Cadex

Regularly time trial a NA C6 and have yet to solve the heating issues here in low humidity Nevada weather. Oil temps are fine with a separate oil cooler however water temps still are not under control despite Dewitts, 160stat, water only.

Have read a lot of posts on louvered hoods and the world challenge offering from LG. However, I must be blind as I can't find any confirmed before/after effects on coolant temperatures. For those with vented hoods that race...what effect have you seen on engine coolant temperatures (not underhood temperatures).

Thanks much all.

grantar2

You indicated you are running water only which of course is an issue. But have you tried adding water wetter. You will have to check, but I believe that is legal and it was supper effective for me.

bowtiguy

+1 on water wetter...

I'm pulling my weather stripping from where the back of the hood meets the cowl. In my 4th gen B4C track car it worked great and created a bit of downforce.

BUT..

On a C6, the hood will flex something fierce in the back ( hinged in teh front) so you have to leave about 6" of factory weather stripping in the middle to support it properly. I haven't worked out the exact square inch's of vent but I can ASSURE you its cheaper than an aftermarket hood/paint.

I'll let you know how it works in a couple of weeks..

davidfarmer

I was always told by teams with Wind Tunnel access that removing the cowl insulation did not work, since the base of the windshield is a high pressure area. Using a properly louvered hood will improve airflow through the cooling system, but I don't know of anyone that can quantify it.

I bolted some JC Whitney louveres into my C5 NASA car, and it definitely helped.....how much, I can't say!

bowtiguy

Interesting...

I can smell oil vapor fumes from my non PVC vent can set-up while driving so I know something is getting out. how much...... I'm not sure.

If it is in fact a high pressure area ( I.E. 1970 chevelle cowl induction) then it should not have much effect at speed.

It worked well on my $th gen F-body....Nothing left to do but test it

2000BSME

racing radiator, vented hood, going to put some water wetter in soon, I can only keep mine around 235ish now, 255ish before all the changes.

160 tstat isn't doing anything for you, except making everyday driving more corrosive to your engine.

davidfarmer

looking at this photo, the high pressure areas are at the base of the windshield and all across the nose.... the low pressure area (where you want your louvers) is around the center of the fenders.

When I don't know the answers, I share what I've been told by those I trust. Maybe right, maybe not.....

2000BSME

please produce the same data for c5 if you can.

tia.

JVetthead

To take full advantage of a vented extractor hood it helps to have a fwd laying radiator. Thats how mine is setup with no ducting or fans and I never get over 220*. Another advantege is added down force.
This car makes so much down force in front I had to go to a #1300 front spring and am thinking of a shorter splitter..
<-----

That big hole in front helps too.

Cadex

thanks for the responses thus far. Yes, I run water wetter and have the fans set to kick on much sooner. I'm actually not too bad with my current setup at 225-230 coolant and 250-260 oil peaks so I'm only looking for a hopeful 15-25 degree coolant temp drop.

On the fwd radiator...agree this appears the optimal path. I'm looking to determine actual results or experience like all that have posted already from those with a louvered hood such as the World Challenge from LG before spending the $1500-2000. If the results just aren't there...then I'll go down the fwd radiatior with the previous C6R type hood for a bit more labor and hassle with our lovely 5mph bumpers.

Thanks much all.

davidfarmer

I agree moving the radiator, as well as closing the floor under the front of the car, are the ideal scenario. However, from GM, the air can only spill under the car, or through the fenders, so giving a low-pressure area above the hood can only improve both cooling and reduce lift. It takes a lot of effort to actually create a car that has serious downforce, but I think a relatively simply hood-mod can improve cooling and reduce high speed lift without rebuilding the entire front of your car.

trackboss

FWIW, I designed my own radiator and made it double pass. I previously had a dewitts, and it worked well however it got bent so I chose to make my own starting with a common circle track radiator size to keep the cost down. I've used double pass in my race car, but it's new to my C5 so I don't yet have it running with before/after. I wanted to tilt it forward, but it's unpractical on a street/track car that must pass smog here in CA simply because re-locating the air cleaner will cause a fail. I made my own mount, single fan, etc., etc. For oil I will either go to a large air/oil cooler or a laminova in the lower hose if I can fit it. Not there yet. I originally cut out the oil cooler from my dewitts that I planned on enclosing in a piece of a timed out aluminum 3" driveshaft I have, but I don't think it will fit in the space I have and the dewitts oil cooler is really wimpy. Great for a street car, but the oil still gets way hot on the track if run hard.
Here's what I was planning on doing with the dewitts oil cooler:

1stZ

I have the wc hood, Dewitt radiator & also replaced my stock oil cooler with an after market oil cooler & relocated it to where the driver side fog light used to be. Finally, I run mainly distilled water & couple of bottle of water wetter & it runs good enough for me even on summer runs like last weekend. Ambient temps were 108 & my water temps only got up to 255* & my oil temp was only 265* after 35-45 minute session. During summer runs back in '07, I could not finish 30 minute session without backing out of it cuz both my water & oil temps were near 300f. Runs great now all day long!

davidfarmer

I meant to post this yesterday, but I think the Computer simulation I posted above would still be pretty accurate for a C5 and C6, with or without splitter. I think the high pressures zones would be at the front, and at the cowl. I think the low-pressure zone would be directly over the fenders, possibly slightly forward.

ace996

Yep, I've always heard about the "cowl induction" positive pressure zone at the front of the windshield, but I'm starting to doubt it some. Seems I filled my windshield washer tank a little too full and when it leaks out, it blows water out the back of my hood...right where this "cowl induction" high-pressure area located. Even at 70 mph, after I've rinsed off the car, the water sprays out of that area.
Perhaps it is higher than normal, but the pressure under the hood is even higher than that, so air would move out of the engine compartment anyway.

Just a thought.

2000BSME

yeah that's gonna happen because it's a high pressure low velocity area. Anything released there is gonna be blasted everywhere like a waterballoon.

Rob31

On the C4 how were you able to verify this ?

bowtiguy

4th gen..as in camaro.

B4C ......as in police package camaro.

Car ran cooler and I could feel a bit more downforce ( A.K.A. less lift on the front end at high track speed)


Those huge C4 clam shell hood things may need a bit more than 6" of cowl weather stripping to keep them from flapping...

Rob31

When I saw b4c I figured you just couldnt type ... my bad

godzilladude

I pulled the rear hood weaterstripping off of a 2004 GTO at the Texas Mile, I instantly ran 2-3 MPH SLOWER. Did a few runs that way just to confirm, then put it back on and voila got my 2-3 MPH back.