rotorocks

Yep. And the point of this discussion was NO CUTTING. :-)

mac11

iTrader: (1)

don't be a *****.

rotorocks

Hah!!
You call me what?
Dude I hope you are joking.

I started this tread because, as I explained at the beginning - I like the way OEM hood looks. WTF does it have to do with me being a *****?

If i want to do something with my car. I just go ahead and do it.
I ripped out my intake and exhaust, designed from scratch, build and put in a turbo system into my car. The kind that no RX8 owner has ever had back then and not to this day, while my car remained a DD. All of it in my garage with just basic tools. And the car was off line for only a couple of days while at it.

Trust me, fear of cutting things is the last on my mind.

Next time you better put a smiley and "P.S. I was kidding" next to stupid statement like that.

P.S.

But then again talking about being a *****....

Kane

iTrader: (1)

I also like the OEM hood best of all I have seen!

Had you considered the fender vent as well? Then measure after both? I would be very curious to see results.

rotorocks

Nope, I haven't.
Maybe some other time. So far I am happy with the results as they are.

mac11

iTrader: (1)

take it easy there honcho. seriously. take a joke.

rotorocks

Ok. Since this tread has already accomplished it's purpose, there is no point to keep it on the topic anymore, and just like the case with most other treads, after a while they seem to drift more into the area of amusement. And I know that everyone enjoys this kind of crap, so I'll make one more post in reply to^

mac11 in case you don't know, there is a difference between a joke and an insult. A big difference, of which I don't care to go into detailed discussion.

I can take a joke just fine, so I can take constructive criticism and irony.

What I don't want to take is cheap crap from someone who doesn't have the ***** to admit his mistake and at the least apologize.
But then again, what can one expect from someone, who cant even learn from from a quote in his own signature.

this one (it is in case you are wondering): "Life is tough. It's tougher if you're stupid"

...nice day honcho

savedsol

Maybe we can incorporate safety into this hood thing too...
http://www.motorauthority.com/news/s...lp-save-lives/

r0tor

iTrader: (1)

maybe we can also have some controlled test to determine if this mod on this car somehow breaks a few fundemental pricipals of automotive and aerodynamic design before calling it a sucess...

mac11

iTrader: (1)

What do you propose?

rotorocks

If you want to add to it, and post your findings, be my guest, but please don't overcomplicate things.

As far is my requirements for this particular little project were concerned, this project is a complete success.

r0tor

iTrader: (1)

oh I don't know...

run the engine consistantly with and without the mod until you reach the point where the thermostat is wide open (disable the fans) and see where the coolant temps settle to on the same stretch of road at the same outside temp and same driving conditions?

Perhaps to this while having some yarn taped to the edge of the hood and compare whats happening. Is the yarn doing anything different with the molding removed?

At the same time perhaps have a thermometer taped to the engine cover and when the test is over immediately check it?


anything rather then "it looks like..."... which if you read this forum long enough, you'd know the "it looks like..." method leads to profound discoveries like lowering your cruising rpms by using a Revi, a greddy oil pan lowering your exhaust gas temps, and a set of retardely stiff coilovers improving the daily driver ride quality....

mac11

iTrader: (1)

I am a step ahead of you and on the same track. Yesterday at lunch I taped about 30 pieces of ribbon ~4inches long on the hood, windshield and cowl area of the car to map the airflow. I think having actual oil and water temp gauges would be a more accurate measure than a thermometer taped to the engine cover but I don't have those gauges yet.

What I found is that airflow does infact flow in the directions stealth pointed out. however there is very little - if any - airflow inward under the hood when at speed in the center of the hood a-la behind the rotor. All the intake air seems to be on the sides of the hood. It seems to make sense to me. The air from the sides can flow around the sides of the motor. Air coming in the center would hit the top of the motor, which would be great if we had a carburator and top mount air filter like the pic of the hood you put up. But since all we have is a throttle body and 2 piece intake manifold the air would cause turbulence, stagnate and reduce the cooling properties of the traveling air.

As far as what kind of benefits would be had by either opening up this opening I would like to see some oil and water temp gauges because those would be a lot more useful than under-hood temps, IMO.

thoughts, comments?

rotorocks

And if you had spent some time reading the earlier posts instead of taping ribbons, you would have found that MM and myself posted the results of our own tests from yesterday. And in fact MM laser temp reader, had shown that the hot air comes out of the opening at the temps of 160F and variable of up to 140F while moving, and it also rased his overhit threshold too, just as it did on mine.
I also posted some the cooler temps that were reported bythe temp sensor gauges in my Int-X EMS.
To be specific, It runs at an average of about 6-10C degreed lower on my turboed engine.

rotorocks

Oh, and another thing.
when I was in college age, I worked as a limo driver in NYC, and being in traffic all day long, especially in the summer it was uncommon to see our those Lincolns go hot. As a remedy we would pop our hoods and leave it open but locked, and drive like that. This trick was the only thing that saved most of us from boiling up.

r0tor

iTrader: (1)

coolant temps are highly variable...

staticlag

Its not venturi effect that would move air in this situation, so the air profile picture wouldn't apply. It would simply be the air coming through the radiator having another exit path. Since that is the case, it would be wise to remove as much obstructing plastic as possible, battery/airbox trays.

