Max boost, stock tune? Before codes?

[Dark Sun]

[QUOTE=FASTFATBOY;11388539]When vacuum drops past "X" and the ecm see's the TPS high enough yes the flap closes.

Once again, the blower pulley and or RPM dictates max boost(all else being stock or the same car to car), and nothing else. When that flap closes and you are at 3500 rpm the rpm of the blower speed dictates available boost, not the bypass valve.

Traction control is handled by the throttle plate and timing AKA "Torque Management"

DA also contributes to max boost some.

I have a screen shot of one of my datalogs with a 2.4 upper pulley, I will try and post it.

This car sees 14lbs right before you shift it with a 2.4 upper pulley in cold air, notice the boost PSI, the TPS% and RPM on this log. Pedal is on the floor at 34 mph, pretty sure this is 2nd gear(manual).

[/QUOTE
That is an awesome screenshot, it shows the exact psi of the factory spring rate in the bypass actuator at 9.66 psi that I’ve already mentioned. Now, where is the percentage of the charge air solenoid supplying the pressure to open the bypass actuator on this screen shot? Is it fully closed, 10% open, 55% open?

[FASTFATBOY]

[QUOTE=Dark Sun;11388547]

Originally Posted by FASTFATBOY

When vacuum drops past "X" and the ecm see's the TPS high enough yes the flap closes.

Once again, the blower pulley and or RPM dictates max boost(all else being stock or the same car to car), and nothing else. When that flap closes and you are at 3500 rpm the rpm of the blower speed dictates available boost, not the bypass valve.

Traction control is handled by the throttle plate and timing AKA "Torque Management"

DA also contributes to max boost some.

I have a screen shot of one of my datalogs with a 2.4 upper pulley, I will try and post it.

This car sees 14lbs right before you shift it with a 2.4 upper pulley in cold air, notice the boost PSI, the TPS% and RPM on this log. Pedal is on the floor at 34 mph, pretty sure this is 2nd gear(manual).

[/QUOTE
That is an awesome screenshot, it shows the exact psi of the factory spring rate in the bypass actuator at 9.66 psi that I’ve already mentioned. Now, where is the percentage of the charge air solenoid supplying the pressure to open the bypass actuator on this screen shot? Is it fully closed, 10% open, 55% open?

Fully closed, I adjusted it to fully close under WOT. AKA "adjusted boost bypass" mod.


Here it is right before I shifted it

[Dark Sun]

Originally Posted by FASTFATBOY

It does not work like that, the bypass does not "maintain X pressure" under WOT, it may under part throttle.


When vacuum drops past "X" and the ecm see's the TPS high enough yes the flap closes.

Once again, the blower pulley and or RPM dictates max boost(all else being stock or the same car to car), and nothing else. When that flap closes and you are at 3500 rpm the rpm of the blower speed dictates available boost, not the bypass valve.

Traction control is handled by the throttle plate and timing AKA "Torque Management"

DA also contributes to max boost some.

I have a screen shot of one of my datalogs with a 2.4 upper pulley, I will try and post it.

This car sees 14lbs right before you shift it with a 2.4 upper pulley in cold air, notice the boost PSI, the TPS% and RPM on this log. Pedal is on the floor at 34 mph, pretty sure this is 2nd gear(manual).





This is when I shifted it, notice the same numbers.

Again, where is the percentage of the charge air valve for this amount of boost.

[FASTFATBOY]

Originally Posted by Dark Sun

Again, where is the percentage of the charge air valve for this amount of boost.

Bypass valve door is shut, lack of vacuum at WOT shuts the door. This is why you adjust the boost bypass valve to shut the door 100% with the car off so it simulates zero vacuum on the bypass valve.


When I left off the gas to shift, notice how fast boost is dropping as the bypass door opens when vacuum comes back up.

[FASTFATBOY]

There is no way to measure the pressure on the bypass valve, pretty sure there is a solenoid that controls that.

The door is controlled by the ECM through the solenoid. I know big cam cars tend to mess with the solenoid due to low vacuum, you have to hook to replumb it to work properly. I know when the valve or solenoid fails the car will not make boost as the door will not close.

[FASTFATBOY]

Originally Posted by Dark Sun

Again, where is the percentage of the charge air valve for this amount of boost.

