Alfa Romeo Forum - View Single Post - How does chip tuning control turbo boost?

symonh2000 · 02-04-2008

Th variable geometry turbine fitted to some engines is a different setup to ordinary turbo's. Ordinary turbo's do have an electro-mechanical boost solenoid, but on variable geometry systems there is an additional solenoid to control the angle of the vanes in the turbo as well.

The reason for electro-mechanical boost control is usually to give a more progressive power delivery, insted of the all or nothing traditional turbo power delivery. It also helps incorporate safety measures, such as reducing the boost to prevent wheelspin, of to allow lower grade fuels to be used.

On most cars the wastegate is set to open at a nominal value, which is often reffered to as the base boost level. The wastegate usually opens at a pressure of around 7psi. By incorporating a valve between the inlet and the wastegate, the valve can be programmed to open at higher pressures that the base level of the wastegate hence allowing more boost than the wastegate level. When the valve is opened this allows the boost pressure to the wastegate, which casues it to open.

02-04-2008	#5 (Post Link)
symonh2000 AO Gold Member Join Date: Dec 2005 Location: Carterton, Oxfordshire Posts: 7,363 Member car: Fiat Coupe 20V Turbo	Re: How does chip tuning control turbo boost? Th variable geometry turbine fitted to some engines is a different setup to ordinary turbo's. Ordinary turbo's do have an electro-mechanical boost solenoid, but on variable geometry systems there is an additional solenoid to control the angle of the vanes in the turbo as well. The reason for electro-mechanical boost control is usually to give a more progressive power delivery, insted of the all or nothing traditional turbo power delivery. It also helps incorporate safety measures, such as reducing the boost to prevent wheelspin, of to allow lower grade fuels to be used. On most cars the wastegate is set to open at a nominal value, which is often reffered to as the base boost level. The wastegate usually opens at a pressure of around 7psi. By incorporating a valve between the inlet and the wastegate, the valve can be programmed to open at higher pressures that the base level of the wastegate hence allowing more boost than the wastegate level. When the valve is opened this allows the boost pressure to the wastegate, which casues it to open. "Driving a car is very much like making love to a beautiful woman. You should treat it gently during the week, and then Rag the arse off it at the weekend."