How to make car more consistent
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From: pittsburgh raceway park
How to make car more consistent I been bracket racing my camaro for 3 years now and now I'm having problems keeping my car consistent. I run front runners at 40 psi, slicks @ 10 psi, temp @ the tree is 170*, shift points all the same at 5700- th400, launch at 3,500 every pass, mph is 107-109. The problem with my consistence is that I will run a 12.63 first time trial, second time trial 12.60, dial it in at 12.59 and run a 12.49 out the back door. This was today at 85*. By third round I had it dialed down to 12.47 and went a 12.42 temp was 80* outside.
I can handle outside temp changes to the car to pick up et. But what I don't understand is why my car has such a wide et bracket now. I pull the plugs and check after each night to make sure none are fouled.
I guess what I'm asking for is what do some of you other bracket racers do to keep the car consistent during the night. And what should I be looking into to help me find out why my car just keeps wanting to run under.
I can handle outside temp changes to the car to pick up et. But what I don't understand is why my car has such a wide et bracket now. I pull the plugs and check after each night to make sure none are fouled.
I guess what I'm asking for is what do some of you other bracket racers do to keep the car consistent during the night. And what should I be looking into to help me find out why my car just keeps wanting to run under.
Last edited by rob scott; Jul 30, 2011 at 10:05 PM.
We are constantly making adjustment to our car. Although we dont bracket race, we have to make sure that the car does not do anything crazy. We have to test a lot to figure it out but once you know what its gonna do at different density's you can let out early or run in all out. You will have a better idea of how its gonna run
are your 60 foot times changing at all as teh car picks up?
How much heat soak does the car have in it at the start of your day compared to the end of the day? If it's gaining heat, oil could be getting a little thinner, could be picking up a little power when the car's hot compared to when it's cold, alot of possible things could be going on.
Is the car tuned in open loop, or are you relying off o2 sensors still? If so they could be getting cleaned off as the day goes on, or getting sooted up, and that could effect it as well.
Car getting lighter every run from less fuel in it? Not that that alone will do what you're seeing, but again it's another possibility.
How much heat soak does the car have in it at the start of your day compared to the end of the day? If it's gaining heat, oil could be getting a little thinner, could be picking up a little power when the car's hot compared to when it's cold, alot of possible things could be going on.
Is the car tuned in open loop, or are you relying off o2 sensors still? If so they could be getting cleaned off as the day goes on, or getting sooted up, and that could effect it as well.
Car getting lighter every run from less fuel in it? Not that that alone will do what you're seeing, but again it's another possibility.
Do you take a giant dump between every round?
It sounds like DA is the biggest thing effecting your times. Like JL said is everything consistant? I know you said coolant temp is 170* every run but what about oil temp.
It sounds like DA is the biggest thing effecting your times. Like JL said is everything consistant? I know you said coolant temp is 170* every run but what about oil temp.
Trans temp too, and is the car totally warmed up, including the rear end fluid and all that. Take all these small things and put them together, combine that with the weather, and you will probably see what you're seeing.
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My runs between 1pm and 730pm usually are pretty close after that usually 2nd to 3rd round my car picks up a couple tenths just like you are saying. Dial it to get there and drive the finish line.
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Thread Starter
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From: pittsburgh raceway park
My 60's are 1.55 - 1.57. If I run the bottle I can hit 1.41 60ft. I keep the car at 1/2 tank while bracket racing. I run it on street blaze, 100 octane, I still use the o2's instead of open loop. I don't have a oil temp gauge, one thing I have been looking into putting on the car. I have a down time of 40 minutes between my two classes.
My pit spot is a little more the 1/4 mile away from my staging lanes, in the sense of driving the car to the lanes to warm up the rear and trans, temps should be around the same every pass within a reason. When in the lanes I do warm the motor and trans up before I make a pass. I place it on the converter at 1600 rpms for about 30-45 seconds till I reach 160/165 temp then I do my burnout car is 170 all fans on and bump in.
As I get the car into round robin, the 60's seem to pick up as if I were hitting the bottle. When I get to the track I drive the car around the whole track for about 10 minutes at 5-10 mph and open it up once it's warm on the top end of the return roads. temps gets up to 180* after driving and launching it. I park it for about 30-45 minutes before they call our class. Jump back in drive to the lanes. At the end of the night if I can make it to the finals it's heat soaked 180-190* pulling in the lanes waiting to run again. I do ice the intake between rounds and I have not did the thorttle body bypass yet.
