How to launch a driver

[JimNolan]

Guys,
   Some of you know that I'm keeping the 410 in my 57 and getting some DOT bias ply drag slicks this year to run a few nostalgia events. My question is about launch techniques with slicks. Between Ross's and my calculator's I figure we're just looking at @ 360hp. It's a Tremec 5 speed transmission and I'm concerned about bogging the engine on launch. I won't leave the line at an ungodly rpm because it's still an everyday driver, not a dedicated drag car. I know some of you would have had to take cars like mine to the drag strip occasionally and I'd like your opinion of where to start out on air pressures, etc. I'm curious on how some of you guys found a sweet spot to launch a car like I have. Jim

[shady]

in the early 80's I had a chevelle ( got it for free) with a small block, 4 sp. & 4:11s. I used Kelly 8" slicks & would drop the clutch @ 5k. & the rpm's would drop to 3400 right in the torque sweet spot. 1.8-9 60' times.
never broke it. this was a daily driver making a 100 mi commute every day. The secret to longevity I thought was using a 10" clutch & it never slipped. the car really fell off at the far end, but was amazing out of the hole. Lakewood traction bars also helped. You just have to find a spot out in the middle of nowhere, & practice to see what works the best. A lot depends on weight transfer & gear ratios of the rear & first gear. I also had the front swaybar unhooked. Bad news Is, it may take a second pair of slicks after all the testing.

[My427stang]

Jim, I can't argue with Shady's success, but I think guys tend to leave too hard in general.  Keep in mind, Shady had a small block with less torque and likely a taller 1st gear assuming a decent Muncie

I see guys running 9.90s leaving at 3500.  Blair can attest to that.  If it were mine, I'd start at 2500 and creep up until the 60's stopped getting better.  Then play with the 1-2 shift point.  Often shifting 1-2 earlier than 2-3 will get you down the track quicker, with the 2-3 being 300-400 above peak hp rpm.

So, with a 5000 rpm peak motor, launch 2500, shift 1-2 at 5000, 2-3 at 5400, 3-4 at 5400 if you get there.  Take lots of notes and save your slip, and try one change at a time.

Just a WAG, they more experienced racers can chime in and call baloney

[Joe-JDC]

Practice!  Practice!  Practice!  This is the only way to find out what your car will respond to, and how it will respond.  If you cannot speed shift, then you need to practice that aspect so that you can do it without thinking about the process while trying to listen to the engine, watch the gages, etc.  You can be the best driver in the world, but if the car will not hook up, it will not be fast.  Concentrate on getting the car to launch without wheelhop, excessive tire spin, or bogging.  You need to document as Ross said.  Tire pressures equalized in rear, more tire pressure in front than you normally run on street.  Traction aids?  Weight removal of all un-necessary items in the car, lightweight wheels and tires in front, safety items required.  If your car will not transfer weight and the front lift, you are wasting your time even trying to go fast.  If you only want to be consistent, then practice, practice, practice.  Joe-JDC.

[fastback 427]

Just to add to the other guys, with the Hoosiers I'd start about 14 or 15 psi then go down. 12 to 14 works for me. Also mark a line on your rim and tire with your windshield marker to see if you are spinning. It will also see if the tire slips on the rim. If you have a buddy with a video recorder, would be invaluable. Good luck and have fun.

[Joe-JDC]

When you say Tremec 5 speed, is it a TKO, or T-5 type?  That will make a huge difference on how you launch your car.  Which transmission?  Joe-JDC

[JimNolan]

When you say Tremec 5 speed, is it a TKO, or T-5 type?  That will make a huge difference on how you launch your car.  Which transmission?  Joe-JDC

It's the TKO 600 with 3.50 Tru-Trac. With the tires I've got now I have it revved to 2000 now with a lot of wheel spin in first and second. Funny thing is my 60' time is the same by having it revved to 600 rpm at the starting line. Power shifting is all I do, knock on wood, never missed one yet with the TKO. I run 90/10 shocks in front but I don't disconnect the sway bar because I'm driving it all the time. The tires I'm running this year (smaller 26.1") will get me closer to 4750 rpm as I cross the line in forth. As far as shifting at 5400 Ross, I swear I feel it slowing down at anything over 5000. We know I've got the heads (Edelbrock) the intake (Edelbrock RPM) the carb (750) the only thing left to keep me from going there would be my shorty FPA headers and 2 1/4" exhaust system. It's got traction masters traction bars ( no wheel hop ). The cam is 282/288 216/225 dur w/ .515/.540 lift.
Someone told me to air the slicks up to 28lbs and keep reducing it a couple pounds at a time until it boggs at the rpm I choose to leave the line at. Is that a logical approach. I think I read that on one of the tire manufactures websites. Thanks guys.

