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Discussion Starter #1 (Edited)
Best way to keep engine cool 98 cobra? UPDATE: fully boxed-in now!!

What are some ways that I can keep my engine cool on my stock 98 cobra motor? I was running at infineon raceway last week in 90+ degree weather and I noticed my stock gauge riser the "L" or "NORMAL." I know these stock gauges aren't accurate so I do plan to get a "real" temp gauge, but since the temp rose significantly higher than usual I know I'm going to need some cooling mods.

Here are my questions:

1. What mods can I do to cool the engine?

2. How hot can my motor "safely" get before running into issues?

3. What is the normal operating temp of these naturally aspirated 32v motors?

Thanks!
 

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I've been thru this exercise on my ol' 97 Cobra. The L is not normal, it's more like 230 degrees. The engine has 2 temp sensors near the cross-over. One drives the guage, one the engine computer. Hitting 230 at the cross-over puts you up near 250 in the heads near the rear. Flow is bad in the back of the heads since there is no cross flow back there. 250 is enough to warp the aluminum heads on these motors. BUT, fortunately the head gasket handles it well. They will probably need milling if you rebuild.
To cool these things: ditch any underdrive pulleys.
Straight water and water wetter is good for about 6 degrees. The heater is good for about 6, but really sucks. Car must have the littler chin spoiler to provide the pressure differential over the radiator.
The best answer is the big aluminum fluidyne radiator. I can run Thunderhill and Buttonwillow in the summer with that beast.
The temperature guage is actually accurate enough to make decisions off of. Use a ScanGuage to read the water temp from the computer and you will know what temp corresponds to what letter. The computer tracks well with my real guage. The DOHC form actually has a good conversion chart buried in there.
 

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Ditch the stock 13 year old radiator (assuming that's what's in there), flush the system, add an aluminum one such as the Fluidyne and use some water wetter (it does work).

I know it's not apples to apples but on my first track day (a driver's school at that) my '91 with a then stock engine overheated pretty quickly. My instructor bought me a bottle of water wetter, which did help some. The next Monday I ordered a Fluidyne radiator and it was all the difference in the world. I've since then built a new engine with much more heat producing capacity and the Fluidyne still handles it pretty well (though I do have to watch the temp gauge and short shift if it's a real long session or really hot out).
 

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Removing the ac condenser will help quite a bit as well. I don't know if this is an option for you or not. Also, Evans has a high flow water pump for the cobras. Its much better than stock.
 

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I had overheating problems after adding a 2000R-style front bumper cover to my 98 Cobra. Boxing the radiator and ditching the condensor fixed it.
 

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Last race was around 100 out and still no issues with mine. I did not mention but I do not. Have the low pressure creator flap thingy either.
 

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One of the best mods I did to my 95 was to box in the radiator. I used cardboard first to get the shape and then traced it onto 22 gauge sheet metal. If you remove the front bumper it makes it much easier to do. Other things to do would be to get a better radiator. The use of a heat extractor hood makes a real difference as well.
 

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how much do the underdrive pulley's hurt?

i have steeda 25% iirc
no heater, no a/c
pure water, with one bottle water-wetter
autometer gauges
road race car,
big fluidyne radiator, (not yet boxed in)
and no air dam floppy thing underneath radiator,

was hitting 240*F at road atlanta in june, so i bailed halfway through the race,
i had JUST replaced the motor, after throwing a rod there in march,
so i wasn't ready to RE-replace a motor.

sunday morning, we made a small faux-airdam from 2 ply of a rubbermaid garbage can
(don't ya' wish EVERYTHING was made, like rubbermaid???)

i saw a 20*F drop from just that, and it was only ~3.5" tall, and JUST as wide as radiator
 

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. . . The engine has 2 temp sensors near the cross-over. One drives the guage, one the engine computer. Hitting 230 at the cross-over puts you up near 250 in the heads near the rear. . .
interesting,
when tuning the new engine (c-head swap) i saw a 10 degree difference between the datalogger, and my autometer gauge.

i forget which was higher,

anyways,
if both sensors were at about the same place, seems like they'd be about the same temp, (instead of 10*F different).

do the 98's have different locations of the TWO sensors??

more pertinently,
my engine swap, involved a long block from an 05 aviator,
hence the c-heads.

i wonder if those 4.6's had a bigger difference in the two sensors?

thoughts?
 

