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#41
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FWIW - My 1964 GTO convertible, with 3.08 gears, 27" tires and the original Muncie M20 - gets 17 MPG on the highway and I don't live in "flat" country.
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#42
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80 Firebird with two men. 455 engine - 310 CFM heads, hyd roller, 2004R with PTC 3200 stall - locked up. 56 Miles/ 10.2 Liters of gas consumed. RPM was right about 1700 RPM for the drive. Owner spent many hours tweaking the fuel and timing curves. Autometer speedo was calibrated less than 1% error. |
#43
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I have a Lonnie Diers Extreme Automatics 2004r stage 2 hooked to my 800 cfm quad rebuilt by Cliff Ruggles. All I can say is he is the best for a spot on rebuilt carb. I am currently running an SD Performance stump puller cam, cnc'd 320 cfm round port edelbrock heads and a 455 stroker set up from Len Williams. The mileage is very good but due to the right foot it still likes to hear the tires chirp when downshifting from drive to second and then hear that torque chirp the tires in drive once more. The transmission is hooked to a Bowties Overdrive cable and throttle kit set-up so don't be afraid to call them and tell them exactly what you want to do and they are more than capable to get you on track. The quad has not acted up at all in well over nine years now. You can call me if you need more info on the carb or set-up.
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#44
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https://www.dcimotorsports.com/ |
#45
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__________________
Jeff |
#46
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I really enjoy these wild mileage claims. Here are the 1971 Pontiac GTO Convertible 400-4 V8 4-speed (man. 4) specs in stock form:
•Pontiac GTO Convertible 400-4 V8 4-speed (man. 4) , model year 1971, version for North America (up to September) •manufactured by Pontiac in USA •2-door convertible body type •RWD (rear- wheel drive), manual 4-speed gearbox •gasoline (petrol) engine with displacement: 6558 cm3 / 400.2 cui, advertised power: 190 223.7 kW / 255 300 hp / 258 304 PS ( SAE net SAE gross ), torque: 461 542 Nm / 340 400 lb-ft, more data: 1971 Pontiac GTO Convertible 400-4 V8 4-speed (man. 4) Horsepower/Torque Curve •characteristic dimensions: outside length: 5164 mm / 203.3 in, width: 1948 mm / 76.7 in, wheelbase: 2845 mm / 112 in •reference weights: shipping weight 1651 kg / 3640 lbs base curb weight: 1723 kg / 3798 lbs •how fast is this car ? top speed: 188 km/h (117 mph) (©theoretical); •accelerations: 0- 60 mph 6.6© s; 0- 100 km/h 7.2© s (simulation ©automobile-catalog.com); 1/4 mile drag time (402 m) 15.2© s (simulation ©automobile-catalog.com) 1971 Pontiac GTO Convertible 400-4 V8 4-speed (man. 4) Detailed Performance Review •fuel consumption and mileage: average estimated by a-c©: 22 l/100km / 12.8 mpg (imp.) / 10.7 mpg (U.S.) / 4.6 km/l, more data: 1971 Pontiac GTO Convertible 400-4 V8 4-speed (man. 4) Specifications Review
__________________
Triple Black 1971 GTO |
#47
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Another key specification not listed is the rear gear ratio. The devil is in the details. Real world, actually measured fuel mileage (duplicated multiple times) with a 462 c.i., Quadrajet, 4spd Muncie M20, 27" tall tires and 3.08 gears driven on rolling terrain in MN and WI is 17+ MPG. I'm sure someone with 2.56 gears or an OD transmission can easily brake 20 MPG. |
#48
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I probably wouldn't have started this thread except, I have owned two Pontiacs.
1. 1964 GTO 389 bored ,060 tri power other than the bore everything else was stock. 4 speed and 3:23 rear end. At 65 mph it got 18-19 mpg.SOLD 2. Currently 1965 tempest conv. 400 bored .040 crower 60240 cam #15 heads(small valve) performer intake 735 cfm Quick fuel. Overdrive with 3:73 gears final 4th gear 2.55. at 65 mph 12 mpg. Thursday I am taking it a shop and they are going to run it on there dyno and check AFR all the way through the gears. I'm thinking put a tri power on it maybe lightning will strike twice. lol Thanks Last edited by footjoy; 10-14-2019 at 09:18 AM. |
#49
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Fuel mileage is something I've always paid attention to since we drive our classics daily. They have to be at least somewhat respectable on mileage or they'd drive me into the poor house.
These classics can be pretty darn good on mileage, and you don't necessarily need an overdrive to do it. As long as the engine is built to run efficiently, tuned properly and the rest of the cars details are looked at. My 70 RA Formula, with a 400 RAIII, 400 turbo and 3.31 gears will consistently get 17 mpg highway cruising at 70 mph and 2800 rpm. Gets right between 13-14 around town driving. About as good as any new SUV with it's fancy 6 speed overdrive and fuel injection, cylinder deactivation etc... I'm pretty happy with it. A simple overdrive would easily put that car at 20 mpg or better. Our 69 Z/28 with a 302 running a fat 780 holley, M-20 and 3.55's out back gets 14 mpg around town and a solid 17 on the highway cruising at 65 mph which is 2900 rpm. I just recently installed a TKO600 in this one. 70 mph cruising is now 2100 rpm but have not checked the mileage on the highway yet. I fully expect this one to top 20. Around town it's already improved to 15.5 mpg. The 79 1 ton pickup with a 454 and 3.73's gears out back runs a 400 turbo. This thing weighs 5300 lbs. and is shaped like a brick. 65 mph cruising is 2800 rpm and it gets a solid 14 mpg. We have a ton of examples here, they are all pretty respectable on mileage. |
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