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Old 02-26-2009, 04:52 PM   #181
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Quotes from another source: Contrails ! Radiator aerodynamics


Quote:
The radiator in a free stream

Photo GTH

It is often wrongly believed that a radiator or finned barrel directly exposed in a free airstream will achieve efficient cooling.
Actually, less than one third of the air arriving in front of the radiator will effectively flow across the core. The rest will flow around the obstacle, not without violent turbulence.
The efficiency is poor and the drag is prohibitive.
Quote:
It is the pressure difference between the two faces of the radiator core, which forces air to flow through it : the ΔP. Without this pressure difference, no flow through the core, no cooling.
Quote:
Minimizing drag

To minimize internal drag, we thus need a core with sufficient area (volume flow), an airstream considerably slower than the aircraft airspeed, and as high a Delta T as possible.
There is thus some advantage in running the engine as hot as compatible with safe operating limitations.

Quote:
Diffuser

Doc Küchemann & Weber

It is the most important part of the duct. It comprises a diverging portion (not funnel shaped) in order to slow down the airflow without causing any separation.
According to Bernoulli's law, slowing air with no separation raises the static pressure. The presence of the radiator aft of a well designed diffuser renders flow separation still less likely.
The gain is twofold : the increased pressure facilitates the passage through the core, and this pressure on the diverging walls of the diffuser results in a forward force, opposing the drag of the core.
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Old 02-26-2009, 05:15 PM   #182
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someone molded a s13 grill on it before
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Old 02-26-2009, 05:29 PM   #183
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I like when engineer nerds fight.
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Old 02-26-2009, 06:00 PM   #184
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btw, pat is right and you're all powerbottom queers.
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Old 02-26-2009, 06:02 PM   #185
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Quote:
Originally Posted by hustler View Post
I like when engineer nerds fight.


I'm curious as to what everybody on the big-frontal-area bandwagon has to say about this information mazda/nissan and I have posted. Also still curious how you can have different pressures and the same pressure simultaneously.
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Old 02-26-2009, 06:16 PM   #186
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Quote:
Originally Posted by patsmx5 View Post


I'm curious as to what everybody on the big-frontal-area bandwagon has to say about this information mazda/nissan and I have posted. Also still curious how you can have different pressures and the same pressure simultaneously.
Your compression is too low and turbine housing is too big.
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Old 02-26-2009, 07:22 PM   #187
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I suppose it doesn't help to point out that in Savington's case the issue was that he had an oil cooler up there that was getting little if any flow at all, hence the hole. Others like myself who have a large intercooler (same one as you have I think pat) might do something like this to get some flow to the top half of the intercooler. But as to the radiator, I concur that ducting is the most essential element to make the radiator work more efficiently.
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Old 02-26-2009, 10:08 PM   #188
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I would like to see someone use the air flow through the front of the car to help act as downforce as per my article, but that may only be applicable on mid-engine cars
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Old 02-26-2009, 11:07 PM   #189
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Pat, great stuff. It's all relevant for our cars - without huge fuckoff FMICs in front of the radiators. Drop an FMIC and it slows the airflow considerably, heats the air considerably, and changes the game.

I did my hole because I added an oil cooler and I didn't want to stack another heat exchanger in the mouth of the car.
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Old 02-26-2009, 11:38 PM   #190
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Quote:
Originally Posted by Savington View Post
Pat, great stuff. It's all relevant for our cars - without huge fuckoff FMICs in front of the radiators. Drop an FMIC and it slows the airflow considerably, heats the air considerably, and changes the game.

I did my hole because I added an oil cooler and I didn't want to stack another heat exchanger in the mouth of the car.
It's all relevant regardless. It's physics and thermodynamics. Sure, stacking heat exchangers has its some effects, no doubt. But what effects?

Suppose you seal the exit of the IC to the entrance of the radiator, like what I did. Air first goes through the condenser (we will assume A/C is off) and then through the IC where it rejects some amount of heat, causing the air to increase in temperature. PV= RT. Guess what happens when T goes up? So does pressure. It's plausible that the IC adding heat to the air is actually increasing the flow through the radiator, possibly to the point that it's higher flow rate than no IC at all.... Granted the temperature of said air will be above ambient as it exits the IC and presumably the specific volume of air will be lower than if there was no IC in front. But the larger delta P means more air moving faster through the radiator which causes turbulence, which would improve the heat exchangers efficiency, somewhat offsetting the loss in efficiency due to the decrease in delta T.

Point is it's not quite as cookie-cutter simple as people take it to be.
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Old 02-27-2009, 01:08 AM   #191
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Quote:
Originally Posted by hustler View Post
I don't think a fan can move enough air to cool an engine at speed. The hood bulges from pressure at high-speeds...which tells me that we should focus on getting the air out, rather than adding fans.

I'm going to try making a little cup into my shrouding for the first 1/4 of the fmic...maybe this **** will work.
Nope. A properly shrouded fan can and does move enough air to cool @ speed. I won't get into this debate because it's pointless....

Next, the reason you see the hood bulge @ speed is partially based on Bernoulli's principle. Air flowing over a convex surface, like your hood, when @ speed has high ram pressure, but low static pressure. The air under the engine bay is moving slower than the air going over the top of the hood which has less ram pressure but more static pressure. This actually induces lift, just like on a winged aircraft. In the case of the hood though, it will bulge giving people the impression that there is high pressure under the engine bay. Take a look at a 90 some convertible Mustang or Camero when they're on the freeway (they have really poor convertible top bracing). With the top up @ 60+ mph, it bulges quite a bit. Would you suggest that the passenger compartment has high pressure? No, but is does have higher static pressure than the air going over the convex shape of the top.
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Old 02-27-2009, 09:52 AM   #192
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If you continue talking **** to me, like a ------, I'm going to hold this igniter hostage.
not yours:
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Old 02-27-2009, 09:54 PM   #193
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Quote:
Originally Posted by crashnscar View Post
How can you determine what size restrictor to use? I'm up for trying just about anything (within reason and that makes sense) to get this motor to not overheat.
An easy way to make one instead of buying one would be to take the valve out of the center of an old thermostat and just leave the nice hole in the middle. Or buy these from Jegs and try the different sizes out to see what works best for your car:JEGS Water Restrictors - JEGS


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Originally Posted by crashnscar View Post
And what is the pretty/functional comment about???
Regarding cutting a big hole in the front bumper of your car.
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Old 02-27-2009, 11:14 PM   #194
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Quote:
Originally Posted by hustler View Post
If you continue talking **** to me, like a ------, I'm going to hold this igniter hostage.
not yours:
Who are you talking to ?
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Old 02-28-2009, 12:43 AM   #195
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ooops, thought you were savington...damn sig pic!
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Old 02-28-2009, 12:57 AM   #196
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All you pansys need to just vmount with giant radiators and ICs and you are set just like me.

Everyone else = ball lickers.
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Old 02-28-2009, 01:33 AM   #197
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Quote:
Originally Posted by Splitime View Post
All you pansys need to just vmount with giant radiators and ICs and you are set just like me.

Everyone else = ball lickers.
yeah yeah your setup is god blah blah we know this But not all of us have the cojones you do
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Old 02-28-2009, 02:28 AM   #198
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Quote:
Originally Posted by hustler View Post
ooops, thought you were savington...damn sig pic!
Why did you cut the other end of the plug out?
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Old 02-28-2009, 03:55 AM   #199
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that's how one of my friends unplugs things... FTL
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Old 02-28-2009, 08:42 AM   #200
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Quote:
Originally Posted by Savington View Post
Why did you cut the other end of the plug out?
stock footage. My **** is still in tact.
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