I FUND THIS INFORMATION VERY USEFULL, I HOPE CAN HELP WITH YOUR 1/4 MILE TIME
Drag Racing Fundamentals for the SRT-4
This guide is written for a novice drag racer, driving a bone stock or mildly modified SRT-4 on street tires. A glossary of simple tricks, cheap mods, and bolt-ons is also provided to help newbie racers take it to the next level.
First Time Prep
Before you go to the drag strip for the first time, read the tutorials on this web site: http://www.staginglight.com/resources/index.html
. It’s very useful in describing how the tree works, and how to launch to get the best possible reaction time (RT) and elapsed time (ET). A good ET gives you bragging rights, but if you race head-to-head for fun or money, you’ll also need to improve your RTs.
Empty all the junk out of your car. For simple weight reduction, remove the spare tire and jack for starters. It’s also quite easy to remove the front passenger seat – just unscrew the 4 bolts with a 15 mm ratcheting wrench. The rule of thumb is that each 100 lbs removed shaves off approximately one tenth from your ET. You can do lots more with weight reduction if you want to go that way (remove back seat,, power steering pump, etc.) but it’s probably not worth the effort your first few times out, especially for a car like the SRT-4 that has a decent amount of torque.
Bring a good tire gauge and a portable air pump. I have one that plugs into my cigarette lighter – nice to have in case you’ve lowered tire pressure too low and want to raise it again.
Arrive at the track with approximately Ľ tank of gas. Raise the rear tire pressure to max (49-50 psi) and start by lowering the front tire pressure to 30 psi for a baseline run. If you have adjustable shocks, set the rear shocks very stiff and the front shocks very soft. This helps keep the front end planted (rears stiff) and helps prevent wheel hop (fronts soft).
If this is your first time, watch some cars run. Pay close attention to what’s happening in the staging area. It’s one thing to read about it, quite another to watch it, and very different once you do it yourself.
Follow local track rules about tech inspection (if any), and safety rules such as driving 5 mph or less in the pit areas. Normally, you will be assigned a number and write it in white shoe polish on your left side rear window. Once your car is completely prepped, pull into staging lanes with the street cars. Some tracks run separate lanes for street cars, cars with slicks, motorcycles, and dragsters.
Fasten your seat belt. When you’re near the front of the line, make sure your windows are rolled up. If it’s dark out, run with your parking lights only – no headlights.
The starter will signal for you and the car next to you to pull up to the staging area. There is a little dip on each side filled with water for folks with slicks and drag radials to do burnouts. DO NOT drive through the water box if you’re on street tires. Take turns with the other car and drive through the middle area, then move to the left or right, the same position as you were waiting in line.
Note: Some people do a quick spin of the front tires to remove dirt and pebbles. I don’t even bother. Most street tires do best if you don’t heat them up too much, as opposed to slicks, which do much better when heated.
There will probably be two cars at the tree – stay well back until they launch down the track. Pull up to the tree and go very slow when you are near tripping the first light beam. When your front tire breaks the beam, the first row of double lights at the top of the tree will light up. Let the other car do the same – it’s not polite to stage if the other driver is not quite ready.
Take a deep breath and clear your head. Raise the revs to 1800-2000 rpm and slowly ease the car forward until the second set of double yellow lights turns on. Try to stop exactly when the second set of staging lights is on – this is called “shallow staging”, and is more likely to give you the best possible ET. Hold the clutch so it’s just ready to engage, but not quite. Once both cars have tripped both beams, it means you are ready to run.
Hold your revs steady, and now, give the tree your undivided attention. It will count down: Yellow 1, Yellow 2, Yellow 3, GREEN! Conventional wisdom says drop the clutch or release it quickly on the third yellow. If you wait until the green light, your reaction time (RT) will be terrible, though RT does not affect your elapsed time (ET). It only matters if you’re racing head-to-head or bracket racing.
If you launch just right, you will get virtually no wheel spin, then move off the line quickly with little or no wheel hop. Now, concentrate on your shifts. The 1-2 shift comes up fast. Shift around 5800 rpm, and try not to hit the rev limiter. Make your shifts smoothly, quickly, and cleanly. For the 2-3 and 3-4 shifts, you should be at 5800-6000 rpm.
