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JusticeForPhat · 11-26-2003, 02:05 PM

A VATN turbo is a variable geometry turbocharger. VATN means Variable Area Turbine Nozzle. The basic principle of a turbo is that it converts waste heat (exhaust) into energy (boost). All this you probally know. However most people have the wrong assumption that the turbo performance is based on how fast the exhaust is flowing or how much pressure is built up in the exhaust. This isn't really true. The exhuast (turbine) side runs off of heat. As the hot gasses pass through the turbine blades which are arranged so that each blade next to each other forms a nozzle. As the hot gas passes through this nozzle, there is a change in volume do to cooling and the little bugger spins. Normally the angles are set depending on what "trim" turbo you have and the only way to alter it is to buy other "trims" to swap in and out.

A VATN takes an interesting approach to this phenomena. It changes the angles in-between the turbin blades. By doing so it changes the profile of the nozzle, and in the end at which speed the turbine spins. Basically it gives you an infinite number of trims in a certain range.

In theory you can do a whole lot for the system especially by computer controlling it. For one you can almost totally eliminate turbo lag. The two leading causes of lag is 1.) A huge volume to boost before the head, ie the 17 feet of 3 inch tubing and monster front mounted truck intercooler my friend has on his Supra. With a whopping 6psi of boost that thing sucks. and 2.) Rotating inertia inside the turbo. What the VATN allows you to do is optimize the shape of the turbine wheel for lower rpms and to keep the turbine spinning. Once you stomp the gas and the engine makes some heat, you can vary the shape to get it up to operating RPM as fast as possible. Without that at idle the rpms of the turbo fall down pretty fast so it takes longer to get them back up.

Also with the VATN under computer control, it allows me to tune the turbo's amount of boost according to how I want the car to run. With a turn of the know you can trim the turbo for minimum lag times, for an autocross event. Or you can trim it to maximum boost for flat out speed. Much better than a standard turbo with a boost controller in my opinion. Sure you can control how much boost you make with it, but you cant control how the turbo responds.

11-26-2003, 02:05 PM	#16 (permalink)
JusticeForPhat Crazy Location: Philly	A VATN turbo is a variable geometry turbocharger. VATN means Variable Area Turbine Nozzle. The basic principle of a turbo is that it converts waste heat (exhaust) into energy (boost). All this you probally know. However most people have the wrong assumption that the turbo performance is based on how fast the exhaust is flowing or how much pressure is built up in the exhaust. This isn't really true. The exhuast (turbine) side runs off of heat. As the hot gasses pass through the turbine blades which are arranged so that each blade next to each other forms a nozzle. As the hot gas passes through this nozzle, there is a change in volume do to cooling and the little bugger spins. Normally the angles are set depending on what "trim" turbo you have and the only way to alter it is to buy other "trims" to swap in and out. A VATN takes an interesting approach to this phenomena. It changes the angles in-between the turbin blades. By doing so it changes the profile of the nozzle, and in the end at which speed the turbine spins. Basically it gives you an infinite number of trims in a certain range. In theory you can do a whole lot for the system especially by computer controlling it. For one you can almost totally eliminate turbo lag. The two leading causes of lag is 1.) A huge volume to boost before the head, ie the 17 feet of 3 inch tubing and monster front mounted truck intercooler my friend has on his Supra. With a whopping 6psi of boost that thing sucks. and 2.) Rotating inertia inside the turbo. What the VATN allows you to do is optimize the shape of the turbine wheel for lower rpms and to keep the turbine spinning. Once you stomp the gas and the engine makes some heat, you can vary the shape to get it up to operating RPM as fast as possible. Without that at idle the rpms of the turbo fall down pretty fast so it takes longer to get them back up. Also with the VATN under computer control, it allows me to tune the turbo's amount of boost according to how I want the car to run. With a turn of the know you can trim the turbo for minimum lag times, for an autocross event. Or you can trim it to maximum boost for flat out speed. Much better than a standard turbo with a boost controller in my opinion. Sure you can control how much boost you make with it, but you cant control how the turbo responds.