Drag/Acceleration Mods to improve ¼ mile times and unofficial track thread

[xot1]

Do they have a tcu tune ? I know a few of the videos should higher shifting. How much boost are you running in your base tune and do you have xt26?

Yes they change the RPM limit to 7500.
Me? I have no tune for boost. I just use JB4 and my turbos are stock. You seem a bit confused.

 

[Tonkabob]

More tork in cool weather may impact shifts.

Also too little timing drop impacts shifts not sure if it closes throttle though.

Before you raised tork limits did you see this, 4th gear timing pull? This is cool weather so hit around 19 psi rather than 20 or 20.5 (jb4 boost)

 

[xot1]

More tork in cool weather may impact shifts.

Also too little timing drop impacts shifts not sure if it closes throttle though.

Before you raised tork limits did you see this, 4th gear timing pull? This is cool weather so hit around 19 psi rather than 20 or 20.5 (jb4 boost)
View attachment 34022

My logs used to look like this in september:



High boost, no throttle closure, no timing drop.

compared to now :



Low boost, throttle closure, (still no big timing drop)

BTW first pull is 2nd gear 37mph, second pull is 3rd gear 62mph.

 

[Thorne]

if you back off boost a little does it still happen. Sorry for the confusion I misread things while sleepy

 

[Tonkabob]

My logs used to look like this in september:

View attachment 34025

High boost, no throttle closure, no timing drop.

compared to now :

View attachment 34026

Low boost, throttle closure, (still no big timing drop)

BTW first pull is 2nd gear 37mph, second pull is 3rd gear 62mph.

Very strange. You are actually losing speed in 7th gear. But that is a ton of boost for cool weather and would definitely be hitting torque limits there so wonder if you are impacted by some residual impact of those torque limits. Your timing is certainly low but not 0 like what I hit.
20 (jb4) PSI warm weather is no problem but hard to hit that when cool outside. Also keep in mind that 20 JB4 PSI is 21.5+ OBD PSI so we are running a bit more boost than we think.

 

[Terry@BMS]

Timing always drops at the shift per the ECU mapping for torque management. It happens so fast, sometime less than 1/10th of a second, it might occur between logging points and just not appear in your log.

 

[xot1]

Today I did a longer pull than usual to have a closer look at what happens in 7th gear.

(sorry for the quality)

and the JB4 log looks like this:



In the log, the RPM decreases then increases again (which is super weird...) and if RPM was really decreasing I should lose speed, but in the video I am not loosing speed, it is just increasing super slowly and the needle doesnt seem to go backward either.

 

[turboAWD]

Torque converter taking a little while to lock up? I would see similar behavior in 3rd/4th with my Legacy GT when hitting the lock-up point. Before lockup, rpms a bit higher due to "slack" in the system, when it hits locking speed (mapped in the ECU), converter gets locked, and is forced to drop rpm, as the speed hasn't caught up with the rpm value yet. No real noticeable loss of acceleration or speed, but the rpms dropped 2-300, IIRC.

Mind you, in the LGT, it happened around 3200 or 3700 rpm, IIRC, not 5000+. But it was somewhat similar.

Edit: the fact that it seems to happen RIGHT at 5000 rpm seems like it's maybe a programmed converter-lock-up point in 7th? Again, just brainstorming - not claiming I'm super knowledgeable or anything.

 

[Tonkabob]

Looks like you are just maxed out. Not enough power for the wind resistance. 7th gear was a big gearing jump.

 

[xot1]

Looks like you are just maxed out. Not enough power for the wind resistance. 7th gear was a big gearing jump.

I could have kept going to a higher speed, its just that it starts getting dangerous.

Being maxed out is indeed a possible explanation but it is hard to understand how some other car with a kind of somehow similar configuration (piggyback intake wmi exhaust) keeps going until 300 with not much struggle.
Only difference is
- my exhaust is stock
- I use ethanol vs methanol
- my rear tires are larger diameter than stock

Can't share the video since its not youtube so here are some screenshots, check the video timestamp for yourself:


BTW its a G70 but there's not much of a difference vs. the Stinger from my experience, also a friend of mine pushed the car to 306 with a Stinger.

 

[Tonkabob]

I could have kept going to a higher speed, its just that it starts getting dangerous.

