Something I always ponder...a daily driven gas mileage hot rod

How many MPG's are acceptable for you? A small old carbureted engine with overdrive in a light chassis may suffice, while not getting too far into complexity. I set out to do what your talkin' about 15 years ago when I found my '39 Willys. It has a basically stock 289 Ford with a $100 junkyard AOD/ 3.56:1 gears, and pieced together A/C.
I get about 21 MPG on trips, about 17-19 running around Atlanta. Am now approaching 100,000 miles, and reliability has not been an issue.
I've never made the leap to EFI in my project cars. My opinion, for my skill set, is if everything management-wise is OEM factory transplanted stock, I might be ok, but to start mixing and matching lots of pieces and using low production, here today, gone tomorrow aftermarket latest EFI stuff, I get thoughts of being alone on the side of the road in BFE with my cell phone, panicking. I don't have that feeling with my Autolite 2100. I'm sure a lot of younger guys would be lost looking at that, YMMV!

 

Food for thought ... the 3.7 Ford V6, base engine in Mustangs 10 years ago are 305 HP. They do this n/a, no turbo. I believe it is a six speed transmission behind it. My 2012 Lincoln MKX came with the same motor but turned sideways for front wheel drive. That car has 188,000 miles on it now and I have only had to do standard maintenance and put a new throttle body on it. I would hope a standalone computer could make it run. The Lincoln gets 26 mpg hwy, but I have seen an instant 37 mpg while driving 45 mph behind a semi that was taking all the aero drag off of me.

 

One thing I never hear anybody talk about:
When gas prices go up, you hear people talking, "I got to get something that gets better mileage than what I have now" Well, that's good and all, but how many consider the extra cost it will be to get that better mileage vehicle, and how long will it be before the better gas mileage pays that difference? Of course on an even trade there would be no cost difference, but most vehicles you either have to pay a difference in higher price or pay he cost of building it yourself if you're like most of us. There are deals out there you run across for cash, but still, how long will it take to recoup that purchase price vs buying a little more gas? There is a lot of difference in going from a 10 mpg car to a 40 mpg one, but not many of us do that, we want something simular in size and power to what we already have and any increase in fuel mileage will be much less than anticipated. I've seen a few older folks go from a Caddy or even a Crown Vic to a Escort or VW Rabbit sized vehicle, only to go back to their larger car not long after.

Just do a little figuring--Current MPG of a vehicle you already have--Projected MPG of replacement vehicle--How long to recoup your investment using the greater MPG only. I think you will be surprised, and will really be surprised if you add in higher insurance and regristration costs. That old paid for beater just might be your cheapest transportation!

 

Volvo red block engines

 

My sbc powered Mazda RX-7 gets a little over 20mpg, has been 5.73 in the 1/8mi with a 1.30 60'...

2325lbs with a low compression 355 with a 625 Carter carb backed by a Toploader 4spd and 3.73 rear. No overdrive, 2800rpm is about 61mph. Key to 20+mpg in my case is low tension piston rings, certainly not the 251/261 cam or the 348cfm -11RI sprint car cylinder heads. Key to the 5.73@125 1/8mi with the low compression engine is a nitrous plate.

Grant

 

I kicked around a 267 for a lightweight daily beater
Uncle had one in an elco. Got low to mid 20s with a th350.
Add efi and an OD.

 

Dumb ? What’s a Volvo red block?
Dan

 

Agreed. I had an enviro nut get on me about my hot rod. Said, "why don't you do any mods for gas mileage?" I countered that because unlike chasing performance, mileage mods are usually done for economic reasons. And any $$ spent to gain mileage needs to be recouped, or it's wasted effort. How long would you have to drive to pay for a modest mileage improvement?

 

Volvo 4 bangers from 74 to 98 ish
Had one in the 90s. Turbo car. Fun to drive

 

Plan on a 12v Cummins swap in n my bus (maybe)
The 500 inch caddy gets 6/8 mpg
Selling the 500 would just about pay for the Cummins. The fuel mileage difference would recoup the rest n probably 6 month of driving

 

In the most recent Rodders Journal is Jim Jacob’s Model A roadster with a GM Mercruiser 4 cyl which I believe is the iron duke motor they used from Chevy II’s all the way into the 80s. That with a T-5 has gotta be a gas sipper but not a total dog either.

 

Ford 2.3 with a turbo (and an adjustable wastegate ).

Just find a donor with factory turbo, and you have everything you need (except the adjustable wastegate). Easy way to add 50 percent more HP. Factory wastegate was set at about 5.25 psi. Engine was designed for 7.5 production, but management dropped the boost.

If you go this way, just remember the turbo uses engine oil pressure. ALWAYS idle the engine for 15~20 seconds before shutdown to allow the turbo to spin down with oil pressure. GREATLY increases the longevity of the turbo. This tip given to me by the lead engineer on the engine when I special-ordered one in 1979 (still have it).

Jon

 

I just bought a new Caddy....turbo 4, 8 speed auto, the cheapest cadillac there is. Averaging 30+

 

It is true that once you get past around 20-22 mpg, fuel savings costs you money to accomplish.

But, its also true that if you are starting from scratch to build an old car, there are many options for better mpg that may not add any, or very little cost to the project.

If you need to buy a motor/trans, in this day and age, there are some very fuel friendly combos that would add very little to the up front cost. Those old favorite motor/trans combos from the early 60s are not so plentiful to find in drop in and use condition. If either has to be rebuilt, you would be starting out way behind then if you had found a modern efi motor and trans in good used shape that can be dropped in and used for another 75,000 miles.

Lets get real, most of our hot rods won't see 75,000 miles, but if your planning to put that many miles on, rebuilding any drive train would be expected, so that cost is a wash. If you are really comparing costs, if you just buy a beater, and your planning on using it more then 75,000 miles, you need to consider the cost of it getting to the same finish line.

