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JB4 18.7psi @3,500rpm log w/ E85+93octane
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01-18-2013, 12:11 PM | #24 |
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That my friend is very true. My car is a garage queen. I only push 16.5 max! The maps and firmware that I am using is the older stuff before the aggressive maps so my boost curve is def a drop different. My boost curve is more linear for sure. Either way I still stand by what I stated running 19psi with stockers is asking for trouble and especially if the car doesn't have the supporting mods.
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01-18-2013, 01:15 PM | #25 |
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It really does, but i think it has to do more with rolling into the throttle instead of going right to WOT. here is a better log with improved spool speed going straight to WOT, I dialed the boost down to target 17.9, I hit 18.4psi. I'm still running 11C for fuel economy reasons and I like the exhaust sound with the opened wastegates with a value set at 0 (I know, weird that I'm making a thread like this).
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Prior Car:'14 Audi S5 3.0t DSG [ APR ECU/TCU | Pullies + basic bolt-on mods | 10.861@127.90mph ] Current Car: F82 M4cs | TT-RS | On Order: i4 M50 Last edited by spool twice; 01-18-2013 at 05:13 PM.. |
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01-18-2013, 01:29 PM | #26 |
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Boosting at 19 PSI at 3500 RPM and boosting at 19 PSI at 7000 RPM are two very different values in the realm of the turbo world and efficiency.
We have to remember 19 psi doesn't tell us anything about how fast the turbo's are actually spinning. Remember that 19 psi is actually a so called back pressure in the engine. Here is a basic way of looking at boost pressure: At low RPM there is only so many revolutions where the engine can use the air given. By no accident as the RPM's increase the ability to feed more air is possible, and more of it and at increasing rate. Lets say you have a fan blowing into the engine at a set rate of 300 CFM. Using arbitrary numbers at 3500 RPM you may see 3 PSI. However, if you increase the engine speed to 7000 RPM, keeping that same CFM you might only see 1 PSI. That is because there is less back pressure as engine RPM increases you can utilize that air. The same principal is here. The turbo's arent actually spinning any faster to make 19 PSI at 3500 RPM. In fact they may be spinning less at 19 PSI 3500 RPM then at 14 PSI at 7000 RPM. (I dont actually know I'm not looking at an efficiency graphs, just trying to make a point). In a real world scenario: My last car was supercharged. As RPM's increased so did the speed of the blower. Under normal circumstances so would the boost pressure. However, if you altered the intake valve timing for more or less overlap that would change the actual boost pressure the motor was seeing. This overlap or lack there of is a restriction and by no accident you could inflate or deflate this number depending on the restriction. I hope one of these examples can illustrate that boost pressure is a measure of restriction and not a measure of actual turbine speeds. |
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01-18-2013, 05:28 PM | #27 | |
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The boost value's are (I have slightly modified AFR values too): 1500 15.4 2000 16.7 3000 17.8 3500 18.5 4000 18.5 4500 17.8 5000 17.4 5500 16.9 6000 14.2 6500 12.2 7000 10.9 I originally started at 19.5psi in the midrange, but I ended up with avg ignition correction value of 1.4. I started to play around and taper the boost in the midrange until the correction value was 0, then dialed back the boost an additional .5psi in the midrange because my car reliably overshoots target. I dialed back boost, too much wheelspin, even starting in 3rd gear @ 2,500rpm. I reckon i'll have better traction when the temps aren't hovering around 60F. 1500 15.4 2000 16.7 3000 17.3 3500 17.5 4000 17.5 4500 17.3 5000 17.2 5500 16.8 6000 14.2 6500 12.2 7000 10.9 When I run methanol (which I haven't had time to install my replacement pump), I taper to 14.7psi at redline with the additional fueling it brings. I prefer the settings in bold for the time being, I may consider rerunning close to 19psi once it gets warmer and I can get the methanol pump back on.
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-Loe P.-
Prior Car:'14 Audi S5 3.0t DSG [ APR ECU/TCU | Pullies + basic bolt-on mods | 10.861@127.90mph ] Current Car: F82 M4cs | TT-RS | On Order: i4 M50 |
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01-18-2013, 07:30 PM | #28 | |
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thank you so much! what is your open loop fueling set at? |
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01-18-2013, 07:32 PM | #29 | |
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01-18-2013, 08:39 PM | #30 | |
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Then again, I don't know why I just don't keep it set at less tapper and just short-shift right before 6,300rpm, it's easier to set the shift light than hooking up the laptop to change boost values kkashanchi, you can experiement with boost levels up top if your car is happy with it. My AFR value's are +10 from the default G5 ISO values at 3000 and 4000rpm, and +5 @ 2,500 and 4,500rpm. I'm still below the efficiency range/ max boost per rpm of these small TD-03 below 5,000rpm. Try it at your own risk though.
