0-60 data

[bobl]

I was playing around with a data log I made of a 0-60 run after installing my new Toyo drag radials. I found it interesting and thought I would share. This is a Holley HP efi system. I edited the graph to only show the window of interest. There are 2 parameters shown. Throttle position in purple and RPM in green. Across the bottom is time. You can see reading left to right at time zero where I dropped the clutch at 4000 rpm. It started spinning and I feathered the throttle holding the rpm until the tires started grabbing at about 1.3 seconds. Then you can see the TPS go to 100% as I open the throttle. I’m only at wot for about .5 seconds before I have to shift at 6500 RPM. That took about ¾ second (no power shift there), then back to WOT around the 2.8 sec time. Reaching 5425 RPM (which is 60 mph) at the 3.4 second mark. You can tell by the smooth green line that once the tires hooked in first gear they never spun again. If it were spinning much you would see some ripples in the rpm. One big takeaway from this is that I spent just a little over 1 second at wide open out of a 3.4 second time. Kind of shows why these cars can get such good 0-60 times with just modest power. I’m running over 500HP but you can see I’m not using much of it. Hope you found this to be of interest.
Bob

[GoDadGo]

Thanks for posting Bob!

[CraigS]

So now will you try more runs to reduce your wheel spin? Seems to me you might be able to get a < 3.0 sec time w/ a little practice.

[bobl]

I will certainly do some more testing. That run was just a first try to see how the tires worked. They had too much air and the road wasn't very good.

[NAZ]

Drag radials on a roadster? Are we thinking of a little drag racing?

That T-5 doesn't have very long legs in 1st and really helps crank a lot of torque to the axles. You can lower your launch RPM down to ~3000 and play around up and down from there and may find a sweet spot where your torque at the axle is low enough for the tires to handle it without falling on its face. Radials don't like to be hit hard and when they do slip, they don't recover as well as biased ply tires. They do like more air pressure than bias ply but most folks with big tires on light cars tend to run way too much air pressure. You need some sidewall flex (from lower air press) to take some of the shock out of the hit. Bias ply tires are much more forgiving of the shock from a clutch car.

Have fun.

[bobl]

Drag radials on a roadster? Are we thinking of a little drag racing?

That T-5 doesn't have very long legs in 1st and really helps crank a lot of torque to the axles. You can lower your launch RPM down to ~3000 and play around up and down from there and may find a sweet spot where your torque at the axle is low enough for the tires to handle it without falling on its face. Radials don't like to be hit hard and when they do slip, they don't recover as well as biased ply tires. They do like more air pressure than bias ply but most folks with big tires on light cars tend to run way too much air pressure. You need some sidewall flex (from lower air press) to take some of the shock out of the hit. Bias ply tires are much more forgiving of the shock from a clutch car.

Have fun.

I'm an old drag racer and that will always run in my veins. One of these days I'd love to see what it would do, but I know the roll bars are not legal, so it's always in the back of my mind they wouldn't let me run anyway.

I'm running an Astro performance T5 with 2.95 first gear so that carries a little better. I wasn't trying for a great time, just some data. It's pretty difficult to find a stretch of road to experiment. Lot's of room for improvement for sure. I also have a launch control system integrated into the ECU, but wasn't using it on this run. I believe these tires need to be heated to get good bite and I haven't tried that yet either. They were inflated to 25 psi, which was way to much. I've since let them down to about 20 but haven't made any more attempts. One thing I noticed when I got these tires was that the sidewalls were very stiff. They felt just about like the NT05's that I took off.

[NAZ]

20 PSI is a good start on the tire pressure but you may get closer to 15 or even under depending on the tire size. Like you, I know how much trouble it is to make a FFR car NHRA compliant so it can run down the strip. These cars are just not designed to easily accommodate modern safety rollover protection and then like you said, finding a place to safely (and sort-of legal) stretch these light car's legs is a problem. I need at least a couple of seconds at WOT to get good enough data to tune the carb. My car does 0-60 in less than 2-seconds so in no time I'm at 75 MPH and barely have enough data on my logger to tune with.

Have fun with your ride. And when you've exhausted everything else start looking at your anti-squat.