[Allnighte]

My mind wanders quite a bit, and thinking of little tricks to improve my MPG is something I spend WAY too much time on :lol:

Anyway... which would yeild better mileage results:
softer suspension? or harder suspension?
and why?

I know softening the suspension would hurt the Insight's already fragile handling, and I wonder if stiffening the suspension could put more stress on the body. I also have a feeling the results would be very very minimal, but every little bit helps, right?

Any thoughts on the subject?

and if someone were to change the suspension, would lowering the car help mileage at all?
Thanks in advance!

 

[b1shmu63]

Work = Force X Distance. A spring absorbs energy when it is compressed and releases energy as it expands. If the spring is 100 percent elastic no energy is lost. A shock absorber turns a low loss spring into a high loss spring. Therefore, shocks use up energy and decrease mileage.

1. Eliminating the shocks would improve mileage but the difference would likely be to small to be measured accurately except on a test bed.

2. The difference would be less than the energy normally absorbed by the shocks as other components of the car would begin to dissipate a portion of the theoretical energy gain*.

3. Moreover, if these losses could be eliminated, the cars suspension would be theoretically perfectly elastic and would travel down the road like a ball of Flubber, seldom contacting the road surface.

4. Consequently, the car would be completely uncontrollable.

*This includes PPPPV ( person’s posterior piloting passenger vehicle) :lol:

Lowering the car would help mileage as it would effectively decrease frontal area. It would also make the car less practical and potentially less safe. However, the underside of the car could still use a lot of improvement aerodynamically and the rear skirts could be enlarged. These would not affect handling or safety.

 

[flunkysama]

I would bet that in the real world, the stiffness of the suspension probably has as much impact on the MPG as the color of paint.

If forced to speculate (and It's always fun to speculate) I could come up with these.

* A softer suspension may result in the less sidewall deflection in the tires when impacting a bump. Sidewall deflection may increase rolling resistance.

* When hitting a bump or dip, the car may pitch up or down. For this short period, the frontal area and CD change for the worse. So a less compliant suspension would keep the direction the car travels more inline with the pitch (i.e. minumize pitch) which should minumize aero drag.

Why don't you conduct an experiment and let us know the results.

 

[Guillermo]

The ideal suspension for the Insight is completely dependent on the quality of the roads. If the roads are completely smooth then stiffer suspension is more efficient. If the roads are rough then softer suspension is more efficient.
In the highly competive world of cycling, lots of studies have proven this. Road bikes have no suspension and the ride is stiff, the riders are forced to avoid, hop or just stand up and use their legs as suspension in the bumps. In mountain bike racing full suspension (front and rear suspension) has proven to be more efficient. But for maximum efficiency racing mountain bikes have about 3 to 3.5 inches of quality but relatively stiff travel. Mountain bikes designed for serious fun more then racing have 4 to 5 inches of softer suspension for a good compromise between comfort and efficiency.

But because cycling uses a pedalling motion that can easily cause suspension movement suspension stiffness have a much much larger affect on efficiency then in an automobile.
In an automobile suspension stiffness would be near the bottom of a long list of more influencial variables.

The most advantages comes from having a suspension stiff enough and balanced enough (add a rear sway bar) to be able to turn at high speeds. Being able to turn very well at high speeds is very efficient because you won't have to accellerate as much while exiting the corner. Not needing to accelerate as much will give you the greatest efficiency.

 

[james]

One thing I think would be neat on the Insight (or on a lot of other cars) would be adjustable ride height. Had a Subaru with that once: you could raise it up several inches for dirt roads or snow, or drop it down for freeway travel.

 

[Delta Flyer]

If you could lower the Insight enough, you could drive under 18-wheelers and 4x4 off-road trucks, sort of like Indiana Jones did in Raiders of the Lost Ark

 

[Thorian]

What about a Apexi fuel computer to. My brother has one in his miata apparently you can dial in your air fuel mixture all across the throttle band

 

[b1shmu63]

Citroen designed many aerodynamic cars and had a pneumatic adjustable height suspension for decades. Someone out there with the skill, knowledge, and a shop should design and build something for the Insight. :idea:

 

[james]

Not to mention all the low riders (do they still do those?) in California But for the Insight, it would have to be light...

 

[r.tornello]

suspension ideas

has anyone looked into the possibility of different part numbers for say German Insights as opposed to US insights. BMW's have different/stiffer suspension parts for the same car that is delivered to the US.
Maybe that would be the way to work the suspension.
If anyone knows and it come to be a fact, then we would have to figure a way to order them. For the BMW you need a European VIN.
Rick Tornello
03 CVT
had an 00 5 speed #107.

 

[PlaneJob]

One of the major spring manufacturers will wind your springs for you. I forgot which one it was, but there are only 3 or 4 that make springs in the US (independently). IIRC the cost to get 4 custom wound springs for a VW rabbit (which coincidentally weighs the exact same as an insight) was around 300 dollars and shipping. I'd really like to drop my insight about an inch, or an inch and a half (maybe 1.5 front, 1 rear).

Also, A previous poster mentioned a lot could be done to the underside of the car - Like what? give me some examples?

Also, I was thinking that fron wheel skirts would be awesome, they would have to swing up when turning, but at highway speeds they could stay glued to the car's body.... anybody wanna try it? I wonder how much wheel deflection you could get before having to let the panel swing up out of the way? (initiate cardboard mock up test).

 

[b1shmu63]

The visible body of the Insight is a marvel of smoothly flowing glass and metal. Five detachable plates have been fastened to the underside of the Insight to smooth out air flow but there are still a lot of rough edges down there. I was suggesting that if there are further gains to be made in aerodynamics it would be most beneficial to work on that area. If you look at photos of the Imas prototype it looks as though they have done that along with smoothing the airflow from the front or the car by means of body integrated spoilers. If I had a shop, time and the money I would try to work out a system of using flat plate radiators under the car for engine cooling. This is not an original idea of mine as it has been proposed in the past to reduce drag in racing vehicles and airplanes. In the case of the Insight these panels could also be used as airflow smoothing panels. The front of the car could then be reworked to allow less turbulent airflow around the car as in the case of the Imas proto. If someone was trying for a world record such mods would make sense. I can think of other improvements but they have probably already been tried and either incorporated into a future design or rejected for practical or customer acceptance reasons.

General Motors exhibited the 430 HP Cadillac Voyage and Solitaire prototypes in 1988,1989. Both had moving wheel skirts on the front wheels and also had video cams for rear viewing!

Currently the Insight front wheel wells are designed to suck air out of the engine compartment so as to reduce the amount of air flow under the car. That is the reason for the somewhat unorthodox styling around that area. Note how "open" the engine compartment is to the front wheels. If covers were placed on the wheels openings, more air would be forced under the vehicle. This plus the added weight might negate any mileage gains.