What standalone ecu do u recomend?!?!

[RB25GUY]

Originally Posted by KAT-PWR

You've yet to back up any claims I have seen from you with any math.

No bov = extra torque = (force*radius) applied to compressor wheel while it is still trying to spin, causing deflection and wear on bearings....

You don't need a study, it's physics. The same stuff turbo manufacturers use to develop their products and the same reason why turbo manufacturers SAY TO RUN A BYPASS/BOV.

(Already have spoke to two mechanical engineers regarding this)

What im saying is not all Surge is deadly like the "lifting" surge king called it in the snapase video. I know people who have put 15k on big turbo builds without bovs, guys running stock setups of no bov having no issues at all. Corky bell author of maximum boost says bovs are put on cars to get rid of the turbo flutter noise and hes never had a issue with turbo failure with no bovs ever hes been in the turbocharging field for decades...



http://www.volkspage.net/technik/04/maximum_boost.pdf

[Kingtal0n]

Originally Posted by RB25GUY

What im saying is not all Surge is deadly like the "lifting" surge king called it in the snapase video. I know people who have put 15k on big turbo builds without bovs, guys running stock setups of no bov having no issues at all. Corky bell author of maximum boost says bovs are put on cars to get rid of the turbo flutter noise and hes never had a issue with turbo failure with no bovs ever hes been in the turbocharging field for decades...

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15k is nothing. try 200k, 250k. You can get 250k out of a JDM BB OEM turbocharger- but only if you keep the proper bypass on it, and use a good air filter, and always have clean oil, and never over spin it. Its all of these things; not just 2 of them.

The best reason NOT to run a bypass/bov is for simplicity, when you have a car that absolutely needs the minimum (simplest) setup to win a race for $$$, so that there is less to fail/leak/go wrong. Like If I was going to race for pinks, blast the engine with nitrous/every trick in the book. Or a true race car, competition only, where you have 'unlimited' turbochargers, engines, and funding. Not having the bypass might mean lower wheel speed and more turbo wear, but if it guarantees that the shit isn't going to pop off, fail/lock open, or otherwise cause you to lose the race... its worth the additional drawbacks of having to change parts more often. BYpass/bov are best served in RELIABLE applications, mostly daily drivers, people who need to get 200k+ out of their setups.

Originally Posted by ADIDASilvias

What do you think Kingtal0n? Run it cold side and VTA, run it cold side with a long run back to the intake, or run it hot side and plumbed back?

If the goal is protect the turbo, then you want the bypass as close as you can get to the compressor wheel. Some turbos now come with them integrated to the compressor housing.
The fewer quantity of air molecules between the wheel and the bypass the faster a similar diameter hole will be able to evacuate the plumbing and reduce pressure.

Imagine a length of pipe extending from the compressor wheel outlet to infinity. Where would you plumb the bypass in this situation? At the far end, near infinity? The pressure would never drop in the pipe by the compressor wheel if you did that. On the other hand, If you place the bypass exactly near the compressor wheel, the pressure could stay elevated in the pipe at the length of infinity, while the local pressure by the wheel could be managed through the bypass, assuming the air does not flow backwards in the pipe (applicable to engines since they never breath backwards, there will always be some number of air molecules M traveling towards the engine even at idle speeds)

[hanzbrady]

Originally Posted by Kingtal0n

15k is nothing. try 200k, 250k. You can get 250k out of a JDM BB OEM turbocharger- but only if you keep the proper bypass on it, and use a good air filter, and always have clean oil, and never over spin it. Its all of these things; not just 2 of them.

The best reason NOT to run a bypass/bov is for simplicity, when you have a car that absolutely needs the minimum (simplest) setup to win a race for $$$, so that there is less to fail/leak/go wrong. Like If I was going to race for pinks, blast the engine with nitrous/every trick in the book. Or a true race car, competition only, where you have 'unlimited' turbochargers, engines, and funding. Not having the bypass might mean lower wheel speed and more turbo wear, but if it guarantees that the shit isn't going to pop off, fail/lock open, or otherwise cause you to lose the race... its worth the additional drawbacks of having to change parts more often. BYpass/bov are best served in RELIABLE applications, mostly daily drivers, people who need to get 200k+ out of their setups.