For those of you who don’t have much experience with a manual tranny, try to relax. Do not put a death grip on the shift knob and slam it into each gear. (Hint: If the shift knob comes off in your hand, you’re doing something wrong!) For the 1-2 and 3-4 shifts, just pull the shift knob back firmly and smoothly with your index, middle, and ring fingers. For the 2-3 shift, push the shift knob forward at a slight diagonal with the palm of your hand. The spring will naturally pop the shifter to the neutral point between 3 and 4, and you continue to push it straight up into 3rd gear. A clean 2-3 shift is a little tougher, but you’ll get it right with practice.
Some people like to power shift – that’s shifting while holding the accelerator to the floor the whole time down the track. I don’t think it’s worth potentially blowing your transmission or destroying your clutch to shave a tenth of a second. It’s a personal choice, though.
Make sure you keep it floored until you pass the timing tower. Hit the brakes and take one of the turnoffs, making sure you don’t cut off the other car in the process. Drive up the little road and pick up your time slip at the booth, then go to the pit area to let your tires and engine cool off for a while.
After your run, take a few moments to think about what went right and what didn’t. Also, look at your time slip for clues. Your 60’ time is a good indicator of how well you launched, and your launch is vital to the run. It’s possible to get a 60’ time in the 2.0 – 2.1 second range with the stock tires.
To get your 60’ time down, adjust ONE thing on each run. First, get comfortable with your launch style. Some people like to drop the clutch, others slip it. My best RTs and 60’ times happen when I inch forward on the second yellow and release the clutch fast (not dumped) on the third yellow. That’s for a cold track. If the track is warm, I do just as well by just releasing fast on the third yellow. You will have to experiment.
Once you are comfortable with a launch style, keep it consistent. Now, start adjusting your front tire pressure. If you’re spinning too much or getting wheel hop, lower by 2-3 psi per run until your trap speeds get worse, then go back to the previous “best” tire pressure. Some folks go as low as 18-20 psi up front. Below that, you risk damaging street tires or debeading them (they come off the rim). I usually don’t need to go below 25 psi. Again, you will have to experiment.
Now, adjust your launch rpms. If you are spinning too much, lower by 200-300 rpm per run until you find the best rpm. Similarly, if you’re bogging, raise the launch rpm 200-300 per run until you get a little wheel spin. Somewhere around 2000 rpm plus or minus 200 rpm works best for me with a bone stock SRT-4, depending on track conditions.
If you have adjustable shocks, you can tweak those to get your best launch with the least wheel hop. Again, ONLY adjust one thing per run (front tire pressure, front shocks, back shocks, rpm, etc.) Otherwise, you won’t know which adjustment helped, and they may even cancel each other out.
As an example, my best stock run was with 49 psi in the rear tires, 28 psi up front, launched at 2000 rpm and each shift at 5800 rpm, but that may not work best for you. Track conditions or the weather can easily change the “optimum” parameters, even at different times of the same day.
Remember, one of the best mods for your car is practice. Learning your optimal launch technique, launch rpm, tire pressure, shock settings, and shift points will make a world of difference – and no two cars (or drivers) are exactly the same. Practice, experiment, and most important – have fun!
NEXT STEPS - Simple Tricks, Cheap Mods, and Bolt-ons
It’s nice to get some baseline runs at the track, just to see what you can do “bone stock”. After that, you’ll be itching to lower your ET, so here are a few (relatively) inexpensive tricks, mods, and bolt-ons. Detailed instructions for the mods and expected hp/torque improvements are beyond the scope of this guide, and can be found by performing a search of the forums and the FAQ.
Bag of Ice – Some people cool off the intake manifold with a bag of ice between runs. Of course, the ice will eventually melt, the bag will spring a leak, and if you’re in the staging lanes, other drivers and/or the officials will not appreciate you dumping water all over the place. Use your bag of ice in the pit area and remove it while you’re waiting to stage.
Boost Controller – Does just what the name says. There are relatively inexpensive manual boost controllers (MBC) ranging up to some expensive, sophisticated Electronic Boost Controllers (EBC).
Burnout -- You don’t need to do a burnout on street tires. You can give them a quick spin to remove small rocks, but if you heat them up too much, your traction will get worse. The opposite is true for drag radials or slicks – they need to be heated up to give you the best traction. To perform a burnout: drive through the water box and stop. Put the car in second gear, pull up on the e-brake, and raise your revs to 5000 rpm or so. Drop the clutch, and your front tires should start spinning and smoking a bit. Once they’re spinning, release the e-brake and let the spinning tires pull your car forward toward the staging lights, then let off the gas. DO NOT go flying past the staging lights unless you are driving a pro stock or a dragster.