Being maxed out is indeed a possible explanation but it is hard to understand how some other car with a kind of somehow similar configuration (piggyback intake wmi exhaust) keeps going until 300 with not much struggle.
Only difference is
- my exhaust is stock
- I use ethanol vs methanol
- my rear tires are larger diameter than stock

Can't share the video since its not youtube so here are some screenshots, check the video timestamp for yourself:
View attachment 34111

BTW its a G70 but there's not much of a difference vs. the Stinger from my experience, also a friend of mine pushed the car to 306 with a Stinger.

Pretty sure you are maxed 300 kph / 186 mph is damn fast and not much behind your friends. No Exhaust , ethanol and tall tires all hurt you compared to your friends setup. Can you run meth? Makes a little more power and runs a little cooler. More O2. Maybe you would pick up an mph or 2. Also take off your muffler axel back see what happens. Put stock tires back on if you have them. 305!
What is drag coefficient for g70 vs Stinger?
Edit
G70 .28 with 18s and .29 with 19s
Stinger .30

 

[xot1]

Torque converter taking a little while to lock up? I would see similar behavior in 3rd/4th with my Legacy GT when hitting the lock-up point. Before lockup, rpms a bit higher due to "slack" in the system, when it hits locking speed (mapped in the ECU), converter gets locked, and is forced to drop rpm, as the speed hasn't caught up with the rpm value yet. No real noticeable loss of acceleration or speed, but the rpms dropped 2-300, IIRC.

Mind you, in the LGT, it happened around 3200 or 3700 rpm, IIRC, not 5000+. But it was somewhat similar.

Edit: the fact that it seems to happen RIGHT at 5000 rpm seems like it's maybe a programmed converter-lock-up point in 7th? Again, just brainstorming - not claiming I'm super knowledgeable or anything.

That explanation also makes sense to me. I am no expert either so I will ask around.

 

[xot1]

double post

 

[Tonkabob]

New Dragy record. No WMI, no brake mods, 18 Jb4 PSI. Stacked the Jb4 on Tork ECU tune to add a little high rpm boost. 35 degrees and 30 foot elevation. Should be able to hit 11.4s.

 

[xot1]

Congrats now show us a 11.4

 

[CoconutRob]

Flash tuners typically enrich the low end AFR target and disable lean spool mode, providing a fixed AFR target across the power band. I've always been convinced they do it to make their logs prettier and not for any tuning reasons, as both provide drawbacks (more fuel demand causing fuel pressure crashes, potentially slower spool up, etc), but as many know trying to reason with some of these flash tuners is like pissing in the wind.

With a JB4 flash fuel wires are only needed if you want to change the air/fuel ratios set in the flash. On other applications where this is more popular people tend to lean out the flash air/fuel ratio in the midrange to allow more boost without crashing fuel pressure.

So are you saying If I want to run map 2 out of the box adding fuel wires won't change anything? I ask this because some are saying that map 2 with fuel wires performs better.

 

[Terry@BMS]

New Dragy record. No WMI, no brake mods, 18 Jb4 PSI. Stacked the Jb4 on Tork ECU tune to add a little high rpm boost. 35 degrees and 30 foot elevation. Should be able to hit 11.4s.
View attachment 34313 View attachment 34314

Congrats! That cold weather really kills the factory boost target. Try IAT spoofing up a bit?

 

[Terry@BMS]

So are you saying If I want to run map 2 out of the box adding fuel wires won't change anything? I ask this because some are saying that map 2 with fuel wires performs better.

If you're running the JB4 with a flash the first step is to log map0 (flash only) so we can look at your flash and decide the best way forward on JB4 settings for your specific tuning objectives. With a flash and the JB4 you may or may not find a benefit with fuel control wires, it depends on the flash, so for starters just leave them disconnected.

 

[CoconutRob]

If you're running the JB4 with a flash the first step is to log map0 (flash only) so we can look at your flash and decide the best way forward on JB4 settings for your specific tuning objectives. With a flash and the JB4 you may or may not find a benefit with fuel control wires, it depends on the flash, so for starters just leave them disconnected.

Ok thanks

 

[xot1]

Congrats! That cold weather really kills the factory boost target. Try IAT spoofing up a bit?

Using IAT spoofing will increase boost more effectively than increasing the boost target?