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Old 08-24-2015, 08:37 PM   #101
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<p>Do you have dyno plots? For complete&nbsp;comparison sake?</p>
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Old 08-24-2015, 08:53 PM   #102
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<p>Do you have dyno plots? For complete&nbsp;comparison sake?</p>
He stated no change. A dyno of his setup would be irrelevant to whatever dyo plot of manifold/dyno/car/weather you might have access to.

Just wait for A/B. Same car/dyno/day.

The interesting point is no gains by removing the butterflies. That surprise means the endemic suckiness is strong with the VTCS runner/plenum configuration. POS long before it reaches the butterflies it seems.
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Old 08-24-2015, 11:36 PM   #103
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<p>
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He stated no change. A dyno of his setup would be irrelevant to whatever dyo plot of manifold/dyno/car/weather you might have access to. Just wait for A/B. Same car/dyno/day.
The car and the dyno are both extremely repeatable.&nbsp; I've taken tons of pulls on this one.&nbsp; If a new feature needs to be tested or the dyno needs to be tested, this is the car I use.&nbsp; It makes 114 whp every time, hot, cold, humid, dry, whatever. 01 with standard bolt ons and a MS3.&nbsp; For reference, the car made about 100 stock and a bone stock 1.6 made 78 whp on our dyno.
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The interesting point is no gains by removing the butterflies.
Indeed.&nbsp; I was expecting to pick up a couple, and was surprised to see my current plots line up exactly on my comparison plots.&nbsp; At least I took a pound or two off the car.</p>
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Old 08-25-2015, 12:45 AM   #104
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<p>I'm not claiming its not creditable or anything, just for completeness sake.</p><p>Looking forward to the VICS test.</p>
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Old 08-26-2015, 08:01 PM   #105
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Every dyno chart I've ever seen shows that gutting a VICS manifold essentially ruins it. I bet removing your VCTS butterflies nets you power everywhere over your friend's setup, Ben.
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No change
Color me surprised, but there it is. The bottleneck must be further up, which makes the VTCS manifold even more impressively bad than previously thought
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Old 08-26-2015, 11:59 PM   #106
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Color me surprised, but there it is. The bottleneck must be further up, which makes the VTCS manifold even more impressively bad than previously thought
Yah that points to (maybe) the plenum volume resonance tuning being more important than we thought. I still can't figure out what the inner, short vestigal runners that terminate in the resonance chamber are doing. I can only guess that they are sending the return wave back down the intake tract as if it were a shorter runner manifold. Opening and closing the VICS butterflies changes the pressure differential between that chamber and the pulse coming back through the runners. Dunno, just spit balling but clearly there is some dynamic there that we're all successfully tuning with but don't fully understand. Gah.
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Old 08-27-2015, 12:26 AM   #107
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Yah that points to (maybe) the plenum volume resonance tuning being more important than we thought. I still can't figure out what the inner, short vestigal runners that terminate in the resonance chamber are doing. I can only guess that they are sending the return wave back down the intake tract as if it were a shorter runner manifold. Opening and closing the VICS butterflies changes the pressure differential between that chamber and the pulse coming back through the runners. Dunno, just spit balling but clearly there is some dynamic there that we're all successfully tuning with but don't fully understand. Gah.
+1 million.
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Old 08-27-2015, 10:59 AM   #108
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maybe they are for sound. like the little helmholz tube on the 01 crossover pipe.
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Old 08-27-2015, 03:57 PM   #109
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maybe they are for sound. like the little helmholz tube on the 01 crossover pipe.
By sound I assume you mean intake resonance tuning, yes of course they are. It occurred to me that the little shorty runners in the VICS (not having measured them), might be generating a 2nd order harmonic. That would just be coming in above 7000 and might explain why the VTCS falls on its face past 6400. Most OEM manifolds, including the B6/BP, use 3rd order harmonics due to space constraints. Opening and closing the butterflies might change the pressure differential in the VICS chamber just enough to neutralize it's effect as a barrier to that pulse. IOW, if that pressure wave rolling up the runner hits a a sharp pressure delta, either positive or negative, it's speed will change and that bounces all or most of that pulse back down towards the valve where it can chirp your tires in 2nd. Perhaps Mazda was able to time things so that when the butterflies open or close they can successfully negate the effect of that chamber on the pulses.

The dyno results we have all gotten bear that out. VICS without butterflies make a wee bit more above 8000 but die in the midrange on EP engines. VICS with butterflies opening early make the best overall area under the curve on engines with rev limits below about 7800. VTCS die on top no matter what you do.
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Old 08-28-2015, 12:14 PM   #110
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And the non-USDM manifolds (EU/JDM) squaretops are just power up top at the expense of midrange and torque across the entire band?
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Old 08-28-2015, 01:14 PM   #111
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And the non-USDM manifolds (EU/JDM) squaretops are just power up top at the expense of midrange and torque across the entire band?
A few dynos floating around, only two that I have seen seem to be sorta controlled A/B. FM's didn't retune in between so that data is corrupted. The other plot was several months apart for the two manifolds.

