Weight difference: Power vs manual windows.

[Peter7307]

I was having an informal discussion recently with some engineers about weight saving in cars and some of the mods people can do themselves when the topic of windows came up.

The general thoughts of this group were these days the weight savings were about nil as modern power window mechanisms weighed about the same as their manual counterparts.

Does anyone have any numbers or comments on this?

Peter.

[Frank Lee]

I don't have numbers but that sounds right. Also I've heard the Insight 1 came only with power windows for weight saving reasons- that is also the car that had special lightweight carpet?

[Vekke]

Lupo 3L has manual windows and the total window lifting mechanism weights about 1.5 kg. (took them out) Although today the electric window lifter version is lighter, but the difference is not big. If I remember correctly one kilo saving for four side windows etc.

[nimblemotors]

Originally Posted by Peter7307

I was having an informal discussion recently with some engineers about weight saving in cars and some of the mods people can do themselves when the topic of windows came up.

The general thoughts of this group were these days the weight savings were about nil as modern power window mechanisms weighed about the same as their manual counterparts.

Does anyone have any numbers or comments on this?

Peter.

In my 89 Jeep, I took the power motor from the back and moved it to the front to replace the dead motor, and put manual in the back. The manual was lighter for sure, but not by a whole lot.

If you want lighter, don't fight gravity.
and use slider windows, not roll-up and down windows.
I'm still trying to figure out how to do the windows on the MGeo as light as possible, and thinking sliders.

[skyking]

basjoos-type aero > any weight reduction carving
But that is just my opinion.
EDIT: I got to thinking, what if your average speed is low, lots of light to light, stop and go?
I keep assuming people live in the more wide open spaces where you can get rolling, like Basjoos. That is a bad assumption on my part.

[nimblemotors]

I'm not sure what this disregarding weight reduction I'm hearing lately.
perhaps because you can't get high MPG in stop-n-go traffic.
Bragging about big MPG is going to need highway runs and aero is big there.

Lower weight is also a big factor in highway mileage too, why?
Because a very lightweight car CAN USE A MUCH SMALLER ENGINE
to get it up to speed, and thus get better highway mileage..because it has
a much smaller engine. Of course if you have an existing car and can't change engines, the lighter car isn't going to matter much for HIGHWAY mpg.

And I didn't even mention that a lighter car will accelerate faster, and make driving more enjoyable and even safer, oh I just did.

Originally Posted by skyking

basjoos-type aero > any weight reduction carving
But that is just my opinion.
EDIT: I got to thinking, what if your average speed is low, lots of light to light, stop and go?
I keep assuming people live in the more wide open spaces where you can get rolling, like Basjoos. That is a bad assumption on my part.

[nemo]

Originally Posted by nimblemotors

If you want lighter, don't fight gravity.
and use slider windows, not roll-up and down windows.
I'm still trying to figure out how to do the windows on the MGeo as light as possible, and thinking sliders.

Or

You could take a page from the drag racing hand book and use a seat belt strap to raise and lower the window. (Hurst Hemi Dart)

[some_other_dave]

Some old (50s and 60s) race cars used leather belts to raise the windows. Lexan window, of course! Attach the belt to the bottom, make sure the window fits in the tracks, run the belt out at or near the top of the inside of the door. Have a hook on the inside that one or another of the holes in the belt hook on, and you can keep the window at that height.

-soD

[pete c]

I have a related question.

We know that open windows are horrible, aerodynamically speaking and AC saps multiple hp from the engine.

Considering that most everyone in america spends at least part of the year needing one or the other, has anyone come up with an aerodynamically cleaner way of getting sufficient airflow to avoid using AC? I would guess that intake vents drawing air from under the car and exhausting it in the rear where there is a low pressure area to suck the air out, might work well.

[Frank Lee]

I can get a gale-force wind through the knee vents in my '59!

I put a moonroof in one of my Tempos and even slightly cracked it lets a lotta heat out when parked and moves air nicely when going. I think the aero hit on a window that tips up like that vs retracting is quite small.

Power vs Crank windows: do these weight estimates include all the extra wiring and switchgear? Power windows and locks really make for fistfuls of wires going all over, especially to the driver's door.