Looking for compressor surge solution

[robvas]

BOV's don't control boost, that's the wastegate. They only release it when you close the throttle. Nobody was talking about big power cars anyway. And your exhaust spinning the turbo makes boost, not a tiny bit of leftover air from the charge that's not compressed anymore anyway.

You keep comparing light through a vacuum to electricity through wires

my point is any kind of delay that would be induced by vacuum lines just doesn't matter - if the valve not opening fast enough was the cause of compressor surge he would have seen it earlier than 23psi.

let's also remember than the psssshhhhh when you shift lasts what, 3/4 of a second? During that time you're hearing all the air come out so it's not like a 1/100th of a second is going to matter anyway.

Marketing poisons people minds. Blowoff valve companies making claims sound great but don't forget to think about if it's even an issue.

Sponsored

 

[robvas]

TurboSmart has recently came out with an electric wastegate btw

https://www.turbosmart.com/product/genv-electronic-ewg60-powergate-60/

 

[Buldawg76]

BOV's don't control boost, that's the wastegate. They only release it when you close the throttle. Nobody was talking about big power cars anyway. And your exhaust spinning the turbo makes boost, not a tiny bit of leftover air from the charge that's not compressed anymore anyway.

You keep comparing light through a vacuum to electricity through wires

my point is any kind of delay that would be induced by vacuum lines just doesn't matter - if the valve not opening fast enough was the cause of compressor surge he would have seen it earlier than 23psi.

let's also remember than the psssshhhhh when you shift lasts what, 3/4 of a second? During that time you're hearing all the air come out so it's not like a 1/100th of a second is going to matter anyway.

Marketing poisons people minds. Blowoff valve companies making claims sound great but don't forget to think about if it's even an issue.

Correct BPVs/BOVs do not control boost they vent the excess boost so when you slam the throttle shut at WOT the boost does not cause compressor surge and stutter to occur. A slow to open BPV/BOV will cause surge/stutter and if bad enough can damage the intake turbine wheel as well.

How do you get comparing light through a vacuum to electricity thru wires. I merely stated that the speed of sound hence air/vacuum travel much slower than the speed of light which is only about 10 to 20% faster than electricity that is not in a vacuum. So, using your 1125 FPS for sound/air/vacuum versus electricity not in a vacuum at 80 to 90% of the speed of light at 186,000 MPS I would say that electricity is much faster to activate a BPV/BOV than vacuum.

It's not as prevalent to have compressor surge/stutter at low to mid boost levels than it is at close to or at max boost. I am not saying the excess pressure does not get released completely by either type of actuation just that a second or two delay in the pressure being released is all it takes to create the compressor surge/stutter.

You're the one that brought up big power turbo cars at 1000 + HP numbers not me.

The waste gate does control the majority of boost, but it works in concert with the BPV/BOV to keep the turbo spooling at a safe and even speed for the power you are requesting with your foot on the go pedal. Either one that is not operating correctly can cause issues with the turbo's lifespan and reliability.

Try deactivating the BPV/BOV and hit max boost at WOT and then take your foot of the throttle completely and see what kind of noise you hear from the turbo or damage your turbo suffers.

It may be possible that the OPs tuner has created a slight delay in the releasing of the excess boost if he is still using the electronic BPV, not likely if vacuum operated.

BD

 

[TeeLew]

that's definitely not how it works. You'd have an infinite loop of boost if it did

No, The throttle blade will be closed. The pressure vents back into the intake and the engine cycles through it in a rotation or two. If you immediately open the throttle before it has time to cycle though what was injected back into the intake system, then there will be some residual pressurized air in the intake and the turbo won't be starting from a vacuum. It will be starting from some low-ish boost number, like 5 psi. This reduces lag.

 

[robvas]

No, The throttle blade will be closed. The pressure vents back into the intake and the engine cycles through it in a rotation or two. If you immediately open the throttle before it has time to cycle though what was injected back into the intake system, then there will be some residual pressurized air in the intake and the turbo won't be starting from a vacuum. It will be starting from some low-ish boost number, like 5 psi. This reduces lag.

so because it vents back to the intake, when you shift (assuming manual trans and you take your foot off the gas when you shift), your mechanical boost gauge never goes into vacuum?

I could be wrong if it works completely different than any other car I've owned, would like to see a camera recording a real boost gauge while you run through the gears at WOT

 

[Therealmattlex]

When I had my 01 with a Vortech on it I had a standard diverter valve with a draw through MAF. it was fine before I had an intercooler because it could recirculate the amount of air when I let off the throttle. After I added an intercooler I needed to switch to a BOV and blow through MAF. There was just too compressed air in the system and it would create major compressor surge. I used a TialQ and was extremely happy with it.

As far as turbo lag I don't know how much it would affect that.

 

[Buldawg76]

so because it vents back to the intake, when you shift (assuming manual trans and you take your foot off the gas when you shift), your mechanical boost gauge never goes into vacuum?