It seems you lose just a few hp below torque peak (circa 4800) and gain some above. From what I have seen on our cars, it appears the gains above torque peak are greater than the losses below it.
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Old 08-28-2015, 04:15 PM   #112
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How about under boost with the flattop? Is it the same basic story as n/a, or are the high-end gains more/less? I have results from my butt dyno, but it doesn't output graphs.
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Old 08-30-2015, 03:58 PM   #113
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Originally Posted by emilio700 View Post
By sound I assume you mean intake resonance tuning, yes of course they are. It occurred to me that the little shorty runners in the VICS (not having measured them), might be generating a 2nd order harmonic. That would just be coming in above 7000 and might explain why the VTCS falls on its face past 6400. Most OEM manifolds, including the B6/BP, use 3rd order harmonics due to space constraints. Opening and closing the butterflies might change the pressure differential in the VICS chamber just enough to neutralize it's effect as a barrier to that pulse. IOW, if that pressure wave rolling up the runner hits a a sharp pressure delta, either positive or negative, it's speed will change and that bounces all or most of that pulse back down towards the valve where it can chirp your tires in 2nd. Perhaps Mazda was able to time things so that when the butterflies open or close they can successfully negate the effect of that chamber on the pulses.

The dyno results we have all gotten bear that out. VICS without butterflies make a wee bit more above 8000 but die in the midrange on EP engines. VICS with butterflies opening early make the best overall area under the curve on engines with rev limits below about 7800. VTCS die on top no matter what you do.
I guess "sound" is really both just simple noise as well as harmonic effects of hte intake charge. In essence, it isn't much different than tuning a ported speaker. You've got resonance chambers, airflow, frequency response and adjusting the chamber or port size/length will have direct effects on the frequency response. That set of butterflies and the dead end tube are effectively a narrow band filter. If, as you said, some frequency or its harmonic(s) are impeding flow at some frequency (directly related to rpm), they can alter it that way.

Fun fact: the obnoxious noise you get with the windows down on the freeway is the same effect. The resonance chamber is very large so the resonance frequency is low. WUB WUB WUB.
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Old 12-14-2015, 04:11 PM   #114
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<p>VICS next</p>
Did you ever get the VICS manifold tested? Overlay with VTCS plz
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Old 12-16-2015, 05:39 AM   #115
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Yah. Stock NB2 ECU on the 01-03 run 14.7:1 closed loop and 0 advance even when stone cold. Runs like poo until CLT hits 100 or so
This was not my experience with my '01. It would run 10-11:1 immediately after startup and would not switch to 14.7:1 closed loop until past a certain temperature.

I was third owner of my car; I believe it was an Oregon car initially (ie, non-CA) but I am not positive. Don't know if there was any difference in CA vs non-CA cars.
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Old 02-16-2016, 09:53 PM   #116
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I'm going to be doing the VCTS to VICS swap soon, and wanted to see which fuel rail people were using with their VVT motors. I've read that there could be clearance issues with the stock NB2 fuel rail and VICS manifold that require the NB1 fuel rail to be used, but nothing 100% confirming this. Is this the case with everyone else that has done this swap - is an NB1 fuel rail required to clear the VICS manifold?

I'm hoping to get some dyno pulls in before and after the swap (gotta get my MS3 installed and tuned, first). If nothing else I'll see if I can get some good A/B comparison data from VirtualDyno.
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Old 02-16-2016, 10:17 PM   #117
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I'm going to be doing the VCTS to VICS swap soon, and wanted to see which fuel rail people were using with their VVT motors. I've read that there could be clearance issues with the stock NB2 fuel rail and VICS manifold that require the NB1 fuel rail to be used, but nothing 100% confirming this. Is this the case with everyone else that has done this swap - is an NB1 fuel rail required to clear the VICS manifold?
I swapped out a VTCS manifold for a VICS manifold one on a BP6D and the BP6D fuel rail did not fit with the VICS manifold.

--Ian
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Old 02-16-2016, 10:52 PM   #118
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Thanks for the confirmation. Looks like I'll need to pick up an NB1 fuel rail for the swap...
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Old 03-23-2016, 04:45 PM   #119
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FU VTCS

Solid: JDM Flat top
Dotted: USDM VTCS 2001

Picked up +15whp at 7000 rpm

Attached Thumbnails
VTCS manifold unpleasantness-vvt-miata_01-manifold-vs-jdm-manifold_reduced.jpg  
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Old 03-23-2016, 05:04 PM   #120
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Wow, 15 hp difference on naturally aspirated is a lot. It's just nothing but gains after 6000.
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