Switching from pull through to blow through effect tune
Launching!
Joined: Jan 2002
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From: Detroit, Murder City
You will definitely need to recalibrate the MAF curve, even if it's the same physical sensor. Placing it in a new location where the air flow hits the sensing element slightly different will change how it reads. But if you're committed to changing from a traditional LS1 style (Delphi) sensor and location anyway, I would recommend going to the newer LS3/LS7 (Hitachi) slot sensor that is more robust to reversion and has a higher measurement range anyway. Keep your old IAT sensor (with the appropriate breakout harness) to keep things simple though.
You will definitely need to recalibrate the MAF curve, even if it's the same physical sensor. Placing it in a new location where the air flow hits the sensing element slightly different will change how it reads. But if you're committed to changing from a traditional LS1 style (Delphi) sensor and location anyway, I would recommend going to the newer LS3/LS7 (Hitachi) slot sensor that is more robust to reversion and has a higher measurement range anyway. Keep your old IAT sensor (with the appropriate breakout harness) to keep things simple though.
I know when it comes to liquid, Flow is 100% the same on both sides of a pump because it can't be compressed, I wouldn't think that a small amount of compression of air would change the reading much at all.
...But if you're committed to changing from a traditional LS1 style (Delphi) sensor and location anyway, I would recommend going to the newer LS3/LS7 (Hitachi) slot sensor that is more robust to reversion and has a higher measurement range anyway. Keep your old IAT sensor (with the appropriate breakout harness) to keep things simple though.
TECH Enthusiast
Joined: Dec 2017
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I used maf on my car till recently. Makes a very quick tune even if it isnt as precise as ve. The reason you have to recalibrate the tune is because of the way a maf works. It doesnt actually measure flow it calculates it off of the table in the tune. It measure the resistance in a heated wire. Wire is heated really hot. The air moving over it cools the wire and changes the resistance. To simplify the example one pound of air moving over the wire cools it the same amount no matter if it is atmospheric pressure or 14psi of boost. So yes the maf will still read the same before or after but the calibration has to be different to add the fuel to compensate for the boost. Now the actual issue is way more compicated due to compression heating the air which effects how much it cools the maf wire etc but one way or the other you still have to recalibrate the tune if you move the maf.
If you are Forced induction I strongly recommend keeping the maf before the compressor
for a variety of reasons
In the past perhaps 15 years ago I tried a variety of blow-through FI setups using turbochargers and it always ended poorly,
You might be able to get it to work. But it may be tedious and never give ideal results.
for a variety of reasons
In the past perhaps 15 years ago I tried a variety of blow-through FI setups using turbochargers and it always ended poorly,
You might be able to get it to work. But it may be tedious and never give ideal results.
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I've ONLY ran blowthrough MAF setups and they all worked just fine. And with the MAF screen in place you have the added benefit of safety in the event something tries to go through the intake.
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Verdad Gallardo In my experience the blow-through was inconsistent. One day 12.0 the next day 12.5 the next day 11.8. it seems like the maf curve would skews with boost at various temperatures (it wasn't supposed to do that). I tried 2.0L 2.5L 3.0L all various maf sensors and designed new tubes/tig welded perfect plumbing etc... only results were inconsistent and leaking maf housings.
Also it was difficult to work on because the maf was often crammed into one small section of tube.
Better off just eliminating the maf completely IMO. I am not sure why some people hold on to the maf when all it does is make tuning a little faster and easier if everything is perfect. I guess if you are not a great tuner it helps (novices and simple engine setups = maf is good)
Oh? Curious about build threads, results, tuning information, etc... Do you have anything at all besides just a few words?
In my experience the blow-through was inconsistent. One day 12.0 the next day 12.5 the next day 11.8. it seems like the maf curve would skews with boost at various temperatures (it wasn't supposed to do that). I tried 2.0L 2.5L 3.0L all various maf sensors and designed new tubes/tig welded perfect plumbing etc... only results were inconsistent and leaking maf housings.
Also it was difficult to work on because the maf was often crammed into one small section of tube.