I think you are confused about how boost enters the LSA, boost is produced behind the throttle plate, not in front of it.


When the throttle plate is WOT there is zero vacuum even when there is boost being made behind the throttle plate.

When the throttle plate shuts there is vacuum in the same way there is on a NA engine.

I am pretty sure the solenoid is to dump the boost either on a no lift shift or when you hit the rev limiter.

[Dark Sun]

Originally Posted by FASTFATBOY

I think you are confused about how boost enters the LSA, boost is produced behind the throttle plate, not in front of it.


When the throttle plate is WOT there is zero vacuum even when there is boost being made behind the throttle plate.

When the throttle plate shuts there is vacuum in the same way there is on a NA engine.

I am pretty sure the solenoid is to dump the boost either on a no lift shift or when you hit the rev limiter.

Boost is made under the rotors not behind the throttle plate. It’s always under vacuum at the throttle plate wither closed or full open, there is always vacuum. Even if it’s .005 hgv.

[Dark Sun]

Originally Posted by FASTFATBOY

There is no way to measure the pressure on the bypass valve, pretty sure there is a solenoid that controls that.

The door is controlled by the ECM through the solenoid. I know big cam cars tend to mess with the solenoid due to low vacuum, you have to hook to replumb it to work properly. I know when the valve or solenoid fails the car will not make boost as the door will not close.

And now you get to the root of it all. The solenoid valve controls the bypass actuator by venting/regulating the pressure to the bypass actuator diaphragm. This is what I’m talking about this entire time. If you changed the duty cycle of that solenoid valve in the ECM, you’d be doing the exact same thing I’ve done mechanically, and no pulleys changed.i knew someone would start to see this. That solenoid valve is used by the ECM to open and control boost psi and maintain it through out the rpm range, not the actuator itself.

[Dark Sun]

Originally Posted by FASTFATBOY

There is no way to measure the pressure on the bypass valve, pretty sure there is a solenoid that controls that.

The door is controlled by the ECM through the solenoid. I know big cam cars tend to mess with the solenoid due to low vacuum, you have to hook to replumb it to work properly. I know when the valve or solenoid fails the car will not make boost as the door will not close.

The mod I have done mechanically, can also be done with a resistor across the wires at the solenoid to lower the voltage the ECM supplies it, thereby closing the valve some, and increasing boost. Different resistors will change the actual boost pressure, and the ECM will still see the same voltage. Or if access to the duty cycle in a tuner program is available, changing that percentage will also do the exact same thing.

[Dark Sun]

So here’s where I’m at now after speaking with Lingenfelter and other tuners. I’m going to get the car tuned for 14-15 psi, fuel/air, and timing. Then I’m going to put a dial in the cockpit that will allow me to keep the boost psi at stock levels, or turn the boost up as needed. As long as I have the tables in the ECM for the added boost, I can dial it up or down. I was also warned to not change the torque management as it’s caused a lot of failures doing so and the torque management program is fine to 630hp and that’s all I’m looking for. My current setup is just a stepping stone.

[FASTFATBOY]

Originally Posted by Dark Sun

So here’s where I’m at now after speaking with Lingenfelter and other tuners. I’m going to get the car tuned for 14-15 psi, fuel/air, and timing. Then I’m going to put a dial in the cockpit that will allow me to keep the boost psi at stock levels, or turn the boost up as needed. As long as I have the tables in the ECM for the added boost, I can dial it up or down. I was also warned to not change the torque management as it’s caused a lot of failures doing so and the torque management program is fine to 630hp and that’s all I’m looking for. My current setup is just a stepping stone.

Once again, max boost is determined by blower speed and or RPM, the bypass if closed 100% is out of the equation at WOT... the end. Even if it's how the factory adjusted it the bypass is not a factor. Will it make 1-2 more lbs if you close it? Yes. Will doing what you did make more boost? No.

With a stock pulley it's not going to make anywhere near 14-15 psi unless you have clogged exhaust. Stock boost is 8-9 lbs and that's what it will make if all else is stock, possibly 10 if the bypass is adjusted closed.

Mine barely touches 14 lbs in cold air at the very top of the shift with a 2.4 upper pulley(the smallest upper pulley you can get without machining), if I had cats on the car it might make a tad more due to the restriction.