[Joe-JDC]

One of my best friends had a "90 LX 5 speed that he raced at Alamo dragway with MT 275-60-15 street slicks.  He ran consistent 11:27/11:28 ets, and he asked me to watch his launch.  First thing I told him was he had to drop the tire pressure down from 28 psi to about 14, but he was afraid.  He had heard that it would get squirrely at the finish line with that low pressure.  I convinced him to drop it down to 22 psi, and he immediately went 11:14.  I talked him into dropping it more, and upping the starting rpm from 4400 to 4800, and he went 11:00ish.  I finally convinced him to drop down to 14psi, and leave the line at 5400rpm, shift at 6800 with chip, and he went 10:76 @ 133+.  He repeated that with 3 runs, 10:75, 10:78, 10:76 and broke a 28 spline axle.  Changed to 31 spline axles the next week, and ran that way for years.  On my own personal drag car, I ran 29.5 x 11.5 x 15 slicks with 7.25psi with tubes.  It takes many years of practice to find what works on your car, especially if you only take it to the track once in a while.

I think you need more camshaft, and at least long tube headers, 3.90 gears, and 2.5 inch exhausts with H or X pipe for you to get into the 13 second range.  The next step is mental.  Do you want a street car, or a race car?   Joe-JDC

[My427stang]

Jim, if it noses over that low, shift lower

Seriously though, I am surprised, but the point is, shift slightly higher than peak HP, regardless what RPM that is

I wonder if you have a fuel supply or valve float  issue?

[JimNolan]

I think you need more camshaft, and at least long tube headers, 3.90 gears, and 2.5 inch exhausts with H or X pipe for you to get into the 13 second range.  The next step is mental.  Do you want a street car, or a race car?   Joe-JDC

Now that's an easy question to answer. A quick Street Car, once it leaves that category I can't use it. I take too many trips and enjoy driving it too much.
 Ross, I put a 3/8" fuel line on it in 2013 and went to the Edelbrock HV fuel pump. I didn't race it last year to see if it made a difference. I've got a different tachometer this year too.

[machoneman]

Guys,
   Some of you know that I'm keeping the 410 in my 57 and getting some DOT bias ply drag slicks this year to run a few nostalgia events. My question is about launch techniques with slicks. Between Ross's and my calculator's I figure we're just looking at @ 360hp. It's a Tremec 5 speed transmission and I'm concerned about bogging the engine on launch. I won't leave the line at an ungodly rpm because it's still an everyday driver, not a dedicated drag car. I know some of you would have had to take cars like mine to the drag strip occasionally and I'd like your opinion of where to start out on air pressures, etc. I'm curious on how some of you guys found a sweet spot to launch a car like I have. Jim

A different approach. If you really do want to e.t. the best, launch at the top of the rpm band (5,000, 5,500, whatever) by dumping the clutch and let her fly. In just a few launchs, you'll find out if the slicks either bite or spin...if spinning, drop the rpms just until it stops spinning off the line. JMO!

[Qikbbstang]

     a high school buddy taught me the secret to fast shifting/power shifting was to put significant force on the shift knob as the time to shift nears. Due to the fact that when the drivetrains loaded/car accelerating it's extremely hard take enormous force to pull it out of gear. With the shifter is pre-tensioned,  the effect is the clutch releases the pre-tensioned shifter making for an lightning fast shift.  Another trick is to practice power shifting while everyday driving, do all the motions of a full bore power shift except don't bother with WOT/high revs.
   The contrarian approach is to push the clutch and simultaneously tell the arm to move the shifter which relies on two actions.

Don't know if the pre-tensioning is tough on the synchro's. Seems to me the force/wear point on the syncro's is in pulling the engaged gears/syncro's apart vs the typical jamming the gears/syncro's together.