LuvC5s

Hey guys, I'm taking my car to the track soon and could use some advice. This will be my first time drag racing with a manual car. Here are some specs on my car: P1SC-1 running 8lbs of boost, McLeod RXT dual disk clutch, 3.73 gears w/hardend shafts, RPM trans with hardened shafts, Z06 shocks & swaybars, 28x10 Hoosiers bias plys, 27.5x4.5 skinnies both on 17" rims, 628rwhp, lingenfelter 2 step the original that only sets your rpm with the clutch engaged. Basically I'm looking for consistency and wondering if I should use the two step or work on just slipping the clutch? I have heard not to use this particular two step cause it could pop the motor, idk how true that is. I also heard with 28" tires I'll need to get the rpms above 4000 so it won't bog. I also recently raised my car a half inch since it was lowered because I heard the 28's will rub. Experienced guy please chime in. Thanks

robz

Since you are new at this I'd start slow and try not to take in too much info from too many people.
The most important thing is safety. I always start beginners out with making sure you can get through the gears and ignore the launch on the first few passes. I start without the 2 step.
I'd put the tires @ 22 psi, try and do a burnout, and stage the car. If you don't get a burnout then launch the car @ 2500 rpms and ride the clutch out slightly and try and shift the car deliberately @ 6000 rpms.
Then do it again and make sure you feel comfortable going down the track.
If you feel comfortable, the car shifts well, and you feel good about everything then start having fun with the launch.
I'd put the tires around 20 hot and try launching around 3500 and see what happens. On my first day out I wouldn't go below 18 hot and really try and get a feel for the clutch, how you need to release it, the throttle squeeze, and the rpm needed. Write it all down including how you released the clutch and hit the gas.
A throttle stab @ 2500 is like a static launch @ 4500.
For the first time out hold the rpm at a given point say 3500, forget the tree, and release the clutch and squeeze the throttle about the same time with the same effort.
If you are new, your burnout might dictate your launch rpm. So try and time it so it's consistent. Make sure you see white smoke and both wheels are spinning. Slicks usually take 2 passes before they are fully ready. It's gonna take practice and you will learn alot about yourself and the car the first time out.
That's all I'm saying for now.

LuvC5s

Thanks for the input Rob. I dragged raced for 3-4years but this will be my first time with a manual. I'm curious about the tire pressure you recommended. Anytime I used slicks I was told to use about 12psi. Any reason why these tires would need more psi?

robz

For safety and stability first and foremost. Make sure you have a clean pass and the car is safe and mechanically sound. going down the track.

Secondly, so you don't have to launch so high for now while you are learning the car and figuring out the launch technique.

The higher pressure will protect the rear as it will make you less likely to dead hook.

Those tires can go 1.5x's @ 20 psi = enough hook for now.

LuvC5s

So I took the car out last week and there is definitely a learning curve with the launch. My best 60' was 1.77 but my best pass was on a 1.80 60' run. I road the clutch longer and felt like I got a much better bite then somewhat dumping the clutch at 3500. The car had a slight bog each time despite hooking well. How can I improve or work on getting rid of the bog? It feels like the car needs to launch at a higher rpm

robz

Nice going. A 1.77 is very good.
Yes, now start launching higher.

Ways to prevent bog:

1) launch higher
2) Ride the clutch out enough to prevent bog but not too much to glaze clutch
3) accelerate into the throttle slightly quicker than releasing the clutch
4) Raise tire pressure
These can be done one by one or in combination.

These are part of phase 2 only after the car is safe and shifting is smooth and effortless.

Start the tires around 17 psi cold
Make sure you get a decent burnout
Pick an rpm around 3500+
Get into throttle very slightly before starting to release clutch.

Hope you see 1.6x's.

Try and shift at 6500, too.
Shoot me specific question anytime.

LuvC5s

Little update for those following this thread. I took my car to the track last night and got in 4 passes. Last week my best 60' was a 1.77 but I missed third on that run and the next I did a 1.80 60', 7.274@ 100.28 at the 1/8, 9.344@ 1000' and the car went 11.109 at 129.05

Here is my dilemma, last night I went 1.702 60' launching around 4000rpm, in the 1/8 i went 7.245 @ 98.23, and 9.383@ 1000' and ET of 11.19@ 125.68.

Next pass and best I was launching at 4000 and slightly rising while riding the clutch.
60' - 1.671
1/8 - 7.174 @ 98.13
1000'- 9.322
ET- 11.154 @ 123.89

The car seemed to be lacking the pull from 3 to 4 and 4th on. The only thing I did to the car since then was changed my catch can to a MightMouse PCV can and it is hooked up correctly. Why could be causing me to lose MPH!?? I figured with that last pass I should have been into the 10's. I am wondering if something is hurt on the car, help!?

GARY2004Z06

Weather?

LuvC5s

The weather was similar in temperature but a little more humid. I was told it could be potential belt slip with the supercharger. I'm going to look for signs of that since I don't really see any currently. If it was the weather that would make me feel a lot better but I can't see it holding me back that much.

HardcoreABN

Robz - how is A throttle stab @ 2500 is like a static launch @ 4500?

LuvC5s

Hey guys, wanted to give an update to this thread and the other one I posted for those interested. I took the car out yesterday and prior to i changed the clutch fluid, supercharger oil and ran some fuel injector cleaner through the car.

First Pass and Personal Best!
Holding RPM around 3800 did a quick slip of the clutch and throttle down simultaneously. The car left real well and I hit most of my shifts on point but I still have to watch my GoPro video to verify. I set my slicks at 17psi and this time I mixed some 116 octane with 93 for a 1/4 tank of gas. The last few runs i was at the track with half to 3/4 tank of 93.
The DA was 1920 on first pass and 1693 on the second. It was a 80 degree day and got more humid at night.