It's still a stock head, intake, 1998 ls1. The only mods that are done to it are, long tubes, fm14, th400, 4k stall, 9" 4.11 gear. 50/50 summit drag shocks, fame connectors, ajustable lca, body torque arm, 28" slicks. reaction times are all consistent with quickest being .0002 to .0015 during the night.
My pit spot is a little more the 1/4 mile away from my staging lanes, in the sense of driving the car to the lanes to warm up the rear and trans, temps should be around the same every pass within a reason. When in the lanes I do warm the motor and trans up before I make a pass. I place it on the converter at 1600 rpms for about 30-45 seconds till I reach 160/165 temp then I do my burnout car is 170 all fans on and bump in.
As I get the car into round robin, the 60's seem to pick up as if I were hitting the bottle. When I get to the track I drive the car around the whole track for about 10 minutes at 5-10 mph and open it up once it's warm on the top end of the return roads. temps gets up to 180* after driving and launching it. I park it for about 30-45 minutes before they call our class. Jump back in drive to the lanes. At the end of the night if I can make it to the finals it's heat soaked 180-190* pulling in the lanes waiting to run again. I do ice the intake between rounds and I have not did the thorttle body bypass yet.
It's still a stock head, intake, 1998 ls1. The only mods that are done to it are, long tubes, fm14, th400, 4k stall, 9" 4.11 gear. 50/50 summit drag shocks, fame connectors, ajustable lca, body torque arm, 28" slicks. reaction times are all consistent with quickest being .0002 to .0015 during the night.
I'd guess he knows the car very well and that's probably not a pro tree.
But, that being aside, I think one reason that you see the car pick up is because the converter, once the trans fluid is hotter and a little thinner, is acting like it's a bit looser then it is.
If you have a TH400, you may want to try the john deere hygard fluid. It's a little thicker but it also doesn't thin out as much with heat and may help your consistancey.
Oil temp ga would be a good idea, since that should help give you an idea if the motor's up to temp 100%.
The track conditions, do they get better or worse as the day goes on? how does the 60 foot on other cars look compared to what you're seeing? Sometimes if they're good with the track prep and redo it during the day you may actually be getting a better surface as the day goes on as well, and that could be effecting you a little bit.
I'd get the 02's turned off, even with the unleaded fuel I have seen them act a little funny when used with anything other then regular pump. And then if you're spraying as well they're probably doing something different on those runs as well.
Ditch the 02's, leave the MAF in place, and see if that helps you at all.
But, that being aside, I think one reason that you see the car pick up is because the converter, once the trans fluid is hotter and a little thinner, is acting like it's a bit looser then it is.
If you have a TH400, you may want to try the john deere hygard fluid. It's a little thicker but it also doesn't thin out as much with heat and may help your consistancey.
Oil temp ga would be a good idea, since that should help give you an idea if the motor's up to temp 100%.
The track conditions, do they get better or worse as the day goes on? how does the 60 foot on other cars look compared to what you're seeing? Sometimes if they're good with the track prep and redo it during the day you may actually be getting a better surface as the day goes on as well, and that could be effecting you a little bit.
I'd get the 02's turned off, even with the unleaded fuel I have seen them act a little funny when used with anything other then regular pump. And then if you're spraying as well they're probably doing something different on those runs as well.
Ditch the 02's, leave the MAF in place, and see if that helps you at all.
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From: pittsburgh raceway park
No delay box, I foot brake it. I have been driving this car for six years. Four years of the six have been bracket racing it, so I know how she likes the bump at the tree. It's a sportsmen tree.
JL, The track prep is always great. The track doesn't start falling off till end of the year, but even then I dead hook. I can't remember having problems hooking other then on a set of et streets, that my car was just ripping apart. I will have to get it retuned and have my tuner put it in open loop. One thing I forgot to mention, I had an o2 blow out the driver side header last year. I had a new o2 bung welded in about 2 inches infront of the old bung, would moving it up 2 inches cause some problems.
