gtonstilts Posted June 24, 2016 Share Posted June 24, 2016 Fuel cut as in run's out of MAP after 7200rpm. There are some times when pulling out from a stop sign making a left or right turn where I go to WOT and the tires break loose in 1st gear and the engine runs out of MAP. I always thought full boost was full boost, spooling is when the turbo begins to come into its its own and you can hear it and begin to feel it make power. You say runs out of map ? I assume you mean maf as in grev and or gs is hitting higher numbers than the map is scaled for. If so that is all in the tune these cars come scaled to 2.5grev from the factory, cobb tunes are scaled to more like 3.0grev i have mine scaled for 4.1grev. If you hit numbers to far past the map scaling you will just keep running the map max number which is not ideal... Also wtf are you reving a 2.5 w an oem turbo to 7200rpm ????? The vf40 runs out of steam and falls flat on its face pumping hot air past 5500 and even the vf52 falls on its face anything over 6k You will go faster shifting at or before 6k vs reving it up to 7200 for no reason. Link to comment Share on other sites More sharing options...
fahr_side Posted June 24, 2016 Share Posted June 24, 2016 They typically make boost threshold (your issue) worse. More volume, less velocity to the turbo. If you wanted to try this the Killer B and Perrin have smaller tube diameters and thus better spool. Former is super spendy but bulletproof, latter has some fitment issues. Uh no, not unless it's a big-tube header designed for a high-hp application. I use a Tomei header (same as GTSpec) and see spool no later than on the stock header unless I've been cruising or idling for ages. With a stone cold header there's maybe 100 or 200rpm in it. I've tuned plenty of other cars with EL headers like the Perrin, Perrin copies, Tomei copies etc. and they all behave in the same way. Luckily, the big-tube headers are all marketed as such, so there's less chance you'll pick the wrong one. Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs. Link to comment Share on other sites More sharing options...
Max Capacity Posted June 24, 2016 Share Posted June 24, 2016 You say runs out of map ? I assume you mean maf as in grev and or gs is hitting higher numbers than the map is scaled for. If so that is all in the tune these cars come scaled to 2.5grev from the factory, cobb tunes are scaled to more like 3.0grev i have mine scaled for 4.1grev. If you hit numbers to far past the map scaling you will just keep running the map max number which is not ideal... Also wtf are you reving a 2.5 w an oem turbo to 7200rpm ????? The vf40 runs out of steam and falls flat on its face pumping hot air past 5500 and even the vf52 falls on its face anything over 6k You will go faster shifting at or before 6k vs reving it up to 7200 for no reason. I understand about shifting before redline. The few times my wagon has hit the point where it falls on its face, it has been in first gear and the tires are spinning as I'm trying to move forward after pulling out from a stop sign turning left or right and go to WOT before the car is straight. As the tires break loose and I'm watching where I'm going, steering the car every now and then the car will fall on its face, I shift into 2nd and all is fine. I assume the car hit the end of its MAP, because I have heard other talk about running out of MAP. To be honest with you, I have no idea what "grev" and "gs" are. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Tuning Alliance Posted June 27, 2016 Share Posted June 27, 2016 You say runs out of map ? I assume you mean maf as in grev and or gs is hitting higher numbers than the map is scaled for. If so that is all in the tune these cars come scaled to 2.5grev from the factory, cobb tunes are scaled to more like 3.0grev i have mine scaled for 4.1grev. If you hit numbers to far past the map scaling you will just keep running the map max number which is not ideal... Also wtf are you reving a 2.5 w an oem turbo to 7200rpm ????? The vf40 runs out of steam and falls flat on its face pumping hot air past 5500 and even the vf52 falls on its face anything over 6k You will go faster shifting at or before 6k vs reving it up to 7200 for no reason. I wouldnt say a 52 falls flat on its face. With a 17lb spring in my actuator I can hold 18.5lbs of boost through redline. -B Contact us for all your tuning and performance parts needs! Etuning the legacy community since 2008! Follow us on FACEBOOK | INSTAGRAM [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
gtonstilts Posted June 27, 2016 Share Posted June 27, 2016 I wouldnt say a 52 falls flat on its face. With a 17lb spring in my actuator I can hold 18.5lbs of boost through redline. -B What is the max boost ? Its not about holding a psi its about making power Its easy to make high pressure at redline but if its hot air power and maf readings drop. Even my ev3 drops off after 6k. Thats why most tunes taper boost off in higher rpm.... Link to comment Share on other sites More sharing options...
Rhitter Posted June 27, 2016 Share Posted June 27, 2016 What is the max boost ? Its not about holding a psi its about making power Its easy to make high pressure at redline but if its hot air power and maf readings drop. Even my ev3 drops off after 6k. Thats why most tunes taper boost off in higher rpm.... Wait? What is the max boost ? Max boost doesn't make sense. Max boost could just be a spike in the middle and then it dies. Making power makes sense. If you haven't seen it here is a good thread on it: http://legacygt.com/forums/showthread.php/unlocking-hidden-power-and-flow-your-oem-turbo-246163.html My OBXT build Link to comment Share on other sites More sharing options...
gtonstilts Posted June 28, 2016 Share Posted June 28, 2016 If its tuned correctly there should be no spikes. Max boost should be the same as the highest target boost. If running 18.5 to redline id assume the target earlier in rpms would be 20-21. Most tuned vf52's on 2.5l that ive seen run 18psi tapering to 15-16ish. In the high rpm it is best to taper boost and run more timing. With a bigger turbo you can run 20psi or more to redline.... Link to comment Share on other sites More sharing options...
xt2005bonbon Posted June 28, 2016 Share Posted June 28, 2016 The few times my wagon has hit the point where it falls on its face, it has been in first gear and the tires are spinning as I'm trying to move forward after pulling out from a stop sign turning left or right and go to WOT before the car is straight. As the tires break loose and I'm watching where I'm going, steering the car every now and then the car will fall on its face, I shift into 2nd and all is fine. This happens to me too in 2nd gear as well. Stage 2 with the good ol' VF40. Does not have to be too cold either. Happened with toyo proxes tires, stock size, and yokohama geolandar at/s tires. With the latter, it is to be expected obviously. Link to comment Share on other sites More sharing options...
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