internet launching lessons needed
10-25-2009, 09:43 PM
#1
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internet launching lessons needed My car is slow and I am getting disappointed.
wednesday on 18 inch street tires (245 40 18) i was cutting 2.2 60' (not great but not horrible). i went to the track last night first time ever with drag radials (M/T E.T. Street Bias Ply 26x10.5x16) and could only cut a 2.06 60' launching off idle at 20 psi cold. my car is a stock lt1 with a 3200rpm stall lm1 exhaust and 4.10 rear end gears stock suspension.
what should i try with my car next time? I only got 3 runs in last night due to an event so i didnt get a chance to adjust tire pressures or burn out time.
2 of my burn outs were untill i saw smoke in the mirrors (side view or rear) and then i rolled out of it. last run I was up against an h/c ls1 camaro and i did my burn out as long as he did and that was when i got my 2.06.
I am not experiencing wheel hop (that i can feel) and the tires seemed to hook hard when i launched.
WHAT SHOULD I DO?
wednesday on 18 inch street tires (245 40 18) i was cutting 2.2 60' (not great but not horrible). i went to the track last night first time ever with drag radials (M/T E.T. Street Bias Ply 26x10.5x16) and could only cut a 2.06 60' launching off idle at 20 psi cold. my car is a stock lt1 with a 3200rpm stall lm1 exhaust and 4.10 rear end gears stock suspension.
what should i try with my car next time? I only got 3 runs in last night due to an event so i didnt get a chance to adjust tire pressures or burn out time.
2 of my burn outs were untill i saw smoke in the mirrors (side view or rear) and then i rolled out of it. last run I was up against an h/c ls1 camaro and i did my burn out as long as he did and that was when i got my 2.06.
I am not experiencing wheel hop (that i can feel) and the tires seemed to hook hard when i launched.
WHAT SHOULD I DO?
10-26-2009, 06:57 AM
#2
I suspect your running into a "not enough power" situation to take advantage of those street bias-ply's. You could run a Nitto tire and garner the same 60 foot w/ ease.
4.10's is def a step up, did you install them yourself?? As those are a wild choice for a A4 car and that should be helping the launch but again on a stock LT1, your not doing yourself any favors.
Have you smashed the throttle off the line? Has it hooked, bogged, or spinned?
4.10's is def a step up, did you install them yourself?? As those are a wild choice for a A4 car and that should be helping the launch but again on a stock LT1, your not doing yourself any favors.
Have you smashed the throttle off the line? Has it hooked, bogged, or spinned?
10-26-2009, 10:10 AM
#3
Are you sure the car is starting in first gear? I tuned a bolt on lt1 convertible with the same gears and tires, a touch bigger converter (250rwhp) and he cuts 1.70's in the heat. If you're not spinning I'd guess you car is starting in 2nd gear or the trans is slipping real bad. What's your process step by step as you pull up to the burnout box?
10-26-2009, 11:32 AM
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I pull up past the waterbox and back up to the edge and do my burn out, roll out of the burnout and stage. when i am staged I let the car idle and hold the brake to keep from rolling (trans in D). on the third orange floor it.
i never thought about it possibly starting in second. I am not sure if it is 100% but i think it is launching in first.
i never thought about it possibly starting in second. I am not sure if it is 100% but i think it is launching in first.
10-26-2009, 11:41 AM
#5
I pull up past the waterbox and back up to the edge and do my burn out, roll out of the burnout and stage. when i am staged I let the car idle and hold the brake to keep from rolling (trans in D). on the third orange floor it.
i never thought about it possibly starting in second. I am not sure if it is 100% but i think it is launching in first.
i never thought about it possibly starting in second. I am not sure if it is 100% but i think it is launching in first.
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10-26-2009, 01:13 PM
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I am starting at idle due to some people at the track telling me to do it that way due to my stall. thats the purpose of this post is to try and learn a good starting point. where should my tire pressure be at? currently at twenty.
10-26-2009, 02:37 PM
#13
Bogging is simply as the tire grab as the throttle is applied and the RPM's drop as either the race weight, gearing, stall, or power is not enough to help the car leave correctly, due to the stock weight, it needs to have the rpms up to a certain level. M6 cars and A 4 cars have different requirement due to their 1st gear ratio and the auto has the ability to consistantly slip that allows for less user error.
To give reference, I had at the time a mis matched 383 LT1 with a SMALL 2000 rpm stall, 3.23 gear ratio 3700 race weight making under 380 rwhp (hot cammed), and at the time I was cutting 1.7's on nittos and nothing else. I install a 12 bolt with 3.42's, BMR TQ arm and LCAs and M/T ET Drag Radials, the original run which had some good compound.
I ended up bogging and not bettering my 60 then 1.8x and you could honestly feel it be slower off the line and see the rpms drop and then pick up from the 60' and onward.
Had I the knowledge back then, the car needed 4.10's and a 4k stall but also 94/95 4L60e's had tuning issues. So thats niether here, nor there.
To give reference, I had at the time a mis matched 383 LT1 with a SMALL 2000 rpm stall, 3.23 gear ratio 3700 race weight making under 380 rwhp (hot cammed), and at the time I was cutting 1.7's on nittos and nothing else. I install a 12 bolt with 3.42's, BMR TQ arm and LCAs and M/T ET Drag Radials, the original run which had some good compound.
