2019 NHRA rules changes (1 Viewer)

While I don't agree with any of that is being advanced because it totally ruins the sport's interest for me the lowly crew chief I'll chime in a bit to give more life to what I do and what those I race against say they do.

The blower combinations leave the starting line with WAY more torque and HP than the tires/track can handle. So they have zoomies which kill low end torque (and greatly improve the top end breathing) and, as Alan points out, huge reductions in timing to keep the piston from being pushed down from its most power inducing point in rotation (generically you want maximum cylinder pressure 15-17 degrees after top dead center to make maximum power but it depends on the duration of your power pulse .... and nitrous motors definitely have the shortest power pulse of any combination so they are hyper sensitive to timing changes ... a 1/2 degree timing change has me so puckered I can barely walk up to the line to help stage the car). Even at the sportsman level 30% or more of the teams i compete against are making timing changes within 10 minutes of staging the car to make sure they go down as intended. If they couldn't manipulate timing they wouldn't be able to run the back half of the track like they do (because they would have less HP throughout the run).

The assertion that within TD/TS that the cars can run the number every time and its just a driver's race is beyond ridiculous. If you see a car running in the fastest 1/3 of the field and compensating for top end driving ET impacts you can tell the car is consistently running the number you should either follow that team into a casino or realize there are some people working their butt off to make that happen. It is challenging beyond belief.

90%+ of my runs start at 26.5 degree BTDC timing and end at 4 degrees BTDC. That said the vast majority of that timing change is because the more nitrous you turn on the faster the flame front of the combustion moves and the more you have to slow the timing to keep the power pulse where you want it. So that kind of timing change is to make more power, not manage for the track. Now, I am not in the norm on pulling timing to manage for the track. I don't try to kill (run super quick) the 60ft so it is rare for me to pull any more than 1 degree (roughly 200hp) to mange for track conditions. When I'm trying to make a fast run my three stages come on (relative to the car first trying to move forward) at 0.00, then 0.35, then 0.70 second out .... so by 3/4 a second out I'm fully uncorked in terms of power. Generally any power management happens between 0.20 and 1.5 out .... and I'm mainly looking at the G meter to decide what I need to do .... I want the G meter to look like a tabletop for as long as possible. I try to use timing as a bandaid, as I learn what the chassis wants most of my tuning is in the torque converter, tire pressure, and what we call a wheelie bar (its a tire set device to me, I use it to manage tire speed ... intentional over rotation). When trying to keep G's high and flat and having multiple large stages of nitrous come on, you are make lots of very little timing changes .... my power management timing map is 15 lines long .... meaning at an extreme i will make up to 15 power management changes between .2 and 1.5 or down track to deal with bumps (pulling more like 1000 hp to keep the car from becoming a Cessna 172). It's fun, and no you don't have to do that to be reasonably predicable and run relatively slow, but the tools that have existed for roughly the last 7 years are very valuable to someone who likes to walk a fairly fine line doing this.

Turn TD/TS into stock/superstock and I'll either move to super stock or another sport. Now do most of the teams approach the class like I do ... hell no, you don't have to and it will drive you crazy .... but its what makes it enjoyable to me.
 
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Cliff,
Not arguing just being conversational, but what would stop that from becoming a faster version of Super Comp? Many cars out there are capable of running in the 5's so they would put on a throttle stop and be ready to go.


Alan

Hi Alan. Hmmmm, I guess in my heart of hearts I'm a dragster guy, altho I like all the classes. I really like T/D and just thought it would be cool to have a heads up class, no dial in. That is what I was thinking about. Maybe like a less expensive version of T/AD??? Also, this class reminds me of T/AD when they were breaking into the 5's years ago. By the way, when you were talking about timing manipulation in alcohol, did you mean T/AD as well? Just curious.
 
Hi Alan. Hmmmm, I guess in my heart of hearts I'm a dragster guy, altho I like all the classes. I really like T/D and just thought it would be cool to have a heads up class, no dial in. That is what I was thinking about. Maybe like a less expensive version of T/AD??? Also, this class reminds me of T/AD when they were breaking into the 5's years ago. By the way, when you were talking about timing manipulation in alcohol, did you mean T/AD as well? Just curious.

Cliff, I think you would enjoy this article

http://www.dragracingonline.com/archive/technical/2014/xvi_5-worsham-1.html

It is old but I had basically this same conversation with Jim Whiteley and Del in the staging lanes in Vegas in 2013. This type of thinking is used all the way down to TD.