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-Loe P.-
Prior Car:'14 Audi S5 3.0t DSG [ APR ECU/TCU | Pullies + basic bolt-on mods | 10.861@127.90mph ] Current Car: F82 M4cs | TT-RS | On Order: i4 M50 |
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01-18-2013, 08:45 PM | #31 | |
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01-18-2013, 09:35 PM | #32 | |
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Now that my flatline is fixed, I can shift at optimal points... it's a great feeling.
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E90 LCI N54 6AT
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01-19-2013, 11:17 AM | #33 | |
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Same can be said with full throttle at XXXX rpm in 2nd gear versus full throttle and the same XXXX rpm in 5th gear. The loads on the engine are completely different because of the gears and the speed of the vehicle, so therefore the exhaust pressure to spool the turbo will be very different as well. |
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01-19-2013, 11:56 AM | #34 | |
dat boost doe
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arent you running meth? ethanol? leaving so much power on the table. i mean in the garage?
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01-19-2013, 11:59 AM | #35 |
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01-19-2013, 01:47 PM | #36 |
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OP, don't mind the banter. I push the shit out of my stock turbo's because I have a single upgrade in my future. I'm running 100% e85 and 100% meth and target boost at 20psi and hit 21 as I spool up. Almost 75k on the same set of turbo's. I think it's luck of the draw a lot of times, so run'um hard and have fun. Just remember, if you play, eventually you pay.
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01-19-2013, 06:12 PM | #39 |
dat boost doe
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i jest.
you gonna be around next week? im having issues with the lighting coding on the car, and i wanna try out "eco mode"
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01-19-2013, 09:04 PM | #40 |
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How do you guys get the boost to taper as you approach redline. Are you playing with Wastegate DC and changing the numbers at higher boost to increase the taper. I'm getting 13psi at redline and want to limit that.
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01-20-2013, 09:17 AM | #41 | |
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I just set mine to target X boost and let the JB4 take care of the rest and target redline boost within +/- .2psi I cranked up boost from: 1500 15.4 2000 16.7 3000 17.3 3500 17.5 4000 17.5 4500 17.3 5000 17.2 5500 16.8 6000 14.2 6500 12.2 7000 10.9 to 1500 15.4 2000 16.7 3000 17.3 3500 17.8 4000 17.8 4500 17.5 5000 17.2 5500 16.9 6000 15.6 6500 13.7 7000 10.9 so far so good, i upshift at 6300rpm though. I'll probably keep these settings, the car seems happy with it, other than having the sensation of some wheelspin once the boost cranks up at 3000rpm in 3rd gear, but that will bound to be better once the weather gets warmer
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-Loe P.-
Prior Car:'14 Audi S5 3.0t DSG [ APR ECU/TCU | Pullies + basic bolt-on mods | 10.861@127.90mph ] Current Car: F82 M4cs | TT-RS | On Order: i4 M50 |
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01-20-2013, 09:18 AM | #42 | |
Rainbow Racer
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-Loe P.-
Prior Car:'14 Audi S5 3.0t DSG [ APR ECU/TCU | Pullies + basic bolt-on mods | 10.861@127.90mph ] Current Car: F82 M4cs | TT-RS | On Order: i4 M50 |
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01-20-2013, 11:54 AM | #43 | ||||
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In fact if you just got downpipes on a stock vehicle you will notice lower wastegate duty cycles and lower boost, however, you would have about the same power, it would just run more efficiently. The stock tune is based on load. So it does not target higher boost if the efficiency is improved. The intention of this design is to have a car that makes "300 HP" in arizona heat, the mountain of Colorado, or the so called normal weather of NYC. Although in practice they dont actually make the same power, the point is the intention is to target load and use the boost to persuade that power up or down depending on efficiency. If you can increase efficiency either with colder air, higher octane, improved exhaust flow or any other means the stock tune will lower boost because it can make the same power with LESS boost because of the improved efficiency. Maybe someone else can clear up load targeting vs boost targeting in a simpler way. I probably confused everyone haha. Also don't confuse exhaust back pressure with engine back pressure in which case the latter has to do with the heads and valve timing for a good portion of that back pressure. Quote:
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Much easier to ramp up the boost in 3rd of 4th gear compared to 1st and 2nd. Last edited by Jeff@TopGearSolutions; 01-20-2013 at 12:01 PM.. |
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