I ended up bogging and not bettering my 60 then 1.8x and you could honestly feel it be slower off the line and see the rpms drop and then pick up from the 60' and onward.
Had I the knowledge back then, the car needed 4.10's and a 4k stall but also 94/95 4L60e's had tuning issues. So thats niether here, nor there.
10-27-2009, 07:47 AM
#15
As for the other stuff only you'll be able to figure what rpm your car likes to leave at. Sometimes the cars leave better off idle when the converter flashes hard, some like stall speed. You'll have to experiment and figure out what works best. If your tires aren't spinning leave the tire pressure where it is and get everything else sorted out. If the car starts leaving better and you start spinning the tires then begin dropping the pressure. There's no reason to run less pressure than you need to.
10-27-2009, 09:42 AM
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I have an A4 and I leave my car in "D" at the track and never had a problem with it.
I think your problem is mostly just the fact that you're leaving off idle and maybe low power has something to do with it as well.
If it's a well prepped track and you have drag radials you definitely shouldn't launch off idle. Hell, I cut a 2.0 60' on 235 street tires, and I didn't launch off idle.
Increase the RPM on the launch until you find the point where your tires break loose, then take it down a little bit from there so you don't spin.
Also the way you give it throttle off the start can have a big effect. Make sure you're giving it enough throttle off the start to assure that it's leaving in 1st, and apply full throttle as quick as you can without breaking the tires loose. If you're doing it wrong you might even feel your car downshift into 1st as you're leaving, but if you do it right it should feel quite smooth.
I think your problem is mostly just the fact that you're leaving off idle and maybe low power has something to do with it as well.
If it's a well prepped track and you have drag radials you definitely shouldn't launch off idle. Hell, I cut a 2.0 60' on 235 street tires, and I didn't launch off idle.
Increase the RPM on the launch until you find the point where your tires break loose, then take it down a little bit from there so you don't spin.
Also the way you give it throttle off the start can have a big effect. Make sure you're giving it enough throttle off the start to assure that it's leaving in 1st, and apply full throttle as quick as you can without breaking the tires loose. If you're doing it wrong you might even feel your car downshift into 1st as you're leaving, but if you do it right it should feel quite smooth.
10-27-2009, 10:06 AM
#17
If that is the case a lot of times it can be fixed in the computer. Those early lt1 computers don't really know what to make of a converter. Sometimes the vss diagnostic stuff needs to be turned off. Basically the computer doesn't know what's going on and the trans goes into limp mode. Burnouts are known to put it into limp mode as well, that's why I asked what gear you were doing your burnout in. For your burnout keep the car in D and get the tires spinning fast with a good amount of rpm. If the car shifts during the burnout that's fine but if you lug the rpm the computer will think there's more trans/converter slippage and be prone to put the trans into limp mode. If you're at the track and you think the trans goes into limp mode disconnect the battery for a few minutes in between passes and that should reset it.
As for the other stuff only you'll be able to figure what rpm your car likes to leave at. Sometimes the cars leave better off idle when the converter flashes hard, some like stall speed. You'll have to experiment and figure out what works best. If your tires aren't spinning leave the tire pressure where it is and get everything else sorted out. If the car starts leaving better and you start spinning the tires then begin dropping the pressure. There's no reason to run less pressure than you need to.
As for the other stuff only you'll be able to figure what rpm your car likes to leave at. Sometimes the cars leave better off idle when the converter flashes hard, some like stall speed. You'll have to experiment and figure out what works best. If your tires aren't spinning leave the tire pressure where it is and get everything else sorted out. If the car starts leaving better and you start spinning the tires then begin dropping the pressure. There's no reason to run less pressure than you need to.
On M/T ET Street DR's I would bog badly.
As for 96-97 ODBII there was never an issue and from my exp back then, there was no need for messing with any trans tables. I'd email PCMforless.com for Bryan Herter to verify the ODBII stuff but def 94/95 had the issues.
10-27-2009, 10:30 AM
#18
Some stalls like to be loaded and some definately do not you will have to experiment with this..
From your previous statement, 20psi is a bit high, however if you are not spinning it is not affecting you in a negative manner. i am sure even with your 3200 stall its bogging down due to lack of power.
Lastly, the mods you have are for a car that already has all bolt ons. 4.10s and a 3200 stall are not bad i would prefer a 3600. get some Lts,1.6rr,Cai and most of all a TUNE. your car will become a whole new animal.....
From your previous statement, 20psi is a bit high, however if you are not spinning it is not affecting you in a negative manner. i am sure even with your 3200 stall its bogging down due to lack of power.
Lastly, the mods you have are for a car that already has all bolt ons. 4.10s and a 3200 stall are not bad i would prefer a 3600. get some Lts,1.6rr,Cai and most of all a TUNE. your car will become a whole new animal.....
10-27-2009, 10:41 AM
#19
Thats great advice, as IMO when racing, run as much pressure as you can get away with. if your not spinning, add pressure until that happens, back off then play with the rest. All cars are different and thus need their own set up. What works for one person may not work for another.