I'm sure Alan will answer MUCH BETTER than me (and in a different color) but I've referred a number of racers to this line of thinking and while its been evolved quite a bit (I have evolved away from it unless I'm lost, but it is a tool when needed), it gives an idea of the thought process we all use and the importance of keeping the rim and tire happy with each other. You have to get the rim in the middle of the tire at some point after the launch and the failure to do so in a coordinated manner is what causes tire shake.
 
WOW! Thanks Jeff, this was really interesting. Ya know what? Now i have some questions & comments. Del talked about putting more air in the tires. I remember hearing about Pat Foster in F/C at Lions. They had terrible tire shake, & someone told them put more air in the tires. It worked, they set the track record. Probably around 1970 or so. They had the same problems with shake even then, both T/F and F/C. At times the shake was so bad that the drivers head hit the roll cage & left marks on the helmet. John Wiebe showed me his helmet once and you could see where it hit the cage. Some drivers got knocked out from the shake.

Black tracking. I see that when the cars make a run. I knew they couldn't hook them up 100%, and had to have a bit of spin to go down the track. This reminded me of T/F way back in the 1950's & 60's, before slipper clutches. Anyhoo, a fuel car would come to the line, & crew would wipe the tires clean with a rag. Tires were hard rubber, not a lot of air in the tire, but not wrinkle walls. Driver would bring up the RPM and on a good run, tires would smoke until maybe 1/2 track. In a sense, this acted like a slipper clutch, kept the RPM "up" so the car would get off the line (kinda, sorta like today), then at the point where the engine caught up with the tires, you would hear the RPM go down, and as the tires hooked up, RPM would go up again and the car was moving hard in the back half. Sometimes they would smoke the tires all the way down & it killed ET. Drivers could see the tires smoking & knew just how hard they wanted to smoke the tires to get a good run. When you sat in the stands by the starting line, you couldn't see the cars because of the smoke, until about half track. Interesting to me that this old technology was kinda paving the way for slipper clutches and what we have today.

Wings - sometimes I wonder which type of wing works better, the T/F wing or a F/C wing. Both cars run about the same MPH, so both designs work and yet are so different.

Finally, all the talk about running nitrous or a blower, etc and changing timing on a run. I guess it's like you say, you do it cuz it's fun/challenge for you. But.... why not just run a naturally aspirated engine w/ carbs, maybe alky, and torque converter. Maybe a big motor that would run, say, 6.30's. Seems to me that would be the hot set up to "repeat" and with a big engine, you could run a milder combination. I have seen lotsa times that all the 6.0 cars go out early and the winner is running 6.50's or like that. You forgot more about this stuff than I'll ever know, so that's why I'm asking. :)

OK, thanks for the info. I really enjoy reading your responses.
 
Putting more air in the tires .... so first off tires of today and tires of the 70's had drastically different sidewalls .... our tires today are 10 to 100 times better than those (they can take tons more horsepower and grip the track better). Forgetting that, think of a standard deviation curve (a profile of a mild hill with equal slopes on each side). if tire pressure is on the horizontal axis and traction is on the vertical axis for a typical dragster you could reasonably say the top of the hill is roughly 7 pounds (this is an example folks, but its in range). That is the point at which the tire will produce maximum traction to accelerate the car. If you put say 8 pounds in it the tire will start to get somewhat round and you'll lose the grip from the outer edges of the tire, If you put say 5 lbs in it, under acceleration the middle part of the tread will lag behind the tire and not produce as much traction to accelerate the tire.

To the best of my knowledge all drag slick racers (Im excluding the radial bunch here) operate on the back side of that traction standard deviation curve .... e.g. they never run down the track above my 7 lb example.

So lets say you are running a tire with a 35 inch diameter (real data here, I run the relatively narrow but tall MT "bubba grande"). So at idle the center of the axle shaft is roughly 17" off the ground (gravity gets involved so forget 17.5"). When the horsepower hits the rim, the rim turns about 1/8 turn before the tire ever moves forward .... the rim "wraps" the tire. The car drops about 2.5" and the rear axle ratio gets a little bit shorter .... at this point the driver is having a shit-ton of fun. Unfortunately, the rim is no longer in the center of the tire. When you put more air in the tire you do a number of things but one of the biggest is that you decrease the wrap of the rim and you substantially increase the odds of the tire unwrapping happily about 1.5 seconds later. In that article Del was helping that by dramatically, but momentarily, decreasing the power to the rim before the shake zone (where the tire is going to unwrap whether you like it or not). You can ALMOST do that without dipping the G meter line in a nitrous car .... almost is why I don't do it anymore, well that and I found a different way to avoid tire shake in my set up. Interestingly when I was playing with that, I had a short stint of helping a pro mod guy in Europe tune his car .... all via Racepak files and texts. It was fun to get up at 3am and help change somebody's personal best by almost 2/10ths .... once they had my various theories and tools they were off on there own. Man it rains a TON over there .... light rain, but RAIN.

