I have a stock '94 Chevrolet Cavalier Z24 w/ automatic tranny. I have been bracket racing this car since I purchased it this past August. I have been fairly lucky to win a few races with it. You really have to "drive" this car because the consistency isn't as good as it could be. It's hard to get it to repeat round after round. I wanted some advice on how to make this car run more consistently. I run two classes at most races I enter (Footbrake and DOT) and once you make it down a few rounds and are hot lapping, the car is deadly but when you have to wait between rounds, it throws you a curve ... usually running a slower E.T. I have my fan wired up on a switch to where I can run the fan "ON" to prevent it from possibly cutting on during a run. I always start the car and turn the fan on a few minutes before I run to get the car at a stable temperature. I feel it's easier to keep a car hot than cool. I'm not looking for the fastest E.T. because I'm bracket racing. I read that modifying the IAT sensor is useless. I was thinking of using a Potentiometer on the ECT sensor to "trick" the computer while racing where I can adjust the exact temperature the ECM will think the car is. Would this be worth trying? Correct me if I am wrong; but the hotter the ECM thinks the engine is the leaner it will be..is that correct? How does this affect the ignition timing? I also never raise the hood being as I run the car hot. I use stock tires but the car doesn't spin so I don't think that's an issue. I race the car in "2" instead of Drive so I can backpedal at the finish line without the car shifting into drive. I stall at 1800 RPM. The point on the track that the car seems to be inconsistent is between 60' and 330'. Would this be an issue of shifting inconsistently? I also thought of putting a transmission temperature gauge in to keep a record of that. I will quit rambling and I look foward to your opinions.

Thanks,

You seem to be doing all the right things, the best is to make sure your car is running in optimal condition. Make sure you are getting good spark, so change wires/plugs, air filter, anything which can goof up the car. Dont try to mess with the computer the key is knowing the car. Get a log book and take notes of what the car does at certain temps/humidity and elevation. This wasy you can predict. The key to bracket racing is knowing the car since you must anticipate what it will do and dial accordingly.

Bottom line, get the car running optimal and take a careful look at each race. As for your 60' and 330s just make sure you launch at the same RPM and monitor your tire pressure like it is your heart. In between rounds is important and keep an eye on temp.

Good luck
Chris



http://members.cardomain.com/vertz24 1998 Z24 Convertible
2.3-2.4 HO ADAPTER FLANGES 65$ shipped, Check GP Forum!

I agree with Chris completely. I have been successfully bracket racing my '93 Sunbird 3.1/5-speed since 1993 (even though it's much tougher to be consistent with a 5-speed), and all of his points are accurate. Basic maintanence is very important, but knowing your car and the weather are even more important. I actually invested in a weather station/ET predictor from TAG Systems, and I have a log of every pass the car has ever made (nearly 1000 of them now). This information helps me to know what the car ought to run if I don't screw up. I also switched over to Drag Radials because it was too tough for me to launch well consistently on street tires. I would either spin badly, or bog the engine, with an optimal launch RPM range of only about 200 rpm. I tend to try to keep my car cool between rounds by using a household fan under the hood between rounds. That doesn't help me in later rounds, but based on my records, I can estimate how much the car should "fall off" when it's warmer.

I am curious about how consistent your 60 foot times are? I have found that the 60 foot times are the most important thing for me (best of 2.14 on street tires, and in the low 2.0s on Drag Radials). If your 60 fts are very consistent, but then the 330s are not, I would think that it has something to do with the shifting of your automatic transmission. I don't have any suggestions on how to fix that, but others might. It would be worth the money if you race enough (additional winnings might pay for it).

It's nice to see some others out there who are regularly bracket racing this platform too!


'93 Sunbird SE 3.1 5-speed
'00 Grand Prix GTP Sedan
sunbird93racer@yahoo.com

Joe,

The 60's are very consistent as long as I'm staging in the same place. As I stage deeper, the 60' will fall off which is normal. I vary my staging depending on the rollout and at various tracks to keep my reaction times .020 (.520) or better. I do have one of the TAG weather predictors that I used when I raced a dragster in Super Pro. I haven't tried it with the Cavalier yet. In fact, I let a friend borrow it. I also have a Computech weather station that I used with the Cavalier. The only thing that I could make any sense out of was when the Air Density Ratio rose above 89, the car would pick up a few hundreths and then stay right there until the Dew Point was within a small margin of the air temperature, and then it would pick up a few more. I have varied two tenths at a one day bracket race before. The car starts slow and as the evening goes into night it continues to pick up. It doesn't pick up every run. It will run a set of numbers then take a big jump and run that number then take another jump. The car doesn't fall off after picking up. For example, start at around 10.53 and then be down to around 10.33 by the end of the race. I have won a few races but it's difficult; especially in Footbrake. On average here in Footbrake you need at least an .050 package. So if I'm having an .020 reaction time, that leaves me .030 and here I'm varying two tenths. I have to dial soft and drive the stripe which can be difficult against 6 and 7-second cars which if very common in Footbrake these days. Sometimes, I have to run 5-second cars. Makes it tough to tighten the stripe down to a couple of hundreths against something closing that fast.

So, you try to run your car as cool as you can keep it? If I make a run with my car at 150 degrees and I come back and make a run with the temp at 195, how much does it fall off?

