Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 I've looked over the web and cant find an answer. Anyone understand the workings of a turbo's amount of boost? My question is how come I can still accelerate with the boost gauge reading negative vacuum until I try to accerlate harder. I just assumed that to get going it would always have to go into the positive zone, catch my drift?? Just curious really. Link to comment Share on other sites More sharing options...
edd_t Posted February 17, 2006 Share Posted February 17, 2006 my boost gauge has a negative reading aswell. so i can watch the needle go round to the posotive no help at all, sorry, just thought i'd let ya know Link to comment Share on other sites More sharing options...
Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 Cheers! LOL well at least I know mine isnt broke - I think! Link to comment Share on other sites More sharing options...
SimonB Posted February 17, 2006 Share Posted February 17, 2006 Basically, when you have negative boost the engine is sucking in more air than the turbo is forcing through, and when it's positive the turbo is forcing more air in than the engine would normally use. The amount of boost produced by a turbo depends on the speed it's spinning at, which depends on the amount and speed of exhaust gas that's passing through it. When the engine is not under much load there's not much exhaust so it doesn't spin fast enough. Link to comment Share on other sites More sharing options...
Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 Cheers Simon, makes sense and thats what I thought but why does a turbo engine stutter if a turbo pipe blows off if it still sucks? Link to comment Share on other sites More sharing options...
SimonB Posted February 17, 2006 Share Posted February 17, 2006 Cheers Simon, makes sense and thats what I thought but why does a turbo engine stutter if a turbo pipe blows off if it still sucks? It doesn't. You just get no boost. If it's got a air flow meter then it would cause trouble because the ECU wouldn't know how much air was going in to calculate the correct fueling. Link to comment Share on other sites More sharing options...
Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 So while its sucking at negative pressure the turbines are still moving, right? Might sound like useless info to know but once I think about something I try to understand it. Link to comment Share on other sites More sharing options...
JohnA Posted February 17, 2006 Share Posted February 17, 2006 So while its sucking at negative pressure the turbines are still moving, right?. yes. The blades are moving from the moment you start the engine. They just don't make positive boost until the load increases. Don't worry about the "negative boost" thing - technically it's vacuum. Can you imagine that n/a owners spend their whole life in it? Link to comment Share on other sites More sharing options...
Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 yes. The blades are moving from the moment you start the engine. They just don't make positive boost until the load increases. Don't worry about the "negative boost" thing - technically it's vacuum. Can you imagine that n/a owners spend their whole life in it? So technically speaking if you keep it in negative it will return better fuel econ? LOL - sure some na peeps will bite, but then again as the title says turbo they might not read it! Link to comment Share on other sites More sharing options...
JohnA Posted February 17, 2006 Share Posted February 17, 2006 So technically speaking if you keep it in negative it will return better fuel econ? Yes of course. Driving off boost uses less air, and less fuel is needed to match it. TTC mode achieves just that, less boost below 4Krpm Link to comment Share on other sites More sharing options...
Alex Posted February 17, 2006 Share Posted February 17, 2006 So technically speaking if you keep it in negative it will return better fuel econ? LOL - sure some na peeps will bite, but then again as the title says turbo they might not read it! Yes if you can cruise at about -.3 you'll return ok MPG's... This is why IanC on a long M-way run managed 27mpg and SoopDogg was at about 22-24mpg (i think). (Ian)T-67 off boost more than (Soop) stock twins. So going big single can help your MPG's....Until you depress the loud pedal! Link to comment Share on other sites More sharing options...
Guest chiefvinso Posted February 17, 2006 Share Posted February 17, 2006 Thats interesting. I am always looking at the vacuum gauge but when a clear road opens up I cant seem to resist especially as I only drive it now and again. Link to comment Share on other sites More sharing options...
Alex Posted February 17, 2006 Share Posted February 17, 2006 It's ok - we don't blame you Link to comment Share on other sites More sharing options...
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