What can I do to tune car to be more cosistant at the track?
12-02-2005, 11:00 PM
#1
What can I do to tune car to be more cosistant at the track? I bracket race at my track. I am tring to find ways to make the car more consistant at the track.
Is there a way to make the car less sensitive to weather changes?
I don't care about speed unless it is consistant.
the car runs 7.3-7.6 on 1/8mile track depending on the weather.
1998 Z28
have stock a4 with 3500 stall TCI.
MS3 cam, 5.3 PRC stage 2.5 heads, headers, bullets, MT ET Streets. and some little things, few weight reductions, QA1's
I have no problems with traction.
No Cats or AIR pump or EGR
It is usually decently consistant but theres always room for improvement.
I notice it seems the carb. cars seem to run more constistant the fuel inj.
Is there a way to tune the LS1 Fuel inj. to run more consistance? I do see fuel inj. setups on dragsters etc. but they don't use pcms and seem to be a good setup. How do they work differently than the LS1. Is there a way to have a simular tune on an LS1?
I know the alcohal cars are more consistant and less sensitive to weather change but I only want to use gasoline.
any suggestions would be appriciated thanks
Is there a way to make the car less sensitive to weather changes?
I don't care about speed unless it is consistant.
the car runs 7.3-7.6 on 1/8mile track depending on the weather.
1998 Z28
have stock a4 with 3500 stall TCI.
MS3 cam, 5.3 PRC stage 2.5 heads, headers, bullets, MT ET Streets. and some little things, few weight reductions, QA1's
I have no problems with traction.
No Cats or AIR pump or EGR
It is usually decently consistant but theres always room for improvement.
I notice it seems the carb. cars seem to run more constistant the fuel inj.
Is there a way to tune the LS1 Fuel inj. to run more consistance? I do see fuel inj. setups on dragsters etc. but they don't use pcms and seem to be a good setup. How do they work differently than the LS1. Is there a way to have a simular tune on an LS1?
I know the alcohal cars are more consistant and less sensitive to weather change but I only want to use gasoline.
any suggestions would be appriciated thanks
Last edited by brandonppr; 12-02-2005 at 11:10 PM.
12-03-2005, 04:32 PM
#2
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
I bracket race my car a lot too and it is very consistent with just a good tune in it. But it does change a little with the weather - the most important thing you can do is KNOW when it is going to change and what it will change to.
The best thing you can do is get one of the weatherstations with a database. You run it before each run and it takes in all of the weather info - then after the run, you enter all of the info from your timeslip. After awhile, you have a database and when you run the weather part before your run, it will tell you what you should dial based on all of the past runs.
If you don't want to spend the money, you can take the cheap way out like I have done in the past and get a small baramoter and thermometer (like in one of those sports watches or small unit) and then keep logs. Then you can flip through the log book before a run and find a run from the past with similar conditions.
Of course neither of these helps till you have some data, but it will add up fast and you will begin to see the trends quickly.
The best thing you can do is get one of the weatherstations with a database. You run it before each run and it takes in all of the weather info - then after the run, you enter all of the info from your timeslip. After awhile, you have a database and when you run the weather part before your run, it will tell you what you should dial based on all of the past runs.
If you don't want to spend the money, you can take the cheap way out like I have done in the past and get a small baramoter and thermometer (like in one of those sports watches or small unit) and then keep logs. Then you can flip through the log book before a run and find a run from the past with similar conditions.
Of course neither of these helps till you have some data, but it will add up fast and you will begin to see the trends quickly.
12-05-2005, 01:15 AM
#3
thanks for the reply.
I do have a weather station like you decribe and do use it.
The thing I am trying to figure out is it seems that late model fuel injected cars tend to run consistant but for no apparent reason jump several numbers at once. I have noted this in other peoples cars as well. But is seems this is not as much an issue in carb cars.
I know that track conditions can cause this but it does not seem to be related to track conditions.
I have won many races with the car but I am always looking for improvement.
The car seems to less prone to running off as many numbers as I see others run off though. I think it may be in part to not having cat. conv.s and the car no longer sprays the extra fuel every now and then to cool them. I have done a few other things that has helped but it still is a problem I am having with the car and would like to find a reason for.
when I first got the car it would run off around .05-.09 numbers just out of the blue.
now when it does it it is like .03-.05 numbers.
I know driver error could play a role in running off but the thing is it will continue to run off for several runs then just go back to where it was or sometimes just stay off the rest of the day.
of course I drive the end of the track as much as I can but if it were a little more reliable I think I could win more races.
I do have a weather station like you decribe and do use it.
The thing I am trying to figure out is it seems that late model fuel injected cars tend to run consistant but for no apparent reason jump several numbers at once. I have noted this in other peoples cars as well. But is seems this is not as much an issue in carb cars.
I know that track conditions can cause this but it does not seem to be related to track conditions.
I have won many races with the car but I am always looking for improvement.
The car seems to less prone to running off as many numbers as I see others run off though. I think it may be in part to not having cat. conv.s and the car no longer sprays the extra fuel every now and then to cool them. I have done a few other things that has helped but it still is a problem I am having with the car and would like to find a reason for.
when I first got the car it would run off around .05-.09 numbers just out of the blue.
now when it does it it is like .03-.05 numbers.
I know driver error could play a role in running off but the thing is it will continue to run off for several runs then just go back to where it was or sometimes just stay off the rest of the day.
of course I drive the end of the track as much as I can but if it were a little more reliable I think I could win more races.
