I've seen some KA/T's with the MAFS relocated just before the throttle body instead of in front of the turbo. What benefit(s) are seen; does it help stabilize idle? Is it worth my time and $ to pursue??
Relocate MAFS on KA/T?
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scotty-2-forty
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scotty-2-forty
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scotty-2-forty
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scotty-2-forty
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klattr1
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hey
have u checked out your air fuel ratios at all at idle and how have u been setting your base timing (procedure)?Not tryin to discredit you but tryin to use process of elimination for helping you out.
This is usually referred to as a blow-through MAF setup. It's no big deal for turbo motors with recirculated blowoff valves, but it can make a big difference for those who want to stay venting open-atmosphere.
With the stock MAF setup, whenever your blowoff valve vents it is of course releasing all the pressurized air in the system. The problem is that all that air has already been metered by the MAF and thus is compensated for by the ECU by adding more fuel. That will in turn create an overly rich condition which causes all sorts of idle-related issues like rough idle, backfiring, etc.
What the blow-through setup does is it places the blowoff valve before the MAF, so any air that is vented is properly metered, which keeps the driveability issues to a minimum.
It's not all golden though, as a lot of MAFs don't seem to like being used in a blow-through setup and have problems metering the correct amount of air. Another common problem is with intercooler pipes popping off where they attach to the MAF. For most people it isn't worth it to switch to a blow-through setup. The only person I know of who had one was Dennis from UnstableHybrids, and I remember he had to switch from a stock Ford Cobra MAF to the Granitelli version because the stock kept having problems...
With the stock MAF setup, whenever your blowoff valve vents it is of course releasing all the pressurized air in the system. The problem is that all that air has already been metered by the MAF and thus is compensated for by the ECU by adding more fuel. That will in turn create an overly rich condition which causes all sorts of idle-related issues like rough idle, backfiring, etc.
What the blow-through setup does is it places the blowoff valve before the MAF, so any air that is vented is properly metered, which keeps the driveability issues to a minimum.
It's not all golden though, as a lot of MAFs don't seem to like being used in a blow-through setup and have problems metering the correct amount of air. Another common problem is with intercooler pipes popping off where they attach to the MAF. For most people it isn't worth it to switch to a blow-through setup. The only person I know of who had one was Dennis from UnstableHybrids, and I remember he had to switch from a stock Ford Cobra MAF to the Granitelli version because the stock kept having problems...
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Evil98Silvia
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PMan_S13
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I've been using a blow through setup on my 240 for a few months now. Stock s13 maf. Runs fine.
The only real benefit I get is I can run an open bov as previously explained. I suppose you might get slightly better throttle response, but I didn't feel any significant improvement.
BTW, they say that the z32 maf with crack under boost pressure. That's what they SAY, but I've used a plastic s14 maf (similar casing) and it didn't crack at all. Of course, keep adding boost and eventually something will pop.
The only real benefit I get is I can run an open bov as previously explained. I suppose you might get slightly better throttle response, but I didn't feel any significant improvement.
BTW, they say that the z32 maf with crack under boost pressure. That's what they SAY, but I've used a plastic s14 maf (similar casing) and it didn't crack at all. Of course, keep adding boost and eventually something will pop.
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scotty-2-forty
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Re: hey
klattr1 wrote:have u checked out your air fuel ratios at all at idle and how have u been setting your base timing (procedure)?Not tryin to discredit you but tryin to use process of elimination for helping you out.
I've played with the A/F settings via e-Manage, but haven't really messed with the timing since the last stage of dyno-tuning.
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scotty-2-forty
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scotty-2-forty
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Evil98Silvia
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PMan_S13 wrote:I've been using a blow through setup on my 240 for a few months now. Stock s13 maf. Runs fine.
The only real benefit I get is I can run an open bov as previously explained. I suppose you might get slightly better throttle response, but I didn't feel any significant improvement.
BTW, they say that the z32 maf with crack under boost pressure. That's what they SAY, but I've used a plastic s14 maf (similar casing) and it didn't crack at all. Of course, keep adding boost and eventually something will pop.
Cracking is the only issue? I have back up MAFs so I should be good. Are there any other precautions? I dont see how there would be. Im just obsessed with my engine bay and the recirculation hose bothers me lol.
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PMan_S13
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well one other thing I've heard is not to remove the screen on the front or back of the meter. They are supposed to equalize the airflow just before it hits the sensor so you get the most accurate reading. S13 mafs don't have this BTW..
You should also use the same size piping as the meter itself. If you use bigger or smaller piping (especially just before the meter) you are more likely to have inaccurate readings, which is a lot of why you hear problems.