1st Pass
60'- 1.63
1/8- 7.056
mph- 99.74
1000- 9.124
ET- 10.877
mph- 129.01

2nd Pass
60'- 1.628
1/8- 7.039
mph - 99.41
1000' - 9.126
ET-10.895
mph- 127.93

The DA was lower but the car slowed down a little bit, could have been driver error. Im definitely making progress since I started out doing 11.30's and I've only been to the track 3 times. The previous owner tom "TSAB" was able to get this car down to 10.28 @134 with a 60' of like 1.45 with great weather i might add. I am not sure what else he was doing differently but I know the car definitely has more in it. He was running a 26" tire and I am running a 28". Can anyone tell me if they think the 28 may be slowing me down or harder to 60' with? I went up on RPM to like 4500 ish and the car left pretty well but then had a slight slip/chirp. 60' ended up being a 1.66. I am still learning on how to set the car up to get the best launch out of it. Any advice be appreciated.

Here is a video of the 1st pass. 10.87

Last Pass Car slipped a little and went 11.03 with 1.66 60'

GARY2004Z06

Congrats on the new best.
As for the first pass, it was more like someone trying to leave on a DR. The quick slip was close; however, it could be a little quicker with more throttle input. (The car was more so rolling out. A slick requires spin of several revolutions.) The second pass required more rpm or more tire pressure. It bogged coming out.
Keep practicing.

28s are a little aggressive for that setup.
Better 60's do not necessarily translate into better ETs.
All numerically the same DAs are not created equal.
Trap speed can be affected by ECT, IAT, driving, etc.
BTW- I watched Tsab make the 10.2 pass. Track prep was stellar and he was slightly aggressive and did find the correct amount of wheelspin.

robz

Nice. I know your car well and have driven it before on the drag strip and worked with Tom on those 1.4x's.
I believe he used 26" tires which are a little better suited for your setup. But you can do the same with the 28's.
I agree with Gary.
You can either launch higher or air the tires up a little or both. You bogged on the 2nd pass.
Higher pressure, more throttle, higher launch rpm, or ride out clutch just slightly more can all lower your 60.
Keep in mind you can spin the tires 4+ revolutions and still cut a 1.4x.

I'd start by adding ~4 psi to the tires with a good burnout and launch at a similar rpm with a more aggressive hit to the throttle and that should cut about .1 off the launch.
As the tires spin a little the car may kick out a bit but it should do so in a controlled fashion. Your instinct may be to let up on the throttle which is fine until you get a good handle of the car and how to control the launch.
After you feel comfortable you can launch without lifting off the throttle and that will yield your best 60 but of course safety first so be vigilant.

robz

A throttle stab @ 2500 is likely more aggressive than a static launch at 4500. A lot depends on the clutch to know what type of launch will work best.
If you truly stab the gas pedal and hold it to the floor often times the rpm with be 3000+ rpms higher by the time the clutch grabs and your TP is 100%.
If you launch the car @ 4500 static I can tell you your TP is no way near 100% (unless off a 2-step), probably more like 40%.
Just wanted to make people aware of the difference especially when giving or receiving advice over the forums without video or audio.
Hope that helps.

LuvC5s

Thanks a lot for the advice guys. I've been keeping tire pressure around 17-18lbs and trying to launch from 4000RPM slipping the clutch. So you guys think I should raise my rpm or up the tire pressure? The car has a two step in it that is activated by the clutch pedal but I haven't played with it yet. If I set the two step up at 4000 RPM, I would think I'd have to dump the clutch, is that correct? I feel like it may bog if I drop the clutch with 28" tires. What do you guys think?

I also noticed the car runs slower after the first pass, I'm guessing that is from heat soak?

GARY2004Z06

Only dump the clutch if you want to buy drivetrain parts because you will break something.
Heat soak can be a culprit. Always cool the car down between passes.
A 4000 rpm launch off of a two step is much more aggressive than the static or stab methods. (You may wish to start around 3800.) A two step is more consistent and you then can focus more on the clutch release.
As both Rob and I discussed above, adding a little more air is not a bad thing.

LuvC5s

Hey guys, I just wanted to give those of you who have been giving me advice an update. I took the car out last weekend and the weather was awesome and achieved a new PB! I believe it was about 50 degrees and the DA was around 50. I focused more on releasing the clutch quicker and getting my rpms up. I have been keeping my tire pressure at 18lbs. I am launching the car at like 4000RPM. The time slip on the far right is the one. The other two are my best passes on the other two times I went to the track. I made a lot of progress in 11 passes. I think the car has much more in it with a better 60'.

LuvC5s

Hey guys, I hit a new personal best tonight. I launched the car off of the 2 step at 3800 and it created a lot of wheel speed and some spin which I think is good. Tire pressure was at 18lbs. It ran a 10.416 @ 134.23 with a 60' of a 1.542. The 60' stayed the same but car went fast. I'd like your guys opinion on launching the car with the 2step. I had trouble the next couple runs with the car bogging. Let me know what you think of this pass and what I may be able to do to improve. Thanks guys. I ran MS109 gasoline which may have helped.

robz

Nice improvements.
Now you are getting there. Next step is to get the car in the 1.4x's.

Still 28" Hoosiers?

My next launch might look like this:

Quicker burnout to keep clutch cooler.
Set launch rpm to 4000-4200 rpms. Make sure you are on the floor with pedal when launching.
Shallow stage
Set tires to 16 cold.
See what happens.
Adjust accordingly.

Try to be consistent with everything you do and jot it down.

LuvC5s

Thanks Rob. The car is still on 28's. As you see in the video there was a decent amount of wheel spin, was that too much? My main concern is whether I still should be slipping the clutch or just dumping it? I feel like if I dump it I may break something. What ya'll think?