Date: Mon, 26 Apr 1999 06:47:43 GMT From: jvanabranopsamnet Subject: Re: SAAB?
In article <372210C7.4700nopsamnk.com>, kenwashnopsamnk.com wrote: > Doug, > > I guess I will have to be more specific next time. I wrote my answer > thinking that anyone who knew a little about turbos or had read anything > about them would know that intercooled meant water cooled. What was I > thinking? I guess I'll just have to smack myself. > Ken: Before you start getting all arrogant on our Saab-owning friend Doug, perhaps you should do a little research on automotive technical terms. "Water cooling" and "intercooling" are neither the same thing or even somewhat related - they are completely different technologies whose function are both independant and unrelated. "Intercooling" is a process whereby pressurized air coming out of the turbo is fed into a heat exchanger (either an air-to-air exchanger or a water-to-air exchanger) in order to reduce the temperature of that air. It's not unlike a coolant radiator, except in this case the system uses ambient atmospheric air to cool the hot air that the turbo puts out. Most cars use a simple air-to-air exchanger, as they are reliable and simple. Some cars, notably the 4cyl Lotus Esprit of the early '90s, use a water-to-air exchanger which runs a dedicated supply (i.e. NOT from the engine) of cooling liquid through the intercooler to aid in the cooling process. Often time, an air-to-air exchanger is called an intercooler, and a water-to-air exchanger is called a chargecooler. "Water cooling" is a system that uses the engine's coolant supply to aid the cooling of the turbo unit itself, and unlike an intercooler has nothing to with the air coming out of the turbo. In early turbocharger systems, the turbo relied solely on its lubricating oil supply to provide cooling, and in most cases this was adequate. As boost pressures increase, the heat of the exhaust coming through impeller side of the turbo coupled with the heat put out by compressing air (remember, compressing air is an exothermic reaction) additional cooling is 'necessary' to help minimize the heat stress on the turbo and prevent coking of the oil supply. In order to accompish this, water from the engine's cooling system is routed through the compressor housing to provide that additional cooling. As these two VERY DIFFERENT technologies apply to Saab: America: All 8v turbos features neither a water-cooled turbo nor an intercooler. All 16v cars were equipped with an intercooler, but it wasn't until 1987 that 9000s got a water-cooled turbo, and 1988 until 900s did. Europe: 8v turbos were offered (I don't know if it was standard) with an intercooler and, after 1988, a water-cooled turbo. 16v 900s were offered with or without an intercooler (B202 for intercooled, B202S without) but after 1988 all had a water-cooled turbo. All 9000s had intercoolers, but a water-cooled turbo was not added until 1987. Ken, we all appreciate your posts on this newsgroup, but before you start slamming people you need to check your facts. -Justin P.S. Sometime in the future, talk to me about water injection, which is another unrelated turbo technology -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
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