Bushings Kit – The shifter bushings for the SRT-4 are a little sloppy, which can result in a missed shift on an otherwise perfect run. An aftermarket shifter bushing kit is a cheap, effective way to firm up the shifts.
Catch Can – This won’t really improve your ETs, but it will keep them from getting worse over time. The $20 catch can or an aftermarket version will capture oil that gets through the PCV, and routed back to the intake where it can soak your air filter or wind up in the intercooler.
Dollar Mod – A cheap, effective boost bleed that allows you to raise boost above stock levels without a boost controller.
Drag Radials – These tires are a nice compromise between street tires and slicks. They have some tread so they are street legal, but if you drive on them all the time, they’ll wear out pretty quickly. They are typically mounted on a smaller, lighter rim, such as 15x7, so you can mount a wider, higher profile tire. DR’s are more convenient than slicks, because you can swap them on at home and drive on them back and forth to the track. Your 60’ times will be one to two tenths better with DR’s, which translates to 2-3 tenths on your ET. You must learn to do a proper burnout to get the most out of DR’s.
Dyno – Once you start raising the boost, it’s a very good idea to get in a few dynamometer (dyno) runs to make sure your mods are actually adding power and torque, and especially to make sure your air/fuel ratio looks “safe” (around 12:1) so you don’t blow your motor. You can also use a dyno to help tune your mods that are adjustable.
Intake – There are many aftermarket cold air intakes available, and even a few variants of “welfare” intake.
Intercooler Sprayer – A new intercooler is pretty expensive, but you can get more out of the stock ‘cooler by adding a sprayer. Cheaper versions will spray water or alcohol to help cool the intake charge. A water sprayer is yet another way to irritate the track officials if it drips too much water while you’re staging. Also, you don’t want water dripping in front of your tires right before you launch.
Exhaust -- There are some reasonably priced catback exhausts, but a full 3” catback or turboback exhaust can be expensive. Do some research and think about your long term goals before investing. One alternative is to get a 3” downpipe with or without a cutout. Then you can add the rest of the exhaust later if desired.
Exhaust Cutout – This is a short “Y” pipe inserted either on the downpipe or right after it. A manual cutout costs $30 or less. Remove a small plate at the track, and your exhaust gases shoot out the side, bypassing the rest of your restrictive stock piping. For another $150 or so, you can get an electronic version that allows you to open and close the plate from the driver’s seat, without crawling underneath the car.
Fan Mod – A toggle switch and simple electrical connection allows you to run the fan by itself and keep the engine cool. Note that a similar effect can be achieved by running the defroster or air conditioner. However if you run the A/C, your car will start dripping water and you could get booted out of the staging lanes.
Motor Mounts – You can buy filled motor mounts or cheap inserts to help reduce wheel hop when you launch. You WILL get wheel hop as soon as you start modding the car, and possibly on a hard launch if you’re bone stock. Wheel hop slows you down and tends to break axles and differentials, so don’t delay this mod for long.
O2 Housing – This is the piece between the turbo and the downpipe. Some aftermarket units are reasonably priced, but the installation is relatively difficult, especially for a newbie.
Octane Booster – Bone stock, your car will run just fine on 93 octane pump gas, and those of you in California with 91 octane have our deepest sympathies. You can add octane booster from a bottle, or mix in a few gallons of 100 octane fuel at the track. Extra octane gives you some insurance against detonation, especially when you are running higher boost levels, but don’t raise the octane above what you need – performance may actually suffer a bit.
Plugged Airbox Mod – There is a line with a right angle boot that leads back to the airbox. It has a marginal function, but also leaks boost. Plug it.
Practice – Can’t stress this enough. If you’ve never drag raced before, your biggest improvements in RT and ET will come with practice, and not by adding another cheap mod from this list.
Push the Car – Yes, some people actually push the car along in the staging lanes to keep the motor cool. Even if it doesn’t help much, it’s good exercise. It’s also good practice for the first time you break an axle.
