I know this is the correct way to go from F to C, but if you want a close approximation without the use of a calculator or your phone (cuz I think we can all admit, multiplying by 9/5ths isn't the easiest thing to do) double the temp and add 30, gets ya damn close.

edit: at least in the temp ranges we are dealing with, obviously the margin of error goes up as the temps move away from 0C or 32F in either direction, if it's over 40C only add 20, and over 80C add 10, so subtract 10 from the amount you add every 40 degrees celsius

 

I have a 3 dimensional mind and can invent and make things work in my head. That doesn't mean I can easily do mathematical conversions. It all comes down to what your use to. Like I'm way more comfortable identifyling metric socket sizes. SAE??? I'm like WFT size do I need! LOL!!!


Oh well back on topic!

 

There's no exception cause everything happens for a reason. With your under tray mounted and large front mount, your radiator only gets air after it goes through the IC. The larger the front mount is and the closer to the opening it is, the higher the air pressure build-up it creates in front of the opening. Air (like all moving things) will always take the path of least resistance. So the air is more prone to go over the hood and underneath. The air that does make it through the IC core slows down considerably. Once it gets past the IC core, there isn't much energy to force the air through the core of your radiator. That's why your temps are high with your under tray. Without the under tray, there is enough turbulence underneath the front end to bounce some air towards the radiator. This is exactly the reason why I don't like front mounts.

 

Yes, I follow but it definitely goes against the "you must have an under tray installed or else" crowd. All of my front end is sealed up really tight so the only airflow with the under tray on is through the IC and through the AC condenser to the radiator. I had a few vents cut into the bottom of the under tray but these obviously didn't work.

I will revisit this again soon. The plan is to have the body shop guys put larger vents into the under tray with "air directors" installed in it so the air gets directed up into the IC. We'll see.

The reason I would like to do this is to protect the underside of the engine and keep everything stock looking.

 

I have a C-west front, and when I installed it I couldn't install my undertray because it no longer fit (the bumper is longer than stock). A few weeks ago I modified my undertray by extending it, and I then took it on a 600 mile trip, where ambient temps reached around 95 degrees F.

undertray mod thread

Before the install, the car ran around 200-210 degrees F, pretty much at all times. After I modified the undertray and reinstalled it, the temps remained the same.

I think this is most likely due to the C-west bumper having huge openings for air vs. the stock bumper.

So if you are getting enough air to your radiator without an undertray, you don't need one, unless you prefer it to look stock like David mentioned above.

 

Got any engine bay radiator shots? Your new mod may be working very well. It's very possible the air flow has found a new leakiness in you set-up. Remember air will always follow the path of least resistance

 

mine has been running at 105-110 (only in the summer) on the highway for 2 years as a daily driver, no probs, highest it ever went was 112.......that was after an hour of cruising at 90mph in 95* florida humidity/heat. i knew it was running hotter than it should be on average, but i attributed it to the heat here, i had no idea there was supposed to be an undertray! lol

from the FAQ thread i saw these guidelines

65C (150F): too cold. According to service manual, EGR valve is non-operational below 150F, "to improve drivability when cold."
82C (180F): getting warm. Thermostat begins to open, circulating coolant thro2ugh the radiator. Some coolant is still bypassing the radiator.
95C (203F): fully warm. Thermostat is fully open, not bypassing the radiator at all.
100C (212F): boiling point of pure water at atmospheric pressure.
105C (221F): getting hot. Stock ECU will activate fans to cool the car down. Fan speed will be low, or medium (if A/C is already on).
108C (226F): hot. Stock 93-95 coolant thermoswitch activates, changing fan speeds from low>> medium (or med>>high if A/C is already on) (switching to an FC thermoswitch will change this temp to 203F)
115C (240F): getting dangerous. OEM temp gauge begins to rise.
117C (243F): dangerous. boiling point of pure water with 13psi pressure cap.
121C (250F): too hot. OEM temp gauge will point to white line. Boiling point of pure water with 16psi pressure cap.
124C (256F): way too hot. Boiling point of pure water with 19psi pressure cap. Boiling point of 50/50 coolant mix with 13psi pressure cap.
127C (260F): way too hot. OEM temp gauge will point to red line.


i still have the stock radiator for now. ill upgrade it eventually. greddy intercooler, but it is behind the radiator.
i just got a pettit aluminum AST im going to install soon.
i guess i will have to order a factory undertray also........i cant believe the previous owner didnt have it on there.

even with my crappy homemade ducting, the car doesnt get higher than 91* now, even in the hottest conditions. usually cruises around 88*.

 

^ Good to know, and I've seen those temps before in the FAQ. I've known Dave for years now, and know that he's a very conservative guy, so it doesn't surprise me that he recommended not going over 110. :P lol

 

oh he is definitely gave good advice, because mine was running that hot without the proper undertray, that was the only reason it was so hot.

considering how cool the car runs with an undertray, if it now started to climb up to 100+, i would start getting concerned!

 

Oh trust me, I get all sorts of paranoid any time I start even getting CLOSE to 100!!

 

In case someone else out there is as stupid as I am...DO NOT SWAP THE COOLANT CAPS!!!! You will "pump" the coolant right out of the white plastic coolant filler tank (with it's very own plastic cap). Both metal "pressure" caps fit both locations, but the one with the tabs (for ease of opening) goes on the aluminum METAL filler neck on top of the thermostat housing. The metal cap without tabs that says "NEVER OPEN" goes on top of the black plastic overflow tank. The caps are similar but not identical. If you switch them, the system will not hold pressure, but it builds enough pressure to pump the coolant out into the white filler tank, which overflows onto the ground under the right front fender. If you refill the now near empty white filler tank, you will have only a false sense of security, since there is now little or no coolant in the engine and radiator. You will drive away from the safety of your garage, thinking a full white filler tank means a full radiator, only to find out later on the freeway, far from safety, that you are beginning to overheat, fast. Always fill the engine at the metal fill tube first, run the engine a little to get the air out, then fill again. Make sure you can see coolant in the metal filler neck before putting the correct cap back on (the one with the "tabs"). Don't touch the one on the black plastic overflow tank that says "never open". Then fill the white filler tank to where it says "F" on the plastic "dip stick". Make sure all three caps are located and tightened correctly. Start the car and wait for it to come up to operating temperature for a few minutes, before driving away from "safety".

I speak from stupid experience, earlier today, after giving a really great looking Danish girl a ride, I overheated, AFTER dropping her off. Luckily, I was on the way to UMS to talk race tuning. Instead, I spent the afternoon at UMS, adding distilled water and "water-wetter" to my car, after swapping the metal coolant caps back to their proper locations. Now, this is how stupid I really was...why in the world did I drop the Danish girl off first?