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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars |
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Thread Tools | Display Modes |
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#61 |
Zilvia Addict
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Lol. He's practically got me sold! Does pfc have any fail safe options? And how well does their MAP conversion work? I'm planing on running no bov and from my research I found that most recommend to ditch maf if running without a bov
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#62 | |
Leaky Injector
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For what it's worth, one of the reasons I went with the Link is that I will be running a custom digital dash utilizing the CANBUS output. I did a lot of research on the use of the Raspexi program for a digital display, and it just seemed like more work than it should be and not suitable for the primary dash display. As a secondary display though it would work fine. My only reservations regarding the Link is that they do not have a crapload of US representation. I am decently adept at hardware and software implementation, and my understanding of tuning is modest. I am no pro, but I know my way around and should be able to get it set up and modestly tuned before hitting the dyno for the professionals to take over and stretch its legs. |
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#63 |
Leaky Injector
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Out of curiosity, what is your reasoning for running without a BOV?
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#65 |
Nissanaholic!
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You're making me want to punch you in the throat
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#66 | |
Zilvia FREAK!
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Have you let all of the race teams in the world know about this travesty as well? |
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#67 | |
Nissanaholic!
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#68 | |
Leaky Injector
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If a few hundred dollars protects my compressor wheel from blowing up I'll gladly spend it at the cost of a tiny amount of throttle response. Though if you select a quality BOV the pressure loss in the intercooler piping is minimal. |
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#69 | |
Zilvia FREAK!
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Also if you invest in one of them der computing machines ya'll talkin bout you can program yer self sum 2-step and flat bare foot shift for all the boosties. |
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#71 | |
Nissanaholic!
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#72 | |
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To put it in reverse for you to see the same principle applied to naturally aspirated engines, consider this. Install an air filter to a random engine, then measure the pressure in the air filter tract. Now, reduce the air filter size and keep measuring the same location. What happens? The air filter tract gradually will decrease in pressure (more vacuum signal) and the power output of the engine will decrease in a fairly linear fashion. In other words, the more restrictive the filter, the lower the pressure after the filter, the less power the engine will make. Tie the two ideas together now. What would you rather have in the air filter tract, a low pressure (restrictive air filter), or a high pressure (higher than atmospheric if possible). This is what the recirculated bypass does to the air filter tract, it positively assist the pressure there, allowing the compressor wheel to gather more air molecules per revolution, the same way it would help a naturally aspirated engine to gather more air molecules per revolution if we reduce an air filter restriction. Another positive benefit to recirculation is the compressor wheel speed increases in all pre-boost situations. Tightly sealed air filter tracts without any recirculation valve (bypass) have lower wheel speeds given the same exhaust gas velocity/temperature. In other words, the wheel will move slower, because there is nowhere for the air to go in the intercooler plumbing (try putting your hand over the compressor outlet and see what happens to the wheel speed). Any typical turbocharger moves more air, even at idle speed, than the engine will need. On an OEM turbocharged vehicle, the bypass will hang open at idle, so that during idle speed, the compressor wheel may continue to pump air into the plumbing, which is then recirculated by into the air filter tract as we discussed above, in a never ending loop (until the engine demands the air, which is when the bypass will SHUT TIGHTLY). This keeps the compressor wheel speed up, and can be measured with an compressor wheel speed data-logger, which will show that wheel speed will always be higher given a properly recirculated bypass, whether at idle or between shifts. cliffs: 1. bypass recirculated improves response, higher compressor wheel speed during shifts, overall better performance and longer turbo life span |
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#73 | ||
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As far as fail safe, If you are worried about the engine you run a fuel pressure safety switch in any application first and foremost. After that, use the fuel cut limiter in street/daily applications for best results. If you have an expensive engine you also will want an oil pressure data-logger and safety switch for that as well. |
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#74 | |
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PowerFC doesn't have any failsafes. It tells the engine to run in the manner it's programed. It doesn't natively support any sort of failsafe that will cut power to the engine.
