cotbu

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LoverTechnologies "Half Broken Things!"

RB25GUY

It's not small amounts of pressure at 28 psi, its the same effect you get with no bov, all for faster throttle response which helps spool faster .... think about it...

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KAT-PWR

No. the pressure is still being released. Sure there may be some residual pressure that assists by the valve not being large enough to vent all the pressure (pressure staying it pipes). But to say releasing that pressure in front of the turbo into open air makes no sense.
p1v1=p2v2


When air is vented to a non contained space (intake pipe) you're increasing the volume to infinity, as such pressure decreases accordingly to 0

Say you have 28psi (psi1) and a total pipe volume of 10m^3 (v1) you are venting this to the intake which as we know is open to atmosphere (there are other factors but let's not over complicate it) well say you use 100.000m^3
[(28psi)(10m^3)]/(100000m^3) = .0028psi into the intake preturbo aka nothing

You are correct that by keeping pressure up in the pipes full boost will be achieved quicker

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justinbyrant

I think the thought is if you release that air pointed into the turbo at fairly close range, the hope is it will blow through the fins and keep them spinning a bit, seems like hopeful thinking to me but who knows, personally I think running a tighter bov which would ideally maintain a small amount of pressure in the pipes would give better throttle response than anything else, it takes a lot less work to fill 5 feet of 3 inch pipe to 15 psi from 3 psi rather than from -15 psi

KAT-PWR

Yes residual pressure will help. I'm not arguing against that. But venting pressure preturbo will not help.

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justinbyrant

its not about pressure though its about flow, sure atmospheric pressure is 14.7 psi and a air compressor can run 200+ psi, and if you open that anywhere outside it doesn't increase the outside pressure, we all know this I don't think anyone is disputing it however if you now narrow the nozzle and point it at a fan when you vent the 200 psi out of the tank even if you narrow it down to a 28 psi tube and release it that way its still going to turn those fan blades (provided good bearings, close range, etc etc etc) I agree it wont generate any pressure however if its enough to keep the speed of the turbine up even a little then its still going to provide a miniscule advantage over venting to the atmosphere

KAT-PWR

After the air spends a long time losing velocity across the cross over tube. Seems trivial

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justinbyrant

plus the intake is still going to be creating a draw its not exactly a 100% non contained space, if that was the case that air would blow out past the maf backwards and cause all kinds of messed up readings defeating the whole purpose of recirculating

I kind of think of it like piloting a boat down a river instead of across a flat lake or riding a bike in no wind or with the wind, its helpful

justinbyrant

that's why using a smaller crossover tube would be more beneficial, same pressure flowing through a smaller diameter is going to create more velocity, at the same time a smaller tube will create a bottle neck slowing the speed of air escaping the charge pipes thus leaving behind a residual pressure once the valve closes, win/win

KAT-PWR

Only information I could find was import tuner where they didn't release the data on a seemingly factory 2008 lancer ralliart. 2% change in throttle response on a factory engineered car recirculated. Without having the hard data it's hard to determine its statistical significance. And any deviation from factory (increasing intake diameter, changing bov crossover diameter, length etc.) no real way to tell without data-logs if there is any real change

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TheRealSy90

Well, looks like we need someone with a turbo that has a shaft speed sensor to do some logs. Shaft speed between shifts when recirc, vented, and even no bov/blocked bov. And then hot/cold side for all variants lol.


Sent from my iPhone using Tapatalk

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justinbyrant

I would actually be very interested in seeing that lol

RB25GUY

http://www.speedhunters.com/2014/09/...rol-questions/




In a recirculating application this means the return path for compressed air returning to the intake is very direct, which enhances response. However, the air has not passed through the intercooler, so it can also be very hot (up to 100 degrees centigrade hotter than ambient air), introducing extra heat into the turbocharger system. The idea behind mounting the blow-off valve before the throttle body is that the airflow through the intake system continues to flow towards the intake manifold when the throttle is shut and the blow-off valve is venting, but when the throttle is reopened, air is still travelling in the same direction requiring less energy and time for the turbocharger to return to operating speeds. In a recirculating application the return path from the valve to the intake is much longer, however the recirculated air will be much cooler (only up to 50 degrees centigrade hotter than ambient air), thus not adding as much heat into the turbocharger system.

in theory you are right, in the real world its totally different ball game that ralliart they ran test on the CFMs on that baby (turboTD04HL-15T) is pushing compared to the TD06-25G no where near to compare



Ralliart TD04 on a 7 cm (.49 ar) 428 CFM, TD06H-25G is 850 cfm with a 10cm housing roughly (.71 ar) that 2 percent means nothing when the turbine flow difference is 100 plus percent more efficient than the TD04 they used in the "testing"......

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Kingtal0n

bypass valve needs to be as close to the compressor as possible, with as short a tube as possible. Some new turbos are coming with them integrated to the compressor housing.

I made mine from scrap aluminum pipe and some shit I found on the floor of a friends shop

you can do it