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

[Tonkabob]

My question is Terry, Do you know of any case of someone using more then 22psi? I don't care if its meth cpi what ever. Were all fighting the same limiter, and we know for a fact i can't be a direct boost value because my car only see 16psi in its basemap and even with racegas and octane booster my car was un happy around 21psi.

So in a effort to make us all faster I'm willing to share knowledge, and if you have Wishes for more chagnes to make a awesome back end flash let me know. We all want whats best for the community and right now and for the forseable future the best setup

Tork Tune (17 base / Peak timing for more) 5 degrees tiiming on shift
JB4 running map6
Intake of your choice
Muffler delete
METH

But as far as I'm aware were all stuck at 22psi

John rans some 25-26 psi dyno runs but throttle was half closed so not hitting the tork limits.

 

[Terry@BMS]

But as far as I'm aware were all stuck at 22psi

I got stuck around 22psi as the JB4 doesn't have WGDC control but I could see power wasn't increasing much over 20psi so quickly figured out the turbos are maxed, at least on factory hardware. Maybe with primary downpipes there is another 10hp in there at higher boost levels but there is a reason cars are hitting 118-119mph traps at both 18psi and 20psi... It's because increasing boost stops adding much additional power around 18psi.

 

[Terry@BMS]

John rans some 25-26 psi dyno runs but throttle was half closed so not hitting the tork limits.

If the throttle is half closed and you're reading boost pre-throttle as most do then it might only be 18psi in the manifold. Depends how you read it. If I recall correctly he made really low power up there too.

 

[Tonkabob]

If the throttle is half closed and you're reading boost pre-throttle as most do then it might only be 18psi in the manifold. Depends how you read it. If I recall correctly he made really low power up there too.

He had boost readings both ways and they were 2 PSI apart, 25 and 27 if I recall. But yes at half throttle I can't see making much power. Just saying the turbos can make that much boost so there is no hard stop boost-wize at 22, but looking more like a hard torque stop around 22 full throttle. As the boost went up the throttle closed more and more, possibly riding that torque limit depending on what RPM he was at. It was only 350ish HP but could have been low RPM.

 

[Thorne]

I got stuck around 22psi as the JB4 doesn't have WGDC control but I could see power wasn't increasing much over 20psi so quickly figured out the turbos are maxed, at least on factory hardware. Maybe with primary downpipes there is another 10hp in there at higher boost levels but there is a reason cars are hitting 118-119mph traps at both 18psi and 20psi... It's because increasing boost stops adding much additional power around 18psi.

IDeally if your able to run 18-19 on pump gas a meth/e85 car should be able to take a few more lbs and still make power due to the extra cooling provided by both fuel types. In general I think the biggest question is whats the limiter were hiting. We know its not some absolute boost number because jb4 guys hit it. I was curious if it was a Max Fuel tirm issue but Water Meth should offset the trims and allow for more boost.


Also since my car has upped WGA volts for its boost... time for more testing.

John can you add Knock1-6 to the JB4?

 

[Tonkabob]

IDeally if your able to run 18-19 on pump gas a meth/e85 car should be able to take a few more lbs and still make power due to the extra cooling provided by both fuel types. In general I think the biggest question is whats the limiter were hiting. We know its not some absolute boost number because jb4 guys hit it. I was curious if it was a Max Fuel tirm issue but Water Meth should offset the trims and allow for more boost.


Also since my car has upped WGA volts for its boost... time for more testing.

John can you add Knock1-6 to the JB4?

I can run 21 psi on e20 with no wmi. Not sure wmi will add much except a 20 degree iat drop.

 

[Thorne]

20 degree IAT should allow for more efficent use of boost... AKA adding a few more bars. Really need someone with Meth who's willing to tinker to test. Terry send me a meth kit and I'll document everything .

 

[Terry@BMS]

IDeally if your able to run 18-19 on pump gas a meth/e85 car should be able to take a few more lbs and still make power due to the extra cooling provided by both fuel types. In general I think the biggest question is whats the limiter were hiting. We know its not some absolute boost number because jb4 guys hit it. I was curious if it was a Max Fuel tirm issue but Water Meth should offset the trims and allow for more boost.

