[Coupes33]

Originally Posted by bradsm87

Has anyone extensively compared 1st gear launch vs 2nd gear launch when using an XHP transmission flash, which improves 1>2 shifts noticeably? I'm thinking a 1st launch is probably best but if you change diff ratios to something like a 4.1, a 2nd launch and topping out 5th before crossing the line would be damn fast!

I am going to try a 2nd gear launch the next time I am at the strip. 2nd gear in the ZF 6HP21 is 2.34 compared with 1st gear in a TH400/4L80E which is 2.48. I would still use the 3.46 diff ratio or otherwise, it would be revving its head off driving on the street with 4.1 diff gearing. People who have installed the 3.8 ratio M3 diffs have complained of high revving on the street and recommend not doing it. One less gear change will save 0.37s of lost revs and boost which should convert to a better time over the 1/4.

[bradsm87]

Originally Posted by Coupes33

I am going to try a 2nd gear launch the next time I am at the strip. 2nd gear in the ZF 6HP21 is 2.34 compared with 1st gear in a TH400/4L80E which is 2.48. I would still use the 3.46 diff ratio or otherwise, it would be revving its head off driving on the street with 4.1 diff gearing. People who have installed the 3.8 ratio M3 diffs have complained of high revving on the street and recommend not doing it. One less gear change will save 0.37s of lost revs and boost which should convert to a better time over the 1/4.

Sound like they might be pussies

They do around 2300 at 110km/h with stock diff from memory. Would 2500 at 110, still much lower than sooo many cars, really be a problem?

[Coupes33]

Gave my car a run last night at Willowbank RACE YA MATE. It had been raining in the morning and looked like it was raining over the track area when I drove out. But when I got there, it was dry and the track hadn't seen any rain all day. As a result, not many cars turned up (about 12 all up). This meant you could just keep having run after run if you wished. I had 5 runs in an hour before giving it away. I tried a couple of second gear launches that didn't go too well. The transmission doesn't seem to like it too much. However, I did manage my highest speed on the first of these 132.71mph. Three of the times were in the 11.3s area. The last run would have been much better if the engine light didn't come on for the last part of the run. A misfire on cylinder 6 was the cause of this. I did my fastest 330' time ever with a 4.785s. If you take this time and add it to the 330' to end of 1/4 time on the first run, it comes to 11.01s. If I can get it to all come together in one run some day, I might scrape into the 10s.

[Coupes33]

Just looking at the 330' times by some of those in the US doing high 10s and my 330' time on the last run is similar so it is the last part of the run where I am losing the time.

View post on imgur.com

[DR-JEKL]

gearing or do you think you're down on power on the big end compared to those guys?

[Coupes33]

Originally Posted by DR-JEKL

gearing or do you think you're down on power on the big end compared to those guys?

Not sure Shane. If it will do 132mph on one run but can only achieve 126mph best on the rest, I am thinking more transmission. To achieve 132mph, I believe it indicates enough power but whether the transmission fluid is getting too hot after the first run and causing it to slip, I need to investigate. The gearing is no different to these other guys who are pulling 10s. Unfortunately, the transmission certainly doesn't like the 2nd gear launches. If I stall it up to 3,000rpm, for some reason, it just dies off the line and very slowly revs out. At 3,000rpm launch, it should be leaping out of the hole. Whether that is a transmission software issue, I am not sure. A 4L80e transmission would probably fix all these issues. I have sent the datalogs off to my tuner so I will see if can see anything wrong that he can improve on.

[mikenazz]

I have the same issue with 2nd gear launches Coupes. When i ran 11.1 @130 2nd gear launch it gets off the line then upshifts around 3000-4000rpm to 3rd by itself.... I noticed if i put 2nd on 22 psi instead of 26 it doesn't always upshift.

The car hold a 27 psi 2nd gear pull perfectly on the street. Just doesn't like 2nd gear launches.

125k km on tranny and fluid changed at 100k with motul fluid. Perfect shifting.

[Brule]

Good mph.

[Coupes33]

Originally Posted by mikenazz

I have the same issue with 2nd gear launches Coupes. When i ran 11.1 @130 2nd gear launch it gets off the line then upshifts around 3000-4000rpm to 3rd by itself.... I noticed if i put 2nd on 22 psi instead of 26 it doesn't always upshift.

The car hold a 27 psi 2nd gear pull perfectly on the street. Just doesn't like 2nd gear launches.

125k km on tranny and fluid changed at 100k with motul fluid. Perfect shifting.

My transmission has only done 7,000kms since being pulled apart, checked and new filter and fluid. When you did 130mph what gear were you in? 4th or 5th. I find it difficult to get to the finish line in 4th gear.

