09-04-2019, 05:16 AM | #23 |
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I was thinking the same thing. I'm interested in improving sound but a 3.5" replacing two 2.5" pipes has a smaller area for flow if my math is right? I would think this would increase restriction in the exhaust however slightly thus hindering performance a bit? May not be noticeable 3.06 sq in vs 3.125 sq in for 3.5" and two 2.5" pipes; respectively?
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09-09-2019, 09:26 AM | #24 | |
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09-11-2019, 08:35 AM | #25 |
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09-11-2019, 08:52 AM | #26 | |
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Area of a circle = pi * r^2. Area of two 2.5 inch pipes (1.25 in radius): 4.91 x 2 = 9.82 square inches. Area of single 3.5 inch pipe (1.75 in radius): 9.62 square inches. 9.82 / 9.62 = 1.021, or a 2.1% increase in area vs VRSF midpipe. I'm not accounting for what happens to the airflow, but on most builds, I highly doubt 2.1% on a boosted engine is going to make much of a difference in either direction. You're making a bigger difference by deleting the secondary cats. Making incorrect assumptions here, but 2.1% at 600hp is 12hp. Dyno skews are larger than that. Conclusion: Pipe is for sound. Last edited by ntg44; 09-12-2019 at 09:59 AM.. |
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09-12-2019, 10:51 AM | #27 |
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Doesn't the surface area of the pipe make a big difference in flow? I want to say I've read somewhere that with similar volumes a single pipe is more efficient because it has less surface area causing drag on the exhaust flow...
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09-12-2019, 12:40 PM | #28 | |
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Q = flow rate A = cross sectional area of pipe V = gas or liquid velocity Flow rate is not impacted by surface area of the pipe. It is impacted by the cross sectional area of the pipe. With that said, the VRSF midpipe is going from 2 x 2.5 in -> 3.5 in -> 2 x 2.5 in, so the exhaust gases at the end of the midpipe are the same velocity as the exhaust gases entering the midpipe because of the above equation. They just speed up ever so slightly entering the single 3.5 inch portion, and slow down the same amount exiting the portion. Bottom line: The midpipe isn't doing anything for exhaust flow, other than removing secondary cats. That has its own discussion, but there's nothing special about the design that makes it better or worse, until you hit some seriously high exhaust velocity. Even then, it's only 2.1% less cross sectional area than stock, so assuming a theoretical maximum exhaust gas velocity, the 3.5 inch section would be able to flow 97.9% of the two 2.5 inch pipes, or 2.1% less flow. |
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09-13-2019, 04:37 AM | #29 |
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Single 3.5" flows less than twin 2.5" so we're reducing the flow rate with a single midpipe for what reason particularly a couple of inches from the downpipe flange?
The same note as the single midpipe can be achieved joining the twin 2.5" pipes together in an oval section about 5" long and exiting back into twin 2.5" without flow loss. I think the V8 muscle car guys need to build exhausts for these cars! |
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09-13-2019, 09:14 AM | #30 |
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We've all participated in high school physics, these are ignorant statements made without the consideration of the most important factor of all which is weight. Cars go faster when they weigh less and two 2.5" pipes will greatly outweigh one single 3.5" pipe. Weight is the primary advantage when switching from a dual pipe setup to a single and strapping on a 5" dual exhaust isn't somehow going to make you a 2000whp dragster.
A 3.5" diameter tube has been proven to support up to 1100whp without restriction whereas two dual 2.5" pipes used in this example will weigh more than 20lbs more than the single and will create more friction due to the smaller circumference. The weight loss of a 3.5" pipe is your biggest advantage. It's silly to think that you need to flow enough to support more than 1100whp when you're not planning on breaking half of that. Last edited by Tiago@VRSF; 09-13-2019 at 09:19 AM.. |
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09-13-2019, 11:34 AM | #31 | |
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In all honesty, I believe I was reinforcing what you wrote in the above quoted text rather than bashing your product. I used high school physics to illustrate practically what you've written about huge HP numbers. I also stressed how decatting was almost definitely more valuable than a negligible 2.1% less cross sectional area. We're on the same team, man |
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09-13-2019, 11:48 AM | #32 | |
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I understand the weight saving but on your sight I believe you said it was an 18 rwhp increase? Was that actually ever tested? I cant find any results on that. |
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09-14-2019, 01:00 PM | #33 |
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There's a potential power gain with the secondary cat delete and I think Akrapovic quote 7hp with their catless midpipe. The problem with a 3.5" single midpipe is there's no room for resonators to smoothen the note.
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09-20-2019, 06:01 AM | #35 | |
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This midpipe will require cutting on both the OEM and MPE exhaust simply due to the fact that the midpipe tubing needs to be cut to mate to the OEM rear. I haven't personally fit one on an MPE but we have a few customers who have without issue. |
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09-20-2019, 06:12 AM | #36 | ||
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All sales aside, IMO the gains were solely based on the fact that there's less restriction in the system due to the loss of the secondaries. The gains are realized in the upper RPM range due to the loss of restriction and increase in flow. With that said, most people choose to go with the single midpipe over the twin to combat the natural raspy S55 engine note. The couple dozen pounds you save is an added benefit |
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09-20-2019, 10:26 AM | #37 | |
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The single mid pipe gets rid of the V6 dual exhaust farty sound, but only a perforated tube packed resonator gets rid of the raspiness where there's no room to resonate a single midpipe effectively as you can retaining the twin pipes. V6's with dual exhausts or an inline 6 with a 153624 firing order and dual exhausts off split headers with an insufficient balance pipe sounds like the S55 engine. Last edited by RevNev; 09-20-2019 at 10:36 AM.. |
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09-21-2019, 12:25 PM | #40 |
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Installed yesterday and sounds great. No rasp at all. Have downpipes and mpe exhaust.
Only cutting is before mufflers. Not too loud or low! Just right imo
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09-21-2019, 07:34 PM | #41 |
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09-22-2019, 07:46 AM | #43 |
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Awe Tuning center support
Last edited by turbo v6; 09-24-2019 at 02:41 PM.. |
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