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#1
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Cold Air Intake
K, another big one, I was thinking about moving my battery into the cavity that removing the giant exhaust will make, then splitting the two banks into two seperate cold air intakes, and I have some questions as I'm not very familiar with the electrical A/F methods of this car.
1) If I didn't use a second MAF on would the ECU automatically adjust the pulse width to adjust for the extra air or would the ecu have to be re mapped? 1b) If the pulse width were increased would the duty cycle of the injectors get too high (aka above 80%) 1c) Would the stock injectors be able to handle a pressure rise to create a higher fuel flow rate to account for the extra air? 2) If I were to get my hands on another MAF, is it possible to wire the two together to get a proper air flow reading? (Take into consideration this is an OBDII '97 ECU, I know LAN has this mod with his ECUTUNE but that won't work for my car and I can't afford the standalone ecu just yet) I figured that once the car is running in a closed loop system as long as the injectors would be able to handle the extra duty, the ECU would automatically adjust to account for the extra air, changing the injectors wouldn't really help me, cause I would need to reprogram the ecu anyways because its' open loop tables would be way off.
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'97 Ebony Pearl SVX Lsi Current Mods: K&N Filter, -18x8" Konig Hotswaps with Nexen Tires -Polyurethene swaybar bushings -iRotor Drilled/Slotted zinc plated rotors, ceramic disc pads, stainless steel braided blue covered brake lines, powder coated calipers. Soon - Custom Headers, Cold Air Intake, and Custom Magnaflow Exhaust *New addition*2000 Volkswagon Golf TDi (don't worry, it's my new winter beater, gives me more money in my pocket(less gas) and I can park my car for longer periods of time giving me time to work on it and less damage to the SVX from winter driving) |
#2
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Adding a second intake that large, that is un-metered would not work. I haven't dug to far into the ECU programming and how it all works but some people have talked about doubling the reading that the MAF gives the ECU. I don't see how that would work because the MAF has a fixed voltage range (0v-5v, I believe anyways) that it sends. Maybe you could half the signal it sends and then tell the ECU to read it as doubled? But this is just all guess work..... Two MAF's could work, but again there is gonna be alot of programming behind it. A stand-alone running speed density would be awesome, IMHO. But then you'd need a stand-alone that can run speed density, and a professional tune. Dustin
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-Dustin 1992 Ebony LS-L w/191k miles Mods: a few and acouple more 1995 Brilliant Red L/AWD w/154k miles Mods: Stebro catback exhaust, K&N drop in filter, ECUtune ST1v5, 4.44, lots of JDM goodies 1992 Pearly LS-L w/154k miles Sold Mods: 4.11, rust 2008 DGM Legacy spec.B w/245k miles Mods: Cryotune Stage3, VF52, bushings galore, STi pink springs, Bilstein HDs My Locker The only man alive who drives three "Subu SVS's".......according to my insurance company |
#3
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The performance gained from running twin intakes would not offset the amount of work that would be, I'd put that effort into fabricating a single cold air intake, as that will flow more than enough, and be a lot less effort. (Won't look as cool though.)
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1992 SVX LS-L #1222 Pearl White 1987 GL Turbo wagon, 5 lug conversion, D/R 5 speed (Rice killer) 1992 Dodge Ram 4x4 diesel (car hauler) 1968 Dodge Polara convertible (Camaro killer) 1990 Toyota Corolla FWD auto (330,000 mile grocery getter) 1986 VW Jetta |
#4
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"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." Benjamin Franklin blk 92' LSL w/ average mods pics here http://s306.photobucket.com/albums/nn277/yourconfused/ Cash68: "Hmm, I wouldn't brag about beating Escorts. That's like saying you tricked a retarded person." |
#5
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Well Thanks for the input odepaj, and Yourconfused...well negativity never gets you anywhere, there's always a way of engineering things to work, we run a speed density plot on our SAE car, so I'm sure it wouldn't be too much more work to dyno the EG33, just more mechanical work to get it out of the car and onto the dyno...wish I had a test engine
I'll probably just run the one cold air intake for now, then see where i'll go from there
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'97 Ebony Pearl SVX Lsi Current Mods: K&N Filter, -18x8" Konig Hotswaps with Nexen Tires -Polyurethene swaybar bushings -iRotor Drilled/Slotted zinc plated rotors, ceramic disc pads, stainless steel braided blue covered brake lines, powder coated calipers. Soon - Custom Headers, Cold Air Intake, and Custom Magnaflow Exhaust *New addition*2000 Volkswagon Golf TDi (don't worry, it's my new winter beater, gives me more money in my pocket(less gas) and I can park my car for longer periods of time giving me time to work on it and less damage to the SVX from winter driving) |
#6
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I ran two intakes when I was trying the best combo,mine was two tubes with conical filters that came together into a single going into the maf meter,I truly didn't gain nothing.Anyway you are on the right track by trying different things.
