Evil, i dono why your pissed but I might be a "kid" but i sure as hell know more then most of the ppl who are double my age so u can just shut up with the cuz im older then you ****. I did do my research and the duct design has been PROVEN to get an okay amount of airflow so i figured, wut the hell. Also, if u didnt notice that i said twice, It took an hour. If you have a rx7, and you have a job where you cant work on it at all, then there is no point on having it. Rx7s are enthusiast cars, not something you take to a dealership to get every little thing fixed. And with that, if you have a job where you work 24/7 it isnt worth it. I dont care how much $$ your makin, if you have no time for yourself then whats the point of having $$?
And with that said please keep your comments out of my thread. Thanks.

Anyways, i did remove the weather stripping, I was tryn to get a pic of the hood closed were u could see the filter through the vent but yea.. there was no light in the hood haha. And thats why i didnt make my box depend on that air from the vent, im making it wider so it can scavenge more air from random places haha.
and i dono if i like the scoop thing. If i really wanted super air flow id just take the headlight cover off haha.
~TDR

 

Would water going in affect anything?

 

it might make the car stumble a bit but rotarys cant hydro lock

 

Wanna bet? They sure can.

You'll MAYBE get the filter wet, but that's all. Rain is no big deal.

I agree, the ducts look better than the scoops, but mine will flow better than ANY of yours, because there will be a tendancy for the airflow to just flow right over the opening of the sunken in ducts, whereas mine's actively grabbing the air and pulling it in. When I was getting ready to make it, I figured that the opening size that I could get with a sunken in duct was much less than I achieved with this one, so I went this way.

 

First of all, I am not pissed, I am just confused by your logic. Secondly, it is not my age, but rather my education and work experience that aids me in making aerodynamic assessments. I am not an aerospace engineer, so I am not exactly an expert on this particular subject, but I do know a little more than the average forum member.

So, back to your logic, do I understand you to imply that it is your lack of age that makes you an aerodynamics expert? If not, then how do you justify your position?

Well, at least I follow that logic, lol. That is why I only work 4 days a week. Anyway, I was just answering your question of "who wants to spend 100+shipping to get something you can make youself for about the same gains/loss". Why are you asking a question on an internet forum, and then being rude to somebody who answers the question?

It is great that you have the skill to do that, but most people are not capable of researching the duct, designing the pattern, removing the headlight cover, fabricating the duct, and sanding/priming the cover in only one hour.

Do you have a reference for this proof? I would love to read it.

That would probably be the best idea for a drift car.

This is a public forum. If you don't want people to comment, then either use the Private Message function to converse directly with individual forum members, or ask one of the moderators if you can author a how-to thread in the Archive.

If you do not want to see any comments from some old guy who obviously doesn't know as much as you, then you can click on my screen name and add me to your Ignore list. You will find that I am not the only person on this forum with an education, so you can add more people to your Ignore list as required.

 

Home-made and unlike you I don't have a degree in aeronautics - it's in economics so I will be the first to admit that I know for a fact that it can be improved upon. So you've peeked my interest and sparked another question as well so first is first
1) How would you make mine better?
2) If I wanted to (& I'm going to be vauge here intentionally) desing a vent that would be mounted under the car on a custom belly pan (16ga sheet AL) to pull air into a duct how would you do that?

-B

 

Do you have any pictures of the scoope?

 

If you really want to grab some air, make it a scoop of some sort. NACA ducts and such CAN work well, but they have to be placed correctly so that they properly interact with the airflow over the body as a whole. With a splitter and airdam of some sort, the undertray should be a low pressure area, so you're going to have to go out and grab the air and force it to go where you want. It won't necessarily flow into a NACA duct or anything, especially seeing as the engine by is constantly being pressurized by the flow of air through the nose.

You really don't need a screen, the air filter will take care of anything. I've never found anything in there other than bugs really, and that screen's not going to stop them.

 

Wow, that's really nice for home-made.

The design looks OK to me, but I think you should remove the grating. If you drive the car in an environment in which filter-penetrating flying debris is a concern, you could simply offset the filter from the intake hole...
http://www.triz-journal.com/archives...02/a/index.htm
http://www.uspto.gov/web/patents/pat...-20071120.html

or incorporate a less-restrictive anti-FOD (Foreign Object Damage) system such as Ferrari-style "cheese grater" strakes.
http://www.drivingtoday.com/truckbed...ssa/index.html