Also since my car has upped WGA volts for its boost... time for more testing.

The limiting factor for power is just the factory turbos and their increasingly high exhaust back to boost pressure ratio. On cars with larger turbos (with similar control system flash+JB4) no issues making bigger power at 26psi and beyond. You can tinker around the edges and maybe pickup 1mph or something relatively trivial but the stock turbos are good for around 120mph on average at normal vehicle weight. That isn't likely to change much.

 

[Terry@BMS]

20 degree IAT should allow for more efficent use of boost... AKA adding a few more bars. Really need someone with Meth who's willing to tinker to test. Terry send me a meth kit and I'll document everything .

We have a clean kit on our site but you'd have to buy it. At least use our injector adapter that thing is super clean for install/removal.

 

[Thorne]

We have a clean kit on our site but you'd have to buy it. At least use our injector adapter that thing is super clean for install/removal.

Researcher discount

Is it possible to install it completely under the hood? I don't want M1 in my car

 

[Terry@BMS]

Researcher discount

Is it possible to install it completely under the hood? I don't want M1 in my car

You'd be on your own to figure that out. The the pump needs to be somewhat isolated from heat or fluid can evaporate in the head and vapor lock it.

 

[Thorne]

Vapor lock is bad ..

 

[Tonkabob]

I can see why you might think that but it's not exactly correct.

Timing is indexed on load (boost). The higher the boost the lower timing is mapped and timing will go down as boost goes up based on it's indexed mapping. Boost is governed primarily by a PID WGDC system with throttle integrated as a backstop. When boost goes over target PID aside the other response is proportional throttle closure. If you get enough throttle closure the difference between TMAP boost (psi in JB4 log) and manifold boost (psi2 in JB4 log) will be greater than the pressure holding the diverters closed and they will blow open. The diverter vacuum line also runs through a solenoid (unless you bypass it) allowing the ECU the option to open it more quickly when letting off the gas at higher RPM to better limit surging and the blow off noise.

Timing is generally reduced to limit toque not boost, for example when you're shifting timing is reduced momentarily and trans line pressure momentarily increased. That is the same behavior you're feeling now in park with the brake wire cut. The car would normally not increase line pressure when shifting in to drive at a stop to avoid that thud but with the cut it doesn't know your foot is on the brake.

On your timing drop as I said I think that is a torque limiter in the flash that needs to be raised. You'll need to do more runs like that to see if it's a trend or an outlier. Torque limiter interactions are normally really aggressive as we see in your log. In a perfect world we'd have boost set point and torque set point in the Stinger JB4 logs like we do on other models. I just haven't found a logging source for those yet to figure out how to log them.

You can see the basic operation in place in your other launch log. The launch boost target normally is around 0psi. Since throttle boost is is greater than 0psi the throttle closes proportionally so that manifold boost maintains the 0psi target. You'll note there is no timing reduction during this despite boost being so far over target throttle is closed to 40%. Timing is right where you'd expect it to be mapped for ~0psi.

View attachment 30626

@Terry@BMS and @Thorne - got a new beast mode brake snip log with -10 in first gear. As I expected it made the overboost worse. This launch was fairly tame, no spin, not that fast but throttle closed pretty quick, blew off, and went into boost limp mode this time and then opened the throttle back up. Pretty cool we can hit 26 degrees advance with full throttle and no boost.
This timing and throttle cut was not Torque based at least since there wasn't much torque. ECU shut the shit down based on the perceived overboost.

 

[Terry@BMS]

That makes sense, I expected we'd find an "over boost" trigger point somewhere. It wasn't that the throttle closed per say but rather that the target changed to 0psi. ECU thinks it's making 25psi here.

I was going to suggest setting a separate boost reduction for brake boosting. You didn't really brake boost much here so not sure if it's going to help but it might. Email me and I'll work up some JB4 firmware and send it over. terry@burgertuning.com

PS. Before doing that do a brake boost log like this on map4 so I can evaluate.

