I'm hoping that I'll be able to get really good mileage (and still have a fun ride) when I build my '29 Modified. So far I have a built Chevy 250 L6 (this) and a Ford 8" with 3.00 gears for the rear. I don't have a trans yet, but I'm thinking a Powerglide or maybe a T5 if I can manage to have enough foot room. Because I won't be running a bed and it's an open car, I'm betting that it will be really light. I guess it really depends on my being able to keep my foot out of it! - Joe
SanDiegoJoe, I'd want some gear selection even in a light car for cruising. The fourth gear as an overdrive is one way (modern trans), but even more efficient is the 3.08 or 2.70's rear gear w/one-to-one thru the manual box. Seems that every gear-ed transfer exacts a small energy charge. The Muncie wide ratio worked well in my coupe.
My 95 Chevy Pick-up got 15mpg as my daily. Now I have a 93 Chevy Pick-up with a V6 and it gets 25mpg. My Merc(400m/C6/3.16rear)gets about 20mpg now that I changed the rear gears from 4.11's. The RPM's dropped about 1200 with the new gears. Now it's at 2000 RPM"S on the frwy instead of 3500+ before! I'm thinking about getting an AOD tranny for it.
I get about 19-23 mpg in my '38 ford truck running a sbc 350 with six fully operational 94s. But thats with 2.70's rear gear.
I have that Granada rear w/ 3.00s... I was thinking that I'd try to find a 60's Nova Powerglide (the one with internal cooling) to run behind it... I know that 3 petals is WAY cooler, but I want to be able to fit my feet in there, too. - Joe
Our LT1 did upper 20s at high speeds in a TA. 80-85mph, 25-27mpg. 3.28 gear, 4L60E. The 61 weighs less, plan to do a basic 350 with an Edelbrock carb (boring huh?), stock or small RV cam, make the valvetrain geometry perfect, no more than 9:1 compression, regular gas, point dizzy, OD auto or stick (want my sweetie to drive it so...), and a 3.08 rear gear. I honestly expect mid 20s plus in the mpg dept at hiway speeds. Should be a perfect car for long trips to meets and such. Everything is a long trip for me so why not.
It's really just math. Weight vs. horsepower once you are at speed. The most overlooked factor is that it may only take 20-30 hp to keep a car moving at 70 mph, but if it weighs 4500 lbs and has 2.70 gears, it will take 300 hp to get it there in a reasonable time. Now you have to factor all that with the reality that it takes a half pound of fuel per hour for every HP. You can't change the physics that limit gasoline to a certain BTU of energy. You can choose components that make the most of it and combine them with gears and vehicle weight that provide the least wasted energy, but it really comes down to how much time you spend at X rpm and how much HP you make there. Those 35 mpg vettes are very slippery, light and have extra gears to run minimum rpm at speed. That's a tough thing to match with a 455 Eldorado or a 50 Ford.
Something for us California folks to remember is that our gas is different in this state. You can expect AT LEAST 10% better mileage outside of California. I have seen it time and time again. Driving my 1994 Impala, I get about 21 miles to the gallon on the freeway in California. Once I fill up at the Nevada border I get 23-24 easy. I don't think you can really compare California gas mileage to outside California gas mileage (without a correction factor). Mike
I averaged about 32 mpg with an Iron Duke 151 in my 31 roadster. It was light, fast, and fun. Wish I hadn't sold it.
Our '50 Stude did have the flat head 6 and the over drive. It got 28 plus down hill with a tail wind. Same with the MG, got 32 out of it when dropped the OD into it. But you aren't going to be anywhere near the point where the HP starts coming on if you are loping down the freeway at 1500 rpm. You'll need to downshift two gears to get the rpm back up and accelerate over a cigarette butt.
Both my cars with 225 Slant Sixes get around 20-22 MPG. Both are also hopped up a bit and running 4bbl carbs. I could see 25-30 as feasible with stock motors, single bbl carbs, taller road gears, etc...
Total speculation here, but considering the fact that my old 65 Impala with a stock 283 and a glide was getting like 20mpg, I would imagine that a similar motor with a T5 in a vehicle weighing 1500 pounds less would have to come pretty close to pulling down 30. It's all in how you drive it though. My old Porsche 911 supposedly got like 26 mpg, but the little digital gas mileage indicator never showed me getting more than 13 or 14. Yeah, I drove it a little hard.
i had a 9 second ranchero that got 45 miles to the gallon... with nothing but a carb change and some headers... but if you think back in 84 or 85 government stated that they needed to improve gas mileage... and now the government wont push the bill even more... there were electric cars at one time... if you want a 30 MPG rod, take a ford escort engine and turbo it.... you should make out with 32 or so.
A ZO6 Vette is .5-1 in 6th gear to get the mileage. Combine that with 3.42 gears and you can see why it gets the mileage it does. A buddy had an older Vette with the Nash 4 speed OD that always got in the mid to high 20s for mileage
Scottybaccus, wondered what you thought of the difference between running say: points and edelbrock torquer based AFB or Holley on a 350SBC, or using all electronic, ECU , HEI and FI? Maybe Mr Squirrel will offer some opining here perhaps?
Been following this thread for a while and have a GM 2.8 V-6 in the machine shop as we speak. Will use a wolverine camshaft a new rebuild and a adapter for a nos fish carb. Installed in a roadster hot rod , i am projecting 30 plus.... News when we start the build...
...might be of interest... http://www.jalopyjournal.com/forum/showthread.php?t=432220&highlight=brick .
64 GM EH Holden , bored 186cu.in. / worked powerglide/ 2.78 diff. getting 10L/100Km on the Hume Fwy at 65-70 mph.
i get 27 mpg with this junk. 305, 5 speed and 3;08 gears all donated from an 87 camaro.i canned the tbi and used a 600 edelbrock carb.
Skratch, The junkyard 283 Chevy, T4 tranny, 2.73 gears, 235/75R15 tires in my '29 Model A truck gets 20 mpg with 70% in town driving, somewhat aggressively. I think pure highway it would get about 21, but much over 60 mph and wind resistance really comes into play. My 1946 Studebaker truck with AMC 258 six, 727 auto, 3.23 rear with 31" tires only gets about 15 mpg. My new Model A sport coupe project is getting a Ford 2.3L with T-5 tranny, 3.73 rear with 7.50 rubber. I am hoping for 25-27 mpg with that one. A lot of times mileage is affected by geographical locations, altitudes, and fuel blends just as much as vehicle specs. I live in WNY which is about 540 ft above sea level and I usually run Sunoco gas which has 10% ethanol added. I bet that my vehicles would get different mileage in high places like Denver or dry places like New Mexico. Did you get Cherry Pie done? I saw you were going to build it in your interview on the "Back From the Dead" dvd. Josh Quick Quick Speed Shop
That junk makes me wish I'd bought the fenderless '38 DeSoto my parents' neighbor was selling for $50. I jus didn't have any vision, I guess. -Dave
48 Fleetline, 250 Mercruiser, 4bbl Edelbrock, headers, th350, 3.36 rear = 19 mpg. An OD trans and a smaller carb are planned.
22 mpg with our '48 Pontiac convert, 19 mpg with the '51 wagon. These are powered by stuff nobody here wants to hear about, so we'll leave that out. The 472 Cad in the '36 is good for just under 20 mpg overall, and it's carburated, so that one is HAMB friendly. Best mileage we ever got with ANY of our hot rods was a '48 Chev convert I put a 283 2bbl/Powerglide in back in the late 70's. It got mid 20's, with no thought whatsoever to trying to drive economically.
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