dev1360

Added some pressure into the bias plies and some RPM to the launch. Still getting the hang of it, but it's going well. Need to kill that last bit of bog.

Car specs are in sig.

Here's the video and a copy of the slip.

STEVEN13

Bad A$$

Suprfly

where are the mods listed? nothing done to the drive train?

dev1360

In my signature. It should show up below my post unless you're on mobile.

PatG 230/238 cam, Halltech CAI, McLeod RXT, 4.11 gears, OBX longtubes, catless X with NPP mufflers. DSX (DSteck) tune.

09+ differentials have Z06 shafts, carbon clutches, and Z06 pinion carrier in them from the factory. I built my own differential, only swapped the gears. Driveline is stock.

robz

Very Nice.
You could use a little more tire speed on those launches.
I'd launch a few rpm higher and get into the throttle just a hair quicker before the clutch release.
Raising the tire pressure was the right move when you were bogging a lot on the first few passes. It almost looked like you got off the throttle.
You want to be able to go full throttle on the launch and never pedal. If you start to spin too much then you can lower the tires a bit as long as you aren't bogging. When you get it right you will see 1.4x's and that's still achievable with several revolutions of tire spin coming out of the hole and the car kicking out a little bit.
Put a wide white stripe on your tire and have someone video from side and count the revolutions in slow mo. If your tail doesn't kick out once in a while then your launch is too passive. But of course be safe.
With that said it looks like you are doing everything right and just need some fine tuning.

Maybe try this out.
I used to call it power launching.
Hold the rpms at given rpm like you were doing in the video but slightly lower than normal.
Instead of releasing the clutch and squeezing the throttle at the same time, try hitting the throttle slightly before releasing the clutch so the rpms are climbing as you are releasing the clutch. This won't work with every clutch but most.
It's like launching on a two step but less aggressive. It will take some practice and tweaks.
And shallow stage and don't creep like you did on some of those passes. Creep will kill 60'.

dev1360

Thanks. The first pass on the video was my first pass off of the street. Not enough RPM. As the night went along, I added more RPM to the launch. The last pass had the most tire spin, it's hard to hear. At the end of the night I was cutting consistent 1.5xs. Holding the RPMs at about 5k and goint WOT then riding out the clutch quickly.

I'm sure they will come down with more time. This is my first time consistently in the 1.5s and second time on Bias plies. I spent a lot of time messing with radials before these. Won't go back.

robz

And full burnouts are good but not at the expense of overheating the clutch. The colder the clutch is at the launch the better. So quick burnouts and let the clutch cool between passes. Sometimes a broomstick helps keeping the clutch disengaged in the pits.

dev1360

Clutch felt great all night. For the burnout, the car will start to hook. Once the RPMs start dropping, I let off the brake and let the tires spin until the hook and push the car forward. Hard to explain, but I can feel them grab and push.

robz

Sounds good man. Some of those minute changes will get you in the 1.4x's.

robz

I dug up a 10 year old video that shows the technique I was describing in an exaggerated fashion. I believe this setup had 3.90 gears, cam only, and was on MT et streets (bias ply).
396whp

Joe G. in his C6 and many other racers have had success with this launch technique over the years.

Please ignore the silly captions. lol

You Tube

[/URL]

dev1360

Yup. As the night went on I started getting the RPMs higher. My last pass of the ight was my 10.86 and my highest launching 60. That last pass is hard to hear, but I did what you did in the video, just to a little lesser degree. It's going to take some more seat time to get into the 1.4x range.

robz

Looks like fun, I miss those days.

dev1360

Lol. It's a load of fun. I was saying the other night that I don't even care what the rest of the pass is. I just want to launch.

The sound of a stick car ripping out of the hole on bias plies is awesome.

Thanks for all of the input. I'll get back to the track eventually. As much fun as it is, these differentials just don't last forever when driven this way, and I like to drive my car too much to have it down building a diff. Thank god I build my own differentials, saves a ton of money lol

Joe_G

Great driving Dev.

This advice is dead on and got me consistent 1.4 60's time and time again back when Robz offered it up. I actually floor the throttle when the tree starts to come down then release the clutch in a smooth motion. It took me some practice to learn how to do this, and frankly, to have the nerve to just floor the car then let the clutch out. I do it now from habit and sound and I almost always get the car moving around 5800-6000 rpm or so. Releasing the clutch while the engine is accelerating vs. just sitting at rpm seems to be the key and as Rob stated it's what a two step does for you.

I also do a first gear burnout. It's easier on the clutch and you don't need a very long burnout as you can see from my videos.

Here's an in car video of how it looks and sounds:

dev1360

Once I got into the consistent 1.5x 60s I was WOT when the clutch was coming out. I think I worded what I did poorly lol.

I hold it about 5k then on the final yellow I floor it and feed out the clutch quickly. I'm not sure if I was riding the clutch too much or it was a tire pressure issue. I need to play with pressures A LOT more to see how they react. I was leaving pressures the same and playing with launch techniques until I got them down. Then I started changing the pressures but the track was closing.

Joe_G

17 psi is my go to number. Works great for me.

ajrothm

Congrats!! That's some killer driving! Very fast for a cam only STICK car.... Nice job with it.

Joe_G

Dev1360 one other thing helped me a lot, I started scanning my runs with Ho tuners. It allows you to see exact launch and shifting parameters you executed so you can judge your performance along with the car's.

dev1360

I agree, and I'd love to scan my runs. I have a buddy with HP Tuners, but will I need to buy credits to only scan my car?

Hard to justify $500 to scan my runs. I have a simple "Torque" app on my phone. I use it to monitor IATs and can do simple logs on it. Idk if I can log RPM throughout the run.

Joe_G

No you can scan for free. Only need to spend $100 to tune your car if he will let you use his cord. You need to install a wide band to do any effective tuning. I've found tenths playing with my tune at the track. Perhaps more importantly I've once in a while seen knock and backed off timing which may help explain my lucky longevity.