 

[Tonkabob]

That makes sense, I expected we'd find an "over boost" trigger point somewhere. It wasn't that the throttle closed per say but rather that the target changed to 0psi. ECU thinks it's making 25psi here.

I was going to suggest setting a separate boost reduction for brake boosting. You didn't really brake boost much here so not sure if it's going to help but it might. Email me and I'll work up some JB4 firmware and send it over. terry@burgertuning.com

PS. Before doing that do a brake boost log like this on map4 so I can evaluate.

I assume the boost target of 0 is what opened the wastegate and put it into boost limp mode?
Tell me more what you are looking for in the map 4 log? Same as the -10 beast mode launch I just did?

I didn't brake boost long cause you cant, it freaks out pretty quick. On limp snip I can brake boost for 1 second no problem.

 

[Terry@BMS]

Map4 doesn't use the boost by gear settings, it's a separate valet map. Should target around 6psi below stock across the board. I want to see how your flash reacts to it during a brake boost launch. It will also reduce boost when brake boosting while the boost by gear setting currently only does it above 80% throttle which you are not hitting.

The set point changed around timestamp 70. We don't log flash set point (yet) so you can't see it change but can see the effect. Boost dropping (as ECU opens up WGs), throttle moving as boost is momentarily over target, etc. It's basically an "over boost" limp mode from hitting 25psi+ on the ECU side.

 

[Tonkabob]

Map4 doesn't use the boost by gear settings, it's a separate valet map. Should target around 6psi below stock across the board. I want to see how your flash reacts to it during a brake boost launch. It will also reduce boost when brake boosting while the boost by gear setting currently only does it above 80% throttle which you are not hitting.

The set point changed around timestamp 70. We don't log flash set point (yet) so you can't see it change but can see the effect. Boost dropping (as ECU opens up WGs), throttle moving as boost is momentarily over target, etc. It's basically an "over boost" limp mode from hitting 25psi+ on the ECU side.

I didn't make it to test the brake boost, well I got to the location but wasn't worth the car stress. In map 4 I over boosted, limp mode and got a P0200 CEL on the way there just by flooring it. I think I'll just stick with some IAT testing and +1 or +2 PSI in the cold weather.

Weird how I'm still getting full boost - 19 PSI when the car is seeing 25 PSI. Seems like the boost targeting isn't working.

 

[Terry@BMS]

The brake boost launch on map4 is the information I'm looking for. It's going to throw an over boost code at some point during a run so just change to map4 before you go to launch.

Probably your WGDC tables have been increased setting a "floor" on how low boost can be controlled and why you're seeing so much boost in 1st gear preventing you from being able to brake boost like all the other AWD guys. They hit 14psi on launch and don't rip the tires off while yours hits 20psi and does. To get the "good times" that is going to have to be resolved one way or another. Maybe they can set your boost target lower just in 1st gear in the flash.

 

[Tonkabob]

The brake boost launch on map4 is the information I'm looking for. It's going to throw an over boost code at some point during a run so just change to map4 before you go to launch.

Probably your WGDC tables have been increased setting a "floor" on how low boost can be controlled and why you're seeing so much boost in 1st gear preventing you from being able to brake boost like all the other AWD guys. They hit 14psi on launch and don't rip the tires off while yours hits 20psi and does. To get the "good times" that is going to have to be resolved one way or another. Maybe they can set your boost target lower just in 1st gear in the flash.

View attachment 30721

The code was an injector fault if you want to add that to the jb4 app.
I just figured if the upward boost spoofing couldn't control the boost there wasn't much reason to overboost again launching, especially after getting the CEL
@Thorne already has a low boost ecu tune if you can talk him into a snippy snip.
I don't want to use the snip launch much so don't want to change my main stream tune to use it.

 

[Terry@BMS]

What is the code ID? It should be an over boost fault code.

In any event there is definitely more potential wear and tear but you're going to be stuck .2-.3ths behind everyone else unless you get it sorted. On my to-do list is to figure out JB4 EWG control which would make lowering boost on flash maps much more direct.