Boost Taper with MBC Evo 9 MR
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From: Tri-Cities, WA // Portland, OR
Originally Posted by ROK EVO
Is the taper less evident on 5th (or 4th) gear?
Originally Posted by jcsbanks
Evo kid, my reply on page 1 to you was based on datalogs of the factory map sensor and digital read out on AVC-R. Can you give me info on the taper on the 8?
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Joined: May 2006
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From: UK
Thanks for the data. What I'm interested in particularly is the taper when the turbo is maxxed out - ie can you get x PSI more at 7000 RPM on an 8 vs a 9? Is anyone holding over 21 PSI at 7000 RPM on stock actuator on an 8?
If Evo kid's point about the MIVEC is correct, then the higher VE from the MIVEC engine is like the turbo blowing into a bigger engine than the 8, so it is not surprising that the exhaust manifold pressure blows open the wastegate at a lower boost level.
If Evo kid's point about the MIVEC is correct, then the higher VE from the MIVEC engine is like the turbo blowing into a bigger engine than the 8, so it is not surprising that the exhaust manifold pressure blows open the wastegate at a lower boost level.
Maybe the MBC's true setting (ball lets air pass by) is low - like 19 psi - and the 23 psi is really a spike from lack of air getting to WGA from MBC (if there's a long hose from MBC to WGA - like 3' or poor quality tubing, spikes would be likely).
A IX can produce more volume and pressure upon spool than a VIII anyday, so the MBC has to be that much more responsive regulating WGA supply (mechanical) air to achieve the boost equal to MBC spring. As soon as WG starts to open, boost was allready 23psi
You do not have to live with taper or get a larger turbo to maintain respectful topend pressure, especially with the IX.
Tight and responsive MBC/WGA plumbing can easily give you like 23spike and tapering no less than 21.
Another thing to consider is the OEM BOV not only has a diaghram port on top, but one internal that assists manifold evac and it does it by venting boost during build up - the more boost you build, the more it lets go by
good luck - check 4 leaks 2
A IX can produce more volume and pressure upon spool than a VIII anyday, so the MBC has to be that much more responsive regulating WGA supply (mechanical) air to achieve the boost equal to MBC spring. As soon as WG starts to open, boost was allready 23psi
Basically, you can live with the taper and enjoy the low end sppol up and torque or go with a bigger turbo that will eliminate the taper and lose early spool up and torque.
Tight and responsive MBC/WGA plumbing can easily give you like 23spike and tapering no less than 21.
Another thing to consider is the OEM BOV not only has a diaghram port on top, but one internal that assists manifold evac and it does it by venting boost during build up - the more boost you build, the more it lets go by
good luck - check 4 leaks 2
Originally Posted by ak47po
You need a WORKS P2 brain flash.
WORKS was the very first EVO tuner in the U.S. to reflash the factory ECU. Our Software Engineers have been disassembling US-Spec EVO VIII code since April '03 and have software control unparalleled in the industry. Nothing comes close to the plug-and-play performance and reliability of the WORKS Brain Flash series.
The Brain Flash P2 represents an upgrade to the Brain Flash P1 by increasing and holding the factory peak boost level. This WORKS flash is very unique in that NO other flash on the market can properly control boost internally through the factory ECU! The P2 provides addictive acceleration by eliminating the factory boost taper in the higher RPMs. By eliminating this boost drop-off, the total area under the torque and horsepower curve is enhanced and the car responds with increased urgency as the power band winds up.
WORKS' Engineers spent many months analyzing the stock boost control system. Then improved upon the factory design to bring you a true peak and hold system. There is no bypassing the wastegate solenoid with a questionable bleeder/emulator, no attempt at fooling the ECU logic and no manual boost controller (that can change with weather and taper boost) nor electronic boost controller is necessary! This proprietary system represents a tried and true, reliable design that takes the safe factory system one step further. With the unique WORKS Boost Hose Assembly (which appears identical to stock), we are able to modify the wastegate solenoid ECU maps. WORKS has total boost control. We can raise, lower, make a sine wave, or even have the boost taper upwards all through the factory ECU! Of course the P2 upgrade involves a comprehensive performance ECU remapping of the air/fuel ratios and ignition timing to compliment the rock-solid peak boost. Expect peak gains in the mid 20s with total area under the power curve increasing by 10%-20%. US-Spec EVOs do not have a top speed limiter to remove but we have raised the RPM limit to 7800 and the P2R version available in the WRP (WORKS Racing Program) raises the launch control RPM limit at no extra charge.
The ECU can be reprogrammed back to stock if necessary and, of course, is backed by our Factory-Matched Warranty.
*Custom tuning is also available. From just one gear at Wide Open Throttle all the way to multiple gears at various throttle positions. Please call for details.
Application: '98-'06 EVO V/VI/VII/VIII/IX including RS and MR. Please download and complete the Brain Flash Checklist when ordering.
WORKS was the very first EVO tuner in the U.S. to reflash the factory ECU. Our Software Engineers have been disassembling US-Spec EVO VIII code since April '03 and have software control unparalleled in the industry. Nothing comes close to the plug-and-play performance and reliability of the WORKS Brain Flash series.
The Brain Flash P2 represents an upgrade to the Brain Flash P1 by increasing and holding the factory peak boost level. This WORKS flash is very unique in that NO other flash on the market can properly control boost internally through the factory ECU! The P2 provides addictive acceleration by eliminating the factory boost taper in the higher RPMs. By eliminating this boost drop-off, the total area under the torque and horsepower curve is enhanced and the car responds with increased urgency as the power band winds up.