The torque app for Android and a elm32 blue tooth adapter will tell you what boost it's making for about $40, it also does all kinds of other stuff.

These cars in cool air on crap tires even stock will spin the tires and put you in the ditch, that's not a determining factor if it is making any more power or not.


Please post up after the tune before and after graphs and power. It would be awesome if you used a stock bypass valve for a pull, then swapped your modded one on made a pull and then tuned it to see what happens.

Make sure the dyno graph if on a Dynojet shows SAE correction factor please.

[Dark Sun]

Originally Posted by FASTFATBOY

Once again, max boost is determined by blower speed and or RPM, the bypass if closed 100% is out of the equation at WOT... the end. Even if it's how the factory adjusted it the bypass is not a factor. Will it make 1-2 more lbs if you close it? Yes. Will doing what you did make more boost? No.

With a stock pulley it's not going to make anywhere near 14-15 psi unless you have clogged exhaust. Stock boost is 8-9 lbs and that's what it will make if all else is stock, possibly 10 if the bypass is adjusted closed.

Mine barely touches 14 lbs in cold air at the very top of the shift with a 2.4 upper pulley(the smallest upper pulley you can get without machining), if I had cats on the car it might make a tad more due to the restriction.


The torque app for Android and a elm32 blue tooth adapter will tell you what boost it's making for about $40, it also does all kinds of other stuff.

These cars in cool air on crap tires even stock will spin the tires and put you in the ditch, that's not a determining factor if it is making any more power or not.


Please post up after the tune before and after graphs and power. It would be awesome if you used a stock bypass valve for a pull, then swapped your modded one on made a pull and then tuned it to see what happens.

Make sure the dyno graph if on a Dynojet shows SAE correction factor please.

Yes and no, blower speed increases cfm, restrictions make psi, now I know the stock pulley will not make 15 psi at the given cfm, but it will make 13 as I’ve done. I’m just going to have my ECM programmed for it anyway. I’m working on getting everything to prove this. And I’m tired of explaining this simple system. The bypass valve is what the ECM uses to control the psi by opening the butterfly as the supercharger speed increases to maintain the exact psi all the way through the entire rpm range. Example: starting to make boost, butterfly closed, at 7 psi the butterfly is opening, at 10 psi, the butterfly is opened further, this is THE ONLY WAY to maintain a fixed psi level with cfm increasing from the supercharger rpm that is mechanically fixed to the engine rpm. The excess cfm is vented back inside the housing and not to atmosphere because it’s already been metered by the MAF sensor and ECM, waste not want not. All this information is known and anyone can patent search how a supercharger bypass valve/butterfly/controller works from the 1920’s all the way to today. Most even have pictures you can print and color.

[Dark Sun]

“At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. As engine load is increased, engine vacuum is decreased, causing the spring in the bypass valve actuator to overcome the applied vacuum, closing the bypass valve and allowing the boost pressure to increase.

The bypass valve starts to close when the vacuum measures 250 mm Hg (10 in Hg) and is fully closed at 90 mm Hg (3.5 in Hg). When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet.


Supercharger boost pressure is regulated to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) limits boost pressure to 83 kPa (12 psi)”.

Not my words, but a man in Europe explaining how a supercharger bypass actuator works with a pressure/vacuum diaphragm and a boost control solenoid. Obviously no one in America understands it.

Text from GM “ The bypass valve is operated by a vacuum/pressure actuator. Inlet vacuum and manifold pressure are used to open and close the bypass valve as needed.”

[silversleeper]

Now I remember what I'm reminded of, a poster on other forums goes by rubber duck and has lots of pseudo science posts. Not quite applicable to a performance boost or the thread in real life, but refers to some science and if you don't know differently some people think he is a wizard genius lol. e.g. the infamous Bill Nye the "science guy" who real scientists laugh at...let's talk phony global warming....
https://www.blockerandwallace.com/wh...ower-Blog.html
and somehow putting a spring on a bypass valve that is ALREADY OFF, will increase boost at a given rpm lol.
Not to mention the world's only STOCK 2.4" upper pulley and unk lower LSA
https://www.google.com/url?sa=t&rct=...p&opi=89978449