 3.73 gears dropped that to a respectable 17+ MPG over the same trip
4 years later, the CFI was yanked by a friend, replaced with a 650 carb & old intake lying around, resulting in 14.0-second @ 95 MPH performance in the 1/4 mile:
a quick check over 90 miles (equal-parts highway & city driving through Orlando) showed the same 17+ MPG
09-27-2011, 01:59 PM
#29
Safety Car
Mostly stock Crossfire Injected 350 with 700R4 and 2:73 rear gets average about 16 driving like a nut.
I have gotten 25mpg on a steady highway run. The 82 vette runs at 2000rpm at 80mph.
I have gotten 25mpg on a steady highway run. The 82 vette runs at 2000rpm at 80mph.
09-27-2011, 08:56 PM
#31
Le Mans Master
Jim that is VERY impressive! Might have to look at doing the EFI swap
09-27-2011, 09:48 PM
#32
Le Mans Master
[QUOTE=mrvette;1578810553I think injection is wonderful, but not for any 1800 bux.....that's severely overpriced when you can get L98 setups off ebay/craigslist and DIY ..... [/QUOTE]
Sort of where I am with it all as well. Looked at the Holley, Edel and Fast systems and just couldn't justify the $ outlay from a performance or even mpg point of view. The TPI is of more interest but 2nd to adding a 5 sp to replace my M22. When fully tuned my 383 was getting about 19 mpg on the highway which I usually keep it btn 60 and 65. So putting out roughly $6k for a Fast/Holley/Edel system plus a 5 sp to gain 4 or 5 mpg just doesn't make a lot of fin'l sense for my usage in the relatively short season we get up here. I still read where some here have done these mods yet still either take their C5/6 on long road trips for comfort etc. or hitch a ride with someone else. Guess I was a CFO for too long at one point.
I'll probably just keep essentially my setup with some minor mods and keep the original parts if possible.
[/QUOTE]Sort of where I am with it all as well. Looked at the Holley, Edel and Fast systems and just couldn't justify the $ outlay from a performance or even mpg point of view. The TPI is of more interest but 2nd to adding a 5 sp to replace my M22. When fully tuned my 383 was getting about 19 mpg on the highway which I usually keep it btn 60 and 65. So putting out roughly $6k for a Fast/Holley/Edel system plus a 5 sp to gain 4 or 5 mpg just doesn't make a lot of fin'l sense for my usage in the relatively short season we get up here. I still read where some here have done these mods yet still either take their C5/6 on long road trips for comfort etc. or hitch a ride with someone else. Guess I was a CFO for too long at one point.
I'll probably just keep essentially my setup with some minor mods and keep the original parts if possible.
Last edited by gdh; 09-27-2011 at 09:50 PM.
09-27-2011, 10:05 PM
#33
Race Director
You don't need fuel injection, you need invest is a wideband O2 A/F meter and tune whatever carb you have correctly.
I have a 600HP 427ci small block with a 825 Race Demon (flows 975cfm) a 3.08 rear end and TKO 600 with .64 OD and I get 24 mpg @ 80mph on the highway and 14mpg around town, this was @ 13:1 AFR. I could lean it out a bit and get even better mileage
I have a 600HP 427ci small block with a 825 Race Demon (flows 975cfm) a 3.08 rear end and TKO 600 with .64 OD and I get 24 mpg @ 80mph on the highway and 14mpg around town, this was @ 13:1 AFR. I could lean it out a bit and get even better mileage
Last edited by MotorHead; 09-27-2011 at 10:09 PM.
09-27-2011, 10:09 PM
#34
Melting Slicks
My '73 has about 330 HP, 3.08's, Holley 650 Double Pumper. Gets about 14 highway, 12 around town. I'm told fuel injection and overdrive transmission should bump highway mileage into the mid 20's at least. Was also told replacing the carb could improve mileage as well.
I always check mileage. When mileage drops, it tells me something is up that I need to check.
DC
DC
09-27-2011, 10:30 PM
#35
Racer
Member Since: Jan 2010
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I got less than 10 mpg, 350 mild cam stock heads headers, but 4:11 gears.
I am dreading what the 427 i have just installed will be like, was think 5-6 mpg.
A mates old L88 clone with hilborne injection got about 3-4 mpg!
10-02-2011, 07:22 PM
#37
Burning Brakes
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[QUOTE=bucky katt;1578806337]my L48 car has the pace car rear spoiler. i figured that one of those would hurt mileage, but then i dont know a whole lot about aerodynamics
QUOTE]
The spoiler front and back actually helps mileage. They both reduce the drag coefficient. Maybe you get another 1/2 mile to the gallon.
QUOTE]
The spoiler front and back actually helps mileage. They both reduce the drag coefficient. Maybe you get another 1/2 mile to the gallon.
10-02-2011, 08:00 PM
#38
Instructor
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gas mileage
Mine gets about 19 around town, and 21 when cruising.
68 Coupe, 327 /300 + 030 (331 inches). Pertronix electronic ignition in stock distributor, MSD blaster coil with MSD 6. Intake is Edelbrock performer, carb is Summit Racing 600 CFM. Stock heads, roller rockers, Comp Cams split duration hydraulic; CL12-234-2
Hooker headers and dual exhaust using chambered pipes (no mufflers). Trans is Tremec TKO, 3.08 posi rear. 1300 RPM at 50 MPH.
Of course, my 5000 pound Silverado 5.3 gets the same mileage......
68 Coupe, 327 /300 + 030 (331 inches). Pertronix electronic ignition in stock distributor, MSD blaster coil with MSD 6. Intake is Edelbrock performer, carb is Summit Racing 600 CFM. Stock heads, roller rockers, Comp Cams split duration hydraulic; CL12-234-2
Hooker headers and dual exhaust using chambered pipes (no mufflers). Trans is Tremec TKO, 3.08 posi rear. 1300 RPM at 50 MPH.
Of course, my 5000 pound Silverado 5.3 gets the same mileage......
10-02-2011, 08:50 PM
#39
Le Mans Master
when my '82 was bone-stock (CFI, 700R4, 2.87:1 gears), it took exactly 10 gallons to cover 236 miles, mostly highway/Interstate, A/C blowing ice-cubes, at 70+ MPH (filled to the gills both before, and after, at the same SUNOCO station)
a swap to 3.73 gears dropped that to a respectable 17+ MPG over the same trip
4 years later, the CFI was yanked by a friend, replaced with a 650 carb & old intake lying around, resulting in 14.0-second @ 95 MPH performance in the 1/4 mile:
a quick check over 90 miles (equal-parts highway & city driving through Orlando) showed the same 17+ MPG
a swap to 3.73 gears dropped that to a respectable 17+ MPG over the same trip
4 years later, the CFI was yanked by a friend, replaced with a 650 carb & old intake lying around, resulting in 14.0-second @ 95 MPH performance in the 1/4 mile:
a quick check over 90 miles (equal-parts highway & city driving through Orlando) showed the same 17+ MPG
10-02-2011, 09:10 PM
#40
I own a 1969 (original owner) and from day one, I could care less what I get for mileage. Don't get me wrong but there must be many like me out there who don't care about mileage but just the thrill of driving the best built USA built sports car.