If the goal is protect the turbo, then you want the bypass as close as you can get to the compressor wheel. Some turbos now come with them integrated to the compressor housing.
The fewer quantity of air molecules between the wheel and the bypass the faster a similar diameter hole will be able to evacuate the plumbing and reduce pressure.

Imagine a length of pipe extending from the compressor wheel outlet to infinity. Where would you plumb the bypass in this situation? At the far end, near infinity? The pressure would never drop in the pipe by the compressor wheel if you did that. On the other hand, If you place the bypass exactly near the compressor wheel, the pressure could stay elevated in the pipe at the length of infinity, while the local pressure by the wheel could be managed through the bypass, assuming the air does not flow backwards in the pipe (applicable to engines since they never breath backwards, there will always be some number of air molecules M traveling towards the engine even at idle speeds)

Just a quick note, both of our shop's drag cars are >1000whp and both feature a blow off valve, as do Dave Briggs' and Kelsey Rowlings' drift cars.

[Kingtal0n]

Originally Posted by hanzbrady

Just a quick note, both of our shop's drag cars are >1000whp and both feature a blow off valve, as do Dave Briggs' and Kelsey Rowlings' drift cars.

They obviously care about their equipment, good job that. Always protect it if you can. I would never personally run a car without protection, its like going without a condom.
You might get lucky but....

[ADIDASilvias]

Originally Posted by Kingtal0n

If the goal is protect the turbo, then you want the bypass as close as you can get to the compressor wheel. Some turbos now come with them integrated to the compressor housing.
The fewer quantity of air molecules between the wheel and the bypass the faster a similar diameter hole will be able to evacuate the plumbing and reduce pressure.

Interesting. My reasoning behind running it cold side was based on the back pressure of the throttle body butterfly valve suddenly closing and causing the pressure wave. So if I located it close to the throttle body it would catch the back pressure wave as early as possible, thereby mitigating the effects. The Synapse DV transient response is super fast so I thought I could get away with a VTA since the pressure spike would be taken care of almost immediately and the valve closed quick enough to retain sufficient pressure in the IC and piping.

[Kingtal0n]

Originally Posted by ADIDASilvias

Interesting. My reasoning behind running it cold side was based on the back pressure of the throttle body butterfly valve suddenly closing and causing the pressure wave. So if I located it close to the throttle body it would catch the back pressure wave as early as possible, thereby mitigating the effects. The Synapse DV transient response is super fast so I thought I could get away with a VTA since the pressure spike would be taken care of almost immediately and the valve closed quick enough to retain sufficient pressure in the IC and piping.

You need to ask yourself, where is the drawback of having the pressure spike at the throttle body? Is there something wrong with having a high pressure spike in this location? What exactly is the goal behind evacuating the pressure in the plumbing?

In short, any pressure spike seen near/at the throttle body is not going to increase wear and tear of any parts in that region. The part you are trying to protect is the compressor wheel.

[hanzbrady]

Originally Posted by Kingtal0n

You need to ask yourself, where is the drawback of having the pressure spike at the throttle body? Is there something wrong with having a high pressure spike in this location? What exactly is the goal behind evacuating the pressure in the plumbing?

In short, any pressure spike seen near/at the throttle body is not going to increase wear and tear of any parts in that region. The part you are trying to protect is the compressor wheel.

I agree, the only time that you see throttle body failures are on insanely high boost situations or in nitrous applications. That's why race builds, especially drag cars use aftermarket throttle bodies such as the Ross units.

[ADIDASilvias]

Originally Posted by Kingtal0n

You need to ask yourself, where is the drawback of having the pressure spike at the throttle body? Is there something wrong with having a high pressure spike in this location? What exactly is the goal behind evacuating the pressure in the plumbing?