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Infinity supports a failsafe for any parameter it reads if you want there to be a failsafe on it. I've got my sr20 Infinity setup with wideband afr, fuel pressure, oil pressure, boost, water temp, oil temp and ethanol content, all going directly to the ecu itself. If I set a max or minimum parameter I want for any of these the computer can trigger a fail safe. I've basically got the Infinity set up to a point where I couldn't blow up my sr20 if I tried, aside from an all out catastrophic component failure. |
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#75 | ||
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2. The PFC contains what every stand-alone contains: fuel cut rev limiter. Which is more than enough for a daily/street application at any power level, and safe to use. 3. Even the AEM does not contain a fuel cut safety switch. Those must be added to ALL setups if you care enough, and are cheap enough $15. Not really a big deal. The idea behind it is to remove the decision from the ECU (do not depend on a computer 100% to save the expensive engine... use alternative "redundant safety features") and give an alternative safety net, extra protection any setup can use. 4. The minute you say E85, alternative race fuels, etc... you will want to step up into the AEM or similar category of stand-alone. PFC is generally great for gasoline, but those using E-85 and so forth will want the option of flex fuel compatibility and as you say, a wide range of loggers. Those engines should be over 180hp/liter for this kind of fuel/expense. i.e. I can support 600rwhp using plain 93 octane + meth/water in a 3.0L (200hp/liter on gasoline is possible) engine so there is no reason to step into that kind of ECU, as E85 holds no real advantage. Once I pass that range into the 700rwhp+ for 3.0L I will need the E85 and better ECU, especially if I want to keep a reasonable compression for a street car. |
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#76 | |
Nissanaholic!
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No bov = extra torque = (force*radius) applied to compressor wheel while it is still trying to spin, causing deflection and wear on bearings.... You don't need a study, it's physics. The same stuff turbo manufacturers use to develop their products and the same reason why turbo manufacturers SAY TO RUN A BYPASS/BOV. (Already have spoke to two mechanical engineers regarding this) That being said this doesn't mean your turbo will blow up in a day
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#77 | |
Leaky Injector
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It is something I have explored in depth, and being a mechanical engineer, I understand the reasoning behind exactly what you are saying. |
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#78 | |
Zilvia FREAK!
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#79 | |
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#80 | |
Nissanaholic!
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http://www.volkspage.net/technik/04/maximum_boost.pdf |
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#81 | |
Leaky Injector
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I was just commenting on the typical response given when you search forums about BOV/BPV set-ups. I personally will be running a Synapse Diverter Valve so I can fiddle with the push/pull set-up which I find quite interesting. I like tinkering though, so YMMV. I haven't yet decided if I will plumb it back before the turbo or run it VTA. I want to keep my diverter valve close to the throttle body, so it's a bit of a run back over to the intake. If I ran the valve on the hot side it would be a no brainer to plumb it back. What do you think Kingtal0n? Run it cold side and VTA, run it cold side with a long run back to the intake, or run it hot side and plumbed back? |
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#82 | ||
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The best reason NOT to run a bypass/bov is for simplicity, when you have a car that absolutely needs the minimum (simplest) setup to win a race for $$$, so that there is less to fail/leak/go wrong. Like If I was going to race for pinks, blast the engine with nitrous/every trick in the book. Or a true race car, competition only, where you have 'unlimited' turbochargers, engines, and funding. Not having the bypass might mean lower wheel speed and more turbo wear, but if it guarantees that the shit isn't going to pop off, fail/lock open, or otherwise cause you to lose the race... its worth the additional drawbacks of having to change parts more often. BYpass/bov are best served in RELIABLE applications, mostly daily drivers, people who need to get 200k+ out of their setups. Quote:
The fewer quantity of air molecules between the wheel and the bypass the faster a similar diameter hole will be able to evacuate the plumbing and reduce pressure. Imagine a length of pipe extending from the compressor wheel outlet to infinity. Where would you plumb the bypass in this situation? At the far end, near infinity? The pressure would never drop in the pipe by the compressor wheel if you did that. On the other hand, If you place the bypass exactly near the compressor wheel, the pressure could stay elevated in the pipe at the length of infinity, while the local pressure by the wheel could be managed through the bypass, assuming the air does not flow backwards in the pipe (applicable to engines since they never breath backwards, there will always be some number of air molecules M traveling towards the engine even at idle speeds) |
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#83 | |
Zilvia FREAK!
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Quote:
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#84 | |
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You might get lucky but.... |
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#85 |
Zilvia Addict
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Honestly....who here thinks they'll put on 100-200k worth of miles on a motor or turbo? We all abuse our cars pretty bad. The motors we tend to swap all come with high mileage (we all know those 60k jdm swaps dried up centuries ago lol) and you want to put on another 100-200k? Hardly unlikely, unless you drive it like a grandma. I've put on 7k miles over the course of 6 years. Obviously my setup isn't a daily. So if I can get 15k out of a new turbo I'm a happy camper. Not only that! Turbo flutter sounds way better than any bov.
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#86 | |
Zilvia FREAK!
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Stupid noises>functionality and reliability Did I get that right? |
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#87 |
Nissanaholic!
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Spend money but do it sloppy because you won't use it that much so break stuff to rebuy it when you don't have to.
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#89 | |
Leaky Injector
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#90 | |
Zilvia FREAK!
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#aintcare bro |
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