Quote:
Originally Posted by moebius
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for the same reason a supercharger is no good, so is a vnt no good : budget :-)
including shipping the holset (530hp turbo) came to 750nz thats 1/4 of what a brand new garret of equal potential would have cost. i went to the expensive end of holsets offerings because i'm fussy and i wanted it pretty new and therefore A reliable, and B efficient. i got what i wanted. my turbo was supposed to have done about 2500miles or so, and its like brand new. literally.
evo : that ign cut system is less sophisticated and worse than the heavy retard system thats easy to get happening with ms and no further mods.
but, i dont like what it will do to the exhaust valves on the way out...
gavin, thanks for posting that link, very interesting indeed. i hadnt considered the idea of "blowing off" straight out the exhaust :-) a pretty clever idea, but i dont think it would work for me on the street. if you welded in a 5th runner to the collector such that it aimed straight for the turbine, and didnt use the air to ignite fuel in the exhaust, but just to blow the turbine around, it would work nicely during shifts. off idle though, it couldnt build boost like i want.
i'm not concerned about spool between shifts, thats not too bad as it is even with the sucky ratios. what i want is for the turbo to not unspool when i lift to control a slide or prevent a slide when cornering hard. the latter, i'm sure you know what i mean.
i mean, i've slid cars all my life, i live sideways, but i took the ute round a largish roundabout on the way home after tuning it for boost in the wet, and i tried to slide it smoothly all the way around... i couldnt. i could lean on it and it would build boost and skid out, but when i lifted, the turbo would more or less stall, and upon reapplying, there was no torque to keep the skid happening, result : lots of skid angle, no skid angle, lots of skid angle, no skid angle. i couldnt slide it smoothly.
i'm sure with practice i could get it better, but i'm good at that [shizzle], and i couldnt do it off the bat. i found that frustrating, cause its one of my favourite things, that and sex. its a hard call which i like more.
hence "proper antilag". perhaps i'll just have to wait and try it myself :-)
i could use a control strategy to take the vac feed away from the bovs and thereby create pressure at the same time releasing a controlled amount of air into the exhaust (rather than all of it as audi seemed to do) and without the boost pushing the valves closed, the would bleed off any excess pressure that exceeded their spring pressure. i could log a second map sensor for tuning it. to see what sorts of pressures were found. i'd need to replumb the wastegate feed to pre throttle to ensure that it vented exhaust gasses if there was a need also. that ought to keep it from over spooling, and yet make sure that there was pressure in the intake ready to pass the throttle after i stop lifting. i'm not too worried if the system cant start it spooling, so long as it can keep it spooled when i'm doing skids/cornering hard at part throttle...
i hope you lot all see where i'm coming from now :-)