Post your base timing table

[iNVAR]

You must be running a MBC. I'm adamantly opposed to those. Otherwise, I don't see how you can say TD isn't required. As you pointed out, different gears will produce boost differently. If you disable TD, you have to tune your car to 5th and make everything below 5th gear suffer. Otherwise, if you tune for 3rd, 5th will spike hard, especially without TD.

[BlazeRex]

I'm guessing you've never had a MBC They're great. Seriously. I have one on my 02 WRX, not the LGT.

 

And actually the opposite on boost spiking. The car will respond much more predictably. What tends to happen is the TD jumps around a bit in upper gears. Without TD, The turbo does how it wants and responds smooth as glass. Try it, I was skeptical until I tried it this way.

 

I probably sound crazy over here but I don't jump on bandwagons of what others are doing, I experiment a lot and find what I believe to work best.

[iNVAR]

Nope, never had one. I'm well aware of the pros and cons of them though. I had considered getting a hybrid setup to control the spiking from TD, but decided not to bother with it. If I'm not knocking, the spike is acceptable. Still, just because you can produce 16 # at redline on the VF40 doesn't mean you should.

 

I posted this in a thread where someone was having problems with their boost shooting up too high in the winter. List of pros and cons.

• Hardware wise, the stock BCS can be replaced easily with a 3 port EBCS like I've done. Many options for this are available, with the cheapest being the GM BCS.
   
  
• Tuning the stock or a 3 port BCS well requires more work than just tossing in an MBC and setting all the WGDC values at WOT to 100% and turning a knob.
   
  
• Completely eliminating the BCS disables all the failsafes built into the ECU. If your IAM dips below 1 due to bad gas, you will still be producing full boost. In the OP's case, he hit fuel cut and should've thrown a CEL which on a BCS controlled vehicle would've dropped him to WG boost.
   
  
• Completely eliminating the BCS disables the compensations the ECU allows for. The OP likely would've never had this problem in the first place because the WGDC temperature compensation table would've prevented the problem.
   
  
• Partial Throttle Full Boost (PTFB) is a concern with an MBC.
   
  
• MBC allows for better spool/response without the spike seen by a BCS setup that has an aggressive TD Proportional table.
  
• MBC is adjustable on the fly. Turn the knob and go. BCS requires a map reload, which is a pain using ECUFlash (need a laptop, shut off car, connect green plugs, etc.). At least the AP has realtime maps that load lickity split though without even shutting off the car.
  
• MBC doesn't allow for a boost taper towards red line because if you set it for a certain PSI (16 PSI, for example) it will drive your turbo trying to make that 16 PSI the entire way, which is not productive at redline. You'll essentially be running a flamethrower.
   
  

 

Here's a link to the thread if you want to look. I sort of get into it with another guy who disappears.

 

http://legacygt.com/forums/showthread.php/accidentally-moved-my-boost-controller-help-198837.html

 

Anyway:

 

Last few things I'll say:

Kastley85891, I'm not the only one that says the BCS is better. In the link Diavolo dropped, EFI logics holds the same position I do. And the quote I cited in my last post is from Infamous. Both of them tune TONS of cars, and they tune them well. So as much as you want to believe I'm clueless in my position, I'm not.

 

I'm willing to concede that if you want to get the absolute most of your car and it's not daily driven, then an MBC might get you to that easier and get you slightly better results... but as I pointed out, if you're demanding 18# from a VF40 and using an MBC, it's going to demand that 18# even at redline, which isn't realistic and you'll really be stressing the turbo and losing effieicny, so I still have my doubts about how effective this is.

 

But for all of the other reasons I listed, the BCS should be maintained on something like 99% of cars... the failsafes are gone, and manual adjustments *must* be made for temperatures.

 

Diavolo, you are actually a good example of why I strongly, strongly believe the stock BCS should've been retained. Look at the difficulty you've experienced so far, from temperature fluctuations.

 

Your tuner in that thread says this

 

But it's a fact (there's no disputing) that boost is produced much more easily in the cold than in the heat. You *have* to mess with the MBC after the tune. There's no way for the ECU to compensate!

 

I also wonder if you've been knocking, and I wonder if your IAM has been reduced below 1 which still wouldn't throw a CEL. If it has, your MBC prevents your ECU from pulling boost to protect your engine. Keep that in mind.

 

Anyway, that's the last I'll speak about that. My advice was to go back to a stock BCS. And it was the same advice in your other thread, and numerous other people suggested the same.