In short, any pressure spike seen near/at the throttle body is not going to increase wear and tear of any parts in that region. The part you are trying to protect is the compressor wheel.

I get what you are saying. Do you think the longer run of vacuum tube from intake to BOV will result in any BOV lag?

It wasn't necessarily the idea that you need to protect the TB or equipment, but moreso that the pressure wave would be caught early and dealt with prior to the shift event ending and the TB opening again. I am unsure of the speed of the pressure wave and whether it reaches back to the BOV next to the turbo quick enough to open the valve, vent the spike, and close before the exhaust is spooling the compressor again. Could this result in overspinning the compressor wheel? By that I mean, if the BOV is open and the turbo is being spooled could the compressor rpm spike without the pressure building in the IC plumbing?

I'm just throwing my thoughts out here, not trying to be obstinate. There are a lot of things happening at this point in the cycle, and the fluid mechanics isn't a simple equation. I did well in Fluid Dynamics in college, but that was 10+ years ago and I don't deal with it regularly at work.

[Kingtal0n]

Originally Posted by ADIDASilvias

I get what you are saying. Do you think the longer run of vacuum tube from intake to BOV will result in any BOV lag?

Longer vacuum lines and longer intercooler plumbing will create more lag in setups, slower response times, larger pressure differentials per unit time. Large diameter, short vacuum lines work better (more unit area) than long, thin vacuum lines.

It wasn't necessarily the idea that you need to protect the TB or equipment, but moreso that the pressure wave would be caught early and dealt with prior to the shift event ending and the TB opening again.

I believe you are overlooking the pressure in the hot side as a significant factor. When you lift to shift (or from WOT), the pressure is already high in the hot side (whether you have a spike or not in the cold side) and it needs to be 0psi or less, in the next instant. If the pressure at your "relief valve" drops 1psi, it must then drop the pressure in the nearby plumbing 1psi as well, releasing air molecules until that happens, and then the intercooler, and then the hot pipe, and then finally the compressor outlet will see the 1psi drop after all those air molecules are let go from the other side. The quantity of air molecules being vented in that situation is too great to expect a hole of that size (typical bypass) to vent the entire intercooler plumbing and both intercooler tubes in the time it takes to let go of the throttle. Some stock engines use a cold-side bypass (S15 silvia iirc) but they have a relatively tiny volume of plumbing to deal with (side mount intercooler). A cold side bypass becomes less useful as the plumbing volume prior to it becomes larger. Think of a situation where you install a 10000L intercooler and fill it with boost pressure. Now try venting all of that air through a cold side bypass- It would never drop the pressure on the hot side in time to shift, the compressor would be surging the entire time.

I am unsure of the speed of the pressure wave and whether it reaches back to the BOV next to the turbo quick enough to open the valve, vent the spike, and close before the exhaust is spooling the compressor again.

Any spike in pressure is brief and negligible, as the engine turns and continues to turn, even at idle, air molecules will quickly be removed from the cold side of the plumbing first. It isn't the spike you should worry about, it is the pressure already built in the plumbing from the boosting engine and the sudden stop to flow that accompanies the shutting throttle body. The pressure doesn't need to spike; it's already very high (boost pressure), and needs to vent from the compressor wheel outlet. The reason we vent is to keep the compressor wheel from feeling the high pressure at the outlet while also having a no or low flow situation, which runs the compressor off it's map and into surge. If the compressor cannot freely turn and send air molecules into the outlet, whether there is pressure or not, even in a vacuum, there may be consequences. It will not be beneficial to any setup.

Could this result in overspinning the compressor wheel? By that I mean, if the BOV is open and the turbo is being spooled could the compressor rpm spike without the pressure building in the IC plumbing?

To spin the wheel you need exhaust, and if the user shuts the throttle body the exhaust will suddenly also diminish accordingly. So regardless of whether the compressor is even hooked up to anything at all, it cannot spin without the accompanying exhaust flow. The biggest contributors to overspinning compressors is users who push their turbo past its limitations, and users with boost leaks that don't know it.