2019 RAV4 Hybrid Limited

[freebeard]

Thanks, I guess. Bummer. I already have a single-motor Lexus axle with an open diff.

I'm not sure what they're getting a here:

As with its strictly gas-sipping sibling, the RAV4 Hybrid rests on the Toyota New Global Architecture (TNGA), which extols the compact crossover with a solid and predictable platform for tackling twistier tarmac. Likewise, the Hybrid’s tiller adds appropriate heft through turns with no on-center slop.

Ah, well; Arcimoto has a twin motor drive. I should get one of those ...eventually (it's been 3 years already).

[aerohead]

Originally Posted by GK13

This is the lip I'm looking at. Thinking of then putting a rubber 90 degree air dam on the bottom of it. I thought that might be better than trying to put the same rubber air dam straight on the car. Thought that it would bring it out just that bit wider to get around the front wheels.

Then I was going to try and fabricate some kind of radius to get air around the front wheel wells. I'm also working on rear wheel skirts for it.

If I'm doing the air dam, would figuring out wheel spats be worth looking into also? Or would it not help anything due to the air dam?

It will add downforce-induced drag.I'd stay away from it.The Toyota nose has no doubt,all ready been optimized in the wind tunnel.Grille-blocking may already be optimized as well.I'd pay attention to the belly,sides,and tail.

[GK13]

Belly is totally smooth as much as possible from the factory. Must say they did a good job on that front.

I do know that they are trying to make it more off road capable than previous iterations, and thus have raised it up in the air quite a bit. Thats where I'm thinking of doing an air dam like posted earlier on the Chevy Volt might be helpful. I was thinking of adding exactly that where it comes down 90 degrees from the edge to create a square edge. And I thought with it coming out in front of the tire some, it would provide a good air blocking effect to it. Between that and the rear wheel skirts, I'm hoping that might help it.

Found a listing with better pictures. Hope these help some.

Thinking about it, I could possibly put an angled piece from the front edge back to the bumper to eliminate any downforce. Thoughts?

[freebeard]

Belly pan and airdam is like belt and suspenders.

[GK13]

Originally Posted by freebeard

Belly pan and airdam is like belt and suspenders.

Ok. Then since it does have a full belly pan, you don't think that having the air dam closer to the ground would help anything? I thought that by having the car so high in the air, that increased drag as well? I thought that was one of the main things with an air dam.

Also, if I'm not doing the air dam, how would I go about getting air around the front tires more efficiently? I know I've heard of people using mud flaps in front of the tires to try and redirect airflow. Does that provide enough benefit you think?

I'm having a hard time figuring out what else I can do to get more mpg squeezed out of the Rav4.

[redpoint5]

You've got tradeoffs. Does the airdam overcome the added frontal area it adds by smoothing airflow, or does it not?

An experienced aerodynamicist might have a good hunch, but the rest of us have to test.

My inexperienced hunch is that adding frontal area will not improve efficiency, but I'd love to be proven wrong with a good experiment.

[freebeard]

The underbody cavity is a plenum with one moving and one stationary wall, with all that that implies.

More clearance means less interaction between the road and vehicle, but allows rolling vortexes to move air in or out between the wheels. If one looks at the aeroCivic, it has dual side skirts between the front and rear wheels.

A central notch in the airdam can be beneficial, else wheel spats.

[IMG][/IMG]

[aerohead]

Originally Posted by GK13

I would very much like to lower the wheel arch gap if I can. Been thinking of getting some ABS plastic that matches the fender flares and trying to fabricate some that would look seamless. Not too sure how to work with ABS plastic though. Thinking I can score it, bend it to match the curve, drill holes to match the existing wheel well fasteners, and go from there. Wanting to make it not stand out too much if at all.

As far as the tires go, I found out that they just have pretty standard all season tires on it. In AZ where it doesn't snow and barely rains, I'm thinking a low rolling resistance highway type tread would be the way to go. I was thinking of going with a taller, narrower tire if I could fit it on the same rim.

I saw the idea on here of sealing the panel gaps. Does that really help much? I decided to take some rubber door edge guard and put that around the gap of the hood to the front fenders/grill. Don't know if I'll see much difference though. Was thinking I could get the same stuff and wedge it in all the gaps. Use a clear or something. I'm just not sure if it would be worth doing though. Being a new car, they're pretty tight already.

With the underbody already being smoothed out with the factory belly pans, would an air dam be any benefit?

I'm also wondering how I could safely add additional battery storage to the hybrid system and add a grid charger as well. Ideally, be able to have the grid charger only charge the "extra" set of batteries so I can mitigate the risk of damaging the battery pack that came in the car. I just have no knowledge of electrical systems unfortunately.

For a few years,we had an ABS manufacturer locally.They heated the sheeting in an electric pizza oven while clamped to a metal framework.As soon as the plastic drooped,it was quickly moved from the oven and immediately stabbed over a nearby vacuum table,which held a male,wooden form,drilled with hundreds of passageways.The frame was air-clamped with a foot-operated air-valve,which provided vacuum from a spherical accumulator.The plastic was sucked down over the tooling,and within a few seconds set to final hardness and was de-clamped,to receive the next piece of prepared,heated sheeting.
The whole process moved very quickly.
ABS is flimsy without some sort of corrugation designed into it.Without heat-forming I don't know how you'd achieve its full potential.

[aerohead]

Originally Posted by GK13

Ok. Then since it does have a full belly pan, you don't think that having the air dam closer to the ground would help anything? I thought that by having the car so high in the air, that increased drag as well? I thought that was one of the main things with an air dam.

Also, if I'm not doing the air dam, how would I go about getting air around the front tires more efficiently? I know I've heard of people using mud flaps in front of the tires to try and redirect airflow. Does that provide enough benefit you think?

I'm having a hard time figuring out what else I can do to get more mpg squeezed out of the Rav4.

I recommend Goro Tamai's book,'The Leading Edge.' Tamai was involved in MIT's solar race car projects and has the the most comprehensive data on underbody aerodymanics I've ever seen.You'd be able to design cars of Cd 0.10 with his data.

[freebeard]

You'd be able to design cars of Cd 0.10 with his data.

Given sufficient frontal area, you could even use a RAV4 as the donor vehicle.

My parents had a vacuum-form machine like the one you describe, with a capacity of 1 1/2x2ft. It had a heating bed on one side, and a vacuum bed on the other, of a piano hinge. One could probably fabricobble one with infrared heat lamps and a shopvac.

tip: Heat the sheet vertically, instead of swinging it 180°.