Help with surge under part throttle

the reason for my smilie faces is that I am the guy that makes all the different devices (Translator Pro, ISAC (alky controller and boost controller), fancy chips, SD2 chip etc.)

I don't usually get into these threads because I don't want to appear self-serving....

lots of guys, lots of different experiences, lots of knowledge, theories, and guesses.

My comments are based on what has actually worked for me, many other approaches can be used to solve the surge problem. Thus the questions about reducing the boost controller to stop the surge.

Getting back to the OP's question, exactly which "boost controller" are you running and how is it plumbed?

Bob
 
Bob, I'm running the MBC that GN1 packages with their downpipes. From the turbo nipple, the line runes to a Y, to the side port on WG, the line coming out of the MBC goes to the top port on WG. It holds steady at 22 PSI at WOT.


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we4Mateo said:
No easy fix guys. The compressor, coupled with the alky, is just feeding too much air for the engine to eat at that boost level. Change the turbo, port the heads, a cam change might help as long as exhaust energy isn't also increased. I bet if you turn off the alky, you won't have this problem. You won't be able to hit 20psi, but the problem will be gone at 15psi. The alky just makes the charge too dense and the engine can't eat it. I've tuned my alky so the window is more narrow for surge, but hard to eliminate completely. It's really only wot surge that you need to be worried about. Drive around it otherwise. A tornado pre-turbo in the intake might slow down flow just enough to help too. The tornado is the easiest fix. I used to take mine out for track days, but it made no difference. It is just enough of a restriction however to really help the part throttle surge. Try that and report back please.
Click to expand...

I somehow missed this post.... The intake manifold and heads have been fairly heavily worked over by Indy Cylinder Heads, the heads also have the larger valves installed. I would be open to trying the tornado.


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I have been using a Tornado for 7-8 years now. No issues and it did resolve my part throttle issues I had using the TA-49 with an RJC front mount combo.

Dannyo
 
with an 8 lb spring in the gate, one idea would be to run 2 "MBC"'s (it sounds like their MBC is a pressure regulator), and use the boost solenoid output on the ECM to switch between them based on throttle.

you would need a 3 port solenoid, another MBC, and a chip update to set the boost output up that way.

trying the tornado would certainly be the easiest thing to try first.

Bob
 
The correct way to eliminate it 100% is with a recirculation valve. The problem is you need to tweak it so it doesn't open when the throttle is wide open. If you put a gauge in front of the throttle blade you would see much higher pressures than behind it. The pressure behind the throttle blade is of little value for analysis. Run a turbine and compressor that takes more ex pressure to drive or design a recirculation setup to minimize the chance for surge or don't drive at low throttle angles where it occurs.


BPE2013@hotmail.com
 
Tom Tom Turbo said:
I somehow missed this post.... The intake manifold and heads have been fairly heavily worked over by Indy Cylinder Heads, the heads also have the larger valves installed. I would be open to trying the tornado.


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Click to expand...
What's after the throttle blade has little influence on it at low throttle angles. If you had Chapman stage 2 heads you'd likely still have the surge at low throttle angles.


BPE2013@hotmail.com
 
I'll give the tornado a shot first....

Bison, could the stock throttle body be a potential culprit also? I see many people make the switch to 65 or 70mm but then there are a ton of them for sale too, which leads me to believe many people don't see an improvement.


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Tom Tom Turbo said:
I'll give the tornado a shot first....

Bison, could the stock throttle body be a potential culprit also? I see many people make the switch to 65 or 70mm but then there are a ton of them for sale too, which leads me to believe many people don't see an improvement.


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Click to expand...
As I posted above you have high pressure in front of the throttle blade and the compressor is operating above the surge line. Flow is very unstable in that area. You can still get the same open area with a larger tb. The cross sectional OPEN area determines the flow. The throttle angle would be a little less with a larger blade. You need to drop the pressure in front of the throttle blade at lower throttle angles. Then the compressor flow will stabilize because it will be moving more air at a lower pressure instead of less at higher pressure.



