2nd place in class at BBORR - video

Finished 2nd out of 11 or 12 in the 135 mph average class - we averaged 135.010 mph (.225 seconds off target). Stopwatch only.

Got the car up to 161 mph for a bit (2:24 in youtube video). Water temps went to 243*F at the end of that long straight.

My gearing is poor for this event - shifted to 5th at 125 mph at 3800 rpm and left it. Never made it over 5,000 rpm.

Enjoy.



https://youtu.be/9dJD4RmxXGE

Awesomeness...

Thanks Tom

Now to figure out a solution to get the coolant temps down. Can't run a faster class if I'm cresting 240*F everytime I go over 160 mph. Talked with AFCO, got some ideas. The radiator I'm running is used in 700-800 hp dirt track cars with bad airflow.

Awesome Wade, that is a serious accomplishment. I have wondered about the effect of cooling at speed, my car has always struggled with it at speed even over 80-85 mph. Almost think its a trapped heat issue in the engine compartment. I know airflow is there in spades because when I first put my glass lift off hood on with no center rear hood pin, first pass down the quarter it turned into an umbrella at the rear. Lesson learned, but now where does all that air pressure go?

I seem to run cooler at higher speeds from 80-130.

I wonder if it has to do with the grill opening, shape, and obstructions?

I have a lower valance and get air from under the bumper between the valance too.

I've considered blocking off part of the grille opening for aero until I see a heat rise.

A friend brought up a point I haven't considered:

Why not just leave the electric fan on? I've got it programmed to not run at 30% TPS or greater. The temps would drop in the corners at BBORR - well that partially might be because the fan was coming on.

Obviously the fan solution isn't fixing the root of the problem, which is a lack of a pressure differential great enough to cause significant airflow.

Potential problems causing the lack of a pressure differential:
- 1" gap between hood and top radiator crossmember
- hood is not sealed to body at all
- hoodscoop
- holes in front radiator crossmember (behind the parking lights)
- AC condenser in front of the radiator (apparently needs to be 3/4"-1" away from radiator)
- Oil cooler in front of AC condenser (only behind the bumper - ran 240*F oil temps, btw)

Things I've done:
-lowered the lower radiator crossmember (and extended it to the sides with an airdam)
-Sealed the front airdam / splitter to the bumper
-sandwiched foam between radiator and radiator crossmember
-sealed a couple small holes in the radiator crossmember

BTW - I checked my temps from a recent TWS track day. Never got over 220*F. I also ran a session without the fan in the car - temps were nearly identical.

Post-race. tons of bugs. car was clean before the 118 mile round trip. Shows the air-dam and splitter. Which did a great job of keeping the front end down at high speed.


General location of the coolers:



Unlimited class cup car hit a buzzard at 160-180 or so. Finished the race looking out the passenger side of the windshield!

That's a lot of stuff in front of the radiator.

Need to seal top of radiator support to hood.

Maybe experiment with plugging air scoop.

Shim the back of the hood up so that there is a gap and see if that releases trapped air under the hood at high speed. If so you know you have an airflow "out" issue not an "in" issue going on.

I would think you want the seal between the core support and the hood to force the air to go through the radiator, not over. I would try that first.

I wouldn't be surprised if the scoop is the culprit, I have same one, but I absolutely MUST run my fans at freeway speeds. Air comes through radiator then what?

I also sealed my core support to hood with garage door seal. That was worth probably 10 degree drop. Wade that oil cooler is freaking hilarious dude!

at 160 mph a lack of seal between the hood and radiator support isn't an issue. Remember, what does in has to go out and if it can't get out, it can't get in either.

I told you it was huge! Hide it behind the bumper with no airflow and it STILL keeps it cool.

You just had to one up me on oil cooler girth didn't ya! LOL!

Awesome video and great car. I did one of the defunct nevda events years ago. Grerat fun and i hope to get my Challenger to one in the very near future.

