CO ZX2, I was hoping you would weigh in with your thoughts about the belly pan. Also do you think my wheel skirts are fine as they are.

You make me feel horrible.

So tell me more about your car. What power options does it have P/S, a/c etc. Do you think I should pull the resistor leave the HAI as it is. I'd like to see your pics of your belly pan, skirts, and especially the front rings.


COZX2

I'd like to know how you keep your front skirts from bowing back in and rubbing the wheels.

Also note that our MPG Leader CO ZX2 still has belly pan on his todo list. I'm guessing that huge piece of lawn edging hanging off the front bumper has a lot to do with it :)

I remember your belly pan thrash and admired the determination you put into getting it done. I thought I remembered that you had a gain at the time. You also inspired a lot of people to get up and do something.

On my own car I had an underpan that covered everything back to the front of the front tires. That had been a definite improvement for me. I couldn't wait to add to it. I added a 4 foot section to the rear of it and my pressure/flow gauges immediately showed me it messed up the gain I had made on negative pressures at the rear of the car. After rechecking my gauges and tubing, I removed the new piece alongside the road. My pressure readings were back where they were. I do not totally understand why this happened but it did. These pressure gauges have been my most important discovery recently. See pic in my garage(link below my sig.).

Your skirts look real nice but I wonder if they may be bulged out too far. On my car I had mine bulged more than they needed to be. I have rearranged my skirts to clear the closest part of the wheel by 3/4 inch. They are considerable more flat to the body than before. I also proved that is better with the gauges. If you have interest, I may have an extra gauge to spare. All it takes to use it is a couple fittings and some plastic tubing to run to the spots on the car you want to check. Gauge is inside the car and just read at speed(I use 60 mph).

You might also look at my front end pic in my garage. I would never have believed that big air dam would work. It has and I've even added 3" to it. That was the item that worked best to reduce negative pressure at the rear of the car.

One more thing I will mention. Sealing the belly pan around the front and sides as much as possible made a difference for me. Sealing my grille block and fender skirts is also important to me. Without a tight fit, I was not getting all there was out of these mods.

Don't be discouraged with having to drive slower to do your best. Do that when you can, but if you need to speed up, just do it. A while back we were taking the cat to the vet and wanted to get there as soon as we could. I didn't worry about FE much even though I got 20 mpg less than usual.

Keep a good attitude and we all know you're a worker.

I wasn't trying to make you feel bad. I was trying to say your goal is realistic. I think your car is very close to mine and you have done nicer work than I. My belly pan looks like yours except I put up no framework. Mine is just coroplast and tie straps with a few screws. You did a very nice job. My middle is actually hanging on the exhaust system with heavy wire. There are pictures on the site but I will find later.

My car is not even an SL1 it is just an SL. It has AC, PS, PB and CD player but windows and locks are manual, no cruise. I am running an NAPA belt that runs between the crank-AC-and water pump. I just got lucky and this belt fit. I roll it on but it is too loose to run the AC. CO's system of turning the alternator off internally is better. If I get caught out somewhere I will need to install the belt that is in the trunk.

I have my mirrors inside. I think that helps. Did you see CO's clear mirror streamlines? I would never have thought of that. I think blocking the air that enters full width at the front of the hood matters too. My car did not have a molding there though there were holes for it. I just used foam tape weather strip. I know I have not documented like many here have.

I will take pictures of my front wheels and rings. Most of the skirt clears the tire by less than 1 inch. This will have to be a bit later. If VW can get 300 mpg without front skirts I decided I would do what seemed easier to me.

At this time I don't believe in IAT resistors. I may go back there in the future. I relocated the sensor into the body of the intake box. I had to tap a hole but it was just in plastic. I was not the first to do that. I like heated intake air.

60 psi makes a difference but it is beyond sidewall recommendations and does affect traction a bit. The tires will slip a bit easier on uneven surfaces.

Skirt pictures later.

The plastic I use has some stiffness and I bow it slightly to the outside when I put it on. I have a half inch plastic ball on the inside of the skirt that barely contacts the center of the hubcap. The ball also takes some load off the rubber inserts when the wheel turns. The screw in the middle of the skirt holds the ball in place.

Here are some pictures but please bear in mind I just did what I thought looked nice and have not done any real testing. I will just post the links this time. Other wise it might take a while to load.

Right rear pant only about 1/4 inch clearance with 1/4 inch spacer at front.
https://xs.to/xs.php?h=xs117&d=07286&f=rrpant.JPG

Right rear pant again
https://xs.to/xs.php?h=xs117&d=07286&f=rrpant_2.JPG

Right front pant. Tight at back . Open at front. Just trying to control imagined air flow through wheel well. I was trying to get a radius for the air coming out of the wheel well. I reasoned that the tire formed a nice radius at the front. Anyway that fit the length of hose I had cut off at that time ;) .
https://xs.to/xs.php?h=xs117&d=07286&f=rfpant.JPG

Right front pant again showing spacer block at back. This is not a smooth transition to the car body.
https://xs.to/xs.php?h=xs117&d=07286&f=rfpant2.JPG

Plastic vacuum hose used for radius. Tie strapped on. Yes it rubs and makes noise when I hit bumps and turn. Yes those are screw holes in my fenders. I paid for the car and I put the holes in it :) . The plastic is not going to rust either.
https://xs.to/xs.php?h=xs117&d=07286&f=flexradius.JPG

Rear pan
https://xs.to/xs.php?h=xs117&d=07286&f=rearpan.JPG

Front pan
https://xs.to/xs.php?h=xs117&d=07286&f=frontpan.JPG

Front pan installed. Pardon the low resolution. It is not so smooth after a few thousand miles.
https://xs.to/xs.php?h=xs117&d=07286&f=frontpan_on.JPG

Hope this answers more questions than it raises. Again I have not tested any of the aero stuff. I really want to test the front skirts on a hill roll down. I just have not done that yet. They are the only part of the aero package that I could not easily tell it helped. Please note my belly pan is not continuous front to rear. The middle bottom of the car looked substantially flat to me and only the easy part was covered. I am not covered near the fuel tank for about 40 inches.

Thanks!

Lovemysan, what part are you unhappy with?

>> My goal for the car is 50mpg at 70mph. <<

I think I need to slow to about a steady 65 mph or less on level to get 50 mpg out of my SC1. At 70 mph it drops to about 47 or 48 mpg if I remember right. That is with just me in the car, no a/c.

BTW, I had zero luck doing aero mods. They looked more aerodynamic, but any mpg increase was not enough to notice on my standardized test runs. I never did try a belly pan or skirts, though.