35 MPG 1966 Chevelle

[67-ls1]

I'm new here and thought I would share my project. I know that a 35 MPG goal pales in comparison to some of your achievements, but I think it's a pretty aggressive goal for a old Chevy.
My project started out as a 283 V8/2 speed auto, 2 door Malibu. I weighed it with very little fuel in it prior to tear down and it weighed 3,172 lbs.
I bought an all aluminum 3.8L/220 CI V6 and a 6 speed double overdrive automatic transmission from a 2013 Camaro. The Camaro shows that it weighs approx 3,850 lbs. I never got to weigh the actual doner car.
My goal is to bring the finished project in at around 2,850 lbs. The new engine/trans is a lot lighter then the old iron V8, I have added lighter suspension and brakes, will use lighter weight seats, aluminum radiator, aluminum wheels, fiberglass hood, etc. I don't think the 2,850 lbs will be tough to reach.
The Camaro's EPA rating on the highway was 30 MPG. I believe that my car being approx. 1000 lbs lighter, lowered 2" from stock, a front air dam, and whatever other tweaks I can add, 35 MPG is a realistic goal.
What do you guys think?

[ksa8907]

Sounds like an interesting project for sure! My only concern for you is getting all the electronics for both the engine and transmission to be friends.

I will be doing something similar in the next decade. My dad has a '64 chevy stepside that has been sitting in their barn since before i was born ('89). Since there is no money in restoring it to factory, I will be installing a v6, probably turbo charged and a 6speed tremec. 3300 lbs stock. Though when I build this truck I won't nearly as concerned with mileage as fun.

[Insight for life]

Welcome! You are close to me! Looks like a doable goal.

[Frank Lee]

Looks like a double goal to me.

[CAPTAIN CHAOS]

Personally I love your idea and your plan.
I’ve wanted to build an old car to drive that would get acceptable mileage for some time now but time/money constraints have prevented such a project. I have a 69 Mustang I’m trying to finish up now but it is being built for anything BUT mileage. I’ve often daydreamed about a 64-65 Falcon with a 2.0L 4 popper swapped in getting 35-40mpg. If I could pull off that feat with a wagon version that would likely be the last car I ever buy as I’d drive that thing for decades! I used to drive vintage cars almost exclusively and I loved every second of it. Gas prices drove me out of that and starting a family has slowed any kind of progress towards building/modding one to drive (though it is in the long-term plans).

As far as your plan. I think you’re on a good path. However, I don’t know if I would focus quite so heavily on weight reduction (unless you just have oodles of money to blow). I’d probably just grab the ‘low hanging fruit’ on weight reduction and work more on ideas for decreasing drag, especially aero drag. At 3100 and some change your car is already pretty light by modern standards but the aero is almost certainly a wreck. The real trick will be making it ‘slicker’ through the wind without ruining the sweet lines of a classic car. The aero, I think, will be the biggest holdup towards reaching your goal.

I for one would LOVE to read about your progress and how the project goes so keep us posted.

[Daox]

Sounds like a fun project. I agree with the captain though. I'd focus on Aero before weight.

[exccel]

I posted something on here earlier about growing up with a 1960 Chevy Impala 4 door with 283, 2 speed powerglide that routinely broke the 20 MPG on the highway with 4 people in it and a trunk full of suitcases. So I dont think the 35 mpg is out of the question but I read somewhere that a 100 lb reduction in weight was only about 1/10 of a mile per gallon improvement. So I agree with the other folks that say to put less resources in weight reduction and more time into Aero and driving technique. Good Luck

[user removed]

I sectioned and channeled a 49 Plymouth businessmans coupe and put it on a Nissan pickup truck frame with a 240Z engine and transmission. The weight dropped from 31-3200 to less than 2400 pounds, just about what the original Z car weighed.

With a newer, much more advanced engine and transmission, you should be able to get to 30 MPG but I think 35 will be a stretch un less you stay below 55 MPH, where the aero is not so significant.

regards
mech

[ChazInMT]

I hate to rain on this parade, your cause is very noble. I think a 66 Malibu/Chevelle will be aero limited at highway speeds to 30mpg or less. The 2 things that really kill you that can't be modified are illustrated below. The front end is a bull dozer plow. The idea for efficient aero is to have as much of the air hitting the front of the car to go around the sides and top, and as gently as possible, get it headed that way. The Chevy front end is quite the blunt instrument.



The second major issue is the transition area at the top of the windscreen to the roof, if you look at the most aerodynamic cars being made today, this transition no longer exists, it is just a smooth arch.



The real big issue is that the air will be so disrupted by these 2 areas it will never have a chance to smooth out and take advantage of any aerodynamic enhancements made to the rear of your car. It's pretty much a brick.

I think at moderate speeds and driving around town, you'll get way better mileage with the new engine, at 40-45 you'll get maybe 34mpg give er take, but as you get much over 45-50mph you're MPG will start to go down.

Again, I just wanted you to understand why we say the aerodynamics is a fly in the ointment for your cause, I hope I didn't offend you here.

[Hypermiler1995]

may need to do this
that would fix the windshield transition. :/