I want to build a 100-mpg car (and I want it to look vintage)

[sgtlethargic]

Originally Posted by aerohead

AeroVironment

Sidenote: Years ago I was interested in working there, then their unmanned air vehicles became involved with militarism.

[changzuki]

Originally Posted by ProDigit

Edit: Like mentioned in the beginning of this thread, a diesel might get the MPG you'd want, and if you're ok with no acceleration, you could even hit 120MPG. The Kubota engines are probably going to be able to get the job done, however they're not a very pleasant engine for that purpose.
They are pretty low power, and don't have much reserve (meaning, you'll run a pretty low acceleration down low, all the way to up top of the rev range.

This is a great thread! I would encourage the original poster to set an initial goal and then go for it! Win-Lose-or Draw, the journey to get there and the educational experience are both priceless!!! There are plenty of tried and true basics as seen here on ecomodder and elsewhere that do work - prove it to yourself with your own project; that is what I did.

As for the Kubota.... I do agree they are pretty low power as advertised, and like so many others, I had a preconceived notion it couldn't fight its way out of a wet paper-bag - that's one of the reasons for actually doing the project. All said and done, acceleration is generally not an issue - especially down low. They key is to match everything with the engine's abilities. To put this into more realistic terms, at the Green Grand Prix, the little 17hp D850 Kubota was hauling a 1080 pound car and two passengers (round the entire mess up to 1400 pounds). To compare that with newer cars, multiply everything by two and you get a 2,800lb car with 34 horsepower. Multiply by three and you come up with a 51 horsepower car that weighs a total of 4,200 pounds - either of these sound like a real winner right? Well, that's the reality of the build and the results still stand today. Travelling several hours down the interstate with traffic - no problem. Then during any of the three Green Grand Prixs there was no need to take it out of its top gear even up that crazy hill after turn #1. RPM's were low (like 1850ish in 8th, or "4th gear in high range" depending on how you want to label it).

Lastly, and to prove the acceleration issue, the car drove to, and rode in, the "Grand Prix Festival". Prior to the event there was a similar concern and I had to assure the Rally (oops, parade) organizer multiple times I could keep up with the group (specifically up the first hill by TOPs gas station). Failure to keep up at anytime during the event, would result in being pulled from it. The car ahead of me was a nice Bugeye Sprite convertible that I could've easily pushed up that hill. The Ford Anglia behind me failed partway up the hill and nobody caught up during the remainder of the two laps. There's no particular problem with the little Kubota if it's setup correctly.

Battery technology needs to make another magic leap and if it does, Centurion's 250mpg record may likely fall by way of a gorgeous fully electric version (which is the third version of these cars sitting here in storage - behind the little gray and black one.) Until that happens, the bar for the tiny Kubota Diesel is very high. It's still running great and continues to see invites to vocational schools, etc...
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~CrazyJerry~
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[ProDigit]

One thing hybrids all have wrong, is they all expect to have gasoline engines that have sufficient power to accelerate the car at highway speeds, and their electric motors are 'helper motors'.
That pattern of thought is just plain wrong.

Instead, what they should do is base a hybrid on an all electric vehicle, cut the battery by 1/3rd to 2/3rd, and the weight savings, stuff a 'helper engine' in there.

With that I mean, the electric motor needs to be powerful for high regen braking and acceleration.
All the while, in the front have a 2 cylinder 400-600CC ptwin engine, that has enough power to keep you cruising, but no acceleration power.
A 600cc engine could keep you cruising at 60MPH with no trouble. Gear it right and you'll get good gas mileage.

Doing it this way, you can combine a 104eMPG motor, with a 100MPG engine.

The good is, if you're running the engine below 60MPH, you can charge the battery on the go.

All you need is some gear slider.
Eco gear runs the engine at lowest RPM without lugging ~1000-2000RPM (fully gasoline, no charging).
-1 gear runs the engine at higher RPM (torque peak 2000-4000 RPM), drive slow, and remaining power is routed to charge the battery (maximum efficiency).
-2 gears, runs the engine at a high RPM (close to HP Peak 4000-6000RPM), Rout as much power to charge the battery as possible (less efficient, for more quickly charging a drained battery).

You don't really need a big battery for this.
A 35 mile battery, with the possibility to charge while driving at below 60MPH gets you enough range to basically run indefinitely (like a gasoline engine).
At >60MPH (eg: 80MPH), a 35 mile all electric battery charge, could possibly get you 100 miles or more, as long as the helper engine is running the brunt of the load.

All you need is about 5HP to do 45MPH, and 12HP to do 60MPH.
If your engine is rated at 20HP, you could probably hit 65-70MPH, and let the electric motor fill in the remaining energy at anything above this.

Reducing the battery pack by 50-66% is reducing the biggest cost on an electric (hybrid) car!

[ProDigit]

Originally Posted by changzuki

This is a great thread! I would encourage the original poster to set an initial goal and then go for it! Win-Lose-or Draw, the journey to get there and the educational experience are both priceless!!! There are plenty of tried and true basics as seen here on ecomodder and elsewhere that do work - prove it to yourself with your own project; that is what I did.

