VTCS manifold unpleasantness
07-13-2015, 09:45 PM
#62
<p>We have 2 nearly identical builds at the shop:</p><p>(1) My car. 2001 chassis, BP6D VVT motor, VTCS manifold</p><p>(2) Kevin's car. 1990 chassis, BP6D VVT motor, VICS manifold</p><p>Both cars have RB headers, 2.5" exhaust, and MS3-Pro ECUs. Both cars have good compression and leakdown. My car has a virgin VTCS manifold. Kevin's car has a ported VICS manifold with the flaps removed, and has light port matching on the head (CSP rules). Kevin's car makes 12whp peak more than mine on pump 93. The shape of the curve is the same between my car and his until about 6500, where my power falls off and his keeps climibing. I've played with exhaust and traded intake tubes to no meaningful change. The seat of pants difference is large, and frankly this has bothered me to no end, and of course he reminds me of it frequently.<br /><br />Not sure if I have a spare VICS manifold (I might), but I do have a Euro flat top. I'll try to get some back to back with a before/after manifold swap. I need 8 or 10 extra hp like I need air and water. </p><p> </p>
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07-13-2015, 10:00 PM
#63
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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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07-15-2015, 07:14 PM
#67
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<p>
I can swap the manifold with the car on the dyno. I'll try to get some dyno time next week, if I can work it around real shop work.</p>
Useful info and it seems to echo everyone elses results. No ones dynos have been controlled A/B but an informal scatter plot of all the combined dynos seems to support the ~8whp nose dive past 6400 with the butterflies present vs a VICS. I'm a little frustrated that it took me this long to get a clear picture and bring the info to the fore so so more people could benefit.
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07-16-2015, 10:00 AM
#70
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I would think just looking at how the fueling wants to be adjusted would be informative. Injecting the same amount of fuel before and after, and then looking at the feedback from the wide band can't be a bad way of evaluating airflow changes. If you are able to flow more air you should be able to make more power.
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07-16-2015, 12:14 PM
#72
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agreed. I've owned 3 vtcs cars over the past few years, both bp4w and bp6d.
IIRC the "feel" of transition actually varies depending on the solenoid (newer/older solenoids actuate with different speed, this is even more evident with the MSM "bog" solenoid in addition to the vtcs solenoid)
*edit: Emilio just mentioned a similar thing in regards to the ecu calibration end of it too. I'd tend to agree.
My 04 MSM did this vtcs transition WAY smoother than my 01 vvt
agreed. I've owned 3 vtcs cars over the past few years, both bp4w and bp6d.
IIRC the "feel" of transition actually varies depending on the solenoid (newer/older solenoids actuate with different speed, this is even more evident with the MSM "bog" solenoid in addition to the vtcs solenoid)
*edit: Emilio just mentioned a similar thing in regards to the ecu calibration end of it too. I'd tend to agree.
My 04 MSM did this vtcs transition WAY smoother than my 01 vvt
My '02 has the post-recall ECU and it is absolutely noticeable, and somewhat annoying, but it does go away within a mile or so as it warms up. Further, on the other forum, I've seen numerous posting from '01 and '02 owners who've never had their ECU recall done and they do not report the same level of light switch transition during cold operation. SO much so, in fact, that the remaining non-recalled ECU's are coveted by some for that very reason. It seems plausible to me that recalled vs. non-recalled ECU's could account for a lot of discrepancy as to the drive-ability accounts we're seeing.
.02
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08-04-2015, 07:04 PM
#73
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<p>
We don't have anything business related going on the dyno until next week, so I went ahead and put my car on it. I'm going to swap manifolds and take pulls at lunch time every day for the rest of the week, so should have 1 comparison per day. Tomorrow I will compare stock VTCS vs butterfly removed VTCS. VICS possibly Thursday, if we can find a spare VICS manifold (we have 2 or 3, but can't put our hands on them). Square top Friday.</p><p>If/as needed.</p>
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08-04-2015, 11:52 PM
#74
<p>We don't have anything business related going on the dyno until next week, so I went ahead and put my car on it. I'm going to swap manifolds and take pulls at lunch time every day for the rest of the week, so should have 1 comparison per day. Tomorrow I will compare stock VTCS vs butterfly removed VTCS. VICS possibly Thursday, if we can find a spare VICS manifold (we have 2 or 3, but can't put our hands on them). Square top Friday.</p><p>If/as needed.</p>
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08-09-2015, 09:24 AM
#79
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<p>Yup of course. Ended up having 2 guys out last week, so I didn't get very far, but I do have the butterflies removed and ready to put the manifold back on.</p>
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08-10-2015, 09:12 AM
#80
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VTCS With Butterflies Removed
Here's a little more scattered data for ya.
This is from a rebuilt 2001 motor (nothing special, no porting just a slight shave) with the butterflies removed and the end holes tapped and plugged. MS1, VVTuner, typical diy intake with no MAF, cheap OBX header and exhaust with no cat. I was pretty happy with the numbers but keeping an eye out for a flat top.
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