PRE-Z06

I'm just stating the conditions as they make a difference in my experience, have you ever run a faster mph in worse DA because of a huge tailwind? I understand it's not as bad as say a '72 V8 Vega that I started drag racing with, but still plays a factor IMO. Brian's ls3 C6 was there and down on mph and it's slippier than a C5 though it weighs more. Think his has a chance at 9s though as it hasn't even been tuned at the track by James, running stock seat, with filter in, belt on and no jockey behind the wheel. Never said that was my goal though I do wonder how much faster it'd be if it had gears again, aftermarket intake, ewp and new tires. Though tracks around here are dropping like flies and with the baby coming soon I doubt I'll be able to chase a number/weather. Will be content with beating the two fastest 6-speed ls2/3 manual runs in my neck of the woods(Andrew/Vic) which I believe is possible the way it sits. Appreciate the congrats though, not sure of any other c5 with an ls2 besides yo-el that has posted times?

I wish I could control the weather and when the tracks open, but let's be realistic. You have to remember we start off at ~600' elevation and they won't run under 50* as it's considered too dangerous. I'm jealous of the abundant opportunies that the NE gets for -DA regardless of the wind and the lower elevation that y'all start with which is almost a tenth gain from here to Houston. Have you ever run at Island, I went there once and it's about the same elevation as here. Atleast you still have choices for 1/4 tracks, if it's a headwind at Atco then it's a tailwind at E-town iirc...the next closest one is over 4 hours away now for me. I figure you've been racing long enough to understand weather and don't need a degree, though I originally went to OU to major in meteorology. My point was cool dense air from a front moving through causes high pressure and dry air vs a tail wind which is going to mean moist air from the gulf, pressure dropping and warmer temps. Not ideal for racing of course either way, but that's nature here.

dennis50nj

now I wonder how much that tail wind losses or head on helps if you have a Vararam look at stanger383 342 gears me 373, look at gary 410 vs bruce 342 et and mph, your car ran very good, but i dont believe the mph dictates a very low 10 not in a stick, but I'm pulling for you if you do get it i believe the mph will be at least 136

PRE-Z06

I like to share everything on here as too many people who don't know better get on the forums and read about hero times that get posted and then think that's the norm everywhere, not taking away from those that are privileged enough to pull off the incredible passes just don't want the sheep to be lead astray. Though racing is generally deceptive as I posted the results of the hellcat to give an idea this was an average day for most, could have easily told him I had just a cam only LS1 and taken his money. The camaro I ran in the video was the bolt on gen5 record holder and now has h/c/i fwiw, raceweight was 3800lbs.

I agree it would take a minimum of 136mph to go 9.999, lets do some ricer math just for giggles...

15mph tailwind instead of headwind for a delta of 30mph less resistance-1mph
Ported fast 102-1mph
3.90 gears-2mph (I crossed the traps in 4th at 5700, not past peak...4.10s were worth .3 previously)
EWP-1mph

Motor had 200 miles on it with 20-50 non synthetic oil in it too btw, figure after it loosens up with synthetic it might make a little more. Regardless that's an estimated improvement of 5mph, which would put it at 137.5 based on the best of the night...feel free to share your thoughts as I do value everyone's experience in this thread, some real heavy hitters for sure.

dennis50nj

the gains are harder the faster you go, the 102 not much since you have ls3 heads the water pump is only good for getting temp lower on return taking the belt off and by the way i didnt. the oil isnt much if you run hot but if you run cool the synthetic is, now the gears will help for sure, rotating weight is your best hope and mimicking Rob or Gary

PRE-Z06

For sure, the fact that you understand drag increases exponentially needing more power to overcome it would make me think you realize the winds effect...ie at 105 in the 1/8 with a 15mph headwind it's like trying to accelerate from 120 to 147 on the back half if the car traps 132 vs if there's a 15mph tailwind it's only fighting wind resistance of 90-117mph, how much faster do you think that is? I know you've been around long enough to know the power difference needed to go 90 vs 120 in the 1/8 or 117 vs 147 in the 1/4. There's always weight loss reduction to be had, mine only had the passenger seat out and titanium mufflers removed. The stock unported intake/stock throttle body did seem to be holding it back up top on the dyno based on cam specs, so I do believe the 102 or msd if it ever comes out will help a bit. Can add meth too if need be, 136 was referenced for you auto guys...though Brian's doesn't even have a lock up converter so his mph is even lower.

LSOHOLIC

Dennis.....

