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Discussion Starter #1
I can get an electronic boost controller for a decent price from my neighbor. I have 3.90 gears and DO NOT benifit from these gears in 1-2 gear. The car does not have enough resistance with these gears. I wonder if the electronic with this fuzzy logic can compisate for this gear ratio, and help a better spool up, and combat the boost dropoff I seem to suffer? Any comments? Or should I try a differant manual controller?
 

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Hes saying the gear is not long enough to spool the turbo, the shorter gears are fine they wont hurt your car any, get a BOV to help keep the turbo spooled in between shifts, also you will come off the line alot harder with 3:90s so once you hit 3rd and 4th it will be fine, what kinda tires you have before you turn the boost up I would worry about traction with the short 1st and 2nd gear you will spin the tires when the boost hits 1st gear for sure with more boost. The electronic boost controllers are good so if you get a good deal go for it. Although if not just get a manual boostvalve from www.boostvalve.com $40 bucks



Post Edited (Mar 7, 10:06pm)
 

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where can we get 3.90 gears?
 

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84-86 turbo.. amazing what a search will do. i bet take off would slaughter the tire(1) with that open differential, but 3rd and up would pull harder with the slight lower ratio...
 

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Discussion Starter #8
Nobody has answered my question, let me simplify my Question, is an electronic boost controller better than manual in a car with lower gears?(with an answer based on experience, not opinion) I spool to about 11psi in 1-2 gear, after 3 rd it will go as high as I set it. I guess the 3.90 gears are too short for what I want on the street, any body have a 3.70 or 3.54 ratio? Boost controller is not my problem. I shift thru 1-2 gear so fast, It never stays in the gear long enough to get over 11 psi.
 

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I have 3:70s in my car I have no problem getting 25psi in first gear.Boost controller would not fix the boost problem, you would have to change gears or you might have a bad gauge or something. If you have no intercooler 15 psi should not be hard to hit in first and second gear, unless your spinning then the boost would drop a bit.



Post Edited (Mar 8, 5:27pm)
 

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the basic theory of a boost controller is the same regardless of whether its a MBC or an EBC. the EBC cannot help the physical boost characteristics very much in order to "make it spool faster".. if you want to see the maximum spool characteristic just unplug the wastegate - it wont get any better than that.. the boost controller regardless of what it may be just changes it from that base non functioning wastegate mode.
 

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If the wastegate is creeping open before full boost, then you could definitely benefit from a better boost controller. A way to test this is to wire your wastegate shut, and see if the spoolup is any better in 1-2 gears (being careful not to overboost).

Do you shift thru 1-2 quickly to avoid overrevving, or to get traction? If traction is the issue, then you could definitely benefit from a diff with higher gearing, if you have the torque to support it. Most V8s are setup with 3.54 or 3.36 gears for the same reason.

I have the same problem on my 73 240Z Turbo w/ 3.7 open differential. First and second gear go by so fast, that there is not enough time to reach full boost before shifting. I break the tires loose in first, second and third gear, so I really don't need more boost in these gears.

I am going to try a 3.54 LSD and see what happens. The longer gearing should help traction while at the same time help spool the turbo in lower gears.

Sean
73 240Z Turbo, L28ET, T3/T4, NPR IC, 88 ECU w/ custom program
232 RWHP @ 10 psi, more boost soon after injector upgrade.
 

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having a higher gear is not going to help your spool, its only going to hinder it. the slower your RPMS rise, less exhaust is being expelled, lower turbine speed. Creep is defined as progressively higher boost in higher gears, caused by different load characteristics. Only crappy boost controllers or weak wastegates/too small of a wastegate will produce this.
 

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I know alot of people with 4 cylinders that dont reach full boost until 3rd gear alot of it has to do with the size of your engine compared to size of the turbocharger a bigger turbo will take a little bit more time but from what I can tell most people always end up going with 3:27-3:73 in most cars not just z's either from traction or boost, my car has a 3 inch inlet on the turbocharger and I can hit max boost in 1st but its ballbearing. Hey sean I bet your car is fast with that light body, you get a track time yet?
 
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