WORKS' Engineers spent many months analyzing the stock boost control system. Then improved upon the factory design to bring you a true peak and hold system. There is no bypassing the wastegate solenoid with a questionable bleeder/emulator, no attempt at fooling the ECU logic and no manual boost controller (that can change with weather and taper boost) nor electronic boost controller is necessary! This proprietary system represents a tried and true, reliable design that takes the safe factory system one step further. With the unique WORKS Boost Hose Assembly (which appears identical to stock), we are able to modify the wastegate solenoid ECU maps. WORKS has total boost control. We can raise, lower, make a sine wave, or even have the boost taper upwards all through the factory ECU! Of course the P2 upgrade involves a comprehensive performance ECU remapping of the air/fuel ratios and ignition timing to compliment the rock-solid peak boost. Expect peak gains in the mid 20s with total area under the power curve increasing by 10%-20%. US-Spec EVOs do not have a top speed limiter to remove but we have raised the RPM limit to 7800 and the P2R version available in the WRP (WORKS Racing Program) raises the launch control RPM limit at no extra charge.
The ECU can be reprogrammed back to stock if necessary and, of course, is backed by our Factory-Matched Warranty.
*Custom tuning is also available. From just one gear at Wide Open Throttle all the way to multiple gears at various throttle positions. Please call for details.
Application: '98-'06 EVO V/VI/VII/VIII/IX including RS and MR. Please download and complete the Brain Flash Checklist when ordering.
I could have sworn AL said he was first? But you can remove the taper with ecu flash, just takes a lil trial and error just becareful.
Originally Posted by mchuang
But you can remove the taper with ecu flash, just takes a lil trial and error just becareful.
Most of the taper is being caused by WG and BOV opening, thats with no boost leaks. Turbo may run out of output in first from 5000 rpm up
why can't you just ramp up the #'s in the boost "map" in the ROM?
I know the turbo will still run out of steam at high rpm, but on my subaru I could ramp up the Waste gate duty cycle up top to reduce boost falloff.
I take it that doesn't work on Evos?
one can overdo it of course, and run the turbo at a pressure ratio that is so inefficient that the car would be better off with less boost and a leaner A/F, but on out lil 2liter I think a big 16G would be able to keep up...
:flamesuit on:
I know the turbo will still run out of steam at high rpm, but on my subaru I could ramp up the Waste gate duty cycle up top to reduce boost falloff.
I take it that doesn't work on Evos?
one can overdo it of course, and run the turbo at a pressure ratio that is so inefficient that the car would be better off with less boost and a leaner A/F, but on out lil 2liter I think a big 16G would be able to keep up...
:flamesuit on:
Last edited by texrex2002; Oct 24, 2006 at 02:20 PM.
Ok for those that were saying works doesnt elimante taper, your full of SH*T. They do have it figured out quite well. I have had it on the dyno with a 3 bar map hooked up, and boost was rock solid all the way to 7500. I have to agree with the fuel and timing though, my afr's were set at 11.1, timing changed not too drastic, and mivec was stock. I would have liked to see more of a change with the tune, but the tune plus exhaust dropped me a full second in the 1/4. It was a good learning experience on how the ecu is controlling boost as well. Ive managed, with help from others on this board, to change my boost up and down from what works had it at.
[quote]why can't you just ramp up the #'s in the boost "map" in the ROM?[quote]
No flames from me on this one. Thats actually exactly how I have raised my boost from my works flash. Set desired engine load at 159 and ramp wg duty up from around 55 or so, sitting at 99.5 at 7k right now from memory. That gives me just a touch of taper, and I could ramp up more, but its hitting 1.5bar full boost and tapering to 1.4. Im happy with that on 91 octane.
For 100 octane, I have a special gift of green from someone that will remain nameless haha. Im sure he knows who he is from that statement, but his map boosts to about 1.7 and tapers to 1.4-1.5 at 7500.
[quote]why can't you just ramp up the #'s in the boost "map" in the ROM?[quote]
No flames from me on this one. Thats actually exactly how I have raised my boost from my works flash. Set desired engine load at 159 and ramp wg duty up from around 55 or so, sitting at 99.5 at 7k right now from memory. That gives me just a touch of taper, and I could ramp up more, but its hitting 1.5bar full boost and tapering to 1.4. Im happy with that on 91 octane.
For 100 octane, I have a special gift of green from someone that will remain nameless haha. Im sure he knows who he is from that statement, but his map boosts to about 1.7 and tapers to 1.4-1.5 at 7500.
Last edited by 20psiMR; Oct 25, 2006 at 04:45 AM.
Originally Posted by 20psiMR
Ok for those that were saying works doesnt elimante taper, your full of SH*T. They do have it figured out quite well. I have had it on the dyno with a 3 bar map hooked up, and boost was rock solid all the way to 7500. I have to agree with the fuel and timing though, my afr's were set at 11.1, timing changed not too drastic, and mivec was stock. I would have liked to see more of a change with the tune, but the tune plus exhaust dropped me a full second in the 1/4. It was a good learning experience on how the ecu is controlling boost as well. Ive managed, with help from others on this board, to change my boost up and down from what works had it at.
Originally Posted by 20psiMR
Ok for those that were saying works doesnt elimante taper, your full of SH*T. They do have it figured out quite well. I have had it on the dyno with a 3 bar map hooked up, and boost was rock solid all the way to 7500
i know my friends were playing around with the ecuflash and they were trying to get 22 psi thru the whole time... but its never just 22 psi... they got all the gears on the mr but the 6th gear going 22 psi and tapper down to 21.... 6th gear would just spike 25 and tapper 21....
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Originally Posted by nj1266
I would like to see data to back this up. Since you have been on the dyno (and I presume more than one run) please post ALL the boost plots that you have. I think a lot of us here are skeptical because we have heard this from WORKS, but we would like to see actual data. I have yet to see a boost plot on a stock turbo that does not taper by at least 1-2 psi.