As for the Kubota.... I do agree they are pretty low power as advertised, and like so many others, I had a preconceived notion it couldn't fight its way out of a wet paper-bag - that's one of the reasons for actually doing the project. All said and done, acceleration is generally not an issue - especially down low. They key is to match everything with the engine's abilities. To put this into more realistic terms, at the Green Grand Prix, the little 17hp D850 Kubota was hauling a 1080 pound car and two passengers (round the entire mess up to 1400 pounds). To compare that with newer cars, multiply everything by two and you get a 2,800lb car with 34 horsepower. Multiply by three and you come up with a 51 horsepower car that weighs a total of 4,200 pounds - either of these sound like a real winner right? Well, that's the reality of the build and the results still stand today. Travelling several hours down the interstate with traffic - no problem. Then during any of the three Green Grand Prixs there was no need to take it out of its top gear even up that crazy hill after turn #1. RPM's were low (like 1850ish in 8th, or "4th gear in high range" depending on how you want to label it).

Lastly, and to prove the acceleration issue, the car drove to, and rode in, the "Grand Prix Festival". Prior to the event there was a similar concern and I had to assure the Rally (oops, parade) organizer multiple times I could keep up with the group (specifically up the first hill by TOPs gas station). Failure to keep up at anytime during the event, would result in being pulled from it. The car ahead of me was a nice Bugeye Sprite convertible that I could've easily pushed up that hill. The Ford Anglia behind me failed partway up the hill and nobody caught up during the remainder of the two laps. There's no particular problem with the little Kubota if it's setup correctly.

Battery technology needs to make another magic leap and if it does, Centurion's 250mpg record may likely fall by way of a gorgeous fully electric version (which is the third version of these cars sitting here in storage - behind the little gray and black one.) Until that happens, the bar for the tiny Kubota Diesel is very high. It's still running great and continues to see invites to vocational schools, etc...
-
~CrazyJerry~
-

-

The good about this low-revving engine is you can do with a very simple transmission. Do a 3:1 reduction (3 revolutions on the engine to 1 revolution on the wheels), which is just 2 cogs, and you'll get the best MPG with that (no transmission).
The problem might be acceleration from a dead stop. That's why an electric helper motor might work.

[aerohead]

It would be instructive to take a specific hybrid vehicle, and work through your methodology, and see where it goes.
Personally, I'm of the opinion that they've already got it right.

[Stubby79]

Originally Posted by ProDigit

Instead, what they should do is base a hybrid on an all electric vehicle, cut the battery by 1/3rd to 2/3rd, and the weight savings, stuff a 'helper engine' in there.

Chevy Volt & BMW I3 and/or I5.

Me, I like these plug-in hybrids that can do 60Km on a charge without ever turning on the engine...I'd need like 2 tanks of gas a year, and no need for a second vehicle.

[ProDigit]

Originally Posted by Stubby79

Chevy Volt & BMW I3 and/or I5.

Me, I like these plug-in hybrids that can do 60Km on a charge without ever turning on the engine...I'd need like 2 tanks of gas a year, and no need for a second vehicle.

No, the volt is not direct drive. Too much losses converting gasoline into electric.
It's efficiency would go up, if the generator engine was directly driving one of the wheels (through a simplified gearing system).

[JohnAh]

I think it may be clever to base an eco-vehicle on a real vintage car, as long as you chose one that have some aerodynamic basics right, particularly in the front. Very few cars have a good rear end when it comes to really efficient aerodynamics, so adding a DIY boat-tail to a vintage car with a more rounded front may give a good platform to start with. Chosing a vintage car makes half the build done, as you get at functional chassis with simple components.

The big question is WHAT vintage car to chose. I should be obvious to chose the smallest car possible, off course with a smooth and rounded front, not the trapezoid shapes from the 1970's. I'm actually planning to let my next car project be an extreme eco-vehicle, based on an old Saab 96. The front is rounded, the wheels are far inside the fenders and almost the entire lenght have a perfectly flat belly. The rear slope is too steep, but that can be modified, and the same goes for the windscreen. I plan to attach something like a boat tail, but the most drastic modification may be to cut the roof in half and create a narrow tandem cabin to reduce projected frontal area. This may not do much in itself, but it allows a both shorter and more efficient boat tail.

For engine I hope a tiny 2-cylinder Kubota diesel may give an acceptable cruising speed, then I have two electric motors that may add another 50% of temporary power for acceleration. I'm an electronics engineer, therefore I plan to keep the electronics simple! ;-) Regenerative braking is nice to have, but it seems to be something of a marketing scam, fooling EV-buyers into thinking that braking returns you all the power, when it in fact only recycles 20-30%. For an electric or hybrid DIY vehicle the electronics and batteries can be kept much more simple and cheap if you skip the regenerative braking and instead improve the driving skills. "Driving Without Brakes" is a verry rewarding practice in any ordinary petrol car! -Learn from NASA and spaceflight, never input more power into the equation than you need for any part of the mission!

[ProDigit]

It was my suggestion to an engineer who wanted to create a bath tub that was propelled in the air by 6 or 8 electric propellers.
He was complaining about low range.
Especially for in the air, you'll want to keep things as light as possible, so I suggested him to use a small (~100cc) 2 stroke engine to use as main propeller, to keep him in the air; while electric propellers are more effective for short boost bursts, which can be used to create stability with wind gusts, or turning the vehicle.

For cars, weight isn't that important, and 4 strokes might be better.

[Cd]

I didn't read all the pages of this thread.
I did see you want something vintage looking , and need grear aerodynamics.

Why not try and buy the PriaGhia if he is willing to sell, and further modify it into this : https://ecomodder.com/forum/showthre...shop-6720.html