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The under drives made a noticeable difference on mine, at least the water pump pulley did. I used the stock water pump pulley and one size bigger belt. I did the big radiator before I put the stock crank pulley back on, so it was undetectable. My autometer gauge reads higher that the computer.
 

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I pop riveted a 4" wide piece of ABS over the stock air deflector flappy thing and it brought my temps back down and it now never goes up over the origional temp.
 

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Discussion Starter #14
I finally had some time today to work on the car and I went ahead and boxed in the sides of my radiator and added a "custom" 3.5" deep air dam.

For the box I used foam and cut it to size (used cardboard as a template first) then wrapped it all in black duct tape to protect it a bit.

For the air dam, I went to Lowes and bought 3.5" wide garden trim. I cut it just a tad bit wider than the stock air dam and attached it on top of the stock air dam.

I have one last question for you guys... should I block off the bottom of the left and right side of the bumper? If I recall correctly, the stock bumper has a piece of plastic that attaches to it on each end of the bumper that blocks air from going up the sides. :??:

Here is my attempt at boxing in the sides of my radiator...notice that I still have the stock rubber/plastic pieces that act like somewhat of a "box" for the radiator. I left them in place but my foam pieces are what will really box in the air.

TOP VIEW OF DRIVER SIDE:



TOP VIEW OF PASSENGER SIDE:



BOTTOM VIEW OF DRIVER SIDE:





BOTTOM VIEW OF PASSENGER SIDE:






HERE IS THE 3.5" AIR DAM (with my faux sponsor IMPRM:eeek::...it's my buddy's company:cool:)



 

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Discussion Starter #15
Thanks to everyone from various forums that commented on my boxed-in sides and deeper air dam, I went ahead and tackled the next step: boxing in the bottom of the radiator.

I bought some thin aluminum, a pop rivet gun, and some rivets and went to town! I basically boxed in the bottom the width of the radiatorand sealed off any gaps with some high strength Gorilla duct tape. It's not nearly as "pretty" as some of the fab work I've seen on other cars but I think it'll do the job.

I retained the foam sides of the box that I previously made but somewhat recovered them in the lower bumper opening for better "boxing" and so It'd look a little better LOL!

Now I have to figure out if I "need" an air dam still...whether it be in the stock location (I can re-install the air dam I made) or on the bottom of the bumper, somewhat like the Mach 1 lip.

Here are some pics...It was dark when I finished up so the pics didnt come out as clear as I would've liked, but here you go:


Bottom of the box:



Driver side - inside the lower bumper opening:







Passenger side - inside the lower bumper opening:







Driver side - underneath the car



Passenger side: underneath the car

 

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Discussion Starter #17
I used "Gorilla" duct tape. It's probably the stickiest and strongest tape I've seen. I didn't use it to hold anything in place, rather just to cover my foam pieces (cosmetic) and to block all the small air gaps.
 

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Discussion Starter #19
looks nice
i wish i weren't so damn lazy

need to, . . . .
get, off, . . . .
arse.

(nope, nap time)
Thanks! I know how you feel:rofl: I pushed this project off for a couple months because of two things: 1) it looked like a pretty difficult project to tackle and 2) I was just plain lazy>:p.

When I actually took on the project last night it was actually pretty easy. Using foam for the side pieces definitley made it easier for me since it kind of molds itself once you shimmy it between the radiator and bumper. Then the aluminum at the bottom was pretty straight forward. I used a cardboard template for the shape and then went to work with my new best friend...the rivet gun:)
 

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my next MOD! idk why i never thought of boxing my rad...

1. need to install my hollowed out Cobra grill
2.box radiator with styrafoam and aluminum
3. either larger air damn or front splitter
 
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