smallsmall Posted March 23, 2009 Share Posted March 23, 2009 hi any bros out there, could any kind soul explain the below? understand that for lgt, the turbo starts to cut in when we ram rpm above 2.5k now if we accelerate constantly and say we achived 120km/h and now rpm is above 2.5k does the turbo cuts in in this case? kindly advice Link to comment Share on other sites More sharing options...
itsme Posted March 23, 2009 Share Posted March 23, 2009 Are you talking about boost? Boost is determined more by pedal position then rpms. You can drive at 3k on the freeway and you can run 20 hg of vacuum(negative boost). But when you get on the pedal the waste gate closes and you build boost. Racer X FMIC for '05-'09 LGTs, '08+ WRX and '10+ LGT,'14+ FXT, and '15+ WRX TMIC Racerxengineering.com Link to comment Share on other sites More sharing options...
mwiener2 Posted March 23, 2009 Share Posted March 23, 2009 the turbo is never 'off' My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
NORULZleggy Posted March 23, 2009 Share Posted March 23, 2009 the turbo is never 'off' yes it is. Do you not have a turbo switch you hit at about 2700 RPM's, hehe Link to comment Share on other sites More sharing options...
smallsmall Posted March 24, 2009 Author Share Posted March 24, 2009 so am i right to say that the turbo is never off and the boost is not determinded by the rpm but by the positaion of the padel kindly correct me if i'm wrong Link to comment Share on other sites More sharing options...
LuckyBob Posted March 24, 2009 Share Posted March 24, 2009 It's determined by both. Under a certain RPM value (~2.5-3K RPM), it doesn't matter if you floor the car as there won't be enough exhaust flow to build boost in the turbo. Above that, it's determined by throttle position (oversimplified). Link to comment Share on other sites More sharing options...
Reuben Posted March 24, 2009 Share Posted March 24, 2009 I think smallsmall needs to read up here. http://auto.howstuffworks.com/turbo.htm The whole turbo not boosting below a certain RPM is called lag. When it "cuts in" is usually refered to as when it "starts to boost". This will usually be a certain RPM, at wide open throttle. Speed doesn't play into it a whole lot. Smallsmall, to better understand lag and boost, go find an empty backroad, and stick it in 3rd, and slow down to about 1000-1500 rpm... then floor it, and hold it till you are at a staisfactory speed. Strictly speeking that's not good for the car, you should never drive below 2000 rpm under any sort of load, but it will be a good demonstration of turbo lag. You 2.5 guy's should try that in a 2L with a VF39. Doesn't get to full boost till 4K, but boy does it kick you in the back when it does boost Link to comment Share on other sites More sharing options...
PhilT Posted March 24, 2009 Share Posted March 24, 2009 The turbo builds boost according to load on the engine. Pootling along downhill at 80 mph isn't putting any load on the engine. Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
BAC5.2 Posted March 24, 2009 Share Posted March 24, 2009 Turbo response is directly related to engine load. More load, more heat. More heat, quicker spool. Watch a boost gauge. Floor it in 2nd at 2000RPM and note when you hit peak boost. Now floor it in 3rd at 2000RPM and note when you hit peak boost. This point is countered slightly by surge. Surge is when you attempt to flow more air than the turbo is actually capable of flowing at a given pressure ratio. Meaning that the engine is sucking air through the turbo at a rate higher than the exhaust powering the turbo would be capable of allowing. It's called surge (and it's different than compressor surge). I haven't seen a compressor map for the stock turbo, but I doubt surge is much of an issue and the above comparison should hold mostly true. It's actually quite a bit more complicated than that, but for the most part it can be generalized that turbo response can be directly related to engine loading and not engine RPM. [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
NSFW Posted March 24, 2009 Share Posted March 24, 2009 The turbo builds boost according to load on the engine. Pootling along downhill at 80 mph isn't putting any load on the engine. Word of the day. Link to comment Share on other sites More sharing options...
o2s0i0r3is Posted March 24, 2009 Share Posted March 24, 2009 You are all so wrong! The Turbo is normally off until you flip the regulator switch under the tachometer which then sends a signal to the odometer which then calls the nearest subaru dealership to confirm turbo activation, once activated the turbo then begins building boost at rate of 3psi per engine stroke depending on the altitude of the car. But that is only in the spec B series of the legacy. Pootling. Link to comment Share on other sites More sharing options...
Merc6 Posted March 24, 2009 Share Posted March 24, 2009 boost gauge would be best visual ade to show what the snail is thinking/doing and I would wanna say yes to your 76ish mph question depending on how much pedal is being pressed. 2005 Satin White Pearl Subaru Legacy 2.5 GT Unlimited 5EAT (Project Car) 2019 Agate Black Ford Explorer XLT 4WD (DD) Link to comment Share on other sites More sharing options...
zenfamily Posted March 24, 2009 Share Posted March 24, 2009 So, where does the VTEC sticker play in all this. I hear it gets you at least 10 to the wheels:lol: Link to comment Share on other sites More sharing options...
BAC5.2 Posted March 24, 2009 Share Posted March 24, 2009 So, where does the VTEC sticker play in all this. I hear it gets you at least 10 to the wheels:lol: Only to the front wheels. VTEC stickers are bad for your center diff. [URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard Link to comment Share on other sites More sharing options...
Merc6 Posted March 24, 2009 Share Posted March 24, 2009 Only spec b get that. 2005 Satin White Pearl Subaru Legacy 2.5 GT Unlimited 5EAT (Project Car) 2019 Agate Black Ford Explorer XLT 4WD (DD) Link to comment Share on other sites More sharing options...
700watts Posted March 25, 2009 Share Posted March 25, 2009 :lol:pootling .... Link to comment Share on other sites More sharing options...
PhilT Posted March 25, 2009 Share Posted March 25, 2009 To pootle along Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
mwiener2 Posted March 25, 2009 Share Posted March 25, 2009 I htought pootle was a setting on SI Drive. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
noswad Posted March 25, 2009 Share Posted March 25, 2009 Word of the day. Sometimes I like to pootle along Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? -George Carlin Link to comment Share on other sites More sharing options...
NSFW Posted March 26, 2009 Share Posted March 26, 2009 To pootle along I would have wagered real money (well, like $5 or so) that you made that up. Link to comment Share on other sites More sharing options...
Jacks GT Posted March 26, 2009 Share Posted March 26, 2009 It's quite an English word, I use it alot Link to comment Share on other sites More sharing options...
dtmenace Posted March 26, 2009 Share Posted March 26, 2009 where's pootie tang to defend his good name? Link to comment Share on other sites More sharing options...
smallsmall Posted April 24, 2009 Author Share Posted April 24, 2009 can advice on the stock boost for my 04 2.0L GT Link to comment Share on other sites More sharing options...
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