Suction throttling involves placing a restriction orifice or restrictor plate over the inlet to the compressor in order to operate at a lower flow than desired. This will reduce the pressure at the compressor suction and increase system resistance. By doing this, the operating point of the compressor can be controlled.

This is used with success in the oil and gas industry on turbo compressors usually via an automated butterfly valve that is controlled based on a flow meter and corresponding logic.

I've also heard of this used with superchargers. An enthusiast buys a larger blower and restricts the inlet in order to limit overall manifold pressure and power. The result is more airflow sooner, a broader torque curve and then the blower is limited at higher rpm. I've never personally used one myself.

With the boost control issues I'm experiencing on the TTiX kit, I'm contemplating trying this out. A circular plate with a smaller opening would be located over the inlet to the compressor housing with the intention of limiting airflow into the compressor and hopefully gaining control again via the wastegate.

I understand how flow will be limited, but can't quite quantify what happens next. Obviously, less airflow into the engine should equal less exhaust flow out and less overall power.

My guess is that the compressor will now have to spin faster to reach the same airflow as before? Pressure ratios will be different and overall total output will likely be reduced?

Has anyone tried this before with an automotive turbo system?

What are the negative effects from an equipment reliability standpoint that should be considered? More heat? Higher stresses on the compressor or turbine wheel or shaft?

Any turbo machinery or rotating equipment experts out there?

 

Hmmm not sure how that's going to work Ben, but it might. Sort of the same as putting a restrictive exhaust on right? Just the other side?GL!

 

i believe it is standart practice to have standartised restrictors before the compressor in certain racing categories (or was).

 

I'm with him, it will just limit overall power I think and possibly slow down spool. I haven't seen many try it thought so good data never hurts

 

I have an aps twin turbo car myself. The APS inlets are restrictive and limit my boost and power (this is a fact as I can remove the inlets from the compressor housing on the dyno and make more boost & power). I've done some research on this subject and read comments that starving the turbo on the inlet side can cause oil to leak into the compressor side. I have not experienced this, but you might want to research the possibility before trying it. Hope this helps.

 

Yes, I'm trying to understand how it works and what could go wrong before trying it out.

I've read about some of those instances for open wheel classes back in the day. I'm sure they changed turbos after every race.

I'll test it out once I understand it and know how it works and any possible issues that it may cause. If I can't get a good consensus, then I'll just stick with what is already working.

Do you know if these comments were related to completely closing the inlet or just restricting it slightly?

 

sounds like what the centri guys like ECS and A&A do to try & make it feel more like a PD blower. i'd bet you could talk to them about it, since a centri works pretty similarly to a turbo.

 

Many if not all of the major turbo manufacturers websites all address restrictive inlets as being a cause of oil being sucked past the oil seal on the compressor side and into the compressor housing which causes smoking, oil in inter cooler etc. I just offered this info as food for thought. It sounds like your inlet system is to good. I wish I had that problem! Good luck.

 

Blower speed is direct correlation to engine rpm. Turbos are not. If you are trying to reach 10psi and put a restriction in front of the turbo it will spin faster to make that boost.

 

TurboGeist. How much boost with no spring in wastegate?

 

yeah, i know how each type works - i just meant the compressors are similar & wasn't sure if the turbo would just try harder to achieve its target.

 

6# spring - 22.3 psi @ 6200
6# spring - 18.5 psi @ 5200
No gate - 18.5 psi @ 5200

*Gate was completely removed from the system.

 

I'm not very familiar with your setup, are you on external gates or internal?

Will be interesting to see how it pans out, but seems to me that the turbo will just spin harder to make less power. Like you mentioned above I can see IAT's going up for sure.

 

5-bolt internally gated housing but setup for external gates.

 

I'm just dying to see Jon weld a good gate to your turbine housing and solve all your boost control problems.