Cyprus Posted April 30, 2007 Share Posted April 30, 2007 i recently read a post on this forum where a member was stating that his PSI level had rose from 7psi to 9psi just by installing a FMIC .. how exactly does this occur when the stock ECU still has a boost soleniod setting of 5psi low and 7psi high Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/ Share on other sites More sharing options...
Al Posted April 30, 2007 Share Posted April 30, 2007 The factory smic is restrictive, thus if you where to measure the boost b4 the smic it will be higher than the boost after the smic. Installing a better flowing cooler will have less restictions, therefor the boost b4 and after the cooler will almost be the same. The factory solenoid is similar to a bleed valve, as is calculated/manufactured to allow the turbo to boost up to 9psi. This is with the restictive smic, replace with a fmic will reduce restriction, therefor flow more air. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3086505 Share on other sites More sharing options...
DRD-00F Posted April 30, 2007 Share Posted April 30, 2007 agreed... i notice the increase... Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3086622 Share on other sites More sharing options...
STATUS Posted May 1, 2007 Share Posted May 1, 2007 based on my experience with silvias the factory cores have on average a pressure drop of about 2-3psi an aftermarket one has on average less than that and the average differrence in pressure drop is realised as a boost increased. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3087573 Share on other sites More sharing options...
paulr33 Posted May 1, 2007 Share Posted May 1, 2007 this also depends on where the actuator gets it signal from on the r32 it comes off the compressor cover so it wouldnt be an issue on the 32 but the r33 gets it post intercooler so its after intercooler core drop Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3087753 Share on other sites More sharing options...
foznice Posted May 1, 2007 Share Posted May 1, 2007 ahhhh thanks for clearing that up paul. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3088086 Share on other sites More sharing options...
Cyprus Posted May 1, 2007 Author Share Posted May 1, 2007 yes! thank you paul.. you really help't me out there cuz i needed an answer on that big time Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3088865 Share on other sites More sharing options...
paulr33 Posted May 1, 2007 Share Posted May 1, 2007 yeah so if you are seeing psi increase after a fmic then move the actuator signal to pre intercooler Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3088974 Share on other sites More sharing options...
rob82 Posted May 1, 2007 Share Posted May 1, 2007 based on my experience with silvias the factory cores have on average a pressure drop of about 2-3psi an aftermarket one has on average less than that and the average differrence in pressure drop is realised as a boost increased. Pressure differentials across intercooler cores is based on airflow more so than boost pressure. Its just that higher boost pressure usually means more airflow. So your figures are a little ambiguous. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3089614 Share on other sites More sharing options...
mad082 Posted May 2, 2007 Share Posted May 2, 2007 Pressure differentials across intercooler cores is based on airflow more so than boost pressure. Its just that higher boost pressure usually means more airflow. So your figures are a little ambiguous. if an intercooler is a restriction then the pressure will be higher before the cooler than after. the more of a restriction the higher the difference. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3090184 Share on other sites More sharing options...
foznice Posted May 6, 2007 Share Posted May 6, 2007 it's interesting, because we all not that standard boost for an RB20 is 10psi, and standard boost for an RB25 is 5/7psi... but they're measure from different locations... but if we were to measure them from the same place we might get similar figures. Just thinking out loud. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3101960 Share on other sites More sharing options...
Cubes Posted May 6, 2007 Share Posted May 6, 2007 it's interesting, because we all not that standard boost for an RB20 is 10psi, and standard boost for an RB25 is 5/7psi... but they're measure from different locations...but if we were to measure them from the same place we might get similar figures. Just thinking out loud. You won't as the r32 actuator is rated to open at a higher pressure. Grab an r33 actuator and r32 actuator; the r32 actuator is considerably stiffer. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3102015 Share on other sites More sharing options...
MBS206 Posted May 6, 2007 Share Posted May 6, 2007 You shouldn't really get a pressure increase at all! The same pressure is hitting the solenoid, at 7PSi before or after the intercooler change. Alot of people actually notice a pressure DROP (If pressyre taken before intercooler) due to a more affective cooling intercooler (Pressure is dependant on temperature too!) And if the actuator gets it's pressure from AFTER the intercooler, there should be ZERO change in pressure. If the actuator is set to open at 7PSI with x amount of air bled off, then it will open at 7PSi after some air is bled off. Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3102119 Share on other sites More sharing options...
foznice Posted May 6, 2007 Share Posted May 6, 2007 You won't as the r32 actuator is rated to open at a higher pressure.Grab an r33 actuator and r32 actuator; the r32 actuator is considerably stiffer. I was just wondering to myself, if Nissan would have compensated the pressure drop into the adjustment of their actuators, but then I wondered where WE are measuring boost from, so that probably comes into play. But hey like you said the r32 actuator is stiffer anyway so there you go... (still thinking out loud) Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3102427 Share on other sites More sharing options...
Roy Posted May 6, 2007 Share Posted May 6, 2007 this also depends on where the actuator gets it signal fromon the r32 it comes off the compressor cover so it wouldnt be an issue on the 32 but the r33 gets it post intercooler so its after intercooler core drop LOL...ah, now you agree with me. I remember you thinking i was on drugs when i was commenting why R32s make more boost at the inlet after a fmixc install Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3102438 Share on other sites More sharing options...
gts-4 dreamer Posted May 7, 2007 Share Posted May 7, 2007 hmmm....fmic = MUST more driveable car with more consistent results. cold nights also make a BIGG differnece where as before was always crap by comparison. split front / dump 4psi increase with stock controller..... *yeS* Link to comment https://www.sau.com.au/forums/topic/166768-fmic-increases-psi/#findComment-3103557 Share on other sites More sharing options...
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