[Coupes33]

Originally Posted by Brule

Good mph.

Yes I would be happy with that speed if it was there on every run but it isn't. After sending the datalogs to Dimitri (BQ Tuning), he has changed the timing, boost and vanos as I was getting timing corrections on all runs on 3 or 4 cylinders. I will see how the new tune goes.

[bradsm87]

Originally Posted by Coupes33

Not sure Shane. If it will do 132mph on one run but can only achieve 126mph best on the rest, I am thinking more transmission. To achieve 132mph, I believe it indicates enough power but whether the transmission fluid is getting too hot after the first run and causing it to slip, I need to investigate. The gearing is no different to these other guys who are pulling 10s. Unfortunately, the transmission certainly doesn't like the 2nd gear launches. If I stall it up to 3,000rpm, for some reason, it just dies off the line and very slowly revs out. At 3,000rpm launch, it should be leaping out of the hole. Whether that is a transmission software issue, I am not sure. A 4L80e transmission would probably fix all these issues. I have sent the datalogs off to my tuner so I will see if can see anything wrong that he can improve on.

Have you put XHP Stage 3 on it yet? Stock calibration has a full meltdown and applies huge torque reduction when stalling it up, especially with a high stall converter.

[Coupes33]

Originally Posted by bradsm87

Have you put XHP Stage 3 on it yet? Stock calibration has a full meltdown and applies huge torque reduction when stalling it up, especially with a high stall converter.

Yes. I have had the XHP Stage 3 installed ever since it came available.

[bradsm87]

Originally Posted by Coupes33

Yes. I have had the XHP Stage 3 installed ever since it came available.

Cool. I suspect they haven't removed all the stall safeties. A few of the tables are time-based (like they apply more limitation the longer you hold it stalled). Try only stalling it at the very last minute - just enough time to get the turbos starting to spool - and see if that helps. Unfortunately there are still so many tables for torque converter expectations and a high stall converter is way outside what the TCU is expecting without these changed.

[mikenazz]

Originally Posted by Coupes33

My transmission has only done 7,000kms since being pulled apart, checked and new filter and fluid. When you did 130mph what gear were you in? 4th or 5th. I find it difficult to get to the finish line in 4th gear.

4th @ redline when i pass the line. 7000 when i pass the line. sometime i would shift the 5th as i pass the line. its borderline.

pretty sure if we can sort out this 2nd gear launch issue 10s will be easier. Its almost like a safety, too much torque in 2nd at low speed and it will shift up??

[Rob@RBTurbo]

Originally Posted by Coupes33

Yes I would be happy with that speed if it was there on every run but it isn't. After sending the datalogs to Dimitri (BQ Tuning), he has changed the timing, boost and vanos as I was getting timing corrections on all runs on 3 or 4 cylinders. I will see how the new tune goes.

Definitely nice trap (133mph is no joke!), but these corrections will absolutely destroy your power band and kill your potential in going faster. Not sure if you are on full E85 or what, but definitely get the proper fueling in there and make sure the tune is spot on.

Also regarding the gearing, we'd mentioned this prior, but we feel that a bit longer gear would be helpful in avoiding that last shift at the trap for those running 130+mph along with making 1st gear most useful for the launch.
http://www.e90post.com/forums/showth...1427709&page=3
(Post #64,65,66)

But agree this is certainly a ~10.8-9sec car, just need to get everything on your side with the tune and the launch.

PS. Not sure your vehicles weight but some of the cars you maybe comparing to may have a couple hundred less pounds than you to tote around as we well, a rather large factor in drag racing.

Rob

[101Duck]

Originally Posted by Coupes33

Gave my car a run last night at Willowbank RACE YA MATE. It had been raining in the morning and looked like it was raining over the track area when I drove out. But when I got there, it was dry and the track hadn't seen any rain all day. As a result, not many cars turned up (about 12 all up). This meant you could just keep having run after run if you wished. I had 5 runs in an hour before giving it away. I tried a couple of second gear launches that didn't go too well. The transmission doesn't seem to like it too much. However, I did manage my highest speed on the first of these 132.71mph. Three of the times were in the 11.3s area. The last run would have been much better if the engine light didn't come on for the last part of the run. A misfire on cylinder 6 was the cause of this. I did my fastest 330' time ever with a 4.785s. If you take this time and add it to the 330' to end of 1/4 time on the first run, it comes to 11.01s. If I can get it to all come together in one run some day, I might scrape into the 10s.

Attachment 1808657

Solid night out there ken! I really wanted to go but the wife had a friend up from Sydney and had a dinner planned. So i drove my car to dinner and then put the hurt on an off its head sounding fg xr6. Car and a half on him by the other side of the lights and he got the jump! Last time i went to the track i got 1 pass. In 2.5 hours haha.

