Tried the 1/8th again... please analyze this vid & help

[Z06phile]

I mounted the new 275/40/17 ET Street Radials yesterday and went to the strip. I started out with 30 psi and went down to 12 psi and still couldn't get a decent 60'.
Temp was around 48 and the track wasn't prepped.

Best 60'---- 1.856
Best ET---- 7.910
Best MPH---- 95.798

I never did a real burnout... tried to hold the brake, but failed miserably
All I could muster was a quick clean-off of the tires.

I'm having to grab 4th due to the 3.90s, so that's costing me a little time.

I learned what "giving somebody the tree" means now after racing the Crown Vic lol

http://video.ls1tech.com/video/f2006...9400f34efc.htm

I kept the revs around 3K, but still spun badly in 1st on every pass. Slipping the clutch is hard to do with this Spec 3+. I think I'm getting the clutch fully engaged between 5-10 feet.

I thought doing a big smokey burnout wasn't necessary with these tires. Am I wrong?
I had very good traction on the street coming home.

Drag guys please chime in.

-Dan

[itchynackers]

Just sounded like you were rolling in to the throttle too quickly. Also, was that clutch slipping in the last two runs?

[robz]

Originally Posted by Z06phile

I mounted the new 275/40/17 ET Street Radials yesterday and went to the strip. I started out with 30 psi and went down to 12 psi and still couldn't get a decent 60'.
Temp was around 48 and the track wasn't prepped.

Best 60'---- 1.856
Best ET---- 7.910
Best MPH---- 95.798

I never did a real burnout... tried to hold the brake, but failed miserably
All I could muster was a quick clean-off of the tires.

I'm having to grab 4th due to the 3.90s, so that's costing me a little time.

I learned what "giving somebody the tree" means now after racing the Crown Vic lol

http://video.ls1tech.com/video/f2006...9400f34efc.htm

I kept the revs around 3K, but still spun badly in 1st on every pass. Slipping the clutch is hard to do with this Spec 3+. I think I'm getting the clutch fully engaged between 5-10 feet.

I thought doing a big smokey burnout wasn't necessary with these tires. Am I wrong?
I had very good traction on the street coming home.

Drag guys please chime in.

-Dan

You need seat time.
I would bet your tires were not heated at all. On the 2nd run you blew right into the limiter spinning. I would do a full burnout everytime moreso in the cold weather. It won't hurt.
You should be able to come out at 6000 rpms with those tires properly heated and 400rwhp.( not that you would). The spec clutch will slip, it will take some seat time.
The shifting needs to be quicker also. You should be pull back on that shifter about the same time you stab the clutch pedal.
I would start with the tires around 18 psi(if your around 380-400rwhp) and do a full burnout. If you don't get a burnout then your run is shot and you'll have to launch like a wus. Adjust from there. Make sure you know the exact rpm each time so you can adjust. Goodluck.

[Z06phile]

Originally Posted by itchynackers

Just sounded like you were rolling in to the throttle too quickly. Also, was that clutch slipping in the last two runs?

I probably am a little too throttle happy.
I noticed the clutch slipping sound too after seeing the vid, but I don't think it's slipping. Maybe I was just slow getting off the clutch... didn't sound like it was slipping on both the last 3-4 shifts. Seems like it would slip more on the 3-4 shift.

Thanks

[Z06phile]

Originally Posted by robz

You need seat time.
I would bet your tires were not heated at all. On the 2nd run you blew right into the limiter spinning. I would do a full burnout everytime moreso in the cold weather. It won't hurt.
You should be able to come out at 6000 rpms with those tires properly heated and 400rwhp.( not that you would). The spec clutch will slip, it will take some seat time.
The shifting needs to be quicker also. You should be pull back on that shifter about the same time you stab the clutch pedal.
I would start with the tires around 18 psi(if your around 380-400rwhp) and do a full burnout. If you don't get a burnout then your run is shot and you'll have to launch like a wus. Adjust from there. Make sure you know the exact rpm each time so you can adjust. Goodluck.

The car made 478 rwhp before the gear swap, so prolly 465 or so now. Maybe I should put the stock rears on and practice holding the brake and heating the tires up or is there a better way?

[IT L GO]

With a 275/40/17 (25.66 in) tire and 3.90 gearing, 3rd gear speed at 6,500 RPM is 98 MPH. You should be able to make it all the way through the 1/8 without shifting into 4th gear.

[robz]

Originally Posted by Z06phile

The car made 478 rwhp before the gear swap, so prolly 465 or so now. Maybe I should put the stock rears on and practice holding the brake and heating the tires up or is there a better way?

Ok so your making alot of power.
I took 2 passes in my friends car who was making about 450 rwhp thru 4.10 gears in an m6 with the same tires(et street radials). I was launching at about 5000-5500 rpms with the tires at about 16-17psi. This was with good full burnouts.