You should also use the same size piping as the meter itself. If you use bigger or smaller piping (especially just before the meter) you are more likely to have inaccurate readings, which is a lot of why you hear problems.
im going to do a blow through once the car is running with the maf in as it should be. Then ill change it over to see if itll run like its supposed to.I am going to do ti so i can hear the bov for the most part--but also--i want to be able to run at the tracj\k with no piping on the compressor inlet. I will ut a screen over it, but itll let more air in with no restriction.
Thanks,
Josh
Thanks,
Josh
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PMan_S13
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The idea of running two BOVs is supposed to be so you have one for high boost and one for low boost.
For example, lets say you have a greddy type s which is easily adjustable between soft and hard. Well if you make it soft, it opens even at the slightest lift off throttle. Good for the turbo, not for spooling. The second you start to shift all the spool is gone. (or at least a lot of it) So you stiffen up the BOV. Now at the high rpm shifts you hear a nice blow off and you keep spool. But at low rpms and lower boost, the BOV won't open, so you get compressor surge. Good for spool, but bad for turbo.
The idea of two BOVs is to have one small BOV for low-rpm/normal driving and one large BOV for high-rpm/full-throttle driving.
That's the only way I've seen it done and why for a single intake motor. You'd think people could find a happy medium before spending twice as much and complicating an already complex system.
For example, lets say you have a greddy type s which is easily adjustable between soft and hard. Well if you make it soft, it opens even at the slightest lift off throttle. Good for the turbo, not for spooling. The second you start to shift all the spool is gone. (or at least a lot of it) So you stiffen up the BOV. Now at the high rpm shifts you hear a nice blow off and you keep spool. But at low rpms and lower boost, the BOV won't open, so you get compressor surge. Good for spool, but bad for turbo.
The idea of two BOVs is to have one small BOV for low-rpm/normal driving and one large BOV for high-rpm/full-throttle driving.
That's the only way I've seen it done and why for a single intake motor. You'd think people could find a happy medium before spending twice as much and complicating an already complex system.
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scotty-2-forty
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Projex240 wrote:... Safety to not hurt the compressor, etc?
Bingo.
B-i-n-g-o. And actually, the "happy medium" is in finding the correct balance between the two. However, as I stated before, when trying to source the idle instability I temporarily closed off the secondary BOV ... but the issue remains. It's not like the car is undriveable, just more of a headache.PMan_S13 wrote:The idea of running two BOVs is supposed to be so you have one for high boost and one for low boost.
For example, lets say you have a greddy type s which is easily adjustable between soft and hard. Well if you make it soft, it opens even at the slightest lift off throttle. Good for the turbo, not for spooling. The second you start to shift all the spool is gone. (or at least a lot of it) So you stiffen up the BOV. Now at the high rpm shifts you hear a nice blow off and you keep spool. But at low rpms and lower boost, the BOV won't open, so you get compressor surge. Good for spool, but bad for turbo.
The idea of two BOVs is to have one small BOV for low-rpm/normal driving and one large BOV for high-rpm/full-throttle driving.
That's the only way I've seen it done and why for a single intake motor. You'd think people could find a happy medium before spending twice as much and complicating an already complex system.
bringin it back....
im thinking about using the blow thru setup myself. would i use the stock s14 maf without hacking it or anything? and just to make sure the order is the BOV to the Maf then to the TB. is that correct? also, is there any limiting factors that i would have to worry about if i use this setup. i have 370cc injectors, walbro pump, and a adjustable fpr. also have a wideband coming in the mail. the reason why im interested in this is bc i have a hks ssq bov and im worried a little bit about the rich/stalling problems.
Zak
im thinking about using the blow thru setup myself. would i use the stock s14 maf without hacking it or anything? and just to make sure the order is the BOV to the Maf then to the TB. is that correct? also, is there any limiting factors that i would have to worry about if i use this setup. i have 370cc injectors, walbro pump, and a adjustable fpr. also have a wideband coming in the mail. the reason why im interested in this is bc i have a hks ssq bov and im worried a little bit about the rich/stalling problems.
Zak
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PMan_S13
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yeah, BOV goes between the MAF and the Turbo. I put mine after the turbo, but before the intercooler. So I won't blow off already cooled air.
There shouldn't really be any limiting factors that a pull through doesn't have. Just watch out for an aging turbo to spit oil on your MAF. Need to get some carb cleaner or alcohol and clean it off.
There shouldn't really be any limiting factors that a pull through doesn't have. Just watch out for an aging turbo to spit oil on your MAF. Need to get some carb cleaner or alcohol and clean it off.
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