The Broken Fiat Club

I wanted to make my first non-intro thread to be as informative as possible. To kick things off I am going to explain how closed loop boost control works. Reason for this, is that it has been brought to my attention that supposedly its another super special thing about Fiats or patented by Fiat. Sorry to break it to anyone who thinks this but there is no possible way to patent a boost control strategy that everybody and their UTV uses it both OEM and aftermarket.

Alright so to get started there are 3 combinations closed boost control known as dimensions 2D, 3D, 4D, and 5D. Going to break each down starting at the simplest and end with the most complex

2D - This combination uses the MAP sensor to measure and provide feedback to the ECU as to how much gain needs to be provided to meet or compensate the commanded boost pressure via wastegate solenoid duty cycle (+0-100%). 2nd oldest form electronic boost control.

3D - This combination adds in a barometric pressure sensor. Like 2D, 3D has on the fly adjustments for atmospheric pressure changes. Anymore modern turbocharged OEM's use this form of closed loop boost control.

4D - This combination adds Exhaust Manifold Absolute Pressure or EMAP for short. When using EMAP you are essentially keeping the turbo in a pressure ratio with high precision. Major advantage is the prevention of too much back pressure which can lead to turbo thrust bearing damage which induces shaft end play.

5D - Known as the ultimate combination of closed loop boost control. This combination adds compressor wheel speed. Every turbo has pressure ratios and speeds listed on the compressor maps from the manufacture. 5D takes the 3 above strategies and creates absolute control over the turbocharger. You can't overspin, zero backpressure, zero turbo damage. Top it all off you are always in the sweet spot of the turbo compressor map. Doesn't matter where you are just as long as you are not underwater the turbo and engine will be performing on a near WRC or F1 level.

Personally I am going to run a 5D closed loop boost control on my Evo 8 to make 1100whp reliable.

I have to admit this is something I'm not highly familiar with. I know that the days of increasing boost by just sticking an aquarium bleed valve on a vacuum line are over though, as the ECU is actively involved in boost control now - as your strategies above explain.

It looks mostly like our Fiats use something similar to 3D... We have barometric pressure sensor and MAP sensor, but there's also a charge boost sensor.

As far as patents go.... it's amazing what obvious and ubiquitous technologies are actually patented by various companies. I wouldn't be surprised if Fiat has patents over several aspects of boost/turbo control. Even the obvious ones.

MadFiat wrote: ↑Fri Nov 02, 2018 8:42 am I have to admit this is something I'm not highly familiar with. I know that the days of increasing boost by just sticking an aquarium bleed valve on a vacuum line are over though, as the ECU is actively involved in boost control now - as your strategies above explain.

It looks mostly like our Fiats use something similar to 3D... We have barometric pressure sensor and MAP sensor, but there's also a charge boost sensor.

As far as patents go.... it's amazing what obvious and ubiquitous technologies are actually patented by various companies. I wouldn't be surprised if Fiat has patents over several aspects of boost/turbo control. Even the obvious ones.

Some OEM's use 2 MAP sensors one upstream and one downstream. The downstream usually is a T-MAP measuring the air density by temperature and upstream is the primary MAP that does load calculations by air mass via pressure measured in kpa and IAT from the T-MAP.