You need a good burnout.
To do a burnout without a line lock and those tires, here's what I would do.
Set the tires around 16 psi. Roll thru the water and stop early. Do not pull too far up even if your rear tires are just at the edge of the burnout box.(Make sure they are wet, even if you have to open the door to check or have a friend check.
You can do a 1st or 2nd gear burnout, it doesn't matter. The second gear will work much quicker but the 1st gear is a little easier to get going esp. when you are first learning.
Assuming your tires are wet I would rev to about 5000-5500 and completely dump the clutch and get on the brakes as fast as you can. Hold the brakes lightly and give more throttle as the tires start to heat up and grab. If you roll forward then you didn't dump the clutch and get on the break fast enough. It needs to be done fast but controlled.
If the burnout starts to die on you or the car begins to go sideways then you may not be feeding in the throttle enough. It's ok to nick the limiter a few times to make sure you are spinning the tires fast enough. If you are losing control then just push in the clutch and try again next time.
It takes a few tries and eventually you'll get it. Don't use the street tires. You'll be fine on the dr and you need to practice with them. I would rather see you do the burnout when the tires are back near the water box with the dr's if you want to practice. With those tires properly heated at 16psi before the burnout, you should be able to launch around 5000 with your car. If you get wheelhop then push in the clutch and abort the run. You should spin a little off the line on a good launch.
If you want to practice without launching so high in the beginning then air the tires up to 18-20, do a huge burnout and launch at 4000 and get the feel for what a good launch feels like.
Ignore the silly caption and the bad shifting, but here's an example of a an agressive launch with 3.90 gears and about 419rwhp on et streets. Notice how I could launch so high with hot tires and not much wheelspin at all but just enough. I was slipping the clutch to prevent too much wheelspin.
http://www.learntodragrace.com/images/rob142.wmv

[Z06phile]

Originally Posted by IT L GO

With a 275/40/17 (25.66 in) tire and 3.90 gearing, 3rd gear speed at 6,500 RPM is 98 MPH. You should be able to make it all the way through the 1/8 without shifting into 4th gear.

I wish I could get 98 MPH out of 3rd. Even with the 305 RIIs which is over 26" tall and a 6900 RPM limit, I'm only getting a little over 90 MPH out of it.
I ordered a 3.90 from DTE and it's tagged as 3.90. I have the stock MN12 tranny.
Here's a vid from another track that's 60' short of an 1/8th mile. You can here me hit the limiter on one of the runs right before I cross the line. That was with the taller RIIs also.

http://video.ls1tech.com/video/d8078...b6ee2031f0.htm

What's going on?

[Z06phile]

Rob, thanks for the info! I definitely need more seat time.
It looks like I need to heat the tires up alot more, learn to modulate clutch release and throttle app.
My 2-3 shifts are slooooooow too. I might look into adjusting my McCloud Master cyl also. It lets out at right off the floor.

The launch in that vid was awesome

[robz]

On my run in the video where I missed 4th gear it all happened before the 8th mile.
My splits were
1.42
4.45
7.0@87mph due to missed shift(usually trap 98+)
So, I think your gearing is correct.

Most of us set the engagement on the adj. master cylinder very high near the top of the throw. This allows for more fluid to be injected and physically gives more abilitly to slip the clutch. I would raise it and practice.

[IT L GO]

Originally Posted by IT L GO

With a 275/40/17 (25.66 in) tire and 3.90 gearing, 3rd gear speed at 6,500 RPM is 98 MPH. You should be able to make it all the way through the 1/8 without shifting into 4th gear.

OOPS

I apologize. The 98 MPH number is based on 3rd gear with a MN6 transmission. With the shorter gear spacing of the MN12 transmission of 1.42 ratio in 3rd gear and a 25.66 in tire, your speed would be 89 MPH at 6,500 RPM

[Dr.Ron]

Rob has given you some sound advice. If you can adjust the clutch to grab higher, allowing you room to slip it some, DO IT!
DO heat up the tires w/ a good burnout, especially in the cold. When it's warm, you won't need billowing smoke every run.
It sounds like you're flooring it too quickly!
With some slip of the clutch you can launch at 6000+ Rpm's for sure.
Make sure traction control is OFF during your run/burnout.
If you can't get traction & have that much RWHP, a burnout should be a breeze. Just need to work on your technique some, or get a line lock.
Don't practice on street tires, they're just be worse then the DR's. Just be more patient on your launch, you have the power to get you down the track.
Many times, I've launched & bogged some off the line, only to find my 60' time was equal to what I perceived to be a good launch w/ clutch slip!
Start at like 16 or 17 psi & adjust from there, but only if you were launching good, not because you blew away the tires. Too little air in the DR's can hut=rt traction as well as too much air.

Good luck!
Ron

[Z06phile]

Originally Posted by IT L GO

OOPS

I apologize. The 98 MPH number is based on 3rd gear with a MN6 transmission. With the shorter gear spacing of the MN12 transmission of 1.42 ratio in 3rd gear and a 25.66 in tire, your speed would be 89 MPH at 6,500 RPM

No problem. I'll probably go with the MN6 if this one goes bad.

[Z06phile]

Originally Posted by Dr.Ron

Rob has given you some sound advice. If you can adjust the clutch to grab higher, allowing you room to slip it some, DO IT!
DO heat up the tires w/ a good burnout, especially in the cold. When it's warm, you won't need billowing smoke every run.
It sounds like you're flooring it too quickly!
With some slip of the clutch you can launch at 6000+ Rpm's for sure.
Make sure traction control is OFF during your run/burnout.
If you can't get traction & have that much RWHP, a burnout should be a breeze. Just need to work on your technique some, or get a line lock.
Don't practice on street tires, they're just be worse then the DR's. Just be more patient on your launch, you have the power to get you down the track.
Many times, I've launched & bogged some off the line, only to find my 60' time was equal to what I perceived to be a good launch w/ clutch slip!
Start at like 16 or 17 psi & adjust from there, but only if you were launching good, not because you blew away the tires. Too little air in the DR's can hut=rt traction as well as too much air.

Good luck!
Ron

I really appreciate all the input from y'all. I feel better prepared (in my head) now.

[z06nut]

The cars sound awesome.