MazdaManiac: can you just give a summary of the conditions you are referring to?

my position is that this mod is effective where driving is at a speed where the pressure at the base of the windscreen is not higher than that under the hood (or a significant portion of it is like that, e.g. stop-go traffic, cool down laps at track).

As for people discounting the Volvo pressure/streamline picture because it isn't of an RX8, I've seen enough similar pictures to know it would be approximately the same for the volvo, for an Rx8, for a Supra and for a NASCAR.

The pressure at the base of the windscreen is NEVER as high as the pressure at the nose!
Why doesn't anyone get that?

On an airplane wing, which force is a greater contributor of lift:
1) The low pressure area above the wing
2) The high pressure area below the wing

If you do not have at least 40 hours in your log book, consider that a rhetorical question.

Its amazing that the only 4 people in this thread to actually take the time to see which way the air flows found different results... :rolleyes:

who cares because the pressure under the hood is not as great as the pressure in front of the nose - and the pressure difference between the base of the windshield and under the hood near the windshield will determine which way the flow goes :Eyecrazy:

the real answer would be

3) airflow circulation around the wing

If you don't have 3 credit hours from a 300 level advanced Fluid Dynamics class and studied and tested the design of airplane wings - consider youself pwn3d

heres some edjumacation for you

http://en.wikipedia.org/wiki/Lift_(force)

Sure it could work, if the new hood opening is eliminating some under hood action (air flow or pressure) that was limiting the flow through the radiator.

That is why you go with what works. Air flow and turbulence is funny. Look at the years of arguing about truck tailgates and the drag associated with them being up or down (and that would seem to be clear cut!).

I would be concerned additional lift or drag after this change. But knowing MM, that has been tested and found to be minimal.

He didn't test the airflow before the mod. What makes you think he tested anything afterwards?:lol2:

I was suggesting a more practical test....

Aerodynamics is not a cut and dry science or wind tunnels would not exist.

Show me a link concerning aerodynamics and the internals of engine compartments and we might have more to talk about.

But I get MM's attitude towards this discussion.

I did. I performed a very thorough dynamics testing on my car before and after.
Here are the results:

I run 140MPH before the mod, and 140 MPH after the mod on a wide and open highway stretch. Car feels the same.

Nice, tight and solid.
The only difference, the first time I came out of boost and my temp gauge was blinking red with temps ovet 100C like out of it's mind.
The second time it was 98C and not even a blink.

How's that for a test?

He heh he he he :moon:


With that, I couldn't give a rats ass where that air comes in or comes out. it could be coming out of Bin Ladden's asshole for all I care, as long as the coolant temps stay at bay, and the car doesn't get airborne. :yelrotflm

and in neither case do you have any idea on the status of either of your radiator fans which activate at that exact temperature... great test indeed :Eyecrazy:

you might have found a great way at reducing cooling enough to kick on your fans more often :rolleyes:

Well saves me from paying for other expensive mods.


:banghead:

You are like my wife when she has PMS. Just can't STFU :rollingla

Are you suggesting that the cooling fans would increase airflow over the radiator at 140mph??

Now who's trying to be a rocket scientist and doesn't know what they're talking about. You bought a Turbonator didn't you.:icon_no2:

No I think it was just this:

MEGA-HYPER ELECTRO-TURBO SYSTEM®[/QUOTE]


:rollingla

are you suggesting a 1/4" gap in the hood will?

Actually it is a 1/2"
You are not paying attention :spank:


You betcha it will.
Just for kicks and giggles try to calculate the size of the opening based on the width of the hood. It is freaking big. How much air can be flown through that hole do you think?

Depends on how much lower the pressure under the hood is compared to the cowl.

intersteing thing about this whole discussion-

i read a quote from Jim Mederer recently about how Mazda has shown less and less ability(or has made more styling over substance decisions) over the years between rx-7s and rx-8s to get proper good airflow thru the radiator and that he/they at Racing Beat have found on the 3rd gen and the 8 that a splitter/diverter spoiler thing that created better flow to/thru the radiator/engine bay made a huge difference in cooling efficiency/keeping the temps down.

now to just find it again.

maybe ill just email jim.

If any of you all need me, PM me. This thread is clogging my box with useless notifications, so I'm un-subbing.

That and the average American would bring their car back bitching about dirt and water stains on their engine cover if the hood was vented.

Yup, I read that too.

I've logged hundreds of hours on a cell phone, it doesn't mean I could design the chips inside.

it is, its just complex and expensive ;) I shudder to think at the time and expense to model, mesh and run a CFD simulation on a FULLY modelled car including engine bay. Wind tunnels are just easy for some stuff, and a good way to verify what you've designed.

If OEMs designed cars to have vented hoods from the factory they could probably do a better job packaging components so everything was properly ducted out, rather than like aftermarket hoods that just have holes placed semi-randomly (and getting dirt/water on engine covers)

Yes I'd love to have a Lotus Elise like setup where the airflow out of the radiator was ducted directly up and out through a screen in the hood. No more engine compartment airflow discussions needed.

Talking about discussions: this thread went like HOLY SHIT!!!! LOL
people left and will be "sucking in" the air at high speeds inside their hoods and disrupting the radiator air flow, causing fans to come on more frequently. lots of fun... :lol2:

By the way, loved the idea. +5 for inventing a new angle to the argument. :xyxwave:

LOL - My favourite line from the whole thread .