When you play the mpg game, if your not setting a miles of use target over so many years, your going to loose. But you also have to consider the hard costs of even getting the chosen vehicle that drive that distance, or you are just fooling your self. Those vehicle cost over those miles has to include all the costs to get there, fuel mileage, tire cost, brake costs, all the vehicle maintenance costs, then divide the total of all those costs it by the intended miles and then you get the true cost of the mpg your getting.

My coupe gets better mpg and cost less to build then my truck does. But the coupe sat parked for 3-4 months every year. If it was the only ride I had, I would have to include the costs associated with whatever I had to drive those 3-4 months every year, when the coupe was not used, if I want a fair comparison. Even at 1/2 the mpg through the winter months, and 3-4 lower mpg the rest of the year, I suspect the truck is very close when over all costs are figured.

Just one more thing. I've had a lot of turbo 4 cylinder cars with OD. Their mpg is just about the same as my efi, V8, OD, 4x4 truck, on the open highway. Unless you are better restrained then I am, don't count on the turbo 4 to get huge mpg numbers. My 90-2000 turbo 4 stuff, was 23 mpg at best, and that was pretty rare.

 

It's been mentioned already, but I've always been a fan of the Ford 302/T5 combo. I had this with a 600 Edelbrock in my old '62 Ford Galaxie and would get 20 mpg on the highway. I can only imagine it would be better in a lighter vehicle.

Also, here's a spreadsheet I threw together a while back. Based on $3.29 average gas cost and 10k miles a year, 16 mpg to 30 mpg is only approx. $1,000 savings per year.

 

but look at the savings from going from 12 to 16....

 

Speaking from Newsom and Harris land, 3.29 for gal of gas sounds like some kind of dream. We pay almost 5.00 now and It will probably go up after the election. How anyone could afford to build now mystifies me.

 

Keep in mind, MPG is not the only thing in scope here. I am looking for a small footprint engine for a car with a relatively small cowl area and full hood. I'm not building for just mileage, but resale as well. If I buy a beater Ford Focus for $3K and drive it for say 3 years, it will probably be worth in the $2,000-$2500 range.

If I build a little fender less roadster pickup, I may have 6 grand in it, granted if I junkyard source and swap meet all my parts, and at the end of 3 years, it should bring in the 10-12K range. I am looking heavily at the 2.3 Duratec. There are stand alone harnesses for those all over the place.

Also, I don't wanna beater. I have been driving them my entire life.

 

We are right around $3 here in Omaha, Nebraska right now, thankfully.

 

Or from 6

 

I have pondered building a little 283 with a small 4 barrel say maybe 500 cfm with a small hydraulic roller cam with a range of 0-4500.
A five speed with a 3.73 gear in an 1800 lb car. Should be able to get in the low 20’ms easy enough.

 

I got 18 pretty consistently with the Vette, 327, small 4bbl (more like 300 cfm), muncie, 3.08 gears, 2800 lbs, very mild hydraulic cam. Then I changed everything on the engine and now it gets 12

 

But it is more fun….

 

Still some work to do to get it all going right....

but it sure runs cooler with the aluminum heads

 

I had a 66 Impala with a 283 2 bbl a three on the tree with I’m guessing mid 3.00 gears I got 20+ mpg but that was back in the 55 mph days. IMO a mild 283 with an OD trans in a light car should be good for up to 25mpg
Dan

 

Find a late 70s 10 bolt and swap the gears in whatever. You lose performance but gain mpg.

I had a 1978 2 door caprice. Installed a brand new gm performance h.o. 350 (330hp, 9:1 cr and mild cam) with a edelbrock 600 on top. A turbo 350, 2400 stall converter and 2.41 gear set in the rear. The car was a slug off the line (2.3 60ft time with ZERO TIRE SPIN) but cruised great with a 30inch tall tire. My absolute best mpg was cruising 65-70mph at less than 2k rpm and getting 26mpg. Mix of city/hwy it averaged around 18-19mpg

 

The merc is getting a 283 basic MT -1 cam and I have a tri power. It’ll run of the CENTER Rochester most of the time. Rounded up a 3speed OD.
Car has 3:92 gears. The OD is .70
Should have good mpg
I have 2 Chevy TBI set ups. I might use one on my other build. Those are simple

 

My brother and I almost built a V6 swapped car a few years back. We bought a 1989 Taurus SHO with the dohc Yamaha motor for a few hundred to use in a demo derby. Afterwards our plan was to mate the motor to a M5od trans to convert it to rwd. We had a friend willing to donate a 63 falcon to the project but we got a good offer to sell the engine so we let it go instead

 

Real mileage savings are from the car not the engine.
If the car is a heavy aerodynamic brick driven at high speed ,you are doomed to pay the price.

One modification I always recommend is "Learn to Momentum Drive" [this is a technique road racers do to squeeze extra speed through corners so exit speed is higher.
Except you apply this technique to light throttle applications, and watch the economy climb.
Momentum Driving is not Hypermiling [life is too short for that]

I regularly get a 25% increase [over EPA rating] using this technique. For example 36mpg from my C7 Corvette.

For a fresh build econobox hotrod, look at the Rover/Buick 215 V8 [all alloy]
raise the compression as much as economically possible, and starve it back with camshaft timing. Use an old Edelbrock SP2P intake and 390 Holley.
Then stack a 5-6 speed manual trans behind it ,also look at low rolling resistance tyres as well

The idea is to increase the driveability at lower RPM [and driver skills to do this] without laboring the engine
In a lightweight hotrod it should easily get 35+ mpg and a bit of performance "on demand"

 

This looks like it’s from the twenty’s.

The only thing that shudder is the fact that it’s a Quad four.