35 MPG 1966 Chevelle
 

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?

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.

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

Looks like a double goal to me. :confused:

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. :D 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. :thumbup:

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

35 mpg
 

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

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

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.

http://i62.tinypic.com/skyr21.jpg

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.

http://i59.tinypic.com/14v5kib.jpg

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.

Attachment 16613

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

Brakes isn't the place to go light. Go as big as you can, there's no such thing as too much brakes. And it doesn't have to be costly if you have any metalfab skills. Sell the 6L80E to buy a used T56. That right there will be 2 MPG.

Smart move w the v6 6speed tranny! Before I read I was thinking a straight six w a manual

Very true. If you are serious about aero, Google "1969 Dodge Charger Daytona" and look at what they did to the nose.

Love this project and say don't let aero be a reason for not doing it. At the end of the day you'll still have a nice car you can drive everyday which is better than I'm doing with my 5.3 getting 17MPG. The swap should be no harder than any LS engine project. I'm sure painless or PSI can hook you up with a stand alone harness and tune. Did you get the gas pedal from the donor car?? To keep things simple its best to get the pedal so you know it will play nice with the computer. Other concern is if the Camaros have electric power steering, not sure if they do but to save more weight and paracitic drag you can the manual steering route.
Don't worry about aero, put a barn-door style air dam on the front like the Bonneville cars, block off and seal up as much of the font end as you can while maintaing cooling ability and start plowing some air! Won't know what MPG its capable of getting until you try. It's nice that you'll be able to use an OBD2 gauge to monitor things too :)

Last thing: take lots of pics and share them with us!

Or even more serious, Google "1969 Plymouth Barracuda Blowfish"...

I have a lot of pictures, but this site won't let me upload them because the per pic size requirement is really, really low.

Only so much I can do with aero. I'm not willing to change the exterior look too much. I'm leaving the passenger side mirror off, so I got that going for me.

Weight is about the only thing I can reasonably reduce. Again, nothing that will change the classic looks. And the height. It will be low and slightly raked.

The engine/trans are in, the harness and ECM are being modified for me by a guy in Topeka, KS, brakes and suspension are all done.

I am using the Camaro throttle pedal, MAF/IAT sensor, I am going to run catalytic converters so staying with all 4 O2 sensors, external electric fuel pump feeding the engine driven high pressure pump (this engine is direct injected). Two electric fans (staggered on) will cool the engine. I am not running AC because the frame was in the way and I already had to rake out a big chunk to clear the oil pan.

I'll try to figure out how to take some low-res pics and post.

Dennis

Many photo editors can knock the size down.

Upload images to somewhere else, right click on the image and get the IMAGE URL, then come back here and click the little landscape icon, and paste it in.

Done!

.

Ditto.

A tastefully done air dam would not take away from the classic look. The grill and other areas can be blocked from the backside with various materials (coroplast, aluminum, plastic, weather stripping) and not affect the classic look.

I had a 1989 Buick Electra Park Avenue Sedan with a 3.8 that was rated at 19/28 mpg (U.S). With a little more air in the tires it would regularly get 30-31 mpg on a trip at 60-70 mph with no aero improvements. It weighed 3,350 lbs.

I think your goal is achievable with some driving adjustments and a scangauge or ultragauge to see what works and what doesn't.

However, what I haven't seen listed is what rear end ratio the car has, and what size tires are you planning on using. (Important stuff)

Cool project...


:)

>

I'll try getting some photos up.
And I can do small aero mods that won't change the looks to much. An air dam will definetly be added.
The rear end ratio is 3.07. It came stock in the car. The tires are 26.7" diameter or 782 revs per mile.
I can revise these if need be once I get it running and get e better idea of speed vs rpm.
I had not thought of a scan gauge but will look into them.

Dennis

Depending on the look you are going for, you should be able to step up to a 28" tall tire without issue. I love the look of the 255-60-15s on my Monte Carlo. Not sure you want to go that wide but the height is good if you can get it in a more narrow tire.

The G-body cars have an aftermarket air dam that isn't ugly or obscene, you might be able to adapt one to your A-body, but chances are that the a-bodies have a better aftermarket than the Gs.

Thanks for the tip about the G-body front spoiler. I'll check it out.

Pics..
http://i904.photobucket.com/albums/a...imagejpg13.jpg

35
 

*From a recent article from Michelin,it looks like if the Camaro actually got 30-mpg HWY,then the 1,000-lb weight drop would fetch 32.58 mpg.
*The Camaro is around Cd 0.39? compared to around Cd 0.45 for the Chevelle.
*Don't know about the frontal area difference.
*You're doing disc brakes and that's gonna hurt a bit compared to the original drums.
*A hidden grille-block could help (ala 'Crisis Fighter Pinto ).
*Electric cooling fan would shave some parasitic loss.
*Same for airdam.
*Lowering won't affect Cd much but it would cut frontal area a smidgeon.
*LRR tires wouldn't hurt if you could live with their 'look.'
*Maybe a modest rear spoiler.
*Under body smoothing wouldn't add much weight,you'd never see it.
I think you've got a shot at it,if the Camaro powertrain lives up to its BSFC promise.:)

I put the body back on temporarily to check transmission clearance. There was none.
I had to cut the transmission tunnel out.
I also put the front clip back to take some measurements for the radiator/electric fans.
http://i904.photobucket.com/albums/a...imagejpg18.jpg

That trans is huge! I'd like to see a pic of it next to an Allison lol. Looks like you'll be cutting out a lot of floor, hopefully you can still use the factory seats and console once all the clearancing is complete.