Awesome! I also wonder about the ability for air to exit the engine compartment contributing to your problem. This is inspiring to watch..

Wade is there any way to have the front spoiler force some air right up into the front of the radiator? Wouldn't take much area to force a bunch of air through at high speed. That's what the C5 Vette uses, about 12 inches, but you shouldn't need that much...

In my opinion, some of you are looking at it the wrong way. Others are closer.

Too much air under the hood.

Instead of helping the air get out you need to limit how much is getting in.
You want a low pressure area in the engine compartment. Doing that will force the air through the cooling package.

Run your next high speed event with the hood scoop taped off. Your engine will draw hot under hood air but you will likely see the radiator temps drop. That's a cheap test that only costs a few strips of duct tape.

Any air coming in contact with the core support and cooling package needs to be handled. The air is stacking up and looking for somewhere to go. You can add paneling/baffles behind the grille to direct air into the cooling package. If so, make it narrower at the entrance than it is at the radiator. Air is more likely to be "trapped" and not spill out over the sides. This helps create a higher pressure area in front of the radiator.
A seal between the core support and hood would eliminate flow up there. I wouldn't hurt to add an under cover extending from the air dam to the back of the engine compartment.

Raising the back of the hood and doing other things to help air get out is essentially treating the symptoms, not the problem.

Air flow is often thought of as fluid movement. Use fluid. Put the car in high speed trim and block off the back side of the radiator. Grab your garden hose and spray the front of the car. The water will go where the air goes. Block off anything that allows the water to get to the engine compartment. Doing that will find your areas of concern. The scoop will be a big culprit. Check the air moving over the top of the bumper too.

Here's the view of your car from Gate 43 (about 15:16 in your video - 150 MPH)

Thanks Lyndal! Great video, great pics as well!

Car got up to 249.7*F on the second leg

What a fascinating video, I watched the whole thing. Man, would it be a learning experience to watch this along with running commentary from you as you recall what you were thinking when driving it.

Most curious to understand why the throttle is on the low side from the 21:00 to 22:00 and 24:00 marks - seems there is opportunity to open up more… but what do I know. I can hear your copilot talking, is he telling you what to expect? And most G-forces you hit are .4 and .5 then that big jump to .7 close to the end made my heart jump.. very exciting to watch.
- Art

Art-

We were trying to dial-in on our 'target time'. We were ahead of pace by 30+ seconds at one point, so we slowed down. Then we were behind so I had to push it a bit!

glad you enjoyed the video. It was fun running it, that's for sure.

My navigator - my brother - was mostly telling me what speeds to take the turns. We wrote down target speeds from watching our previous year's video right before. Excited to have better data for next year!

On this thread, I haven't heard any mention of a radiator shroud, is there one? That's usually the solution du jour here on cooling issues.

jcc:
No shroud in front. Only a Taurus fan behind. And the radiator is sealed to the sheet metal.

The reason I ask is, conventional wisdom has been anything in the path that aids low speed air flow cooling, inhibits high speed air flow, including any fan. It would seem like your cooling issues are in "inhibiting" range. I understand car needs dual range cooling. I would have thought your what looks to be very functional spoiler/splitter would be a bigger plus in cooling then you have shared here. I personally don't think its related to air not being able to escape after exiting radiator, more not enough air getting in. You do have a lot of items in front of the hot water. Guess we can wait and see how you resolve this.

I really enjoyed your video.
I have a question about your oil pressure. The engine certainly seems to run great but the oil pressure seems on the low side, it seems to be settled in the 40 psi range for a lot of the video. Was this on purpose that you didn't want too much pressure? Just curious if you have a theory about it.

I do the same type of racing at Silver State Classic. My 496 stroker would never go below 65 psi (above 2500 rpm) on the hottest days even with 220° water temps, but during Silver State, by 15 minutes in it would settle in at 38 psi at 4900 rpm. It really bothered me and I blame my eventual Crane Gold rocker arm failure on that pressure issue. Ultimately, I ditched the unbushed Crane Gold aluminum rockers for bushed chromoly Comp Ultra Magnum rockers and went to Brad Penn 20W-50. Last run I did not go below 60 psi.

