mobythevan Posted June 4, 2003 Share Posted June 4, 2003 I have the book maximum boost and have read through a lot of it, but I was wondering if there may be a rule of thumb for judging spool up by looking at just the turbine A/R and engine displacement. I realize this would be a rough estimation not including wheel trims and bearing differences, etc. But for example a T04B with turbine A/R of .80, .90, 1.00, 1.10 on a displacement of 180 cubic inches. Is there a estimate on the rpm that would spool each turbo? Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 4, 2003 Share Posted June 4, 2003 Those are all to big. You need the .58 ar on the nissan engine if you run the P trim, you can run a .69 ar if you run the O trim. It is not so much a rule as much as it is previous info. But generally the larger the engine, the larger the AR. However if you have a known ar and you change series of turbo's, ie T3 to T4, then it would make sense to be a little more conservative on your ar selection, and for sure don't exceed what you are currently running, unless it is the .48 ar t3 housing, that one sucks. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted June 4, 2003 Author Share Posted June 4, 2003 I was just looking for a estimated spool for those sizes and cubic inches. Not nissan related in any way. Just wondering if one would spool at 4K, one at 5K, 6K etc... or never Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 4, 2003 Share Posted June 4, 2003 I had a 60 ar on my rotomaster, which is a t4 copy, and it was slow to spool. Not sure what rpm, probably full boost at 4000rpms. I know two things. One, if I did not wind out second gear with my T5, I was off boost when I shifted to 3rd, and if I wanted to pass someone at 50 mph and downshifted into 3rd, I got moving good and hard a couple seconds AFTER I passed the car, which sucked. I have 172 CID. Let me repeat, it royally sucked. Once it was moving good, though it hauled ass, but until you got it there, it sucked. Now if you could turn the engine to 8000 rpms, it might not be so bad. I even had an external WG. I really needed nos to spool it. I don't think the large ar ones would spool, but that would depend on the turbine wheel. Quote Link to comment Share on other sites More sharing options...
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