If you want to get fancy, you could design a vortex generator field on the headlight cover or in the intake tract, which would act as both an air filter and as protection from FOD. I'm not sure if this would be practical though, and it wouldn't have quite the filtration of a barrier type air filter.
http://www.donaldson.com/en/aircraft...ary/052457.pdf
http://www.pall.com/pdf/Army_Aviatio..._CH47_EAPS.pdf
http://www.centrisep.com/file/C.sep%20Pdf.pdf
http://www.pneumafil.com/gasturbine/sc/inertial.html

As for improving the duct itself, see the original 1945 NACA document. Note the "entrance lip" on Figure 2, which is missing from most of the aftermarket attempts at emulating the NACA duct. Also note the raised "deflectors" in Figure 9, which may not be worth the trouble, but are still worth a look.
http://naca.central.cranfield.ac.uk/...a-acr-5i20.pdf

Given the relatively low speed of a car, and the less-critical nature of an Otto cycle engine, I think the most important thing is to have enough cross-sectional area for the engine to breathe, which it looks like you have achieved on your current inlet. If in doubt, just dyno the car with the ducted headlight cover in place, and again with the headlight cover completely removed. If the dyno shows a performance gain with the headlight cover removed, then the duct is choking the engine. If not, then don't worry about it.

Oh boy, that is just asking for FOD, lol. Anyway, a NACA type duct or just about anything would probably work just fine, but once again, you may want to offset the intake tract so that ingested objects do not hit anything vital.

If this is for a heat exchanger, you can mount the core horizontally at the bottom of the car and simply install a lip (air dam) at the trailing edge of the core. If you want to install an external duct, here is how to do it:
http://www.ch601.org/resources/cooling_systems2.htm

OK, now you know just about everything that I know.

 

None up close at the moment, but you can see it in the pic I posted on the first page at the bottom. Mine is also homemade (I've been asked where I bought it from those seeing it in person).

 

sry to be a noob here but what exactly do headlight covers do? I mean, what benefit does it add to the car??

 

Evil Aviator just owned this thread.

 

When you get rid of the stock filter box and snorkle in favour of a cone filter it'll be sucking in hot engine bay air, so the solution is to make a heat shield to isolate the filter from that air. Then the problem is how to get ambient temperature air to the filter, and it just so happens that the filter sits right behind the headlight, so it's only natural to make an opening there so that the air can get in and get to the intake.

So in short, a headlight cover duct supplies ambient air to the engine.

 

So disregarding cross sectional area, am i to understand that the shape of TT's design is good but could be improved upon by the top lip curving in a bit. In addition to it curving in a bit the underside should be relatively flat so that the air will move fasteruder the lip than over the lip causing the underside of the lip to be higher pressure causing the moving air to diffuse to the scoop rather than flowing over it. I would really like to design a proper intake scoop. I couldnt find much in my mech design book by shigley, but i think if i could get the basic design i could maximize the efficiency using some of my overly priced fluid mechanics knowledge and my book of course

 

actually might curving up and then in be better yet based on figure 15 lip 6 of the naca document?

 

No they can't. they CAN if complete submerged in water and then rotated be prevented from making a full revolution, but all you have to do is turn it the other way... and then unsubmerge it, and continue spinning it, a piston engine, at top dead center will lock up to the point you could not spinn it any direction. and a rebuild would be required....
but thats if it was just submerged and then dryed ASAP..

 

Does anyone want to discuss the design of a proper inlet?

 

darkracer , good job on the home made duct.

 

Got some nice closeups of my homemade scoop.

I really don't think that "proper" inlet design is really possible. Sure a NACA duct is a high efficiency design, but it's not like you can make it as big as you want, because there's the headlight and all the mechanisms under there. I found that this would have severely restricted the depth of a duct, which is why I went with a scoop instead, to get more air to the filter.

 

I think you're right about the duct not really being efficient. The duct on that plane was much larger and had a much gentler slope. Also as Evil Aviator said the airplane is moving much faster allowing it to get more air. The scoop is probably the most practical design.

Do you have any pics of the whole front end of the car?

 

Holy f*ck! I can't believe it's been a month since I've been on..... anywho........

Why thank you. I started with a stock headlight vent, some sheetmetal, cutoff wheel, welder and some knowledge on metalwork...... & some glazing putty


Damn. That's alotta reading but I really do appreciate the time you spent typing that out and linking the usefull pages. I will certainly reference that when I'm building those two vents under the car that I need. Thanks again

-B

 

gotta get me some of those for vegas weather. To hot need all the air I can get haha

 

i noticed a few degrees difference in my intake temps at cruise when i would raise and lower my headlights (logged from microtech).

 

I think it looks kinda odd cause there's only one, but then again two wouldn't really serve a purpose. :/

 

Got more pics/info of your car? It looks pretty nice.