JL, The track prep is always great. The track doesn't start falling off till end of the year, but even then I dead hook. I can't remember having problems hooking other then on a set of et streets, that my car was just ripping apart. I will have to get it retuned and have my tuner put it in open loop. One thing I forgot to mention, I had an o2 blow out the driver side header last year. I had a new o2 bung welded in about 2 inches infront of the old bung, would moving it up 2 inches cause some problems.
Last edited by rob scott; Jul 31, 2011 at 06:44 PM.
If you are running open headers, yes it will cause it to change.
I'd get all the o2 sensors turned off... I think that will help you a bit. Do that and see how the car reacts.
My sled with the o2's all off and a stock maf, would repeat on the 10.5x mark @ 3600 all day long before I started spraying it... put a 63 pill to it via a nos plate, and a tighter converter (little too tight car never would 60 with it like it did with the n/a converter) and it would repeat at 9.5x all day as well.
I'd get all the o2 sensors turned off... I think that will help you a bit. Do that and see how the car reacts.
My sled with the o2's all off and a stock maf, would repeat on the 10.5x mark @ 3600 all day long before I started spraying it... put a 63 pill to it via a nos plate, and a tighter converter (little too tight car never would 60 with it like it did with the n/a converter) and it would repeat at 9.5x all day as well.
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Ok. Thank You JL for the help. I will have my tuner shut the 02's off when it's on the dyno. There's a big 3 day race coming up in september with 3 days of big pay outs. So I would like to get it to dial in and be deadly constitent for this race.
Back in the day when I did race bracket I found my car rather consistant. Given the track I was racing at. The big issue was that as the summer went into fall we started running I wanna say 6 pm and the swing in temp was drastic and my car would certainly gain.
Since I drove the car 100 Miles one way everytime it was certainly heat soaked and never really "cooled" so that was not an issue. But I def needed to rely on the 2 practice runs and on the odd day of only getting one, made it hard for the 1st round.
JL pretty much nailed it on the head with the smaller varibles adding up it a major difference when measuring races within thousandths of a second.
Since I drove the car 100 Miles one way everytime it was certainly heat soaked and never really "cooled" so that was not an issue. But I def needed to rely on the 2 practice runs and on the odd day of only getting one, made it hard for the 1st round.
JL pretty much nailed it on the head with the smaller varibles adding up it a major difference when measuring races within thousandths of a second.
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From: central illinois
ive been wondering about this as well.. Ive foot braked my old 72 pontiac year after year and its always pretty good.. its gotten me several track championships in a couple different classes, but ive also raced a handful of modern computer controlled lt1's, ls'1, 3800's and even some 4.6 fords and i have just had nightmares with consistency. no matter the attention to detail i put into staging, temps, launch and shift, they just seem to have a mind of there own. I just purchased my own ls1 car and im hoping i can find a way to make it run the number for the times when i feel like traveling to race, but dont feel like dragging the old pontiac along on a trailer while the truck swallows all my money. thanks for the tips guys
Things I have found:
1: Alloy block engines like to run warmer, and are less sensitive to coolant temp changes. The LS1 cars I have worked with all made the most power, with very little change, from 180 degrees to 210.
2: Oil temps have an influence. Thicker the oil, the more critical. Thin oil is more consistent. Many SS racers I know use heaters in the oil pan, Trans & differential. All lubes need to be consistent temps.
3: Ice on the intake is faster, but just something else to screw with in later rounds. Not as easy if you go alone. Most don't screw with that when bracket racing.
4: Running the car on the lean side makes it less sensitive to air temps. Hot air=it doesn't slow it as much lean. Cooler air=it doesn't like it as well (speed up) when lean.
1: Alloy block engines like to run warmer, and are less sensitive to coolant temp changes. The LS1 cars I have worked with all made the most power, with very little change, from 180 degrees to 210.
2: Oil temps have an influence. Thicker the oil, the more critical. Thin oil is more consistent. Many SS racers I know use heaters in the oil pan, Trans & differential. All lubes need to be consistent temps.
3: Ice on the intake is faster, but just something else to screw with in later rounds. Not as easy if you go alone. Most don't screw with that when bracket racing.
4: Running the car on the lean side makes it less sensitive to air temps. Hot air=it doesn't slow it as much lean. Cooler air=it doesn't like it as well (speed up) when lean.
