Does lowering drag improve Acceleration?

[Phase]

So lower drag pretty much Would help me more when I’m passing slower cars on desert roads?

Sometimes the speed limit is 65/70 and one lane and you gotta stomp it to pass 3 cars following behind a slow Rv going 45/50 mph

I’ve hit 110 mph before for a second when having to pass a slow train of cars in the middle of nowhere in Arizona/Utah

[The Toecutter]

Originally Posted by Phase

So lower drag pretty much Would help me more when I’m passing slower cars on desert roads?

Sometimes the speed limit is 65/70 and one lane and you gotta stomp it to pass 3 cars following behind a slow Rv going 45/50 mph

I’ve hit 110 mph before for a second when having to pass a slow train of cars in the middle of nowhere in Arizona/Utah

The nice thing about low drag is that at very high speeds, acceleration improves greatly, and if you have appropriate gearing for it, so too does top speed.

A typical musclecar like a base model V6 Dodge Charger needs somewhere around 300 horsepower to hold 160 mph. The Opel Eco Speedster could reach the same 160 mph speed on only 112 horsepower. From 120+ mph, their acceleration is probably comparable. The Eco Speedster's low drag also allowed it 94 mpg US combined, with 113 mpg US on the highway.

If you want to improve acceleration at the low end, you need either more power, or less mass. The latter has the benefit of improving fuel efficiency, most especially during acceleration.

People usually think fuel efficiency and performance are mutually exclusive, but it is the opposite that is true. The problem is our cars are designed totally backwards, to make rich people even more richer, at everyone else's expense, as opposed to getting the best performance and operating cost out of the vehicle.

If I ran Stellantis, the Dodge Charger Hellcat would be a streamliner of a land yacht that got close to 50 mpg highway, and was geared for 270 mph top end, using the same 707 horsepower V8 and there would be an EV version competing with the Tesla Model S PLAID.

[aerohead]

https://www.omnicalculator.com/everyday-life/0-60I'm in the ' it's conditional' camp.
With graph paper and some starting assumptions, you could calculate your average velocity per each second of acceleration, and take a look at your 'residence time per velocity regime, up to 60-mph.
It requires differential equations for accurate values, as rolling resistance, aero drag, available power, torque, gearing, friction due to transmitted power, tribological losses, polar moments of inertia, engine accessory losses, ................ are all conspiring against the car in real time.
You might find some calculators online.
My gut feeling is that 0-60 is a 'drag race' and it's all about power-to-weight ( mass ).
High speed passing would be another kettle of fish, and aero would be more 'visible'. Bonneville and Homeland Security demonstrated that for me.
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I'll try for a link

[AeroMcAeroFace]

Originally Posted by Phase

So lower drag pretty much Would help me more when I’m passing slower cars on desert roads?

Sometimes the speed limit is 65/70 and one lane and you gotta stomp it to pass 3 cars following behind a slow Rv going 45/50 mph

I’ve hit 110 mph before for a second when having to pass a slow train of cars in the middle of nowhere in Arizona/Utah

That is actually an interesting question, assuming you are in top gear at reasonably low revs, (say 1000-2000rpm) the engine (assuming petrol and naturally aspirated) will have very little power even at full throttle.

Say, for example, at 50mph you may need 15hp, and the engine is capable of producing 30hp at that rpm. If you cut drag by 33%, you have reduced drag from 15hp to 10hp. But you have also gone from having 15hp to accelerate with to 20hp to accelerate with. Theoretically you accelerate 33% faster.

Doing 0-60, when you are in optimal gear at high revs, the available power/drag ratio is far different, most cars having 100-200hp you wouldn't notice 5hp extra because you have better aero.

[jakobnev]

Aero so bad it matters:

https://www.youtube.com/watch?v=1X35-bGWpEY

[The Toecutter]

Originally Posted by jakobnev

Aero so bad it matters:

0.74 Cd with wing, compared to the stock Corvette being measured as 0.32 in the same wind tunnel.

That means a lot for economy. A stock Corvette of that style with an engine re-tune for leaner burning can get 40 MPG at 70 mph with the tuning for efficiency also accompanying a power increase:

https://www.youtube.com/watch?v=vNIZ25eBMco

A pushrod V8 is far from the most efficient thing in the world, so do keep that 40 mpg figure and what it can mean for something much more light and slippery in mind.

