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#16
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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. |
#17
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Nice
Very nice thread and great info Mychailo. You do realize that this info can spread like a disease to other forums for other models of Subarus right? The later modelled turbo'd Subarus of the late 80's has problems with fuel cut due to the Maf voltage reaching a certain point. If this mod could prove successful in application on these turbo'd subarus, the bypass can keep the airflow at bay by not letting too much air through the maf sensor during WOT thus preventing a fuel cut. Of course a valve can be put in line to regulate how much air can bypass. Also, you could have more than one bypass or use bigger diametered tubing, just in case not enough air bypasses.
Interesting! I posted a thread a USMB today. http://www.ultimatesubaru.net/forum/...547#post365547 Thanks for the info.
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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) |
#18
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One word of caution on the bypass mod -- everyone should notice that Mychailo took a very scientific/engineering approach to the process and used a wide band to measure exactly what the the bypass was doing to the AFR. As a result, we (the SVX community) have a baseline system that we can copy and not have to worry about burning up our engines due to overly lean AFR. The last thing you want to do in this area is adopt a "larger tube is better" approach
-Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#19
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I understand fully. I mentioned that it would probably be advisable to use a wideband, EGT guage or a dyno when doing this mod. My thinking is flawed though. On a boosted car, the boost pressure would push outward from the bypass instead of sucking the air in from the bypass. That is for another thread/another forum. Thanks anyways! Carry on!
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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) |
#20
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new bypass tube...
Went looking for better tubing and found what looks to be ideal. Its the tubing that is actually meant to be used with the fittings. :-) The tubing is flexible yet kink resistant. All the parts are by Carlson Electric. Its 3/4" dia hose and fittings. I found that if I heated the tubing at around 150F in the oven for a few minutes, its much more flexible and easier to install.
Drove the car this evening, and its running great. The idle was a little loppy when I first started the car but after a bit of driving, it steadied out. Seems that initially, the ECU was running the afr a little lean at idle, and when it would swing way lean, the idle speed would take a dip. Under agressive driving, the afr is right around 13.2:1 from 3000-5000 rpm. I'll post a log tomorrow.
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#21
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I still think the valve idea would be the best way to do it. It would effectively be an AFC and would allow you to run at whatever A/F ratio you wanted (fitting the stock maps and not knocking) I think someone looking into a turbo setup could use this pretty effectively. maybe even use a throttlebody from the junkyard, attach it after the MAF to the intake tube. (before the turbo if its a turbo car, have a similar, or more restrictive filter) and voila! insta air fuel control. you could even get all fancy and have an electronically controlled actuator to control the TB valve. I would however suggest making sure your knock sensors are in perfect working order before you tried this. (Maybe that J&S safeguard or whatever its called)
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Greg 97 Red SVX LSi clean 96 Black SVX LSi beater 90 Red Eclipse GSX track ho 99 Ford F250 work horse My Locker |
#22
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I wonder if the H-6 cover still fits without touching the tube
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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. |
#23
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David B. SVXipedia @ SVX-IW.COM -- SVX Information Warehouse 2.0 coming...eventually! Ebony 1992 SVX LS-L 5 spd Koni/GC Stebro 187k miles RIP (Rust In Pieces) 1993 SVX 5 spd Koni/GC Stebro Polyurethane bushings still available! |
#24
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What would the ~60 psi FPR out of an XT6 contribute to this??? I'll ship one out if anybody with the proper meters wants to play
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Dave - 03 Baja - 92 SVX - 86 Brat - 08 OB 3.0 |
#25
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#26
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Dave - 03 Baja - 92 SVX - 86 Brat - 08 OB 3.0 |
#27
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This new version looks terrific. Did you get a chance to do that log? -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) |
#28
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Anyhow, I'll try to get a log tonight.
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#29
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After a few more days of driving with the MAF bypass, I have found that when the engine is not up to full temperature, there is some tendency for the engine to stall, at least with my 5MT. No stalling problems when the engine is stone cold, and no problems when the temperature needle is in the full warm spot, but about halfway between stone cold and full warm, there is some tendency. Putting a slight restriction in the bypass line should fix it.
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#30
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phil
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
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