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.