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All things Drag Racing.

If you can launch at 1500 without spinning, but it spins at 2000, then a stickier tire might put that number up to 2000 to 2500 without spinning at all. You would be surprised at how hard a car hits the rear tire, when it is hooked up 100%. Most of the time, we can't tell that it is spinning, because it is a small amount, all of the way through 1st gear, and the bottom of 2nd. Even your 2nd gear shift will seem a lot harder with a drag radial.
 
And related. Moved it over since this corner of Ck5 has slowly become the “it’s not a truck or it’s a drag race conversation”

Hydrazine

If you’ve read much about racing, you have heard this. If not: The Story of the Leathal Fuel Called Hydrazine by Tony DeFeo This was a common scene for engines that ran on hydrazine It’s the liquid so potent, so deadly, so illegal that those in Drag Racing who have unleashed its wrath dare...
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76zimmer said:
How is just a stickier tire going to improvement 60’ time? How many ponies?
from what I gather its only 350 hp?

I have a decent Coan “2600” stall right now….how much more convertor before street manners start to go away?

Right now I can only get a 26” tall 225/60 under it. Hoping for a little more after the offset trailing arms and narrower spring install, but not sure I can get up to a 255/60.
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I'm saying your MPH shows you got the HP to go 115 in the quarter.

But your 60 ft time is slow for that MPH, and you said you couldn't launch at too high of RPM or throttle or you are spinning correct?

So you put a sticky tire on like a Hoosier Quick Time Pro or a M/T Drag radial or something and let that thing eat off the launch and your 60 will drop and so will your ET, but your MPH will likely be the same or a tad lower because when you put more heat in the converter on the launch it tends to not pull the exact same MPH up high unless you can lock it. But you get to the finish line quicker.
 
I'll add some math to my above statement. In my app it estimates HP based on ET and MPH.

So if I guess your car weighs 3200 lbs, and you ran a 12.24 at 115, it says your HP on ET is 344 and your HP on speed is 380. So if you can put that 380 down the whole pass instead your 60 ft will drop, and thus your ET. Get some good tires and some good air (and maybe even a 3000 stall 10" converter), and watch that ET drop.

I use that as a tool. It may not always be correct on the HP because it assumes your chassis is excellent and you are putting down all the power you can, but even if you are not, the ratio is still there. If the ET power is low, your 60 ft needs work. If your MPH power is low, then its falling off at the big end and you need to work on your tuning, fuel flow, airflow at speed, etc. When the car is running decent, the ET and speed power estimates will be close to the same.

Now, the HP estimate might still be lower than you actually have, because it also assumes you are geared for that race and your chassis setup and converter are near perfect. So if you could run a 4.56 gear and 4000 stall converter and and you are only running 3.73s and a 2500 stall, you aren't going to put as much power to the ground. Because we make compromises.

I do the same, I only have a 3.60 gear and a 4500 stall converter. I could put a 5500 stall and some 4.10s and I would be faster on motor, but then on spray I would over run the converter and also run out of RPM at the big end. So I have it in between.

Screenshot_20220815-085559_Gearhead Pro.jpg
 
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Some frustrating fun this past weekend.

Car goes faster as the day progresses even considering worse air and a looser track. I got some theories. May need to start using the two step. I kinda hate that thing.

Racing again this coming weekend. Have an opportunity to get some new data on the car Thursday.

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Nice run Kert!

General rule of thumb is to set the two-step up 10% lower than your WOT RPM on the brake. So if its 5K then set it for 4500. This lets the engine get a small run at the converter when the Tbrake releases.

Are you warming the drivetrain up a little before your 1st passes in the morning?
 
folkenheath said:
Nice run Kert!

General rule of thumb is to set the two-step up 10% lower than your WOT RPM on the brake. So if its 5K then set it for 4500. This lets the engine get a small run at the converter when the Tbrake releases.

Are you warming the drivetrain up a little before your 1st passes in the morning?
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I am but I suspect I’m not getting it as warm as it is after a few passes. The other variable is how long I’m on the brake. Qualifying passes, no tree handicap. Elimination rounds handicapped and the further you go, seems the slower cars you run. I don’t always see their dial on the boards so I’m guessing when to rpm the brake.

