Help me finding low hanging fruit mods

[krrcan]

I drive a skoda felicia hatchback:
Å*koda Felicia - Wikipedia, the free encyclopedia


I have a somewhat clear understanding of drivetrain and friction and such, and have done some mods allready.

However, when it comes to aerodynamics... I'm quite lost.
I generally don't travel especially fast, never over 50mph, mostly I'm around 35-40mph.
These things taken together has made me postpone aerodynamic mods, but now I want to do some!!

What are the easy low hanging fruits to pick on this vehicle?
What I have done, is a grill block, but that was mostly for retaining heat.

[kach22i]

+30 mph you should be able to feel by the seat of your pants the results of aerodynamic treatments.

Aerodynamics Photos by kach22i | Photobucket


In your climate I suspect that you will be weary of going too low (snow) with the air dam and side skirts.

However the grill block could be a seasonal attraction, although I personally avoid such things.

Perhaps a smooth belly pan will weather a hard winter if installed correctly, but again it's your call.

[wmjinman]

I notice you said you did an UPPER grille block. Maybe finish blocking off the whole thing. In my 4 cylinder Suzuki Swift, I blocked off the entire grille opening except for a small hole last spring. Then I watched the engine temperature carefully on my ScanGauge. It never overheated, even in the summer, even climbing mountains - I think it hit 208 or 209 once, but usually never over 207. There is room for the radiator fan to pull air from underneath the bumper, though. But in the wintertime in Sweden, I'll bet you can block the whole thing and be ok. I saw about 2 mpg improvement from my grille block.

Otherwise, for "low hanging" aerodynamic fruit, my experience has been that rear fender skirts don't do much, nor does deleting the mirror(s). Probably the biggest boost after the grill block is a Kamm-back, but that isn't nearly as easy to do. But it's what I'm working on next for aerodynamics. Belly pans are a lot of work too, and some report the gains aren't nearly as much as they were hoping for. But the Kamm-back is supposed to be very helpful.

[LeanBurn]

Don't forget wheel covers of course making use of the largest mod you can do is adjusting your driving style.

[wyatt]

Start with:
*Full grill block (winter), most of grill blocked (summer)
*Belly Pan (full if possible, at least do the engine bay)
*Windshield Wiper Block
*Smooth Hubcaps (if yours look like the picture)

I would block basically the whole grill in the summer. A hole the size of a large cell phone should be sufficient. When doing this, also duct the airflow so that it's forced through the radiator, not around it. Next do a belly pan at least as far as over the engine bay. When I did mine, it didn't take long and had a drastic impact on the amount of road noise observed. I also did a belly pan behind the rear axle since that was just a big open cavity. It looks like a windshield wiper block might be a good investment of time also.

My belly pans, grill block (only half the grill, no ducting), and windshield wiper block reduced my drag by ~12% and increased my FE by 6%.

Later on when I built a big 4 foot long KammBack, it reduced drag another 12% and increased FE by another 6%. I think if I had built a full boat tail, I could have been expecting MPG numbers in the 55-58mpg range during interstate driving (65-70 mph sustained).

[krrcan]

I have done a full grille block now, I have forgot to update my profile.

If I do a kammback, to extend the length of my roof to where the rear ends.
what would be the angle I should strive for?

I have the standard skoda felicia wheels, same as in this picture:
which look at least somewhat smooth.
But I could perhaps seal of the holes in them?

Would a air dam (somewhat low) be a better alternative than a underbelly pan?
Or is the underbelly pan superior?

[wyatt]

Some say belly pan, some say air dam... I say (based on observing a lot of cases) that the belly pan helps either way, so go ahead and do it first. Putting an air dam in front of the wheels (think just long spats to deflect air) seems to be a good help also. Those that have done testing on air dams tend to find that as far as drag is concerned, it turns out to be best to cut a bunch out of the middle/bottom of the airdam to allow some air to go under the vehicle. When I look at it I wind up saying, "so you are really just adding big spats in front of the tires..."
Looking at your car, I definitely say that a windshield wiper block would be good, and smooth hubcaps wouldn't hurt anything, but it's hard to say how much of an improvement you would see from them (keep them cheap). You'll thank yourself for doing the smooth belly pan if you do any amount of driving at higher speeds. My wife and I could hold a conversation after I did mine. That is compared to having to almost shout without it. YMMV
EDIT
Oh, KammBack angle should be somewhere between 12 and 15 degrees. Try to make the transition as smooth as possible. Before you build a kammback, you should do some tuft testing to make sure you have attached flow over the roof of the car. I suspect you should, but if not, the kammback will only be a conversation piece.

[Jyden]

How about starting af fuel log here?
The we can all follow your progress
Pump them tires to max sidewall pressure, if you haven't allready done so.

[krrcan]

Originally Posted by Jyden

How about starting af fuel log here?
The we can all follow your progress
Pump them tires to max sidewall pressure, if you haven't allready done so.

Good idea, I have finally managed to enter my backlog scribbled on papers into this site.
The dates for fill-up might be off my a week or so.

I have had 2.2 bars in all 4 tires, but last fill-up I upped that to 2.4.
Not at all sure what I should have, allthough the handbook recommends 2.1 front and 2 back.

[krrcan]

I was at the wheel-workshop yesterday, noticed that my front wheels had uneven wear.

Had Single toe left +0°35', single toe +0°37'.
This was adjusted to +0°03' and +0°05'.

If this faulty toe was enough to cause wear on my tires, I imagine it would have affected my milage in a negative way as well.
Anyone know how much, approx?