Go Fast Bits Turbo Fuse Overboost Protection Import Image Racing

Let me know what you guys think of this. Its an overboost safety device that supposedly converts your existing BOV into a POV.

It seems like a better idea than a mechanical spring loaded POV which slowly opens

 

It sounds like it's some check valves or a vacuum chamber or something. Maybe when boost pressure exceeds some value, vacuum is applied to open the BOV. Functionally it could be like a mechanically controlled charge relief valve like you find on the FD.

How are you supposed to adjust it? Just use the threaded rod? What if you adjust it wrong the first time? Are you going to test it by intentionally overboosting the engine? Even setting it with an air compressor is only a rough approximation of how the engine will behave under load.

Fuel cut happens in milliseconds and is set by software...

 

This is almost identical to the system I designed for my 20B FC using an extra DPO/PWM output on the PS2K. Mine is based on a solenoid plumbed between the UIM, BOV & front turbo inlet (constant vacuum). Under normal situations, the BOV behaves as it normally does (triggered by vacuum in the UIM). When overboost is detected by the Haltech, it triggers the solenoid the vacuum source to the front turbo inlet, forcing the BOV to open and dump all boost. Mine is set to trigger at 14psi, while the wastegate is set to 12psi.

The same setup could be made using an adjustable pressure switch (a Hobbs Switch) in lieu of the Haltech's output. The downside to this is that it is based on a hardware switch whose performance will decline with age. For this reason, I would set the switch to 2psi above what your wastegate is set to maintain. When testing this, be sure to have a manual switch wired parallel to it so you can dump boost manually should something go wrong.

Remember, this is a measure to counter unforeseen failure when proper diagnosis & repair is not an option (ala Apollo 13), not as an excuse to go ahead when you know something is wrong (aka Challenger).

 

Or just turn on the overboost protection in your ECU. No need for any mechanical devices.

I don't often post in this section, just couldn't resist. Why add another chain of failure when the ECU can just cut all fuel above your desired boost? Seems to work for every OEM.

 

Cutting fuel?????? Isnt that why we blow our motors. Wouldn't ignition cut be better. Just flood the motor out.


QUOTE=Aaron Cake;11325946]Or just turn on the overboost protection in your ECU. No need for any mechanical devices.

I don't often post in this section, just couldn't resist. Why add another chain of failure when the ECU can just cut all fuel above your desired boost? Seems to work for every OEM.[/QUOTE]

 

If the fuel is cut completely, then no ignition happens at all.

 

If your running a stock FC ECU, that is the only time that is a problem since it only cuts on one rotor. Every aftermarket ECU has hard fuel cuts and is the best method of overboost protection since it just shuts off, easy.

thewird

 

The ECU cuts all fuel. Not half, not one quarter, not 10%. All fuel. The engine can't run lean if there isn't any fuel.

Cutting ignition is much worse. Flooding the engine with fuel strips out the lubrication film of oil on the sealing surfaces, pollutes the oil, fills the exhaust with fuel (really bad if you have cats) and will cause inconsistent AFRs when the ignition is switched back on (as the engine is soaking in fuel).

 

I'm setting up my PFC-controlled single turbo FD > in your opinion, would it be better to overboost regulate via fuel cut or via an extremely rich mixture with retarded timing? I'm not planning to over boost, just want it set up properly in case there's an issue...


Aaron

 

Overboost fuel cut best way.

thewird