But the downside is that by doing this mod you are changing the drag coefficent of the 8. air is normally at a high pressure in the upper engine bay area, while the air rushing past it through the radiator and on under the car is the low pressure system because of its speed. When you open the hood in such as way it lets out the high pressure system and air suddenly wants to seep into the low pressure area in front of the alternator. But this is blocked by the engine itself, thus causing exponentially more drag than a closed hood or a "real" vented hood.

Personally i like the look of the stock hood, but sometimes you have to make sacrifices.

rotorocks

what are you talking about?
highly variable? LOL The normal operating temperature is between 86 - 98 C above that is already getting hot. Yeah it varies 10 degrees depending on conditions. But I would not say it is highly variable. If i drive 80mph keeping the engine in a certain load range with hood unmodded, and temp is averaging 98C and then with the mod and the temp is hovering at around 90C there is your cooling effect.

I understand you have some sort of undefined issue with this mod, most likely because you are a skeptical person who takes everything in a negative way. But to say something like what you had just said, without continuing your thought just doesn't give you a whole lot of credibility my friend.

mac11

iTrader: (1)

Your results, while noted, don't mean much to me.

Air does not come out of the hood cowl when moving at speed.

Define overhit threshold.

mac11

iTrader: (1)

What do you think of taking out the weather stripping only on the outside of the hood, not the middle in front of the HVAC intake and not adding the chalks? I think it would enhance the existing airflow characteristics of the car when traveling at speed. On top of that my ideal would be to cut out most of the triangular area and vent there from the top of the engine bay a-la evo to release hot air when at a stand still.

staticlag

Its hard to say, I just wish the side vents had a direct path to the engine bay, that would seem like the best solution to this problem.

For the chalks, I would say more is better, the faster and more directly the air can get out of the engine bay unobstructed, the better. If anything, I would say to chalk the hood up higher if you were going to try this.

mac11

iTrader: (1)

Chalking the hood up isn't going to let air out except at stand still and low speed.


And I'm not talking about removing vents. I am talking about removing the weather stripping which would give an unimpeded path into the engine bay.

r0tor

iTrader: (1)

Oh so the cooling system is not highly variable? The first OEM radiator fan will kick in at 97 degrees C and the second at 101 degrees C. How do you know the difference isn't just the fans kicking on that run and not on the previous run? Throw in the regulating effects of the thermostat and thermal lag associated with a cooling system, and its extemely hard to get an apples to apples comparison by just looking at the temp guage for a few minutes.


and yes i am entirely suspect of this mod because i know (and now mac11 has proven to himself) the entire center section of the hood (where you prop it open for more "flow") has no air flow at speed and therefore there can not be any heat transfer in that region.

staticlag

Im talking about chalking up the rear of the hood. It would let air out of the engine bay, the problem is as I have said, its merely "catching" on the engine instead of blowing adequately around it. The solution to this is to chalk up the rear of the hood until the air comes out of it freely. You also need to remove the engine cover and if you battery relocated and have an aftermarket intake, then remove the stock plastic diffusers as well. They serve to help direct the flow under the engine. But in this case we are trying to drastically direct airflow out over the engine. Normally its a moot point of keeping them or not, but in this case the 1/2 inch to 1 inch breathing space that we are using to modify the airflow profile of the rx8 needs all the help it can get.

Example:


This is the profile of a rear wing, because it is easier to visualize than the complex shaped inside of an engine compartment, but the principle is the same.

The first picture, as the air rushes over the closed wing it creates a localized High pressure system, this creates drag but it does not disturb the air as much as you think because air doesnt even try to squeeze in there at some point, it takes the easier way to just go around.

But in the second picture, with a small open space the air pressure profile changes, and suddenly more air thinks it can squeeze in the small very fast moving low pressure area that is the small gap. This majorly screws up the airflow upstream.

And the last picture is an open wing, symbolizing the "real" vented hood. This does create a bit of turbulence but it is negligible

There are other options but as other have said, they involve modifying the bodywork, or the ac system or heating system.

At that point just taking the hit for a real vented hood with loads more capacity than this mod wouldnt sound so bad.

staticlag

Theres not "no" airflow, theres just extremely little. Which is why i just recommend getting a real vented hood over the pita that it would be to chalk the hood up high enough.

extremely little is very difficult to measure in comparison to the great wash of air coming over the hood.

Also, I would only really be intrestred in temp differences of the coolant while driving at 95 mph for about 5 minutes in 100 degree weather. At least we know that will max out the cooling system.