I have a 2000 A4 with a CAI and dyno tune. I run high 12's and have been doing well in the sportsman class. My reaction times are normaly under .1 but every so often I feel a slight hesitation and lose about a tenth on my RT. MY tuner can't see any problems.

I launch at about 1000 and and using drag radial. I am accustomed to punching the gas to the floor at launch. I have been told that rolling the power on will eliminate the "bog".

What do you guys think?

 

Try more air in rear tires to eliminate the bog.

You are launching in 3rd gear right?

 

If there's a bog occasionally you have a problem. You cannot ROLL into the throttle. That is crazy. I think the problem is you and no offense intended. You are losing concentration. For arguments sake, if the bog was that slight you would not feel it.

If you do not agree with me then hook up a laptop and scan all your time shots. If there's a problem, you will see it.

 

Thanks I appreciate all opinions. I am starting in Drive.
After making 300 passes or so I have a "feel" for how I start. I could close my eyes and sense my RT. Last Sunday, in the finals, I felt the "bog" and my reaction time was .173. I see this number range
(.17x) whenever I have the hesitation.

How would are pressure affect the "bog" I usually run 29 hot and have no traction problems.

 

Is it possible that you accidentally dropped the launch RMP to idle as you were watching the tree. The bog may be the converter flashing.

Good advice about that you can't roll on the gas when bracket racing. Your are correct in smashing it down. Do exactly the same thing every time. Can't repeat a roll on the gas the same way every time.

Is this the only time you had the issue? What was the round and what was in your head for that round. If you were thinking "don’t go red" then perhaps you missed your spot on the tree and the bog is driver related.

Having a feel or your RT is an important part of racing. Knowing if you cut a good or bad light lets you adjust you top end strategy.

 

This has happened about 20 times that I can think of. Most were against slower racers and did not affect the outcome. However in the finals...its another story.

What does "flashing the converter" mean? I have also heard the term "loading the manifold" by breaktorquing too long. Heard of that?

Just try to learn to take the human out of the problem.

 

I have thousands of runs and cannot FEEL the difference between a good and bad reaction time. I have had many .000's and knew I cut a good light bad had no idea how good it was. I've had bad lights and didn't have a clue.

If you're talking a difference between .100 and .170 that is a concentration issue. I think Kaz agrees with me. Like I said, scan it.

 

You say you have 300 runs or so.. which means you have a pretty good feel for the car...

I had a 96 with a high stall converter (3200) and would bring the rpm up to 2000...

However with my C6 I have the "STOCK" converter in it, and I honestly do not look at the tac when I stage...

I stage the car and just bring up the RPM until I feel it pulling a little.. (I've checked and it's about 1000-1200 RPM) but I don't worry about if its 1000 or 1100.... I concentrate on the TREE...

But what I think is important, and it had had a BIG affect on my C4 and a "lesser" affect on my C6 is Engine Temp & TRANSMISSION TEMP I always make sure my trans temp is 120 - 150.. and my engine temp is at MOST 180 deg.. I try for 150 deg "Before" the burnout.. so I stage at 180 deg.

 

Ah, engine and trans temps...another whole set of questions.

I have the stock 195 thermosat and temps are around 195 all the time. Trans temps have gone up to 220 during T&T (lots of runs) but is usually 180 when I compete (cooled during rest period). What would Trans temps have to do with engine performance?

I just ordered a trans cooler to keep my trans temps lower. I don't want heat to kill the tranny.

I will take any suggestions I can get.

 

Trans temp won't have any effect on engine performance, but are you sure the BOG is caused by the engine, or could the trans be causing it...

You say the trans temp goes over 220... drag racing (Bracket) is all about Consistency! that being said "WHY" would you make several HOT laps during TT and get the trans HOT the engine HOT.. etc.. then let it cool for eliminations ???

I'm NOT trying to tell you how to race, just how "I" race.. I'll make a time shot.... then wait 20 - 30 min before my next time shot to let the engine & trans cool... to the temps I mentioned before.

Again I'll do the same for my 3rd time trial wait 30 min or more.. I make sure that I will have enough cool down time before eliminations start....


The only time I HOT LAP it is if I go 3 or 4 rounds and the track is calling us to the line... I KNOW my car will slow down . 03 if I have to run at 190+ deg.... (I'm thinking of an electric water pump) I already have a fan switch to run the fan with the engine off.. and if I do the same with the water pump I'll be able to cool it to 150 for EVERY run!

I can't understand the benefit of making lap after lap in the heat unless you "ALWAYS" run the car HOT I assume it will then be consistent... Personally I prefer to let it cool between runs...

Lets see if we get some other opinions here from other "Bracket" racers...