What's causing the timing corrections? Feel free to email me the logs of you want another set of eyes cast over them.

Whats your launch procedure? How much boost do you leave on?

[Coupes33]

Originally Posted by 101Duck

Solid night out there ken! I really wanted to go but the wife had a friend up from Sydney and had a dinner planned. So i drove my car to dinner and then put the hurt on an off its head sounding fg xr6. Car and a half on him by the other side of the lights and he got the jump! Last time i went to the track i got 1 pass. In 2.5 hours haha.

What's causing the timing corrections? Feel free to email me the logs of you want another set of eyes cast over them.

Whats your launch procedure? How much boost do you leave on?

Pity you couldn't make it to the drags as with so few cars you could have had quite a few runs. There was a bloke out there with a M4 with a tune and downpipes who got down to a 11.9s but had 11 runs. There was a new Mustang convertible that had 19 runs. I have attached 3 datalogs below.

https://datazap.me/u/coupes44/datalo...0&data=3-13-21

https://datazap.me/u/coupes44/datalo...og=0&data=3-21

https://datazap.me/u/coupes44/datalo...og=0&data=3-21

My launch procedure is stalling up to 2,500rpm while on the foot brake and handbrake and let it go. However, if I go to 3,000rpm, it just dies off the line as if some limiter cuts in. I might get in touch with XHP and see what they have to say about the software.

[bradsm87]

Definitely try and stall for as short time as possible, only just giving enough time for the turbos to start spooling a bit. Most of the TCU stall protection tables are time based and remove more and more torque the longer you stall it for.

[mikenazz]

regarding what could be our issue?

[Coupes33]

Originally Posted by mikenazz

regarding what could be our issue?

You are most likely on the money with this. The attached datalog of my second attempt at a 2nd launch from the other night shows where it changed from 2nd to 3rd at 3,380rpm on its own. It then had another issue while revving out in 3rd. That run was a 12.07s @ 122mph. I will delve further into this.

https://datazap.me/u/coupes44/datalo...og=0&data=3-21

[Coupes33]

Originally Posted by Rob@RBTurbo

Definitely nice trap (133mph is no joke!), but these corrections will absolutely destroy your power band and kill your potential in going faster. Not sure if you are on full E85 or what, but definitely get the proper fueling in there and make sure the tune is spot on.

Also regarding the gearing, we'd mentioned this prior, but we feel that a bit longer gear would be helpful in avoiding that last shift at the trap for those running 130+mph along with making 1st gear most useful for the launch.
http://www.e90post.com/forums/showth...1427709&page=3
(Post #64,65,66)

But agree this is certainly a ~10.8-9sec car, just need to get everything on your side with the tune and the launch.

PS. Not sure your vehicles weight but some of the cars you maybe comparing to may have a couple hundred less pounds than you to tote around as we well, a rather large factor in drag racing.

Rob

Hi Rob. I am running 100% E85 fuel. I agree that I need to get the timing corrections fixed in the tune. BQ Tuning has sent another revised tune where the boost and vanos have been altered and the some timing taken out. I'll see if this fixes the timing corrections and oscillation in the boost. With your comment on the weight, do you mean some of these cars have been lightened by removing seats, etc. On the gearing, certainly the less gear changes the quicker the time and speed. I guess that is why a powerglide is so good for drag racing. That is why I tried 2nd gear launches to remove 1 gear change but the transmission doesn't like it. 2nd gear in the 6HP21 is not much different to 1st gear in a powerglide. I believe using a 3.15 diff ratio and 1st gear in a 6HP21 would make the gearing even taller than using a 3.45 diff ratio and 2nd gear.

[NapsterAU]

Originally Posted by Coupes33

Hi Rob. I am running 100% E85 fuel. I agree that I need to get the timing corrections fixed in the tune. BQ Tuning has sent another revised tune where the boost and vanos have been altered and the some timing taken out. I'll see if this fixes the timing corrections and oscillation in the boost. With your comment on the weight, do you mean some of these cars have been lightened by removing seats, etc. On the gearing, certainly the less gear changes the quicker the time and speed. I guess that is why a powerglide is so good for drag racing. That is why I tried 2nd gear launches to remove 1 gear change but the transmission doesn't like it. 2nd gear in the 6HP21 is not much different to 1st gear in a powerglide. I believe using a 3.15 diff ratio and 1st gear in a 6HP21 would make the gearing even taller than using a 3.45 diff ratio and 2nd gear.

+1 to sorting those corrections. I would have expected super knock codes with that amount of corrections.
At points you are pulling back -10 which is way too much and is hurting your runs.

Keen to see your logs after the map revision