 

But if that's something you're absolutely not willing to do, then do what Kastley85891 suggested and see if there's a leak in the line running to the WG.

[iNVAR]

Also I see you have an 02 WRX. If you had a lot of experiencing tweaking that and your opinions are formed from that, then consider that the 32bit ECU of the LGT and the TD tables are much better than the 16bit ECU's ones. Even better would be an actual full PID controller, but PI works well enough mostly. merchgod (developer of RR) refers to the 16bit ECU as just a PD controller.

[BlazeRex]

Yes, I had originally formed this idea when tuning my 2002, but I also re-investigated the idea when I had my 2005 STi (and a couple CAN customer cars), which are 32 bit as I'm sure you're aware, and came away with the conclusion that the 32 bits are definitely better with TD, but they're not perfect either. Tuning with TD isn't incorrect, but neither is tuning without it, as long as you have other comps properly in place.

 

Also, forget the notion of running the vf turbos past their efficiency point, that really never happens. vf48/52 etc will keep pumping close to 30psi tapering down to about 12-15 at redline. If anything some weak actuators actually run less boost up top than they should.

 

Also, whoever is having temp and boost swings cause any serious knock has a problem with other aspects of the tune, not the boost mapping. The way I tune, boost could really be virtually anywhere, and the timing will compensate itself.

[fahr_side]

Mechanical boost is indeed super smooth, but for reasons stated, unforgiving when shit happens. The TD system plus compensations isn't perfect, but even with per-gear boost control in use (on later WRX ECUs), it's still necessary.

[BlazeRex]

Its not even close to as necessary as you all are making it out to be. Nice to have? Sure, but getting an EXACT boost number isn't all its cracked up to be. Normal temperature swings cause MUCH larger air flow differences than slight variations in boost pressure. Plus TD on 08+ STIs are a real PITA...

 

I personally value smoothness and predictability than exact boost numbers.

[iNVAR]

If you believe MBC is superior to an EBCS, suit yourself, but I'll say this:

 

If it were superior to EBCS, MBC would be what comes stock from the family. Subaru didn't spend thousands upon thousands of dollars on R&D to implement EBCS for nothing. MBC is a cheaper and more rudimentary system to implement than an EBCS.

 

Neither you, nor the other guy have been able to dispute my list of pros and cons of MBC vs EBCS and like I pointed out in the other thread: EFI logics and Infamous, both reputable tuners, apparently hold the same position I do.

 

It's not just a matter of maintaining boost targets, it's also a matter of hitting the boost targets under varying conditions, and having the car do that on its own. It's a matter of having safety checks and giving the ECU the ability to cut you to WG boost if the need arises (bad gas, for example...) or climbing a few thousand feet if you decide to ascend a mountain and not have to worry about turning the knob.

 

And 4 letters: PTFB.

 

Also, you keep saying the turbo isn't outside of the efficiency range, which simply isn't true. Every turbo has an efficiency range and when you start operating outside of that, it won't perform as well. Trying to drive your turbo to 18PSI the whole time isn't productive AND it'll likely reduce your turbo's life somewhat.

 

You say you value predictability but then you don't even produce boost that follows an expected plot. I don't see how you would consider an EBCS UN-predictable when a properly setup map will have boost produced very, very close to the curve, like you can see for my own pull and plot.

 

Also, I have to revisit this image you posted:

http://legacygt.com/forums/attachment.php?attachmentid=153667&d=1370309477

Am I reading this wrong? Green is your boost, and red/brown is also your boost, but at higher IAT?

[BlazeRex]

MBC's spool quicker and are very smooth, but it doesn't have boost cut for IAM which is why most of my customers, unless they insist, have EBCs. Its just the way I set up my EBCs, I set target boost as a ceiling just below fuel cut in case it does go too high.

 

PTFB is perfectly fine, just slightly inefficient for fuel economy.

 

You wont make 18psi the whole way out, so targeting 18 the whole way or following the target curve exactly will make no difference on boost past the max boost point. Its all decided on WGDC after that.

 

You will also not exceed the point where the turbo stops flowing air. I guarantee you that, and that comes from many VF setups I've tuned.

 

Also, no that's boost on the left and right axis'. I got lazy and pulled a random log that didn't have WGDC logged haha

[fahr_side]

Every tuner has his/her own tuning methodology and I respect that. Like iNVAR I value the ability of the ECU to drop boost at low IAM on street-driven cars. To me, it's worth the extra time to deal with TD and comp table setup. My customers prefer this approach when the choices are laid out for them.