You know exactly what I’m thinking is changing.
 
You are leaving off the bottom bulb correct?

Floor it on the top bulb if that works for you.

Or is your track still on the instant green thing?

Whatever you do, do the same thing every time.

And use the two step, it's more consistent to launch from the exact same RPM every time.
 
folkenheath said:
I'll add some math to my above statement. In my app it estimates HP based on ET and MPH.

So if I guess your car weighs 3200 lbs, and you ran a 12.24 at 115, it says your HP on ET is 344 and your HP on speed is 380. So if you can put that 380 down the whole pass instead your 60 ft will drop, and thus your ET. Get some good tires and some good air (and maybe even a 3000 stall 10" converter), and watch that ET drop.

I use that as a tool. It may not always be correct on the HP because it assumes your chassis is excellent and you are putting down all the power you can, but even if you are not, the ratio is still there. If the ET power is low, your 60 ft needs work. If your MPH power is low, then its falling off at the big end and you need to work on your tuning, fuel flow, airflow at speed, etc. When the car is running decent, the ET and speed power estimates will be close to the same.

Now, the HP estimate might still be lower than you actually have, because it also assumes you are geared for that race and your chassis setup and converter are near perfect. So if you could run a 4.56 gear and 4000 stall converter and and you are only running 3.73s and a 2500 stall, you aren't going to put as much power to the ground. Because we make compromises.

I do the same, I only have a 3.60 gear and a 4500 stall converter. I could put a 5500 stall and some 4.10s and I would be faster on motor, but then on spray I would over run the converter and also run out of RPM at the big end
Click to expand...
this is why I say how can a tire improve et? I get adding convertor, suspension, bigger tire, etc will allow more power to be thrown at the launch, but working w what I have right now, I seem to be at my limit for power at launch. given my et didnt improve between 1500/2000 launch (1.90) I would think I need a higher stall convertor and sticky tires to make a big change in 60’.
 
76zimmer said:
this is why I say how can a tire improve et? I get adding convertor, suspension, bigger tire, etc will allow more power to be thrown at the launch, but working w what I have right now, I seem to be at my limit for power at launch. given my et didnt improve between 1500/2000 launch (1.90) I would think I need a higher stall convertor and sticky tires to make a big change in 60’.
Click to expand...

Your ET didn't improve because your tire put the same 60 ft down at 1500 vs 2000 because you spun, you can't go any quicker than your tire has traction. Currently your tire is the limiting factor. Put a sticky tire on and it will put a better 60 ft and ET.

Then your converter will be the next limiting factor because it may bog down a little with a sticky tire since you will be putting the power to the ground instead of being forced to feather the throttle on the launch.

Then your cam, and/or your gear ratio, then maybe your tire again, then your heads, it's a viscous/fun cycle!

You are correct that a higher stall converter may help, but without sticky tires, your 60 ft may remain the same because trying to put more power to the same tire will result in the same or worse 60 ft.

I would upgrade the tire first. Of course a better converter at the same time would likely help, but the converter before the tire would likely be wasted on lack of traction.

If you increased your launch RPM, and it did not spin, and did not pick up any ET or MPH, then I would agree, but it spun, and thus the tire is your limiting factor. Unless you can tune your suspension to get it to not spin on the launch with the same tire at the increased RPM. But I don't think you have the suspension or shock adjustability to tune that right now.

Think of it this way, if you put your tire on a pro mod they may run close to the same 1.90 60 ft(or worse) but the MPH would be way higher...
 
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I think that your 60ft will improve with the tire change. I launched my friends Nova this morning in front of my shop. I would have bet that it didn't spin. However after looking at the street afterwards, it spun for at least 15 feet out of the hole, but I couldn't tell . I figure, if you can hear it spin, as in a squall, you have lost a 10th. If you can feel it spin, you have lost a bunch!
 
@folkenheath
the 60’ times I posted at both rpms did not spin. 2 runs @ 2000 rpm did spin and those 60’ were 2.04/2.17
2000 rpm best 60’ was 1.904
1500 rpm best 60’ was 1.890



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