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#46
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Oops, i meant 17's on my car...not 16's lol
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#47
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I'm trying to make a clear point here and I'm not sure if you aren't getting it or you are trying to defend your #'s besides it confusing the point i'm trying to make. Fuel injector size calculations using bsfc and desired hp are a good way to decide what fuel injectors to purchase if you are purchasing fuel injectors; however, it is not valid to say that because a calculation using bsfc and desired hp says you should have larger fuel injectors that you can not use the fuel injectors you have. When flow rate is accepted as is the factor limiting how much power you can generate is how much time the injector has to inject fuel. If you give it long enough 1 small injector can fill a barrel with fuel. The time the injector has to inject fuel gets shorter as rpms increase and thus it is at high rpms that the injector will max out first. Maybe this will make it clearer. While the thing we are changing with forced induction is how much air we are putting into the cyllinder with each stroke it is not that the fuel injector can't put enough fuel into the cyllinder for that air it's a question of at what rpm will it no longer be able to put enough fuel into the cyllinder. I'm not going to redo the calculations so this will be ballpark # from the top of my head: at 2800 rpms you have 34 milliseconds to inject fuel into each cyllinder(a lifetime), at 4200 rpms you have 25 and half milliseconds (an awfully long time), at 5600 you have 17 milliseconds (a pretty long time). As your rpms increase the time you have to inject fuel into each cyllinder decreases and somewhere allong the yellow brick road your fuel injectors will not be able to keep up. I can't tell you exactly what rpm this will happen at. It will vary by system and you will not know till you get there. I can tell you though that your car will be plenty drivable while you decide if you want to adjust your boost down to a level the injectors can keep up with at the rpm you want to run or get an additional injector controller, or run higher fuel pressure, etc etc. I can tell you that with the additional power you'll have at low rpms you wouldn't find yourself even wanting to go into high rpms in around the town driving while you figure out what to do for additional fuel. And I can tell you that you will be better able to nail down any other bugs in your newly crafted custom system before doing anything about additional fuel. And I can tell you that you will understand things and be able to make a better choice about if and what to purchase for more fuel after you have driven your working system and nailed down any bugs. Reading is great but you don't really know what you are talking about untill you are there. Your fuel injector size calculator may tell your injectors aren't big enough but what they don't tell you is: 1) they are big enough for the majority of operating time even if they aren't big enough for high rpms 2)you may be happy to turn down the boost to where they are big enough instead of increase fuel 3)you may want to do combinations of things like increase fuel pressure and bring down boost 4)an additional injector controller can be implemented easiest to get you into the higher rpm ranges after you have your system humming with all the bugs worked out The short of it is that untill you have your system working you are really just speculating and the stage 2v3 software is plenty to get your system working and will handle all or close to all operating conditions. Then engine management is no longer a legitmate hold back. If you need additional fuel it will only be under throttle at high rpms and that can be done after your system is built and without screwing with the engine management. |
#48
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Danny 1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon) 1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration 2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection. |
#49
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Thanks very much for all this meticulous explanation Michael. It makes it easier to see that a rolling test bed can be done, without harm. One point I see that would be relevant for forced induction. Bolting on a turbo would seem to be easier than a supercharger. However, the turbo is normally giving its best power at high rpm, where the belt driven Roots or twin screw is delivering full pressure off tickover. This implies to me that anyone considering a turbo will be more likely to run into the maxed out injector problem at high revs, because that is where they are getting their best fun to money ratio. The supercharger will give you all the power at low rpms where even the stock injectors will work. That is why I am going to fit a blower. I will be going with the bigger intank pump, higher pressure and maybe 550cc injectors anyway, but nice to know the stock system would work OK. Thanks again, Joe PS I will be wanting the Stage 2 v 3 from you
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#50
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#51
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Just a quick question for ya Mike. Sometimes when I hit WOT in first and second my car seems to buck. i have a feeling it is because I am pulling too much air and maxing out the MAF. Is this possible for a car with few mods like mine?
Tom |
#52
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Michael,
A lot of performance minded members have installed a 43.5psi impreza fpr in their SVXs. How hard and more expensive would it be to offer a Stage 2v3 for SVX's with this fpr? As you can tell, I have little interest in your Stage 1 OBDII chip, and a lot more in the OBDII version of the Stage 2v3 chip whenever it's released. I just don't want to go back to the stock fpr as I'll be doing some fresh mods on my engine which haven't been undertaken before. -Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#53
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Now let me give you my usual non-answer regarding the obdII stuff: I still can not share any information about when or what we will be releasing for the obdII svx but rest assured that I have listened to everyone during the product development process. |
#54
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You are running a manual transmission so if you are refering to high rpms then yes it is completely possible. If you are referring to low rpms then no. I have not done any personal experimentation/logging/measuring the mass air flow readings on a stock svx. I only know about the software and hardware but I don't know about the airflow on the stock svx from personal experience. This was never needed information for me and this project developed after I no longer had a stock svx on hand to make measurements on in order to give you information to work with. I know the mass air meter maxes out somewhere right around the max output of a stock svx engine but not exactly where. The plots Mychailo posted indicate that the meter is also wildly inaccurate at high airlfows if his log is accurate and his specific case is the case in general then whether you are actually at the max reading on the meter or in the wildly inaccurate reading area of the meter then the maf reading should be suspect for any problems you are running into. |
#55
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-Chike
__________________
"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#56
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Danny 1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon) 1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration 2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection. |
#57
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DITO I am just excited it is even a possibility. . .
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David 96LSi 102k Laguna Blue 95 LS-L AWD, Safety package, 140k Polo Green the Chick Magnet: 91 Justy GL EFI 4x4 154k (new motor @120k) 90 Yamaha V-Max 82 Yamaha XJ650LJ Turbo My Diver Propulsion vehicle: 88 Jeep Cherokee 160k "U-sta-have" 88 XT6 AWD Pearl, 86 XT Lt Blue, 85 XT AWD/4x4 Turbo Space Blue |
#58
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-Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) Last edited by Chiketkd; 07-21-2005 at 09:20 PM. |
#59
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phil
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#60
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LAN is doing our community a great service, and I hope he services his OBDII customers as well as he's servicing the OBDI... -Chike
__________________
"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
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