12-05-2005, 11:25 PM
#6
sd tune as in tuning in sd, or you mean permanent sd? either way, it really doesn't matter, maf or sd is just a matter of knowing how much air is flowing. maf is a bit more flexible, sd is a bit quicker to react. i usually try both and see which one runs better. most cars come within +/- 5rwhp and that's withing margin of error of dyno runs.
Trending Topics
12-05-2005, 11:55 PM
#8
Originally Posted by brandonppr
so what would cause the car to run off for no reason after running consistant for several runs?
could the transmission be resposible for anything?
could the transmission be resposible for anything?
12-06-2005, 10:28 AM
#9
I have torque management turned off.
Does the computer control the transmission and the amount of slip according to the temp?
Is there a way to keep the timing the same no matter what the temp/humd/airpress?
even if I have to reduce the HP in order to get this to happen it would not bother me. is it possible? to do either of the above?
also is there a way to keep the AFR the same all the time?
Does the computer control the transmission and the amount of slip according to the temp?
Is there a way to keep the timing the same no matter what the temp/humd/airpress?
even if I have to reduce the HP in order to get this to happen it would not bother me. is it possible? to do either of the above?
also is there a way to keep the AFR the same all the time?
12-06-2005, 10:31 AM
#10
i guess that is the way to do it: reduce timing and such to a set that is always safe, and then disable all the 'modifier' tables so while it is not the most optimal, but it is the most consistent.
i find the trans to be the biggest problem though, because no amount of computer alteration is going to change the fact that hot oil has different viscous properties and it's just going to shift differently.
but in general, it is definitely something to try.
i find the trans to be the biggest problem though, because no amount of computer alteration is going to change the fact that hot oil has different viscous properties and it's just going to shift differently.
but in general, it is definitely something to try.
12-06-2005, 10:50 AM
#11
Ok that sound like something to try.
don't get me wrong I like to go fast but I'm bracket racing and thats not all about going the fastest.
The trans temp I can try to monitor and see what causes what but the other things are out of my control and hard to judge so any elimination of a variable would help.
so would this also get rid of any chance of knock retard?
don't get me wrong I like to go fast but I'm bracket racing and thats not all about going the fastest.
The trans temp I can try to monitor and see what causes what but the other things are out of my control and hard to judge so any elimination of a variable would help.
so would this also get rid of any chance of knock retard?
12-09-2005, 08:51 PM
#12
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
I would say the trans is the biggest culprit if you don't have a good built one and a cooler. If you don't have a tranny cooler, that is a cheap item that will make a huge difference in the consistency. When I bracket raced with an A4, I had a really well built one and it was vacuum modulated. The car was deadly consistent like that. EFI cars are more sensitive to air density changes than carb cars - that is the nature of the beast. Speed density does help - I run my car in SD now - no more MAF. I run a TH400 now, so I have to shift it myself, but it is still very consistent. Heck, it is even consistent on the bottle - I have run more 10.0's than I can count Just can't get it over the wall!
Try speed density, you may find it helps your car - and if not, it is easy to go back. Do you tune yourself?
Just can't get it over the wall!Try speed density, you may find it helps your car - and if not, it is easy to go back. Do you tune yourself?
12-09-2005, 10:31 PM
#13
TECH Fanatic
iTrader: (4)
Join Date: May 2002
Location: Fairview Heights Illinois
Posts: 1,851
Likes: 0
Received 0 Likes
on
0 Posts
You could run it open loop in SD mode and eliminate as many variables in the tune as you can (KR, CTS, IAT, etc..). Zeroing the effect in the tables in your normal operating range is easy, but if you don't want to adjust the tables you could always use a tricker box for the CTS and IAT for making passes.
EFI is sensitive to voltage changes, so if you're taxing the system, or turning off the alternator, then you'll need a Jacobs accuvolt regulator to power the PCM, ignition, and fuel pump while making a pass. It will feed these devices a steady voltage no matter the condition of the battery.
If you have trouble keeping a consistant engine coolant temp between your first pass and the next pass, you might consider removing the tstat and blocking the coolant bypass passage. You won't get that quick gain in coolant temp while making a pass because the restriction is removed.
EFI is sensitive to voltage changes, so if you're taxing the system, or turning off the alternator, then you'll need a Jacobs accuvolt regulator to power the PCM, ignition, and fuel pump while making a pass. It will feed these devices a steady voltage no matter the condition of the battery.
If you have trouble keeping a consistant engine coolant temp between your first pass and the next pass, you might consider removing the tstat and blocking the coolant bypass passage. You won't get that quick gain in coolant temp while making a pass because the restriction is removed.
12-14-2005, 10:14 PM
#15
TECH Fanatic
iTrader: (4)
Join Date: May 2002
Location: Fairview Heights Illinois
Posts: 1,851
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Pavetim
I am really thinking about leaving my car in SD but do I leave it in open loop or closed loop?
IMO open loop is more consistent, but it does take more work to get tuned.
03-19-2006, 05:27 PM
#16
thanks for the info.
I am located it middle tennessee. does anyone know of any tuners that would know how to do this and how would I explain to them what I want to do. I talked to one tuner and they seemed to be lost when I tried to explain. I don't know how to tume the car. even if they are in a bordering state that would be fine if anyone knows of anyone. thanks
I am located it middle tennessee. does anyone know of any tuners that would know how to do this and how would I explain to them what I want to do. I talked to one tuner and they seemed to be lost when I tried to explain. I don't know how to tume the car. even if they are in a bordering state that would be fine if anyone knows of anyone. thanks
