Boost sag? No, you don't need EBC. - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-18-2010, 05:44 PM   #21
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Put the boost controller at C and be my hero >

And yeah, this is a very concise explanation that should help lots of noobs.
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Old 05-18-2010, 05:45 PM   #22
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I love simple solutions. Why the hell did it take this long for someone to figure this out! (or steal it from someone else who figured it out ;-) )
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Old 05-18-2010, 06:00 PM   #23
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To clarify a tad, I've re-drawn the two charts above to show what's happening both at the compressor outlet (blue line) and after the intercooler (red line), just in case anybody is having trouble visualizing it.


In the first case, we are taking our reference from point A. So even though it appears that boost is dropping off (as we perceive it from the perspective of the manifold) the MBC is in fact doing its job.




Having moved the MBC pickup to point B, we merely change which point in the system is stable.




In both cases, there is a point in the system at which equilibrium is reached. But in the first case, that point is one that we don't particularly care about.
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Boost sag? No, you don't need EBC.-1.gif   Boost sag? No, you don't need EBC.-2.gif  

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Old 05-18-2010, 06:08 PM   #24
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Quote:
Originally Posted by wayne_curr View Post
I swear you could make literally thousands of dollars as a professional technical writer.
Trouble is, then I'd need to start paying for all the artwork that I presently am able to abscond with.

Quote:
Originally Posted by JayL View Post
When will this be available on video?
We are in preliminary negations with DreamWorks, I'm just not real happy about their insistence on Eugene Levy as the voice of the intercooler.

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Originally Posted by cueball1 View Post
I love simple solutions. Why the hell did it take this long for someone to figure this out!
This is old, old knowledge, and just basic fluid dynamics, really. Seems like it's just one of those things that isn't obvious until somebody points it out. Hell, even I needed reminding (by Abe) a few years ago.
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Old 05-18-2010, 06:14 PM   #25
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Well, I think that may be a myth.

Or at least, a half-truth.
It's a full truth. See Mazdaspeed Protege. Also a bad idea for the other reasons you mention.
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Old 05-18-2010, 06:16 PM   #26
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This is old, old knowledge
Indeed. Kinda surprised to see it actually. I thought this was common knowledge by now?
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Old 05-18-2010, 06:51 PM   #27
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Quote:
Originally Posted by Joe Perez View Post
This is old, old knowledge, and just basic fluid dynamics, really. Seems like it's just one of those things that isn't obvious until somebody points it out. Hell, even I needed reminding (by Abe) a few years ago.

That's the problem with old knowledge like this, everyone assumes everyone else already knows it. I haven't seen this topic brought up here in a long time but there have been a number of people with droop complaints.

Now if there was a simple and cheap a solution for over-boosting we'd really have something!
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Old 05-18-2010, 06:52 PM   #28
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Indeed. Kinda surprised to see it actually. I thought this was common knowledge by now?
Me too, but I thoroughly enjoyed the write-up and the visual aids. Needs more special effects and sparkly things to keep the attention of the idiots from CR and other noobs.
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Old 05-18-2010, 07:00 PM   #29
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Sorry for my stupidity, don't mean to muck up a good thread... but what kind of stress (if any) does this put on the turbo? Especially for the guys running 18-20psi. I can imagine that the difference in pressure between the TB and the compressor is pretty large at that amount of boost. Wouldn't the cfm required to keep some peoples max boost push the turbo pretty far out of it's efficiency range?
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Old 05-18-2010, 07:28 PM   #30
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Originally Posted by FRT_Fun View Post
Sorry for my stupidity, don't mean to muck up a good thread... but what kind of stress (if any) does this put on the turbo? Especially for the guys running 18-20psi. I can imagine that the difference in pressure between the TB and the compressor is pretty large at that amount of boost. Wouldn't the cfm required to keep some peoples max boost push the turbo pretty far out of it's efficiency range?
That depends on the efficiency of the individual turbo, doesn't it? What it can flow is what it can flow. In which case, I'd guess that Point A is a better reference to what the turbo is actually doing. There's your efficiency reference. Intake temps are probably a better way to observe what the turbo is doin, as inefficient turbos start making lots of heat.
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Old 05-18-2010, 10:51 PM   #31
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FRT, If you have a large enough intercooler you won't experience as much pressure drop across it at higher flow rates and your turbo won't be as likely to be out of its efficiency range. One of the problems I see is that people often use intercoolers that are sized for little peashooter turbos and 5 to 8psi factory turbo setups instead of the flow rates they actually aspire to run. One should aim for both great IATs and low pressure drop by going large if you really are trying to maximize your efforts. Ideally the air coming out of your intercooler should be as close to ambient temperature as possible. It is hard to do that with a tiny intercooler.
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Old 05-18-2010, 10:52 PM   #32
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+1 for a video release.
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Old 05-18-2010, 11:41 PM   #33
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I really think Joe is thinking of a way to direct his next video...."hmmm, what would be the appropriate beer for this......"

Fantastic writing as usual
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Old 05-19-2010, 01:16 AM   #34
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I think this video should have a snuff film kinda vibe. Its time to break out the gimp mask Joe
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Old 05-19-2010, 11:39 AM   #35
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There's a log of mine with the source right before the TB
2-3kpa difference all the way though Name:  map.jpg
Views: 83
Size:  80.5 KB
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Old 05-21-2010, 12:09 AM   #36
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Does this same theory apply to external wastegates as well as internal? If i'm not having such problem of boost falling off before the redline should I change? I simply have my MBC spliced in the middle of the boost signal from the compressor to the bottom wastegate nipple.
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Old 05-21-2010, 01:10 AM   #37
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<Noob question>

"Using all-silicone tube? (***.) Well, just drill a hole in the colid-side end tank of the IC itself. Anywhere is fine so long as it's after the IC core, and before the throttle body."

Why a different place for silicone? Should one use Vac line another type instead?

</Noob Question>
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Old 05-21-2010, 01:43 AM   #38
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Quote:
Originally Posted by Oni View Post
<Noob question>

"Using all-silicone tube? (***.) Well, just drill a hole in the colid-side end tank of the IC itself. Anywhere is fine so long as it's after the IC core, and before the throttle body."

Why a different place for silicone? Should one use Vac line another type instead?

</Noob Question>
He is referring to people that have the majority of their intercooler piping being made up of silicone pieces instead of hard pipes. In that case, you cant essentially drill and tap silicone.
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Old 05-21-2010, 02:20 AM   #39
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Thanks for clearing that up, im a retard, i was thinking of the actual signal line .
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Old 05-21-2010, 07:16 AM   #40
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Excellent write-up, love the pics too. I would have gone with more of a Barney and friends theme though. Since this site is all about sharing the Love.
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