Underbody Aero...

[Kenrik]

I would like to do this to the underbody of my G35.

I need suggestions on the cheapest and least ghetto way to do it.

[zozoka1212]

Unless if you do it from some type of plastic it would add too much weight to your car. Also you have to make sure you cover everything othervise you make it worse. Creating airpocket. The air goes in and can't go out. Maybe if you do it from .030" aluminium sheet. Hope somebody has better idea. Sheet + bolts would raise the weight too much. Just my opinion.

Zozo

[Sentientbydesign]

A few things to consider, because I plan on doing this too...sorta.

The engine MUST breathe!!! Remember that the air goes through the radiator into the engine bay. It's got to be able to EASILY flow out.

So venting is a must.

Also, be careful with "fins" below. I did some research and read about a prius owner that did a front underbody tray, then tried to build tire deflectors...The problem with the deflectors is that they made the car unsteady at highway speeds. So he ended up taking them off and only leaving the tray.

I would get some ABS or similar material and a heat gun. Alternately (my probable method) is to use fiberglass or Carbon Fiber to make the tray.

I'm also going to integrate an easy access panel for oil changes. I HATE taking off all of those screws or having the oil go everywhere on the inside of the tray.

Good luck.

[CYO44Baseball32]

I would like to do this to the underbody of my G35.

I need suggestions on the cheapest and least ghetto way to do it.

Remember if you cut enough corners you'll end up with a circle.

[Jacko3]

Sentient:

That was my first concern as well---cooling. Will this under body aero allow for the more efficient colling of the transmission and other mechanical parts that tend to heat up under spirited driving?

[Sentientbydesign]

Sentient:

That was my first concern as well---cooling. Will this under body aero allow for the more efficient colling of the transmission and other mechanical parts that tend to heat up under spirited driving?

If the venting is designed properly, then yes. The negative pressure just after the vents should pull the heat out of the engine bay.

With enough clearance, fans could also be mounted below, but I don't think there's enough space down there to do that.

I'd be interested in finding some high flow computer fans that can withstand the engine heat and mount 4 of 120 mm ones at strategic points. I once had an 80mm that pushed somewhere in the neighborhood of 84CFM. Once spooled up, it sounded just like a mini airplane jet engine.

[TeflonG35]

I'm wondering on the benefit of this on a 300 hp street car? Could it really be worth the trouble?

[Sentientbydesign]

My motivation was for fuel economy. The prius gained 2 or 3 mpg IIRC. $30 in fiberglass and a few hours is worth it if I can save $.05/mi.

It would also benefit high speed driving...I'd estimate at 80mph + things would get better.

I read that on average, the underbody of a typical car accounts for 15% of the total drag. Obviously, this will vary significantly based on vehicle height, the smoothness of the underbody, how wide the tires are...etc.

It is definitely worth looking into. Plus like I mentioned above, you could put an easy access oil change panel into the tray and then your work would be two-fold.

[Ilvemynissan]

Just a question. Why do you want to do this to your car? Maybe high speed controll? What are the benefits of this?

[TeflonG35]

I race on the track but on the highway I rarely go over 75(usually not over 65). I couldn't see how I would benefit much from this. Maybe your scenario is different. I really doubt we would see the gains that the prius achieved. Let the car breath. I rather have drag then a hot motor.

On the note of oil change, I just cut the hole bigger so changing the oil is a cake walk.

I know you don't see under the car much but that underbody cover up that was posted is ugly and looks really cheap.

[Ilvemynissan]

Is that Ferarri a real one? It looks like a model car to me

[TeflonG35]

Is that Ferarri a real one? It looks like a model car to me

Honestly does it make a difference? It was just a reference pic to show us what he meant.

[Kenrik]

My reasoning is two fold... Gas Mileage & Highspeed Stability.

My front undertray was damaged by road debris & I have noticed about a 1 - 2mpg loss since that happend so I would like to replace it and extend it further...

The G35 is very aerodynamic but the one place it is lacking is on the underside of the car.

Consider this as Proof of Concept.. going from 60 - 90 MPG just with aero mods (to the extreme but still..)

I would be happy with another 3mpg HWY..

http://ecomodder.com/forum/sho....html

[smockers83]

Its definitely not going to be cheap...there's some engineering that needs to go into this. You need to be able to achieve cooling along with high speed stability. That means figuring out how to channel air in order to not increase upward force. This really isn't an issue for Ferrari since the car is a rear-mounted engine, RWD. That's my guess.

[TeflonG35]

Don't you have a versa for gas milage?

[Kenrik]

Don't you have a versa for gas milage?

Yes but I share it with my wife.. I only drive it about 50% of the time.. the other 50% is the G.

[TeflonG35]

Ahhhh ok.

[Tampa G35 Sedan 6MT]

you might want to take a look at the Lexus LS430 and 460. I know they have some tipe of wind/ sound reducer under the entire car.

That might help

DJ

[Ilvemynissan]

Honestly does it make a difference? It was just a reference pic to show us what he meant.

Yah it does make a difference, because if that was a real car, you could try to find what they used for the underbody.

[Sentientbydesign]

Can we quit the debbie downer syndrom in here.

I know most of you could give a rats behind about fuel economy, but some of us care and would like to save the change.

Kenrik,

Make sure you re-integrate the little down-facing curved lip. I was told that it was designed to assist with underbody drag by the parts department at my local Infiniti.

Also make sure that the suspension has room to travel.

[WhiteyClay]

If u do plastic the heat of the exhaust pipes will melt it.Pipes get hotter then anything on ur car.

[Sentientbydesign]

Yes and no. The underbody is made of plastic already.

I would recommend that Kenrik only do only the front section and possibly both of the sides.

[numskul]

No "least" ghetto way to do it.