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#7
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Hve you looked at how large the twin 2.5" t.b.'s are really in comparison to the size of the motor? the 3" maf shouldn't be the restriction as much as the basic design of the intake tractt going to the t.b.'s really, so modifying that should be your only concern.
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"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." Benjamin Franklin blk 92' LSL w/ average mods pics here http://s306.photobucket.com/albums/nn277/yourconfused/ Cash68: "Hmm, I wouldn't brag about beating Escorts. That's like saying you tricked a retarded person." Last edited by YourConfused; 05-09-2008 at 12:27 AM. |
#8
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would smoothing out the intake give you any noticable/worthwhile gain? i understand how the air would flow better, there is no doubt about that, but what kind of improvements can you expect? would it make it only sound different, or actually give you a noticable, physical (as in performance, not visual) change?
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1992 silver/black LSL - 142,xxx miles power mode switch, ecu crush, intake silencer removal, ecutune, B&M transmission cooler 1971 toyota landcruiser - project.... someday |
#9
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Use the search buton on Tomyx
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____________________________________________ 95 LS-i Red, 31,xxx; bone stock for now; Daily Driver 94 LS-i Emerald Pearl, 106,xxx,; 246 whp; Tomyx snorkus and HKS Cold air intake; PWR aluminum radiator, silicone hoses; Inline thermostat; enhanced coolant routing; external power steering and oil coolers; Phenolic intake manifold spacers; 2004 WRX 5 speed transmission; ACT Clutch Kit, Heavy Duty Pressure Plate, Lightweight flywheel, performance disc; Group N motor mounts; ‘07 WRX 4-pot front calipers, cryo-treated slotted Tribeca rotors; Hawk HPS ferro-carbon pads; Frozenrotor rear slotted rotors; SS brake lines, Axxis Ultimate pads; Rota Torque 17x8 wheels; 245/40-17 Bridgestone RE01-R's; Koni inserts with Ground Control coilovers, Eibach springs; K-Mac camber/caster adjustable strut mounts; Urethane swaybar bushings; Bontrager rear sway bar; Urethane differential bushing; Custom Whiteline adjustable rear lateral links; Outlaw Engineering forged underdrive pulley; custom grind Web intake and exhaust cams (11 mm lift, 250° duration); solid lifters; CP custom aluminum forged 11 to 1 pistons, Brian Crower coated SS intake & exhaust valves; Brian Crower upgraded springs w/ titanium retainers; NGK sparkplugs; RallyBob (Bob Legere) ported and polished cylinder heads; Eagle H-beam rods; ACL Bearings; Cometic Head gaskets; ARP head studs & fasteners; Hydra Nemesis EMS; Wideband O2 sensor; 740cc Injectors; Walbro 255lph fuel pump; Upgraded WRX starter; Equal length SS headers (3 into 1); dual Magnaflow cat converters; 2 into 1 into 2 SS exhaust with Bullet muffler; OT Fiberglass hood; Oil pressure gauge; Programmable shift light, 2017 Subaru Forester XT, metallic dark gray, 29,xxx 2005 Porsche 911 Turbo S Cabrio, 24,xxx 2006 Subaru Outback LL Bean, 166,xxx sold 92 LSL Dark Teal, Smallcar Shift Kit - sold |
#10
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1) A voltage 'totalizer' 2) Two adjustable voltage regulators. Just making these up since I am far from an electrician.
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Kevin Thomas 1997 2.2ltr Subaru Impreza Outback Sport Wagon (AWD/Auto) 13.03@100mph 1989 2.7ltr Subaru XT6 (AWD/Auto) 15.912@85.93mph 1996 3.3ltr SVX (AWD/Auto) 15.070@91.38mph ***R.I.P*** 2010 RAV4 AWD Sport (13.717 @ 99.19mph ) 2015 Honda Fit LX CVT (15.2 @ 90mph) Last edited by Myxalplyx; 05-09-2008 at 09:13 AM. |
#11
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There are heaps of assumptions of linear readings in this thread. Half the flow through a MAF does not necessarily return half the signal. Consider a temperature sender; the results there are on a curve.
