Vented hood + solid underbody

[chicagoisonfire]

I'm really interested in improving the airflow around my car and one of the things on my list is a vented hood and flat underbody panels.

so ive been doing so research and ive decided i'd like to stick with a fiberglass hood rather than CF, so far my favorite that ive found is the on Greddysetgo used to (?) make/sell/be associated with



(stole this picture from an old thread)

From my understanding the deeper the hood combined with proper ducting from the radiator, the better the flow up and over the car (to an extent) so i'm looking for something that more than just a pair of 1 inch slits....


Also i'm looking for a solid underbody, i know EMS sells a set but i'm curious if there are any other options (i.e. making your own?)


So if anyone has any experience in any of these things please speak up

[Raptor13x]

On my 2, I had a border hood like that. I widened the vents in the hood myself, and since my radiator blew, I installed a custom radiator which I angled the other way, to direct airflow out the hood. Then I used some sheet aluminum to block off the radiator airflow under the car. After doing this, I noticed the front end felt much more planted at highway speeds, but I always felt the holes in the hood weren't quite large enough, and I was creating too much air pressure on the underside of the hood, which troubled me, even though I was using hood pins. Still, I had no problems up to 140mph.

[baktasht]

In order to make it truly functional you would need to make a custom hood and do lots of cutting and porting. Simply installing a border style vented hood and changing the angle of the radiator will not give you any sort of measurable gains.

[HeartbreakMR2]

Originally Posted by baktasht

In order to make it truly functional you would need to make a custom hood and do lots of cutting and porting. Simply installing a border style vented hood and changing the angle of the radiator will not give you any sort of measurable gains.

Please explain. May want to take that project on later.

[chicagoisonfire]

Originally Posted by baktasht

In order to make it truly functional you would need to make a custom hood and do lots of cutting and porting. Simply installing a border style vented hood and changing the angle of the radiator will not give you any sort of measurable gains.

i figured that much, but i thought someone was making a hood that was more easily adaptable, but that may have just been wishful thinking.

[chuck]

i think the guy with the red widebody in the phillipeans made his hood, blake gomez has made a few too may want to get some info from him...they may chime in here shortly.

somewhat off topic-does the border vented hood require taking out the spare tire??

[mr2greasemonkey]

I'm working on a design....

[Raptor13x]

Originally Posted by chuck

somewhat off topic-does the border vented hood require taking out the spare tire??

No, the airflow is routed sharply upward and out the vents, which sit forward of the front trunk.

[F_R_O_G]

I'll just put in my two cents and say that unless you have a windtunnel it would be just about impossible to really improve your airflow by yourself. use produts that have been tested.

[Raptor13x]

^ Not the case. Windtunnels can, of course, be used to fine-tune aerodynamics, but basic aero is easy to visualize, and many improvements can be made by someone with even rudimentary knowledge of the subject.

I'm probably unusual in this regard, but I visualize the aerodynamic profile of nearly every moving object I see, especially cars. I examine how the air flows over the car, without even really thinking about it. It's pretty easy to see what's causing lots of drag, where turbulance is forming, and the high and low pressure zones of the body.

[F_R_O_G]

then you have much better eyes than me cuz i can't see air

[Raptor13x]

You don't see the actual air, you see how it flows over the car.

[kbrew8991]

but you can see smoke, mist, etc

in the old days before wind tunnels they'd tape little bits of string all over the surface of what they wanted to see and would film the car driving around and look at what way the strings were being pulled to determine good/bad aero wise

alot of it is intuitive, but getting exact measurements is a little harder to do visually or in the real-life lab

[F_R_O_G]

the point i'm trying to make is that the manufacture made the bodypanels the way they are for a reason and for someone without a international auto company backing them up it would be very hard to improve on.

[Raptor13x]

Originally Posted by F_R_O_G

the point i'm trying to make is that the manufacture made the bodypanels the way they are for a reason and for someone without a international auto company backing them up it would be very hard to improve on.

Aerodynamics is the last thing a typical auto manufacturer is thinking about while designing a car. You're giving those engineers a little too much credit. Much more prominent concerns for them are visual appearance, manufacturing ease, marketability, cost, etc. All too often, aerodynamics are at best improved by accident.

Just look at cars like the Audi TT- they designed the car with no thought whatsoever to the aerodynamic properties of the rear end, then they found that their cars were spinning off the road and crashing as drivers exceeded 100mph because the massive amount of lift at the back end of the car nearly pulled the rear wheels off the ground. They had to go back to the drawing board and add a spoiler to the back of the car, which was little more than a patch on a fundamental design flaw.

If automakers cared- I mean really cared about aerodynamics, cars on the road today would be getting 50+% better fuel economy on the highway.

[DenverMR2]

Lol you seriously think honda or toyota were thinkin about aerodynmics when they made the element and xb respectively?

[F_R_O_G]

ok your the engineer now

[Raptor13x]

^ you're

[kbrew8991]

Originally Posted by F_R_O_G

the point i'm trying to make is that the manufacture made the bodypanels the way they are for a reason and for someone without a international auto company backing them up it would be very hard to improve on.

two words:

Bean Counters

[mr2greasemonkey]

Well, you won't ever know unless you try. Eventually I'll add some sensors to see if my mod's do anything.