[chimera]

MBC / EBCS hybrid? http://forums.nasioc.com/forums/showthread.php?t=602674

[fahr_side]

MBC / EBCS hybrid? http://forums.nasioc.com/forums/showthread.php?t=602674

 

Yes, this has its advantages. Use this on turbos that have a tendency to spike hard or spool earlier than you'd like at smaller throttle inputs. Still requires some tuning of TD though.

[BlazeRex]

Yes, this has its advantages. Use this on turbos that have a tendency to spike hard or spool earlier than you'd like at smaller throttle inputs. Still requires some tuning of TD though.

Depends on how you set it up. I set it to use the MBC as the primary boost control, and the EBC for boost cut and some boost taper.

 

Some people (as appears do you) use the MBC as a 'fuse' to prevent boost spikes, and rely on the EBC as the main boost control.

 

Also, like you said, everyone has their own methodologies and that's fine. There really no wrong way to set up boost or throttle tables (as long as their is no severe overboosting or spiking), its all based on taste/preference.

[iNVAR]

I had much more long winded response but it would be TLDR, so I'll summarize my thoughts:

 

- you make different boosts in different gears, as you stated and know, due to different loads

 

- MBC is great for 1st and 2nd because it'll keep the WG shut instead of waiting for TD to compensate, therefore improving spool and holding boost better

 

- in 3rd and 4th and 5th gear where there is more load, however, you will be overdriving the turbo. what i mean by this is that at a certain point after you hit your peak (WG cracks open to hold peak), the turbo will fall outside of its efficiency range and the MBC will have to shut the WG again to drive the turbine harder. in these higher gears, you will be spinning it a LOT faster with severely diminished returns. lots faster = lots more heat = not as good for combustion/power. also more heat = more stress on turbo. when you're in your efficiency range, WGDC relates directly with the amount of boost you produce. 5% added WGDC may increase boost by 2 PSI (on my 3 port. I have to re-examine my logs) but when you're way outside of the efficiency zone trying to produce another 2 PSI, it may require another 10%, and it may still not be enough. hell, you could probably weld your WG shut and run your car in 5th gear and still not produce anywhere near 18PSI at redline and your turbo would turn into a flamethrower and have greatly reduced life.

 

i posted the pros and cons in the earlier post which i thought made it pretty clear that an MBC, IMHO should not be used on a street driven car.

 

You wont make 18psi the whole way out, so targeting 18 the whole way or following the target curve exactly will make no difference on boost past the max boost point. Its all decided on WGDC after that.

on an MBC car with no ebcs, those tables don't matter at all since the only thing controlling boost is the MBC. so what do you mean by "Its all decided on WGDC after that" when you have no control over WGDC? you have no boost solenoid in the system, there IS no WGDC.

[BlazeRex]

I thought we were still talking about TD lol All true what you are saying, except the diminishing returns. The returns from adding more boost are there, just on a smaller scale.

 

MBCs allow for the quickest reliable spool, hence why I like them, but yes they do have the pitfall of not being able to pull boost.

[iNVAR]

except the diminishing returns. The returns from adding more boost are there, just on a smaller scale.

That's what diminishing returns means.

[BlazeRex]

That's what diminishing returns means.

Haha yes, true... And I reread what you wrote, Its the part about overrunning the turbo I don't agree with. At the boost pressure we're talking, that's not going to happen. The turbo spins the fastest at redline. At redline, boost is virtually fixed by the setup (not boost controller setup) anyways. That's what I'm trying to get at.

[iNVAR]

Again, that's my point. Spinning a turbo faster to try to produce a boost number that simply isn't producable because it's out of its efficiency range is not good for the turbo and it's not productive.

 

The turbine could be spinning at 100KRPM with your engine at 3KRPM producing 18# because that's how efficient it is but it's not going to be able to produce that 18# at 5.5KRPM even if you're spinning it at 200KRPM. And a MBC dialed in for that 18# will keep trying to make it spin more. I just made up those numbers of course, but the condition I'm describing is exactly what happens. The turbo will also start pushing out hot air. You get diminishing returns of boost from pushing exhaust into the turbine once you're outside the efficiency range.

 

An EBCS allows you to taper off your boost targets, so you're shooting for 18#@3K,60%WGDC and say 12#@6.5K,75% WGDC.

 

With an MBC, you'd hit your 18#@3K,the equivalent of 60% wGDc, and then by redline, you'd be running the equivalent of 100% WGDC (WG fully shut) and you'd get what... 12.5# at best? From driving your turbo that much faster and harder? 0.5# more and a significant increase in heat from friction isn't productive.