I also had a trans cooler in my 96 when I had the 3200 converter... in this car IF I go to a high stall converter I will also add a trans cooler.... A very good investment!

 

do you have, or have access to, a practice tree?



in most-instances, WE, and not the vehicle, are the least-consistent variable

 

I think everyone I see that has posted has been racing many, many years. I ask all of you if you can FEEL the difference between .070 of a second? I cannot and I've been doing this since the 60's.

At one time I did have a problem with the car. It would run the numbers and then all of a sudden be about .200 slow so I sandbagged. I scanned the runs and found the fuel settings were way off as well as the timing. This was after having a professional tune. Eventually I tuned it myself and through trial and error the car runs consistently every run. I had no clue the car was running .200 slow when it did.

If he is going to take racing seriously he needs something like HP Tuners to scan and then tune his car. I still think he has a concentration issue. JMO. I'm done.

 

When discussing a specific topic in bracket racing it cascades into many many other topics. Every "little" thing impacts every other "little" thing. Every "little" things is improtant.

Engine water temp, oil temp, and trans temp will impact ET. I like to run everything to the hot side of normal. My car is at the same temps from the first time shot to running round robin in multiple classes.

Yes I can tell the difference between a .00x and .070 lights. I have my car set to cut a .029 light. My window is .00x to .049. If I hit my spot exactly I will be .02x-.03x. If I'm a tad early I know its a great light and if I late well duah. Yes I can tell if I hit my spot or if I was early or late. That is a big window and I'm working on shrinking it down. I have a high degree of confidance that when set up on a .029 light I'm not going to be red. Might be .049 but not red. I do have the option on the line to go to a kill mode light. That moves my window between -.015 to .039. However on that setting I'm red 30% of the time. Being able to win with the car set up on a .029 light leads to further discussions about sandbagging (I perfer to call it putting some in the bank) and driving the stripe. Having a sense of your RT (good or bad) has a huge impact in making the right decision on the top end.

I really thought about the bog thing. From what was posted about happening 20 times especially when running slower cars, I tend to think its the driver and not the car. Sounds like you back off the tree when faced with a slower opponent. The bog may be when your brain says go and when you actually move your feet. Please no insult to you intended. My recommendation is that you attend a track rental if possible. Put the car on a pro .500 tree and see if your RT's are consistant. If you do this it will lead to questions about deep staging and how much anticipation on the 3rd yellow is required to shallow stage. My point about the pro tree is that it takes the drivers anticipation out of the equation and it should allow you to see if the car is actually bogging. I would say to do as many test runs as possible. I like to make at least 3 test passes to validate something and really perfer about 10.

 

I've only raced a dozen times since 1993 (and only twice in my Z28), but when I was racing several times a week at various tracks in the early-'90s, I could generally tell when I was .050 or-worse:
back-then, many local foot-brake racers strived for RT better-than .050, and anything teens-or-better was thought to be 'too-close-for-comfort', but my goal was .007 to .027, with .017 my 'optimal-goal', but I was content in the low .020's.
(I'm 20 years-older now, and it remains to be seen if I can still do that {doubtful})


Sam Biondo once told me if you can achieve that (.017 RT in foot-brake), you'll 'teen them to death', so I spent an hour, minimum, each night, year-round, practicing in the car (I was pretty-****), and I believe in my-personal case, it was worthwhile:
a buddy, who's wife wanted to get-started racing, had her practice for 6 months before he ever let her strap-in to the family's 12-second Camaro, and at a private rental, he had her stage & launch 3 times before every run (stage/launch/back-up... stage/launch/back-up... stage/launch/run), so at the end of the day, she'd made 7 runs, but 21 launches, and she won an event later that season.

 

I hate it when you guys are right!

 

Lots of experience I couldn't buy. I appreciate your help guys. Do many racers use the practice tree? Does it come with a foot pedal? Does it account for the rollout? I am willing to work on the human part. I had the car dyno
tuned in the spring and had the tune reviewed and "tweaked" this week. My T&T felt better on Wednesday.

 

Yes you can get a practice tree with a foot pedal and set it for roll out, pro tree .400 or .500 or a full tree... I forget what I paid but it was well under $200

I have one from "Porta Tree" it will keep track of you best and worst RT and an average...

Also you can set the "opponents" RT to example .035 then it will tell you how many time you won or lost on the tree...

Check it out on the web..

 

I will check out the Porta tree (sounds like a porta potty for dogs), any other brand recommendations?

 

Jeggs has it for $99 + extra for the foot pedal....look up practice trees at Jeggs, or just type Porta Tree in Yahoo,,,

I swear by mine!!

 

Is the $99 version the best? I see the Eliminator for 229. I don't care about fancy features. Just want to get the most for the money.