Slicks – Once you raise the boost and power, traction can be a real issue. Slicks are soft compound tires with no tread, and it’s illegal (and dangerous) to drive them on the street, so you must swap them on at the track – or get a trailer. Like DRs, slicks are mounted on smaller, lighter, wider wheels. You will need to do a good burnout to get the most out of slicks. Your 60’ times will drop an amazing 3 to 4 tenths versus street tires, and ETs will drop 4 to 6 tenths, even on a mildly modded car. You’ll have to lower the tire pressure up front (12-15 psi), and launch at 3000-4000 rpm by dropping the clutch. Don’t feather the clutch with slicks, or you’ll fry it in a hurry. Slicks are great bang for the buck, but that doesn’t include the cost of occasionally breaking an axle or differential with all that extra traction. Think about buying aftermarket axles if you run slicks with high horsepower and torque. Also, a “cheap” way to try slicks is borrow them from a friend to get in a few record-breaking runs before buying a set yourself.
Spark Plugs – The stock plugs work fine with mild mods. Once you raise the boost, it’s a good idea to get a new set and gap them tighter. The stock gap is 0.50, and a good “average” gap for mild mods is 0.40 or so. You can also get aftermarket plug wires, coil pack, and “colder” plugs as you raise the boost and power.
Spring Mod – Another method for raising boost by holding the wastegate shut longer with an external spring that is stronger than the spring inside the wastegate actuator (WGA).
Short Throw Shifter – A short shifter can help cut the time between shifts and keep you in the power band. If you’re installing one, it may be worth installing a better set of bushings at the same time.
Stage 1, 2, 3 -- Do a search and you’ll find a bazillion posts on the Mopar staged upgrades. The cheapest is Stage 1, of course, but it’s a throwaway if you ever decide to go to Stage 2 or 3. Stage 1 complements many of the other inexpensive mods listed here.
Suspension Mods – Items such as stronger springs, adjustable shocks, or coilovers are not cheap, but they are very beneficial in autocross or road racing, so you can rationalize that they were “free” for drag racing. They help minimize the effect of weight transfer on your launch and keep the front end more firmly planted.
Thermostat – You can buy a 160 or 180 degree thermostat for 5-15 bucks. This really helps cool the motor while running, because the thermostat opens at the designated temp (160 or 180) to circulate coolant. There seems to be a “magic temp” around 170, where you can pick up 1-2 mph in trap speeds. (The stock thermostat opens at 195 degrees).
Track – The altitude and condition of your local track will vary. Low altitude is better, though it has less impact on a turbo car than a normally aspirated car. If you run your car on a Test ‘n Tune day, try to pick a day that’s close to a big upcoming track event. There will be more dragsters, pro stocks, etc. hanging out, and suddenly the track officials will get busy, dust off a few barrels of VHT, and actually prep the track for your driving pleasure.
Underdrive Pulley – You can free up a few ponies by minimizing the parasitic drag caused by accessory pulleys and/or the crank pulley. This is accomplished by using larger, lighter accessory pulleys and/or a smaller, lighter crank pulley. The downside is that your electrical system may not support extra loads like your 500-watt stereo, especially when the car is idling.
Vacuum Lines – There are several ways to set up your vacuum lines depending on other mods you have, especially if you have an external blow-off valve (BOV). Do a search and pray you pick the right setup. As an alternative, read lots more about turbos so you don’t have to perform vacuum line roulette.
Wastegate Actuator – An aftermarket WGA will typically have a stronger spring, and some method to adjust tension on the spring, which is yet another way to control boost. The aftermarket WGA can be used alone, or in conjunction with a boost controller.
Weather – The current weather conditions can make a significant impact on your runs. Optimum conditions are cool, dry air with temps in the 50-60 range on a sunny day. The sun keeps the track warm for traction, and the cool air is denser, resulting in more power. If the air is too cold, the track may also cool off and you’ll lose traction. Also, you can lose traction if the track surface is too hot and it starts to get gooey.
Weight Reduction – There are two methods to reduce weight. First, pull stuff out of the car you don’t need for the run: wife, kids, crap in the trunk, spare, jack, passenger seat, rear seat, power steering pump, air conditioner, etc. You can strip the car if you want to go radical. A complementary, but more expensive solution is to replace parts with lighter components, such as a carbon fiber hood, carbon fiber trunk lid, lightweight battery, etc.
Welfare Mods – Do a search on “welfare” for these cheap, effective mods for intake, exhaust, etc.
link to timeslip: 13.459 @ 103.55 on street tires
link to dyno: 250.5 whp, 271.1 wtq