1QWIK7

iTrader: (33)

I rather get a vented hood. IMO

dubulup

If I find some time this week to complete this mod, I should have some before and after datalogs. Same conditions to my best ability.

FDNewbie

iTrader: (10)

That would rock And do you have a stock or vented hood?

dubulup

stock

GoodfellaFD3S

iTrader: (213)

Hi Bob,

Right before I had my car painted back in 2004 I put a lot of thought into whether i wanted a vented hood, what front bumper i wanted, should i change the rear wing, etc.

I came to the conclusion that I really like the stock look (with 99 spec front bumper). I wanted something classy and flowing, basically an FD where I can pull into a Ferrari meet and not feel out of place. The scoot hood, whale tail wing, etc look definitely isnt for me. Plus, having to deal with rainwater inside the engine bay seems like a pain in the *** .

Rich

axr6

The test, every single time I made a modification, was performed on a 2.1 mile flat section of the freeway with 4 runs each time and averaging the results. 2 runs in each direction to account for any wind differences.

If you wonder, at the time, that section of freeway was fairly abandoned at daybreak, when I did those runs. The only variables were the air temperatures but, I used to record them as well, and since most of my tests were done during one CA winter, those temps were probably easily within 10 F degree.

As I look at today's far higher degree of knowledge and modifications, the results of my testing seem to very nicely correlate with posted dyno results. At that time those few of us who were doing these things were kind of stumbing in the dark, taking chances with our mods... still made some incredible changes...

7racer

Your right...I'm not a fan either of gaudy hoods and still love the stock/99 spec look.

I was thinking for of the FEED hood since it doesn't change the look much.

axr6

You probably will not notice much differences at AutoX speeds which are usually way below 100 mph. On my timing sheet the difference in acceleration times really showed up over 140 MPH where the exponentially increasing air drag and resistance must be overcome by either exponentially increasing horsepower or reducing drag.

Kevin T. Wyum

That's a good idea for a number of reasons. So dirt, mud and debris wasn't an issue with the screen in place? I'd think water might be a threat to the fuse blocks etc. coming from underneath.

axr6

No, I never personally experienced any problem with dirt or water. Regading mud, that could be ugly but, you know how ugly it is when you run off a racetrack into the mud and pack it into every possible opening in your chassis and engine compartment. In such case the screen would be the smallest of your mud problem source. I remember spending long hours scraping, hosing and cleaning mud from my racecars following those off road incursions. So, I suggest stay away from mud any time, any car.

As to water problems. It may be a good idea to either move the fuse block or wrap it. Having said that, I did not worry about it as shorts in electrical circuits tend to happen when high voltage arcs across contaminated water. Clear water has very high resistance to electrical current flows. (for instance, in the Bay Area, utilities use Hetch Hetchy tap water to wash their dirty insulators on energized lines up to 500,000 Volts). The low voltage levels (12 volts) represent very little dangers for arc to develop. There is simply very little PUSH behind the electrons to start moving across any resistance. It is the level of voltage that initiates an electrical arc, followed by the appropriate amount of current (that does the damage), according to Ohm's law.

the_glass_man

iTrader: (2)

And which reasons are those?

So did you ditch the whole fender lining and use the mesh or just cut out part of the lining?

axr6

Just cut out the lining inside of the openings and slipped and riveted the wire screen between the steel fender and the rest of the plastic lining.

nashman69g

iTrader: (3)

doesn't this affect air flow for the wheel well?

axr6

I am not sure what your asking here as far as wheel well aiflow being effected? Certainly you will be expelling a certain amount of extra air through the wheel wells but, what is it that worries you about it?

Let's put it this way; I have not found any handling or braking problems as the result.

When I raced the car I had the large brake disks with Wildwood calipers and still ducted cold air to my calipers so, never had any brake problems, if that is what you suggest. I certainly would not expect any problems for cars that are not raced.

Hope I answered your question.

