4000GT
New Member
Here is the map for Hillbillies GT28R turbo
Tell me how much pressure at 1/2 pound per min would be needed for surge? Almost ANY would do the trick agreed?
Are you going to plot the air flow of the motor as well?
1UZ TT Turbo Pulsating
- Thread starter Hillbilly
- Start date
The 1UZFE EGR Delete Kit is available for sale here.
Are you going to plot the air flow of the motor as well?
Again, the pressure is between the turbo compressor outlets and the throttle plate(s). After the throttle the engine has vacuum. See?
I already made a fair estimate of 1 pound per minute mass flow. This is for an engine running say 40mph under vacuum/cruise conditions. Few modern cars take over 15hp to maintain 60mph. Let's use triple that and say 45hp. This would take 4.5 pounds per minute. Divide by 2 for twins and you have 2.25 pounds per minute. Surge would be present at as little as 0.125 bar = 1.8 psi at 45hp engine output. For 10hp output that would be less than half a psi of boost.
Are you going to plot the air flow of the motor as well?
Again, the pressure is between the turbo compressor outlets and the throttle plate(s). After the throttle the engine has vacuum. See?
I already made a fair estimate of 1 pound per minute mass flow. This is for an engine running say 40mph under vacuum/cruise conditions. Few modern cars take over 15hp to maintain 60mph. Let's use triple that and say 45hp. This would take 4.5 pounds per minute. Divide by 2 for twins and you have 2.25 pounds per minute. Surge would be present at as little as 0.125 bar = 1.8 psi at 45hp engine output. For 10hp output that would be less than half a psi of boost.
e-solver:
The throttle body creates a pressure difference from one side of it to the other. You can (and on cars with centrfugal blowers nearly always do) have pressure above atmospheric on one side of the throttle (boost), and below atmospheric on the other (vacuum). The surge problem exists whenever there is too much pressure on the turbocharger side of the throttle, regardless of what the manifold side is doing (the manifold side is what is shown on your boost guage, and most of the time has nothing to do with the pressure present at the outlet of the turbo).
cya
Ben
The throttle body creates a pressure difference from one side of it to the other. You can (and on cars with centrfugal blowers nearly always do) have pressure above atmospheric on one side of the throttle (boost), and below atmospheric on the other (vacuum). The surge problem exists whenever there is too much pressure on the turbocharger side of the throttle, regardless of what the manifold side is doing (the manifold side is what is shown on your boost guage, and most of the time has nothing to do with the pressure present at the outlet of the turbo).
cya
Ben
Ahhhh the dreaded compressor surge
Heres an easy way to think of the situation. In a perfect world air would only travel in one direction. Consider how most people think an engine operates eg air goes in, fuel is added, mixture is burnt and exhaust gases go out. This one way traffic idea is very clear but also very wrong!!!
With almost any engine with air going in and exhaust going out the engine will generate a series of complex inlet & exhaust pulses throughout the RPM range. If you attached a large tube to the throttle body and while varying its length and measuring different power outputs you would see that the inlet system vibrated IE pulsed back and foward.
Add a turbo to this system and the pusing scenario becomes more pronounced, not so much when the engine is under full load but rather in the transition between load and fully shut throttle is reached. We all know that when the throttle is fully closed the BOV is let open depending on the effectiveness of the system there will always be some air that doesnt make its way out the BOV but instead pushes its way out towards the compressor wheel thus creating surge.
The best way to think of surge is as a vibrating spring of air but the easiest way to control this spring is to make it longer. IE on this system would be to make the pieces of pipe between the airfilters and turbos longer and much larger in diameter. Its not just the length thats important but the overall air volume between the airfilters and turbos. The bigger the amount of air you can get in there the more of a shock absorber/ dampening effect it will have on the air bouncing around.
Also another small BOV or just one large BOV eg a Tial will also help solve this problem.
Most of this info has been taken from an issue of
HIGH PERFORMANCE IMPORTS No69
easy to get in NZ and Australia
Heres an easy way to think of the situation. In a perfect world air would only travel in one direction. Consider how most people think an engine operates eg air goes in, fuel is added, mixture is burnt and exhaust gases go out. This one way traffic idea is very clear but also very wrong!!!
With almost any engine with air going in and exhaust going out the engine will generate a series of complex inlet & exhaust pulses throughout the RPM range. If you attached a large tube to the throttle body and while varying its length and measuring different power outputs you would see that the inlet system vibrated IE pulsed back and foward.
Add a turbo to this system and the pusing scenario becomes more pronounced, not so much when the engine is under full load but rather in the transition between load and fully shut throttle is reached. We all know that when the throttle is fully closed the BOV is let open depending on the effectiveness of the system there will always be some air that doesnt make its way out the BOV but instead pushes its way out towards the compressor wheel thus creating surge.
The best way to think of surge is as a vibrating spring of air but the easiest way to control this spring is to make it longer. IE on this system would be to make the pieces of pipe between the airfilters and turbos longer and much larger in diameter. Its not just the length thats important but the overall air volume between the airfilters and turbos. The bigger the amount of air you can get in there the more of a shock absorber/ dampening effect it will have on the air bouncing around.
Also another small BOV or just one large BOV eg a Tial will also help solve this problem.
Most of this info has been taken from an issue of
HIGH PERFORMANCE IMPORTS No69
easy to get in NZ and Australia
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Hillbilly
New Member
Have found a short term fix for this problem 
Went out and purchased a Bosch Compressor bypass valve fitted it to the intake pipe just in front of the TB..
Problem solved
Have been told i need to get larger exhaust housings and wheels to fix it properly but the CBV will do it for now.
Read about the CBV here http://wwwrsphysse.anu.edu.au/~amh110/Technical_pages/blow_off_valve.htm
thought it might work and it did.
Went out and purchased a Bosch Compressor bypass valve fitted it to the intake pipe just in front of the TB..
Problem solved
Have been told i need to get larger exhaust housings and wheels to fix it properly but the CBV will do it for now.
Read about the CBV here http://wwwrsphysse.anu.edu.au/~amh110/Technical_pages/blow_off_valve.htm
thought it might work and it did.
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