That oil, when really cold (under 45°), will be slow to come up to pressure.

Does the radiator have bypass flaps to allow high speed air a route through when it overwhelms the fan? I don't even run a shroud, just a mechanical 17" fan 1/2" off the radiator. Radiator is a Howe Racing 19x27" dual 1.125" core aluminum crossflow generic. The car stays cooler with the air dam since it keeps pressure down under the hood. Your scoop is doing the opposite and offsetting the gains from the dam. Raising the rear of the hood is iffy if it is too close to the high pressure zone at the base of the windshield. Think about the NASCAR guys using the windshield base cowl induction for power gains. Same high pressure as a scoop without the drag.

Heat extractors, louvers, etc. may help tremendously in creating a lower pressure underneath the hood and really improve air flow through the radiator. It worked wonders on my dad's Firebird running 150+ MPH and keeping under 200°.

The old 10 psi per 1000 rpm guide is sadly out of date.

this is pretty cool, I did not know this, I thought it was more for aerodynamics to have the flat hood in nascar with the windshield base cowl

Honestly I would like more oil pressure. This motor has been that way since day 1. I'll probably pull the oil pump and port the inlet- some folks I've spoken with think I've got a cavitation issue, as the pressure drops after 4800-5000 rpm. It's lived through a couple hard track days and BBORR, so I can't really say the oil pressure is a problem.

Supercuda- you say the 10 psi per 1,000 rpm is outdated- is there another rule of thumb to consider? Or anything else to add to this? I agree with you, but sure would like more info on the subject to give me more peace of mind!

The current plan for the radiator is to seal the front crossmember to the hood, seal the hood to the body (specifically in the back at the high pressure cowl area), and seal the scoop to intake so that pressure doesn't bleed off into the rest of the engine bay (though I doubt the scoop builds much pressure). Lastly I'd like to build some ducting on the front side of the radiator to direct and stack air going into the radiator, and block off the grille where no airflow is needed.

I do not have flaps on the fan shroud. I ran closed road course sessions back to back with and without the fan. Zero temp difference. Average speed of around 78-80 mph though.

Your situation is a perfect specimen for manometer tests. Want to borrow one? PM However recreating actual speeds is best and that might be the hardest part, but then you are in Texas.

I actually have one. Bought it years ago after reading the autospeed articles about hood venting, etc.

Time to pull it out!

The NASCAR cowl intake system serves two purposes. It gets a little higher pressure air into the engine (poor boy supercharging) and it relieves the pressure at the base of the windshield.

Very few high speed cars have conventional hood scoops outside the drag racing community.

OK, got it. Thanks. That adds another dimension to the run, so you have to drive very deliberately, which shows in the video. Smart. Like "match racing" at the dragstrip (which at our strip means you declare your 1/4mi time before the run, and you have to beat your opponent without dipping below your declared time. The Christmas tree lights launch you sequentially such that each competitor would theoretically arrive at the finish line according to their declared times). Does it mean next year you'll use a 'target time' that's 30sec less than this year, depending on conditions? Best of luck!
- Art

Specific speed targets over a calibrated distance. Think INDEX racing, with your over or under being you "variance". Silver State is 90.000 miles long. 180 class (index) guys all try to finish in EXACTLY 30 minutes. 135 class guys finish in 40, 120 class guys finish in 45, etc.

Could you do something like this? Block off the grill, take sheet metal and run it down from bumper to splitter the "duct" it all into the rad.. even on the inside. This helped our Chump car. Looks goofy I know but it does help. we also pulled the back of the hood up to help vent, I know you're not looking to bend up your hood, but getting some of that hot air out can't hurt.

