EPP Hotpipe With Tial BOV, vacuum reference for BOV?!

[GotGrip?]

speed density doesn't care, mass airflow most definitely does.

This! ^

 

[Ecoboost_xsport]

Actually come to think of it, location might matter on different types of vehicles. For example a turbo eclipse doesn't read air the same way our cars do, so it might need to be placed before or after a sensor or it could cause issues.

The 4G63 setup found on the Eclipse as well as the Evo reads using air flow, which is different than ours, which uses density (or pressure). In MAF sensing vehicles, you typically do not want to VTA as that air is being "metered" and used in the delivery of the fuel. As far as an optimal placement (if there is one) of the BOV in a MAF vehicle, that I can't answer.

 

[Ecoboost_xsport]

speed density doesn't care, mass airflow most definitely does.

Lol, I was typing my response as you posted yours...basically sayin same thing

 

[stripSHO]

Compressor surge and hydrostatic shock are VERY different things. Air, unlike water, is a compressible gas making “air hammer” not even worth contemplating or elaborating on right now.

The only reason for a BOV is to prevent surge which is caused by pressure differential across the turbo (not the charge piping, not the inter cooler, etc) exceeding an allowable threshold at a given compressor tip speed . If you’ve ever experienced a surging centrifugal chiller (read: 900mm+ turbo) you know it is a very violent force that will erode your wheel tips in short order. You can surge a turbo at steady state operation under a wide range of conditions, not just by slamming the throttle shut from WOT. The electric BOVs offer full protection across the whole surge region and also have the ability to be held open continuously as the turbo spools down, whereas a mechanical valve tends to flutter open and closed repeatedly until the compressor slows down. This may be better for a race-only application that demands instant closing and only runs WOT, but for the street there’s just no comparison really in terms of turbo protection which is all the BOV is there to do.

I appreciate the “old school” mentality of it. But to me it’s just as backwards as my dad’s insistence on replacing electronic ignition with a points distributor on everything he owns. But, to each their own.

 

[SM105K]

Compressor surge and hydrostatic shock are VERY different things. Air, unlike water, is a compressible gas making “air hammer” not even worth contemplating or elaborating on right now.

The only reason for a BOV is to prevent surge which is caused by pressure differential across the turbo (not the charge piping, not the inter cooler, etc) exceeding an allowable threshold at a given compressor tip speed . If you’ve ever experienced a surging centrifugal chiller (read: 900mm+ turbo) you know it is a very violent force that will erode your wheel tips in short order. You can surge a turbo at steady state operation under a wide range of conditions, not just by slamming the throttle shut from WOT. The electric BOVs offer full protection across the whole surge region and also have the ability to be held open continuously as the turbo spools down, whereas a mechanical valve tends to flutter open and closed repeatedly until the compressor slows down. This may be better for a race-only application that demands instant closing and only runs WOT, but for the street there’s just no comparison really in terms of turbo protection which is all the BOV is there to do.

I appreciate the “old school” mentality of it. But to me it’s just as backwards as my dad’s insistence on replacing electronic ignition with a points distributor on everything he owns. But, to each their own.

Interesting I hadn't looked at it that way. I was using the knowledge on that we learned on our big turbo motor. 331 ci SBF with a 88 mm turbo. We kept snapping the throttle blade on our AccuFab throttle bodies. We had our BOV placed before the A2W IC. After speaking with AccuFab they suggested moving the BOV to as close to the TB as possible. We did and never snapped another TB.....

They said, even though we had a BOV (Red Monster Procharger) it was not efficient in evacuating the boost tract. Air was slamming the TB blade and....snap. One was weird, two wasn't a coincidence.

 

[Ecoboost_xsport]

Compressor surge and hydrostatic shock are VERY different things. Air, unlike water, is a compressible gas making “air hammer” not even worth contemplating or elaborating on right now.

The only reason for a BOV is to prevent surge which is caused by pressure differential across the turbo (not the charge piping, not the inter cooler, etc) exceeding an allowable threshold at a given compressor tip speed . If you’ve ever experienced a surging centrifugal chiller (read: 900mm+ turbo) you know it is a very violent force that will erode your wheel tips in short order. You can surge a turbo at steady state operation under a wide range of conditions, not just by slamming the throttle shut from WOT. The electric BOVs offer full protection across the whole surge region and also have the ability to be held open continuously as the turbo spools down, whereas a mechanical valve tends to flutter open and closed repeatedly until the compressor slows down. This may be better for a race-only application that demands instant closing and only runs WOT, but for the street there’s just no comparison really in terms of turbo protection which is all the BOV is there to do.

I appreciate the “old school” mentality of it. But to me it’s just as backwards as my dad’s insistence on replacing electronic ignition with a points distributor on everything he owns. But, to each their own.

Sounds pretty well thought out...

 

[stripSHO]

Interesting I hadn't looked at it that way. I was using the knowledge on that we learned on our big turbo motor. 331 ci SBF with a 88 mm turbo. We kept snapping the throttle blade on our AccuFab throttle bodies. We had our BOV placed before the A2W IC. After speaking with AccuFab they suggested moving the BOV to as close to the TB as possible. We did and never snapped another TB.....

They said, even though we had a BOV (Red Monster Procharger) it was not efficient in evacuating the boost tract. Air was slamming the TB blade and....snap. One was weird, two wasn't a coincidence.

Hmmm well maybe there is a bit to the air hammer theory. But also could have had to do with the general orientation of the original location, similar to how a poorly positioned wastegate will cause runaway boost? Interesting stuff either way.

 

[SM105K]

Hmmm well maybe there is a bit to the air hammer theory. But also could have had to do with the general orientation of the original location, similar to how a poorly positioned wastegate will cause runaway boost? Interesting stuff either way.

We had to add another gate further down the road because of boost creep. However it was only presenting itself at the top of the rpm band. We had snapped both TB blades on lower boost levels. Both times they snapped, the driver had to pedal the car. I think we broke them because the BOV hadn't yeeted enough boost out of the tract. I think it was a combo of that along with intercooler interference, all the while being pulsated with big waves of boost from being pedaled. Plus I think people forget or flat out don't understand how volume along with air compression plays a role in things.

 

[GotGrip?]

We had to add another gate further down the road because of boost creep. However it was only presenting itself at the top of the rpm band. We had snapped both TB blades on lower boost levels. Both times they snapped, the driver had to pedal the car. I think we broke them because the BOV hadn't yeeted enough boost out of the tract. I think it was a combo of that along with intercooler interference, all the while being pulsated with big waves of boost from being pedaled. Plus I think people forget or flat out don't understand how volume along with air compression plays a role in things.

Heh, Yeeted boost

 

[skyshadow07]

I was going to chime in about air and water not behaving the same but stripSHO worded it very well. The sad part is I know the electronic valves are better and do more across the rpm range, But I still want a big ass tial BOV.