With a direct 20mph tailwind and the car moving 20 mph away from the wind.....what is the mph of the air moving over the car ??

dennis50nj

well Caleb I was a drop out, never went to any fancy engineer classes or any fancy college, so if this is a trick question, or just a leading question to prove that head wind is a factor, Im still not buying it. all the theories in the world don't prove facts in the c5 c6 drag headwind class et slips do, i have raced enough in those conditions and have seen its not true, just like all the calculators cant get a grasp on my et or mph vs hp and weight. the answer to your question would be 0 in my uneducated common sense world

LSOHOLIC

Lol...no tricks Dennis. I value your opinion, as you've been around the block a time or two.
Just wanted to hear your logic on basic physics and the laws that govern them, or maybe how laws of motion don't apply to the NE. Would a mass accelerate quicker with or without said 20mph tailwind ??

And does the opposite hold true ??

And does compounding effort in which make it tougher to accelerate (as youve talked about) reflect on this very topic ??

Would or should it be a suprise that most class racer log books hold an column for head wind correction. Matter of fact the Jegs log book has a column for this very function.
Would they create a column for a fictitious phenomenon ??

Please take all this in light humor.....just a simple discussion amongst fellow racers....


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BSPC608

Chris car spun on launch last pass cut a 1.66 60'. The time slip looks very similar to your last slip. I wasn't expecting good track conditions during a TNT which is why I ran with the 315 Hoosiers 5lbs per wheel more versus the 275's. So running 10.16 at 3230 lbs launching at 2000 RPM's and not great air I was pleased with how the car ran.
I think as your 60' improves you should run 10.2. I think I can hit my goal of 9's by James tuning at track, removing 100 lbs and chasing good air. Hopefully you will be able to make it back out to the track this fall after the baby.

PRE-Z06

That's what I figured, thanks for the vote of confidence! Definitely let me know when you're headed back out if James doesn't as I'd like for him to log my runs as well being there was no tuning done with mufflers off or filter out since he was at the mile. Btw I know this 16year old kid who weighs 100lbs soaking wet and isn't scared, so give him a bucket to sit on and I bet he can make that thing go 9s with a tailwind...just sayin

On a serious note, will you be at the annual lonestar corvette event again in a May?

dennis50nj

yeayeayea i have heard it all before but this is 2015 and the coefficient has changed leap years since the days of wind logs, still good for box cars but not the design of corvette, we all know the effects of stepping out into the 15 mph wind with a 4x8 sheet of plywood, now hold it horizontal and you can actually fly, hmmm i wonder with the right angle the 3200lb car could be 2600lb

NGS

That would be the Uncle Jesse coefficient, right?

PRE-Z06

My uncle who was like a 2nd father to me growing up, was an 8th grade drop out...though he still understands a significant head wind(could have been closer to 20, didn't have an anemometer yet the flags were steadily standing straight out on top of the tower) is not helping things, even though it has less of an affect compared to the muscle cars of his day. I was hoping with as many passes as you've made in your c6, that you could provide some data to state how little you think it's hurting as we all now it isn't helping it go faster I hope. I could try to get my cousin who's a nuclear engineer to run some figures as he's done so on top speed drag in cool dense air is not greater than the effect of extra power the engine makes even at 200mph vs warmer "thinner" air fwiw.

dennis50nj

well it seems everything in Texas is bigger so maybe down their it does, you should get but as you say the the northeast mine shaft air maybe it doesn't, I know someone who works for Mister Bob, that a portable pot cleaner. I will have him run some tests, was your shoe laces blowing straight back at ground level like this

dennis50nj

robz

Let's not go overboard with all this headwind theory.
It's not like it's as complicated as Next Generation Sequencing.
From all this talk I just figured out who the real geneus is.

hahaha

LSOHOLIC

You make me smile Dennis.....love the way you put issues into context and not take any of this in a personal way (being sincere).
As I do agree that we are dealing with a aero friendly car here.....but the fact is there are no free lunches. There are consequences for the forces being acted on the car, while these consequences may not be as sever as a 55' shoebox, nevertheless they are still present and must account for something.

At what mph does a vented hood for out cars become applicable (show a return) ?? What does an extra 20mph of air (resistance) do to the "applicable" statement ??
Ever play with a manometer ??

I've seen all sort of sliding scales and such for this "problem". And they are hard to use or put into context with out accurate CdA data.

The four main forces acting against the car are; tire drag, driveline drag, gravity and wind. From my understanding tire and driveline will chew up close to 25% of the resistance.
What do you think eats the largest portion of the resistance ?? And does to work in a compounding way ??

I certainly don't have all the answers.....and look forward to some "hard" numbers for you.

But my experience and common sense tells me a 20mph head wind will effect you roughly 1.5mph and 0.05 et range.

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dennis50nj

its hard to tell unless you look in the trees

robz

haha

It took me about 20 minutes to figure it out as the paper trails over the past few weeks were getting bigger I would assume purposely.

dennis50nj

personally I choose to play with my wife while driving an automatic,and just race! at what speed does the air lift vs down force change standing weight vs weight at speed?, now is that head wind actually giving you a better et by changing the down force?