Boy I sure wish I could start paying attention to mods for my car. Well, if when I get the basics taken care of (like getting the car past inspection) I'll know where to go to start work on the underbelly pan and other aero mods.

Nice work TomO!

One advantage of having the underpan is your engine stays a lot cleaner and there's less road noise. Much of the "road noise" is actually wind noise generated under the car.

basjoos - I have noticed that road noise is diminished. Hasn't been long enough to notice if the engine bay stays cleaner, but I'd have to agree that it would since the dirt really has no place to get into the engine bay now except through the radiator opening.

1993CivicVX - The time for your mods shall come soon enough, lol, and thanks.

Nerds Laugh At Me - It's a mild steel exhaust system that I coated with High Temp aluminum content paint, so basically it's a crude form of aluminized steel. I do have a slight rattle where the flashing contacts the exhaust near the 90 bend. I am going to stuff a chunk of fiberglass in between the tube and flashing to stop it. It only rattles at startup and once in a great while at idle. I'm also thinking that I have a great template now to make an all aluminum underpan. but that isn't going to happen unless I come across a 6'x'10 sheet in the garbage, lol.

Nice work Tom. Looks clean.

Hope it helps more than mine did! I suspect it will, because your ride height is significantly lower than the Flea's.

why not just use all aluminum sheets? isn't aluminum lighter than coroplast?

any prius owners did a underbody? if so post pics too!

Thanks!
How much of an increase did yours make again?

I'm only expecting about a 2% maximum increase from mine.

Cost was a big factor in using the Coroplast vs. Aluminum sheet. And to have an aluminum sheet the same thickness of the Coroplast I used, would have been twice the weight and 10 times the cost.

2% in A-B testing, 3 bi-directional runs for each of A&B. :) Speed was 90 km/h I think.

All else being equal (which it's probably not) I still think you'll see better gains because of the lower ride height/higher flow velocity underneath your car.

I still wish I would win a SuperMID!

I still only do tank to tank averages so it'll still be a week to week-and-a-half before I can start to see results of my under pan. I installed it with 100 miles on the tank already too, lol.

Hopefully I can get a 3% increase as the front of my car is also lowered 1.25 inches more than stock. Time will tell.

Awesome writeup.

I just went from a 92 CX to a 95 DX (hatch) that is setup more as a trackday car. It's my beater, since I have a 99 Si for auto-x/trackdays.

Anyway, I just lost about 10mpg in the changeover. I've been a bit of a hypermiler in that I was able to wring a best of 49.x mpg out of my CX (1.5" drop, skinny tires, VX diffuser, Akimoto cone filter).

The new one has a d16z6 swap, DC 4/2/1 header, stainless 2.25" b-pipe, stock axleback exhaust and Ground Control/Koni yellow suspension.

I just added a VX diffuser to the rear end.

I was surprised to see how much of an effect lowering the front end has. At the moment, the front is higher than the rear (former ownder had it jacked up for winter use) Since my suspension is adjustable, I'm going to drop the front an inch for a total of a 1.5" drop.

My question (after all this) is that I have a nice urethane lower lip for the front spoiler that I haven't installed (don't know if I want to attract more attention to the car). Do they actually do something to improve aero (in terms of efficiency) or does it add drag??

Great forum. Looks like I have a lot to learn...

thanks :D

The VX in stock form has the Front Urethane lip. If it's the stock lip then yes, go for it. But lowering the car dos more than just having the lip. If it's an aftermarket lip, what kind is it as some of those lips will add more downforce and drag than the OEM VX lip will.