Thanks,

Staging in the same spot is another essential. As far as I'm concerned, there are only two ways to do it exactly the same each time. Either very Shallow Stage (for those who don't understand the term, it means only roll in just enough to make the 2nd set of double lights come on and stop), or barely Deep Stage (roll in just until the first set of double lights goes out and stop, and make sure it says DEEP on your window for sake of the starter). I have tried Deep staging, and I never really liked it. Some people feel that it makes it easier to cut a good light, but I do fine by shallow staging. I recommend that people decide which of the two they prefer, and stick with it. Since bracket racing is all about consistency, I am concerned about you modifying your staging spot to affect your RT. If it works for you, great, but that really throws a major variable into each of your runs. I prefer to stage exactly the same each time, and launch at the same point too (blink of 3rd bulb for me). I feel that it makes results easier to predict. If you are managing to average .020 lights or better with your technique, my hat is off to you. When I look back at last year, I was probably averaging about .060 lights. In my "Street" class, that can win races as long as I am running within .020 of my dial. A package of .080 will work against alot of the racers in the class, and I know the ones to watch for that will take a .040 - .050 to beat.

I would say that you need to get the TAG weather station back from your friend and gets some runs logged in it for your Cavalier. It can be every bit as helpful as it was for your rail. Obviously the more runs you have logged the more accurate it is, and make sure that you only store "clean runs" (ones with a good launch when you didn't lift or brake). With the TAG unit, I watch the density altitude very closely. As it goes up, I dial up, and as it goes down, I dial down (very slightly!). The amount will depend on your car. For me it is about .004 per 100 ft in Density Altitude. I don't think I have ever varied more than a tenth over a day of racing (maybe .15, if we began time runs at noon, and I am still in eliminations long after sundown). That is the norm at my track, so I work to keep the engine cool between rounds with the fan in the heat of the day, and then the temps tend to cool after dark, so it doesn't take as long to cool off even into later eliminations. I do tend to dial up a bit in these later rounds to compensate for the extra engine temp, but no by more than .05 or so. I don't tend to see big ET changes unless there has been a big atmospheric change (noted thru Density Altitude changes), or if I screw up!

It was interesting to compare our 1/8 mile times and 60 foots. My 60s average around 2.07 (with Drag Radials), and my 1/8 mile ETs are between 9.95 - 10.05. I guess that isn't too bad for a car with 152,000 on the original stock bottom end!

I also don't like to dial soft, unless I absolutely have to. I prefer to dial what I think it will run, and stay on the gas past the traps. I can comfortably play games at the stripe, but that adds more variables (and you can only really use clean runs to help determine what the car should run), and I don't like that. If you can cut the lights you say you can, I would suggest that you never dial softer than .01 or .02. In most cases, you will force the faster car to breakout if he wants to take the stripe from you. The only pain is if you run someone who really sandbags badly. They will catch you way before the stripe and then "pace you." I hate these people with a vengeance! For them, you need to dial soft by .04 or .05, let them pace you and then dump right before the finish line. That should push them out the back door unless they treed you.

I run a 160 thermostat in my car, and that seems to help me keep the temps down even when hotlapping. If I don't have sufficient cooldown, I will simply dial another .02 to .03 into the car to compensate. I can always hit the brakes if I am way ahead at the stripe.

Hope some of this info may help another J-Body Bracket Racer!


'93 Sunbird SE 3.1 5-speed
'00 Grand Prix GTP Sedan
sunbird93racer@yahoo.com

back when i used to bracket race in high school, i found a very effective way to stage. i was racing a 76 camaro, ran mid 12s. what i did was rolled just into pre-stage and pumped the brakes up hard. i would then bring the motor up to about 2500rpm (thats were the converter stalled) and pumped the brakes 4 times. each time i pumped the brakes, it would creep forward, usualy 3 would take it into stage, then 1 more to go right into stage. i always ended up in the same place, and i was always able to cut very close to a .500 light. its going to be different in a fwd car, but doing it simular to this will put you in the same place consistently.

I agree the best way for consistent ET's is staging the same..preferably very swallow (fluttering the stage light on). Deep Staging is becoming increasingly more difficult in my area because most tracks run on Auto Start. Once both cars have staged, the tree starts in 1.5 seconds whether you are deep or not. It is possible to rush to the line and get in Deep before your opponent but in some instances when your opponent knows you deep stage, they will hang you out. I am not good enough to roll Deep from the pre-stage in 1.5 seconds and not get in too far..which is what you have to do if they hang you out. In time runs, I like to flutter on the stage bulb and when I'm that shallow, I have to leave between the second and third ambers. My car has usually around a 2.15 to 2.20 60' time and my human reaction is usually pretty slow as well. I stall as close to 1800 RPM as possible. If my lights aren't where they need to be for that particular day, I'll bump a number of times after I have the stage light on depending on how much I need to pick up my light. For every hundreth I gain in reaction time by staging different, I know that I lose that in E.T. so I try and dial accordingly.

As far as dialing soft, I try to determine what I think my car will run and hold a couple of hundreths. I don't hold tenths. I try to take the finish line if I'm going to be ahead at the stripe but I try to make it as close as I can. Sometimes, I let the car around me. If I'm not getting there first, I'll dump and if it's close, I'll run it out the back door unless the race just doesn't "look right"...and in that case I'll turn my opponent loose. In bracket racing today especially in this part of the country, everyone is dialed so close that the odds of someone breaking out a few thousandths is greater than the odds of them being off their dial by much....so if it don't look right, I turn them loose and hope I made the right decision.

Bracket racing is a driver's game alot of times. I feel that you do need a good reaction time to win but you also have to be good at the finish line. I'm not the best at the stripe so in turn I'm trying a new approach which is make the car run the number and make my opponent beat me. I know it's harder with a street car to make it run the number. When I had an alcohol-fueled dragster, it was very predictable. I won alot of races by running the car flat out and dialing dead-on while setting up for no worse than a .507 light. My parents divorced so I had to sell the car. I did redlight sometimes but I figured it took at least an .015 package to consistently win so you live by the sword and die by the sword.

Thanks,