A Corvette platform could make for a beautifully-performing custom streamliner given its durability and layout, where both performance and fuel economy alike would match the "best" production cars for those categories, and it would probably be reliable too. Parts are relatively easy/inexpensive to source in the U.S. Frontal area, drag coefficient, and weight could all be reduced significantly over a stock Vette, while retaining the original engine, which is a powerful, reliable, highly tunable workhorse.

I do think a V8 2-seater making 60 mpg highway is quite possible... and it would be relatively easy/inexpensive to make it a top performer at the same time. A Panhard CD Peugeot 66C shape laid out over such a platform, and modified with the bare minimum downforce needed for stability(especially attacking low hanging fruit that add lots of downforce but usually minimizes added drag, like ground effects, and while avoiding the use of wings and items that are very drag inducing). The stock Panhard CD Peugeot 66C shape had a Cd of 0.13, but I think somewhere in the upper 0.1X region is doable while having enough downforce not to lose control at 220 mph, which would likely be its capability with stock horsepower, but that engine is tunable to a lot more than that. But because the car itself might be 1,000+ lbs lighter than a stock C5 Vette, its 0-60 mph and 1/4 mile times would still be able to hold their own with modern supercars that can reach near that same top speed. The difference might be a tripling of typical supercar fuel efficiency while also making a supercar that is inexpensive and reliable to operate, that could even match a Prius in highway fuel economy without even having a hybrid powertrain.

Maybe someday I'll get a chance to make a proof of concept of such a thing.

Of course, the Corvette platform, being as sturdy as it is, lends itself well to some off-the-wall engine choices. You could take that Vette apart and find a way to mount a Cummins turbodiesel in the middle of that chassis, then build around it. So many directions that one could go...

[freebeard]

Which one? According to duckduckgo.com/?q=Panhard+CD+Peugeot+66C&ia=images The 1964 and 1967 Lemans entries have distinct differences.

Rather than changing the body into something else, I could see sacrificing lateral acceleration and go to tall narrow wheels and tires with as much negative offset as possible to accommodate four wheel skirts.

Freevalve four-cylinder?

[The Toecutter]

Originally Posted by freebeard

Which one? According to The 1964 and 1967 Lemans entries have distinct differences.

The 1967 designed by Deutsch Bonnet. With the full tail, its drag coefficient came out to 0.13. The dual rear fins help it to stay stable on the Mulsanne straight without much need for downforce.

Coupled with the low frontal area, this shape over a Corvette chassis and appropriately scaled for width/wheelbase would have about 1/3 as much aero drag as a stock Corvette. As far as cars of the time period go, the C5 Corvette was already among the most slippery available and got decent highway mpg bone stock, so cutting its drag to 1/3 is going to have a massive impact.

And it is easy to find an engine greatly more efficient than that crappy(at least regarding thermal efficiency) pushrod V8 it came with, but it would still get good economy with its original engine.

Rather than changing the body into something else, I could see sacrificing lateral acceleration and go to tall narrow wheels and tires with as much negative offset as possible to accommodate four wheel skirts.

Hard to say what the results of that would be. The Corvette's shape, while more slippery than the average car of its period, still had a lot of compromises made for aesthetics. I wonder what kind of Cd would be possible going that route?

Freevalve four-cylinder?

If you're going to downside the cylinders and displacement, why not the 3-cylinder freevalve engine used in the Koenigsegg RAW concept? 600 horsepower in only 2L of displacement, but overall thermal efficiency comparable to the anemic Atkinson-cycle engine in a Prius. And its low mass would do a lot to keep the weight down.

That might open the door to such a car weighing significantly under 2,000 lbs in spite of the large footprint of the chassis if you get rid of that stock lump of a pushrod V8, and economy would go up even more with a more efficient engine. The wide track and long wheelbase of the Corvette chassis coupled with such lightness with most of the weight in the center of the chassis would have an unholy cornering potential too, even without the typical downforce aids most racecars use...

Maybe 70+ mpg HWY non-hybrid supercar? That would be really sweet.

[freebeard]

Here's why I mentioned four wheel skirts. the Volhart-Sagitta V2 returned 0.217 in a modern wind tunnel.



Four passenger instead of two. I'd not be averse to a three-cylinder.

edit: See also: ecomodder.com/forum/543600-post2421.html

[basjoos]

When I aeromodded the Aerocivic, it had little effect on the 0 to 60 time, but had a huge effect on the 60 to 100 time.