BPE2013@hotmail.com
 
Several papers have been written on this subject since the oem's don't have the packaging envelope for long gentle bends. The air may not always present itself to the compressor inducer as a wave that is perpendicular to the pipe centerline. To gain response OE's are always looking for ways to move the compressor map surge line to the left. The attack point of the air to the inducer is likely trying to stall the compressor wheel. Subtle attempts to re-direct the air into the compressor inducer may show directionally how to proceed. A tight bend close to the compressor could cause surging. A properly oriented vein or straightener or "Tornado" may give direction to a solution. If the Veyhron uses an air director couldn't the Buick?
 
I was one of those guys who would never put a ridiculous "tornado" in "MY" car. that is until I went on a trip longer than I usually do on the interstate, trying to go around the 5 MPH under the limit drivers at part throttle, the surge was insane. Soon as I got home I ordered a tornado and put it in a few days later. Problem solved.
That was about 7 years ago.
 
The Tornado is not a bad solution.
I had to hand it to Bruce for finding a way to implement an idea I gave him using an off the shelf part.
I did EXACTLY what Bugatti did about 4 years earlier than they did on my 63e soon to be on TTipe's car.
That turbo never surged a bit despite what the rep' of that turbo was.
I think it might be prudent to make a few adjustments to the thing before it gets installed though.
The Tornado is designed to control the spin of the incoming air.
Do you really WANT spin or do you just want to straighten it out?
How many vanes do you need?
I seem to remember that different versions of those had different vane counts.
 
1952ray said:
What needs to happen is to slow down the spin, not straighten it out.
Click to expand...


Uh nope,not according the German turbine engineer I spoke with about this idea years ago.
The problem with any kind of spin is that it introduces motion in the incoming air that runs counter to what you want.
The air will spin and be stretched in the direction of the wheel rotation which puts it's angle of entry at an angle to the vanes on the compressor wheel that need to ingest it.
That's not the greatest for efficiency.
Kenne Bell tried to introduce counter spin with their inlet pipe that was designed to "slant" the incoming air down into the vanes,IIRC.
That design introduced friction to the incoming air when it hit the sides of the slanted vanes to be steered or turned ...... kind of like a bullet ricocheting at an angle off a wall.
 
Last edited:
Do you think running a pp would make things worse? I understand the tb being the choke point but having the pp behind it wouldn't make it worse?
 
A simple way to get rid of the part throttle surge is to open the wastegate. The problem is most boost controls (specially air regulator style) keeps the gate closed until boost is close to target then slams it open resulting in part throttle surge.

I use a normally open solenoid and the boost control in my Tpro. In driving mode the boost signal is always on the gate. As boost rises the gate will slightly open bleeding off pressure. This keeps surge in check.

Solenoid activation is done with the Tpro by a set throttle value. Activation is set around 2.50 tps. Half throttle. So below half throttle the gate gets full boost signal. After half throttle the Tpro cuts the signal and goes into spool mode. Solenoid on 100%. As boost gets close to target, the control will pulse the solenoid to achieve the target.

To do this one would need a electronic boost control with a throttle input or a 2 stage boost control with some type of throttle activated switch.

Rick
 
TurboBuRick said:
A simple way to get rid of the part throttle surge is to open the wastegate. The problem is most boost controls (specially air regulator style) keeps the gate closed until boost is close to target then slams it open resulting in part throttle surge.

I use a normally open solenoid and the boost control in my Tpro. In driving mode the boost signal is always on the gate. As boost rises the gate will slightly open bleeding off pressure. This keeps surge in check.

Solenoid activation is done with the Tpro by a set throttle value. Activation is set around 2.50 tps. Half throttle. So below half throttle the gate gets full boost signal. After half throttle the Tpro cuts the signal and goes into spool mode. Solenoid on 100%. As boost gets close to target, the control will pulse the solenoid to achieve the target.

To do this one would need a electronic boost control with a throttle input or a 2 stage boost control with some type of throttle activated switch.

Rick
Click to expand...

Would you mind telling what you are using, also where to buy it. Thanks
 
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