PS: Funny cars have to punch a MUCH bigger hole in the air, but they get the benefit of much, much smoother airflow into the supercharger hat and a smoother, albeit larger, aerodynamic body. As similar as the two nitro set ups would seem to be, Force couldn't make a dragster work with a FC engine .... had to use AJ stuff. They do run the same tire, and I'm certain Alan could find out which tire is crushed more at 300 mph (I use a laser ride height sensor just like they do .... you can see the results of wing angle adjustments and you can see the only suspension I have (the tire) interacting with the track).

I'll comment on your NA 6.30 statement later .... it's time for my 5 hours of sleep before another long day tomorrow!
 
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Hi Alan. Hmmmm, I guess in my heart of hearts I'm a dragster guy, altho I like all the classes. I really like T/D and just thought it would be cool to have a heads up class, no dial in. That is what I was thinking about. Maybe like a less expensive version of T/AD??? Also, this class reminds me of T/AD when they were breaking into the 5's years ago. By the way, when you were talking about timing manipulation in alcohol, did you mean T/AD as well? Just curious.

Cliff,

Yes, TAD and TAFC use much timing manipulation, listen closely when one is on a single and you will hear the engine "Dip" about 1 second out then come back to full song. Here's a graph from a Johnnie Lindburg TAFC, not saying it's typical, this one is pretty severe but the harder you push, the closer you are to the edge so the more you adjust the power via timing. But timing is constantly being adjusted going down the track. Red is engine RPM green is driveshaft blue is ignition curve, notice the timing drop to keep it from breaking the tires loose at the gear changes. As well as the big dip just after dropping the clutch that gets you through the "Shake zone".

Alan TAFC Timing.jpg
TAFC Timing.jpg
 
Thanks Alan. Really interesting to me to see this graph. Can see where the shift happens and finally where it "all comes together" after 3rd gear. I have heard that driving an alky F/C is the hardest car to drive in drag racing. It really amazes me just how quick & fast the alky cars can run, even with rules that kinda "hold them back". I'll get an argument on this, but I think it's harder to run an alky car than T/F or F/C, cuz you don't have nitro to add power. My fantasy is that if nitro got outlawed, what kind of combo would be developed to run alky as the Pro class. So.... 1000 CI, no restrictions on fuel pump, ignition, blower, etc and go at it. Yeah, bring lots of $$$... heh
 
Thanks Alan. Really interesting to me to see this graph. Can see where the shift happens and finally where it "all comes together" after 3rd gear. I have heard that driving an alky F/C is the hardest car to drive in drag racing. It really amazes me just how quick & fast the alky cars can run, even with rules that kinda "hold them back". I'll get an argument on this, but I think it's harder to run an alky car than T/F or F/C, cuz you don't have nitro to add power. My fantasy is that if nitro got outlawed, what kind of combo would be developed to run alky as the Pro class. So.... 1000 CI, no restrictions on fuel pump, ignition, blower, etc and go at it. Yeah, bring lots of $$$... heh
They're already lots of money Cliff! But yeah, I agree, it would be cool to see what an "outlaw" alky car could do. We've seen outlaw PM cars that usually run 1/8 mile go low 5.40s, without many of the restrictions of NHRA alky cars, the blower being one of them. And those cars are, I believe, 2-300lbs. heavier than a TAFC, and are sprung all around.
 
What a pretty graph. I'd give my left 1/4-20 to have an rpm graph that stayed above a straight line drawn from the launch point to the 1-2 shift.

It's also cool to see how he's almost about to lose control of the tire at .75 and whacks the timing to hang on to it.

Alan, if you could get a graph similar to that with the g meter channel turned on .... name your bottle (well within some realm of reason) for a pre 12/25/18 box to the shop.

Jeff
 
What a pretty graph. I'd give my left 1/4-20 to have an rpm graph that stayed above a straight line drawn from the launch point to the 1-2 shift.

It's also cool to see how he's almost about to lose control of the tire at .75 and whacks the timing to hang on to it.

Alan, if you could get a graph similar to that with the g meter channel turned on .... name your bottle (well within some realm of reason) for a pre 12/25/18 box to the shop.

Jeff

I'll see what I can do........
Alan
 
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