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10-17-2013, 01:57 AM | #751 |
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Well, they are both kinda right. If you have a Vf
2L ptfb isn't really an issue. A mbc is easier to "tune" but leaves boost adjustments in the hands of the end user for changes in temp. And a mbc also loses the boost drop if you happen to get into limp mode. An ebcs can utilize the iat temp comps for cold/hot temps and also combat ptfb. And it keeps the boost drop in limp mode. A hybrid setup can do all of it. '
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10-17-2013, 02:19 AM | #752 | |
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Quote:
I'm looking for the best way to describe how it needs to be tuned. Both tuners admit they've never had good results with the hybrid so this worries me...seems crazy that all these home brew users are having great success and reputable tuners can't be bothered with this... It's not like it's harder to tune than just a 3-port right??? |
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10-17-2013, 02:24 AM | #753 |
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No it's not harder than a 3port.
Set the mbc where u want peak boost, then do partial throttle pulls to set the wgdc for partial throttle boost. That is if you want to decrease the partial throttle boost. Which was the point of one of the tuners, you really have no reason to want to decrease the partial throttle boost on a 2L Vf unless you want to try and get better gas mileage by limiting the boost. If u can tune an ebcs, u can tune the hybrid setup. It's basically exactly the same as tuning an ebcs except now u have a mechanical cap for peak boost. Last edited by Phatron; 10-17-2013 at 02:35 AM. |
10-17-2013, 02:40 AM | #754 |
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Well, you bring up a good point that I failed to mention, I do want to be able to spend a little more time in closed loop for better gas mileage and lower emissions, less heat etc.
Additionally, since spinning rod bearings on my EJ205 running just a tuned MBC on the TD04, I'm wary of just an MBC now (and perhaps this is irrational but it was super easy to part throttle boost, even in the 2L). That said, I still think it's nice to be able to turn the boost down if I want and when I'm all in on the throttle, I'll take the spool benefits of the MBC. I could be talking out my ass but the V9 JDM EJ207 with aggressive cam angle, big port heads, AVCS and a twin scroll turbo isn't an EJ205...I think this engine is going to spool and spool fast. Stock ROM boost targets are nearly 20psi and it runs tons of timing advance. I just don't know for sure since I haven't exceeded 8psi or 3500 RPM since I have the MBC backed off until I get tuned. Off boost torque is a completely different animal though. Pretty sure even on wastegate pressure I'll put down as much or more as my tuned EJ205 @ 16psi (211 hp / 221 tq on low reading dyno). |
10-17-2013, 03:04 AM | #755 |
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The whole concept is just kinda weird in itself. Everybody always wants the fastest spool, but yet wants to utilize this setup to detune the partial throttle boost.
If you want to throw another wrench in the equation go checkout perrins dual ebcs setup. |
10-17-2013, 07:40 AM | #756 |
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10-17-2013, 11:36 AM | #757 |
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I like a progressive power delivery that correlates to how far I press down the throttle pedal...
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10-17-2013, 03:55 PM | #758 |
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You're 100% correct, if iirc it's down around 75% throttle on a 2L vf. It's just not as pronounced of an issue as a 2.5L tdo4 car. And most people don't complain and want their boost turned down at 75% throttle. But it's really up to each individual and how they want the car to feel at certain throttle increments.
I just think of ptfb as how it effects daily driving. Like driving up a hill on the freeway. On a td04 or Vf 2.5L the car is gonna be boosting with very little throttle depression and it makes the gas mileage suck. I just assumed that "partial" throttle meant 50% or below. When most people are above 50% their intention is to have power. But like I said its all in each persons personal preference. Last edited by Phatron; 10-17-2013 at 04:08 PM. |
10-17-2013, 05:25 PM | #759 |
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My 2 cents.
I think it's probably worse to try and push the tuner to do something they don't want to do. If the EBCS tuner guy is good, I'd just have him tune your car and be done with it. If later you want to mess around and switch to hybrid (or get someone to help you mess around), you can basically leave most of the map the same and just set it for 100% WGDC at full throttle to let the MBC take over (and do things like eliminate the CL to OL delay, etc...I'll let smarter guys than me comment on details). I think you'll get frustrated pushing the tuner and he'll get frustrated too. The other option is to drive a further distance (or do an e tune) and find someone who is good and happy to tune a hybrid setup. |
10-17-2013, 06:21 PM | #760 | |
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I'm just shocked that none of them can come up with what seems to be a valid argument against it other than, "When we've tried it in the past, it just didn't work well." This leads me to believe there is a high factor of people setting this up wrong which accounts for the poor performance these tuners see. I'm confident I'll set it up well as far as installation so the rest is on the tuner... Secondly, I already have an MBC and I purchased a 3-port. I guess I could sell the MBC but I figure I might as well set up what I want now. I think CL to OL delay is one of the first things tuners get rid of, MBC or not. As I understand it, having set parameters for when you transition to OL are good but the actual delay itself is emissions driven and unnecessary. The tuning strategy points in the article below are some of what's confusing me, especially the parts about setting underboost Turbo Dynamics correction to 100% for 16-bit ECU's and setting boost targets slightly higher than the WGDC will allow for. http://thefactoryfiveforum.com/showt...bilizing-boost |
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10-18-2013, 09:06 AM | #761 | ||
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at 60% tps and up, regardless of load/rpm, minimum afr is set to 12.5:1 for best torque. as a result, unless i'm purposely "getting on it," the car is running stoich fueling. without preventing ptfb this would not be the case, but it is certainly not the only reason to prevent ptfb. every boost control system worth it's salt uses TPS as a primary determiner of wastegate position, since that is the ONLY input the driver has to inform the car of requested torque. i simply cannot understand the rationale behind allowing the wastegate to be either completely uncontrolled (below mbc cracking point) or clamping to a fixed output (above cracking point) with nothing in between. i did that 10 years ago, and IMMEDIATELY took steps to remediate it, because it sucked. the throttle should not be an on-off button--the amount of airmass passing through the throttle should be VERY predictable wrt throttle angle. with an mbc only setup, this is decidedly not the case, as the compressor output pressure can be anywhere between 0 and mbc cracking pressure, which is ALWAYS greater than 0 and wastegate pressure. that difference on my car is 27psi (mbc) - 12psi (wg) = 15psi. assuming a single throttle angle, that's a massive difference in maf. no thanks. |