I could be wrong if it works completely different than any other car I've owned, would like to see a camera recording a real boost gauge while you run through the gears at WOT

If just lifting off the gas long enough to shift (manual trans) to next gear you will likely not see a vacuum on boost gauge since there is not enough time to allow for a negative reading to register as the throttle is only closed for very short time frame so the hot side charge pipe is still in a neutral pressure state. If you let off the throttle and just coast with throttle closed you will see a negative vacuum signal from boost gauge.

If you have a BOV you may see a momentary negative vacuum signal but not sure since I have my BPV connected to recirc the excess boost back into intake tube. I am also an auto car so shifts are very quick.

BD

 

[TeeLew]

so because it vents back to the intake, when you shift (assuming manual trans and you take your foot off the gas when you shift), your mechanical boost gauge never goes into vacuum?

I could be wrong if it works completely different than any other car I've owned, would like to see a camera recording a real boost gauge while you run through the gears at WOT

It depends on how fast you shift, but, in general, when compared to a BOV, yes.

 

[robvas]

It depends on how fast you shift, but, in general, when compared to a BOV, yes.

Do you have a video showing that on an actual boost gauge? Because I have never, ever seen that work that way in real life. Even with a recirc bypass valve

 

[TeeLew]

Do you have a video showing that on an actual boost gauge? Because I have never, ever seen that work that way in real life. Even with a recirc bypass valve

You don't need a video. Any auto car with a gauge will show it. The auto and manual shift in fundamentally the same way; the auto is just faster. The idea is the same for manuals. Whether or not there is positive pressure in the intake manifold will be a function of how quickly you can shift. Reducing lag is the reason to recirculate the boost, as opposed to venting it, on throttle lift. A second concern being noise.

We can't leave the pressure upstream of the throttle blade because it will back-feed the turbine and cause all sorts of entertaining expense. It's got to go somewhere.

I've got pipes and a 50mm BOV on my car, but I'd prefer to have a BPV, because it's better for throttle response. As it is, I've stiffened the BOV spring package so it only vents over 15 psi boost. On vacuum or low boost throttle lifts, it doesn't vent. This change has really helped the lag when going on/off the throttle, but I'm not convinced lag is as good as stock, even though I'm making a lot more power. Once the BOV vents, starting from nothing takes a moment. The spring they deliver them with vents constantly and completely. Playing with this has given me a pretty good idea of how it feels in the car.

Boost recovery when shifting stock was pretty good.
Boost recovery with tuned engine and 50mm RacePort w/ stock spring, very poor. It would often bog on a shift and any time I lifted in a corner.
Boost recovery with tuned engine and 50mm RacePort w/ stiff spring, again, pretty good. There is some venting, but the engine isn't bogging on shifts. I think it might be a little slower reaching it's max torque than the stock engine map did, but the max is a lot higher than the stock max, so it's tough to judge.

 

[robvas]

So the air that gets venting back into the intake, which is no longer pressurized, helps with "turbo lag"

that makes zero sense

https://www.zacmotorsport.com/blogs...lation hose will,help keep the turbo spinning.

 

[robvas]

Also if you have stiffer spring in your blow off valve to only open past 15psi....that's not right. That means if you lift the throttle when you're making under 1- 15psi you're going to not vent the air which is bad

you have equal boost on the other side of the bov which keeps it closed under boost.

the spring is there to keep the valve open under idle vacuum, no stiffer.

this is turbo 101, where did you kids go to school?

 

[Buldawg76]

If the engine is running the turbo impellers are spinning since the exhaust flow never stops driving the exhaust turbine. Yes, the recirc does little to nothing to drive the intake turbine but the fact is it does get sucked into the intake turbine upon being released into the intake tube. It is hot air also but the video you show in the above post is misleading since there is no exhaust flow driving the turbo impellers so the only direction the recirc air has to go is out the intake opening.

Recirc is more for noise reasons than to reduce turbo lag at normal throttle openings but on a WOT upshift especially with auto trans it does reduce turbo lag on turbos with small impellers like the twin scroll ecoboosts.

BD

 

[robvas]

Recirc is more for noise reasons than to reduce turbo lag at normal throttle openings but on a WOT upshift especially with auto trans it does reduce turbo lag on turbos with small impellers like the twin scroll ecoboosts.

BD

Doesn't your foot stay to the floor when you have an auto and it upshifts? Why would you get any turbo lag in that case, and why would the bypass or blowoff valves even open since the throttle never closes?

 

[Buldawg76]

Doesn't your foot stay to the floor when you have an auto and it upshifts? Why would you get any turbo lag in that case, and why would the bypass or blowoff valves even open since the throttle never closes?

Yep, matted to the floor but the trans still takes a millisecond to shift to the next gear which I would believe prevents any turbo lag but not having any way to actually measure if the turbines slow down at all during the upshifts I am not sure. The BPV likely does not move from staying closed also but again no way to accurately measure it.

Thats what the engineers at ford do for a living.

BD

Sponsored