ZD30 - Vacuum to Boost control

[Rumcajs]

Now I fully understand the logic that Nissan had with using a vacuum control on the VNT with regards to safety (line breaks, boost is dumped. Actuator breaks, boost dumps. ECU panics or solenoid shits its pants, boost dumps) however, this leads to poor control unless you have a good EBC and solenoid. Unfortunately, we all know the factory ECU and solenoid are crap at boost control.

G'day,

I'm sorry but above is not correct.

Do you even understand why variable geometry turbocharger is actually used? It is used to control the incoming air but not for safety or power but to control emissions. EGR technology doesn't work (simple laws of physics) if the turbo is pumping fresh air in at higher pressure then the exhaust gases will ever come out! Retarding turbo at will and increasing exhaust back pressure will drop the amount of fresh air coming in and push exhaust gases in instead in the simple explanation. It gets even worse as buterfly like shutters are introduced in the intake to close or restrict the incoming fresh air even more....

So what came as brilliant answer to control if not elimminate turbo lag (variable geometry turbocharging) become a nightmare of emission shackles....

It is not very accurate or quick to control fixed geometry turbo once the turbine is spinning..... btw on heavy truck engines (non EGR) they use compressed air to fully control waste gate via air PWM valve to choke the turbo at will to keep emissions under control. (The compressed air is coming from the brakes system so cheap implementation again, it is already there essentially same as in cars vacuum is already there in the intake or via vacuum pump on diesel engines equiped vehicles)

The only reason they use vacuum control in cars is because it is cheap and easily available. (The brake booster works on vacuum too so why not utilise the existing tech uh?)

Car makers will use the cheapest method available to them at the time....

If they use electric steeper motor now in VGTs it is only because it allows even greater and finer (read faster) control over the turbo charger boost and exhaust back pressure interaction as the emission fraud is advancing to lower levels.

With the Dawes/TILIX/NV mod or your mod all you are doing is simply converting variable geometry turbocharger in to essentially fixed operation where the variability is used as a safety mechanism only aka waste gate like operation. While effective still primitive use of VGT IMHO!

Regards