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10-18-2013, 09:26 AM | #762 | |||
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10 years ago, there were probably around a dozen people on the board who tuned subarus. the reason why is because the tuning tools (ems hardware/software, dynos, widebands) were mega expensive and proprietary. therefore tuners had to be affiliated with a business with deep pockets to invest. the overall depth of knowledge was shallower, of course--we just knew less about the intricacies of the systems--but knowledge of tuning was a lot more concentrated. fast forward a decade and what do we have? people popping up left and right, calling themselves "tuners." the bar for entry is lower than it ever has been--and for people who don't know enough to DIY, this low bar seems ideal, as the increased competition and decreased overhead depresses the cost of getting a tune. but who are these people offering tunes? it is easy to impress someone who doesn't know very much. the very short list of half a dozen or so people i would ever allow to tune my car is the same list it was 10 years ago. that should tell you something. Quote:
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10-18-2013, 12:25 PM | #763 |
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What are your egts at redline running 12.5? Is that from a tail pipe wb or one in the dp?
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10-18-2013, 02:25 PM | #764 | |
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Agree, that's why I was careful to say "established tuners" as both tuners in question are affiliated with a brick and mortar shop, have 9+ years of tuning turbo Subarus and are charging me what I consider to be above average amount of money for their time...
But I know what you mean, I have a photography business that I started when buying a DSLR was also very expensive and have invested upwards of $20,000 in photo gear. Now that a DSLR can be had for ~$500, every stay at home mom in america is now a "photographer." :P Quote:
My plan is to mount the 3-Port where I want it, run the 2 hose lengths from the MBC to the 3-Port, making them as short as possible and then determine where in this line I want to cut and install the T-connection, then routing connection hoses to the compressor nipple and WGA. Has anyone played with installing the T-connection closer to the MBC or EBC? Is it preferable to install it at an equal distance between them? At this point, regardless of tuner preference, I don't think I'm going to change my mind about this setup, I'm gonna do it anyway haha... |
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10-18-2013, 02:53 PM | #765 |
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keep in mind that with an interrupt topology you're basically sending a pressure signal. unlike a bleed based system, ie oem, absolute flow rates should be nearly zero. there is a prodigious supply of signal air coming from the compressor nipple.
in other words, don't sweat it. |
10-18-2013, 08:05 PM | #766 |
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the cost of entry is still pretty damn high. my dyno payment is 3x my mortgage.
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10-19-2013, 06:45 AM | #767 |
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How many etuners use dynos?
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10-28-2013, 04:30 PM | #768 | |
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11-12-2013, 12:35 AM | #769 |
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Hybrid boost control is much better when its ran in series, not parallel. Then the MBC sets the spike and the 3port eliminates the taper.
Really though, hybrid boost control is over rated. In most cases, you can achieve the same boost curve/reliability with just a MBC or 3port alone. |
11-12-2013, 01:25 AM | #770 |
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I'd imagine many of us to not want to keep the boost flat (eliminate taper) when the trade-off is an inefficient turbo blowing hot air up top.
When run in parallel, it is nice to be able to limit partial throttle boost while having MBC control when at WOT. If your aim is to reduce/"eliminate" the taper, you won't achieve that with the MBC alone. I personally like the physical cap with the MBC and as spool-happy as my turbo is, I like to be able to keep my partial throttle boost set lower when in situations like passing in 6th gear. I have also seen an MBC get gunked up and stick allowing a car to over-boost. In a hybrid situation, the EBCS can be use to prevent you from overshooting to 30+ PSI when you were initially running much lower. Other than trying to eliminate the taper up top, I don't see how it's much better in series. |
11-12-2013, 04:20 AM | #771 |
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being an idoit.
Last edited by Boosted Tuning; 11-12-2013 at 02:58 PM. |
11-12-2013, 08:09 AM | #772 | ||||||||
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an mbc does not taper. either a) the turbo runs out of breath or b) sections of the intake tract outside of the feedback loop create pressure drop due to flow restriction. Quote:
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what is not easy is tuning an acceptable tradeoff of response time vs stability. it is ALWAYS a compromise with ANY feedback based boost control, and it is far worse with EBC than with mechanical methods. Quote:
i do know how. i also know it creates other issues with stability and drivability, because i've done it. Quote:
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11-12-2013, 12:16 PM | #773 |
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/\ That.
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11-12-2013, 12:58 PM | #774 |
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being an idoit.
Last edited by Boosted Tuning; 11-12-2013 at 02:58 PM. |
11-12-2013, 01:18 PM | #775 | |
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As far as the motor allowing the turbo to over-boost. I prefer to use the EBCS to start dropping boost over fuel cut. I don't think anyone is "afraid" of PTFB, but on a street car, it can get annoying when the car wants to take off on you when you're just trying to make a simple pass or increase speed. Just how are you getting rid of taper with an MBC-only setup? Exactly how did you set it up in parallel and how did you configure it in the ECU? |
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