Lifting the back of the hood will hurt air flow under the hood.
The base of the windshield is a very high pressure area at 130+ mph. It will flood more air under the hood.

Closing off the hood scoop or ducting it to the throttle bodies would help alleviate some of the problem.

sealing the scoop is a given, however I doubt its getting much air in the first place with flat front. As soon as he gets some pressure/test readings, I think he will get a better idea of what direction to pursue. A go Pro and some tuff/yarn video would also be useful around the scoop.

Nice article from Hot Rod wind tunnel testing with '5 aero mods that almost always work'
http://www.hotrod.com/how-to/paint-body/113-0703-car-aerodynamics/

I guess I should be happy that the Imperial can hold 75 mph.

2 things that stood out to me in the link, 1. raising the rear in our nasty aero cars in their test, actually increased drag, I would have thought getting the undercarriage slightly (1"?) higher would be an even or a plus, and 2, raking the windshield further showed no improvement, however I think that is the case of the sheetmetal in front of it causing such an aero mess, additional rake achieved little..

does this apply to all cars? I should try rerouting my fresh air intake on my car to this area...which brings me to another question. Why are most aftermarket fresh air intakes piped to the inner front fender of front portion of engine bay? If the high air pressure accumulates under the front windshield, wouldn't you want it piped to this area instead?




thanks for the good read! I'm loving this thread BTW, so much good info

Yes.

All cars have a high pressure area where the windshield meets the hood. Some are greater than others.

Aero is different at highway speeds vs 100 mph and different again at 200 mph.

At highway speeds the pressure at the base of the windshield isn't too high. The faster you go the higher it gets.

Most fresh air kits draw from the front because it's convenient, easy, and fairly consistant.

"The NASCAR cowl intake system serves two purposes. It gets a little higher pressure air into the engine (poor boy supercharging) and it relieves the pressure at the base of the windshield."

Not sure about the second point being a plus, or more then an opinion or how even much pressure is really "relieved" by engine consumption. This high pressure area might be actually an improvement in streaming the rest of the air over the roof less abruptly, maybe like the the advantage measured of having the tail gate up creating a high pressure area and smoothing air flow in the back of a pick up vs having tailgate down, and very turbulent. And I believe its high pressure because of the rebound of air from striking the front nose of the car at speed, and less so from slope of the windshield, which the latest HR posted link might also indicate

For crying out loud, put down the micrometers and stop questioning everything everyone says.

Air being forced into the engine does relieve the pressure build up at the base of the glass but not to any massive degree at the high speeds NASCAR runs.

Having a high pressure area at the base of the glass is not a good thing for aero. Trucks are different because they are pulling a bathtub behind the highest point of the vehicle and that is where the circulation arises.

If I recall - this is the test they stuck foam in the aero scoop they had. Because that's the best way to replicate the actual high speed conditions, and the tunnel only spins at 85 mph. One would think the same would apply to the cowl, with the same rule applying - not until a certain speed is reached.

1. I am not crying
2. Nobody on this site can here me cry
3. The link if you bothered to read it, discusses aero changes measured in counts, or thousandths, regarding measurement units, your concern is with them, not me.
4. I only question what I disagree with or statements that have little to back them up, will admit, some get bothered by the public scrutiny
5. This latest nascar statement is ether backpedaling from your earlier remarks made or a contradiction by itself, I can't figure out which.
6. Having a high pressure area might be a good thing vs having a low pressure turbulent area, with out data/measurement to support it either way with certainty, is rather presumptuous.
7. Air doesn't care if its a car or a truck

I thought NASCAR developed the "cowl" system because they are not allowed to have forward facing scoops.... like in the grill, headlights.. ram-air type of stuff.

Since cowl air intake was introduced I believe in the early 60's, My thought was it was more to retain a stock look, it wasn't illegal by the rules, it offered cooler air, was easy, it was always higher pressure area, and air had less dirt when then they ran dirt tracks, and made it easy to introduce "windshield washer fluid" on last lap, but not sure.