For the "Hey, this would be cool" factor, you've got a maybe, depending on your definition of cool. For the "Hey, this might be beneficial" factor, you've got a maybe, depending on whether it works. For the "Hey, this provides gains that are worth the extra hardware and research and monay", I've got to be honest and say that I'll play odds against. If half the flow through each of two MAFs create half the signal and they can be combined, then you're in good shape from the start, but in my experience with sensors, I can't say that I'd expect that to be the outcome. Once you wind up programming a processor to produce a single signal from the two MAFs that matches the flow of a single MAF (see (1) above - spot on, K), you're where you came from, but with less accuracy. Negativity is not defined by contradiction with justification. "A trampoline will not get you to the moon" is not negativity!
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Disclaimer: The above post is on the internet. |
#12
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not being a mechanic, i cant flame. but being a physics student, maybe i can give some insight.
someone long ago suggested eliminating the injector bottleneck in the stock svx by doubling the intake volume and doubling the injector volume. i was planning on doing something similar to what you're thinking about. if you remove the batt and stick it in the trunk, you get a real nice cold air intake chamber. then u take another maf-to-tb intake pipe from an old svx and attach to a cone filter, drop the cone into the cavity where the batt used to be and attach it to the plastic t.b. intake box. this would probably have to be done with a dremmel and some silicone. voila, increased airflow by 200% because your pressure is halved. the MAF consequently will read 50% airflow, telling your ecu to tell your injectors to work 50% less of the time, resulting in **** performance, somewhere near 100 hp, or 50%. so you double your injector size, say to a DET20 or whatever they call the 300z engine. you eliminate the injector bottleneck, add a cold air intake, and set up nicely for possible internals work. |
#13
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Maybe try something similar to this?
__________________
-Dustin 1992 Ebony LS-L w/191k miles Mods: a few and acouple more 1995 Brilliant Red L/AWD w/154k miles Mods: Stebro catback exhaust, K&N drop in filter, ECUtune ST1v5, 4.44, lots of JDM goodies 1992 Pearly LS-L w/154k miles Sold Mods: 4.11, rust 2008 DGM Legacy spec.B w/245k miles Mods: Cryotune Stage3, VF52, bushings galore, STi pink springs, Bilstein HDs My Locker The only man alive who drives three "Subu SVS's".......according to my insurance company |
#14
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I just thought of something around using two intakes. Let's say you have two separate intake tubes but the working maf sensor is only connected to one of them. All you'd have to do is monitor the air/fuel ratio at part and full throttle and make an adjustment via an SAFC (for part throttle) and an SAFC plus a fuel pressure regulator (at full throttle). Simple enough?
Your ECU is only reading half the amount of air since half is going to the other three cylinders, through the one tube. You can compensate for this with a fuel controller and an adjustable fuel pressure regulator if you pay attention to your air/fuel ratio and EGTs. Am I correct?
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Kevin Thomas 1997 2.2ltr Subaru Impreza Outback Sport Wagon (AWD/Auto) 13.03@100mph 1989 2.7ltr Subaru XT6 (AWD/Auto) 15.912@85.93mph 1996 3.3ltr SVX (AWD/Auto) 15.070@91.38mph ***R.I.P*** 2010 RAV4 AWD Sport (13.717 @ 99.19mph ) 2015 Honda Fit LX CVT (15.2 @ 90mph) |
#15
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I thought about doing that too, but it's a real mechanics way of looking at it, it would work, but not very precisely. Both intakes are not going to have the exact same resistance and the maf may be reading even less than half of the air because the side with the maf would more than likely have more resistance. For a really accurate solution one would have to find a way of wiring two maf's in series in such a way that the ecu would see the it's getting twice the air.
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'97 Ebony Pearl SVX Lsi Current Mods: K&N Filter, -18x8" Konig Hotswaps with Nexen Tires -Polyurethene swaybar bushings -iRotor Drilled/Slotted zinc plated rotors, ceramic disc pads, stainless steel braided blue covered brake lines, powder coated calipers. Soon - Custom Headers, Cold Air Intake, and Custom Magnaflow Exhaust *New addition*2000 Volkswagon Golf TDi (don't worry, it's my new winter beater, gives me more money in my pocket(less gas) and I can park my car for longer periods of time giving me time to work on it and less damage to the SVX from winter driving) |
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