-efini-

why is the engine bay low pressure...it has air being forced into it by the front air damn and that air is much hotter than the surrounding ambeint air...in what way would this be low pressure? i dont understand...it doesnt make sense...what teh ****?

f150rx7

This is what the forum is about alot of info that can be shared and discussed ,correct me if im wrong, on a hot day i crack one window open about an inch you can tell air inside the cabin gets vacuumed out(especially for smokers). I open another window and air doesn't get sucked out anymore, instead it circulates around the cabin and cause a turbulance, I understand what you guys are saying but would you rather drive on a hot day with only one window open or feel the temp. actually go down with another window open. If you drive a truck with a window in the back glass, you crack the drivers window only does it get really windy? how bout opening the back glass... then you feel circulation of air ,OK if air doesnt get sucked out from top of the hood and actually reversed than it's very believeable and i now learned it from you guys but it does circulate (vent) under the hood. Now for the radiator actually not flowing correctly because air is trapped due to removing the weatherstrip then what affect does the opening of under the engine bay do when the wetherstrip is on. Theres also been a thread about the solenoid black box from the 96 and up FD's not being able to work on US spec 93-95 FD's, alot of people tried and failed and said it's either not worth it or wouldn't work, I agree that it's alot of work but what is this after tinkering with our cars already. Well I happen to get one of these black boxes anyway and it's currently working on my car right now with the correct boost pattern all you need is a wiring and vaccum diagram and carefully chase each one. I never forced anybody to perform this mod to begin with it's just ideas that might or might not work , everything begins with an idea it's up to you to follow. I will perform a test on coolant temps. with and without the weatherstrip numerously and try to get consistent results. If it really raises coolant temp. than of course I will drop this idea my self, but i do know one thing for sure it will help it when the car is not moving.

chopstix

Tried to find a diagram showing the high pressure that builds at the bottom of the windscreen. Could only find this one, representing lift.

axr6

I do not think that the engine bay is LOW pressure at all. What our testing seem to consistently indicate is that at high driving speeds the pressure build-up in front of the windshield exceeds the underhood pressures, thus is the reverse air flow into the engine compartment from the base of the windshield.

I did the same test as othes in this thread where I taped little piece of yarns onto the hood opening below the windshield. It was not on my FD but on a 83 Mustang and I was looking for not air exit but, cowl induction. Still, the test was consistent with the findings of others. At low city speeds the yarns were being blown OUT from the engine compartment but, when a certain speed was exceeded (forgot the exact number but, probably around normal freeway speeds) the yard were solidly being pushed back under the hood opening beacuse of the pressure built up at the base of the windshield

So, don't think of this as low pressure under the hood. Rather, high pressure against higher pressure.

rynberg

f150rx7:

You are wrong. It has been repeatedly proven. Brian Davies (Wargasm) even tested this with underhood thermosensors and discovered that, if anything, temps went up a degree or two with the weatherstripping removed. Unfortunately, his website is down at the moment.

airborne

I also have cut out the fender liners. I installed a wire mesh and a layer of charcoal screen. Also, I cut out aluminum pieces that I can slip in if I'm going out in the rain.

I did it to try and help out my hot air intake but I didn't notice a significant temp difference. But its been like that for a few years and things under the hood haven't gotten extra dirty.

dubulup

I'm more interested in dumping engine bay heat, so if air is exiting the bay, heat must be going with it, no? I route fresh air up under my intake, and if it has a low resistance exit path, the more air will flow...acceleration would be an added bonus

further
I pulled the liners last night, and it looks like one could improve air flow through the oil coolers as well with a screen section behind each cooler. I know the 300ZX TT guys do something similar with their IC's (same location as FD oil coolers)

homemade louvers on a 300Z board
http://twinturbo.net/net/viewmsg.asp...&msg_id=868066

airborne

Are you referring to the fender liners dubulup? If so thats kind of funny. I thought that the fender liners combined with the vent behind each wheel were meant to *help* flow through the oil coolers.

dubulup

^LOL, I think you are right.

nm, found it




my problem with this is the windshield washer reservoir is right behind it. If there were an opening in the liner, wouldn't that be a less resistive path and generate more flow.

I, for one don't like to hack Mazda's engineering with the car...but hell, at this point there's no turning back, haha! You know, the liner is two pieces and they are stapeled together

dubulup

look at the brake duct in that picture as well

airborne

I noticed that's an R1 diagram. I have a touring and didn't see any ducting at all while I was cutting out the fender well. I guess the poor 1 oil cooler cars have to soldier on with no airflow.