Here is the hole I cut. I will need to cut further back to make clearance for the driveshaft.
The stock console won't work but the stock buckets should still fit.

[IMG]http://i904.photobucket.com/albums/a.../imagejpg3.jpg[/IMG]

[IMG]http://i904.photobucket.com/albums/a.../imagejpg4.jpg[/IMG]

I think that most people could agree that no matter what mileage your ride gets when it's done, it'll be sweet. I know of an LS-powered 69 Camaro with a 6spd that got 27mpg so I'd say 30-35 is definitely possible. I do know from driving bricks, that speed kills (mpg that is). My 89 would only get about 19mpg at 75mph, but 24-26mpg at 60mph.

Edit: a grille block should help a lot, at least it did on my other Dodges. Picked up a solid 2mpg with one.

I had this type of experience with my old Chevette. The aero was horrible, but since the diesel engine was so efficient, I could get 40-55mpg depending on driving style and traffic. The cd was so bad that I couldn't even do pulse and glide driving, as soon as I let off the accelerator, the car felt like you threw an anchor out.

A 2013 Camaro 3.6 automatic actually gets 37.4 mpg on the old highway test before applying correction factors as nobody drives like that. Still that means that it gets even higher then 37.4 mpg steady state highway at 55mph.

i can confirm this, my CTS with the non-DI LY7 will give mid to high 30's MPG at 55mph. getting those 3800lbs up to speed is what kills it. that and i have an intermittent pinging that im sure is costing me mpg from poor power and knock retard.

I'm not so sure on speed killing MPG but I have a very different experience with it. My Monte used to only get about 15-18 mpg with the original engine/trans and 3.73 gears. One year I needed to do a lot of driving for a summer job/internship so I found a 2.29 rear from another car and threw it in. Doing the math to see what RPM was 65-70 I was cruising at like 1600RPM and the engine was lugging and got terrible mileage. So I sped up to whatever speed was 2000RPM and jumped up to 25MPG consistently. So faster was more efficient but more so because of BSFC of the engine than the speed itself.

This is the delima when people don't look at all the factors! Good job on your part to find the root cause!
Taller tires work but it is possible to go 'too tall' causing the engine to bog as you described.

Chaz's comments seem to contradict what I believe Aerohead has commented on before: that as long as the front end isn't too bad, the rear template aero stuff will work well. So, I plan on doing a 61 Ranchero and am wondering if I could get to 40, maybe even 50 mpg highway with a 1.6L Pinto engine and aero mods.

I think you guys are somewhat over-enthusiastic. My 2.3/5mt has to be driven carefully to attain 35+ and my 2.3 a/ts will only get near 35 on the very best of days and my 2.0 a/t gets 35 driven "normally" and over 40 driven very carefully; these are all cars quite a lot smaller, lighter, have fwd, and are more aero than the Chevelle. Someone mentioned if one car got 27 then 35 should be easy... Nah, I disagree. 35 is a LONG way from 27.

Still, 30 would be a good achievement. And if it can get 35 I'd be happy to be wrong!

I dig the old school vibe, but the technology behind the new cars is insane.

I mentioned the 27 vs 35, but that was a V8 that got 27, and this guy is using a V6, which is where my guesstimation came from. Apples to Oranges.

I say the Camaro can get 37, I doubt the Chevelle will. Sometimes old cars with carbs would do better at certain rpm because they were tuned that way, or should I say weren't tuned properly in all throttle and load posisitions. I bet that is what was going on with the above mentioned Monte Carlo. Get the mixture and timing right at a low load 1600 rpm and it would have had better mpg then at 2000. That or it had an aftermarket cam in it. So many times people would over cam those old school engines.

The cam was stock but the SS did get a "hotter" cam than the regular Monte Carlos so maybe my sweet spot was a little higher with it being an SS. The carb and timing were adjusted by the computer so I should have had a more efficient set up compared to an old school completely mechanical set up. I'm not entirely sure an you can tune for a specific RPM when the cam shaft is still playing a major role in the efficiency equation.

I was under the assumption that the new Camaro aero was pretty terrible so I thought that the Chevelle might not be much worse. With an air dam to reduce under car turbulence I think the gap closes ever farther. I really didn't think old cars were THAT bad in the aero department.

2010 camaro .36cd

60's-70's typical car .45cd+

Oh I thought you were talking about an early 70s Monte, the 80s shouldn't of had that problem but the problem they did have mid 80s was they couldn't figure out ememissions. Also the computers were programmed without the ability to learn so when you move it out of it's normal operating range it may have done bad things to the air/fuel or egr, etc.