Better off just eliminating the maf completely IMO. I am not sure why some people hold on to the maf when all it does is make tuning a little faster and easier if everything is perfect. I guess if you are not a great tuner it helps (novices and simple engine setups = maf is good)
In my experience the blow-through was inconsistent. One day 12.0 the next day 12.5 the next day 11.8. it seems like the maf curve would skews with boost at various temperatures (it wasn't supposed to do that). I tried 2.0L 2.5L 3.0L all various maf sensors and designed new tubes/tig welded perfect plumbing etc... only results were inconsistent and leaking maf housings.
Also it was difficult to work on because the maf was often crammed into one small section of tube.
Better off just eliminating the maf completely IMO. I am not sure why some people hold on to the maf when all it does is make tuning a little faster and easier if everything is perfect. I guess if you are not a great tuner it helps (novices and simple engine setups = maf is good)
Last edited by ddnspider; Sep 16, 2019 at 02:33 PM.
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I disagree here talon. I ran blow through maf on my car for years and yes it wasnt as precise as the ve could have made it but it wasnt anything to bitch about either. If you were having issues with temps changing your curve then you really need to look in to your iat adder tables. I dont know what software or hardware you were using but on my e38 or e67 ecms with hptuners i can usually tune any temp derived issues out. Of course its possible comparing a v8 driveability issue to an issue for a 2.5 (4 cylinder?) Could be the deciding factor. Larger cubes usually help with any wierd driveability issues. Calling ddn out like that sucks. All any of us has is our experience and past to talk about. Maybe you can put up some test you ran on a dyno and try to lay it down as law but i can give you 3 reasons for every test why it doesnt fit this situation. You just made a blanket statment that a blow through maf doesnt work. I wish that i had this little internet kernal of wisdom years ago. I got a ton of customers to call and tell them bring there car back cause even if its running great talon says it wont work so we got to change it. Lol my advice dont make blanket statments they will make you look stupid in the end. We all know somethingothers dont. I learn something new everyday. Touting yourself as a know it all makes it glaringly obvious you dont know as much as you think you do.
I disagree here talon. I ran blow through maf on my car for years and yes it wasnt as precise as the ve could have made it but it wasnt anything to bitch about either. If you were having issues with temps changing your curve then you really need to look in to your iat adder tables. I dont know what software or hardware you were using but on my e38 or e67 ecms with hptuners i can usually tune any temp derived issues out. Of course its possible comparing a v8 driveability issue to an issue for a 2.5 (4 cylinder?) Could be the deciding factor. Larger cubes usually help with any wierd driveability issues. Calling ddn out like that sucks. All any of us has is our experience and past to talk about. Maybe you can put up some test you ran on a dyno and try to lay it down as law but i can give you 3 reasons for every test why it doesnt fit this situation. You just made a blanket statment that a blow through maf doesnt work. I wish that i had this little internet kernal of wisdom years ago. I got a ton of customers to call and tell them bring there car back cause even if its running great talon says it wont work so we got to change it. Lol my advice dont make blanket statments they will make you look stupid in the end. We all know somethingothers dont. I learn something new everyday. Touting yourself as a know it all makes it glaringly obvious you dont know as much as you think you do.
I said it might give trouble or something along those lines. And it probably will. Having a bunch of unnecessary intake tract parts, clamps, hoses, and having it put in an awkward position, its all true. and to top that off completely unnecessary. Not only would I not want the maf in the intake tube for restriction it presents (better to have an open tube) I wouldn't want to depend on it to fuel the engine because a small leak completely ruins it's day.
I appreciate your feedback. fwiw I only tried on "old" 0-5v style parabolic maf curves and using mostly factory computer with older engines.
Nevertheless its still dumb to keep an object in the intake pathway with additional clamps and potential for leaks when its completely unnecessary
I guess I don't really believe that anybody has had a successful forced induction blow-through maf installation which has lasted more than a year or two. Most of the engines I've seen with that setup blew because of unreliable fueling. Everyone around me (12~ performance shops I visit regularly, and roughly 50 automobiles) have stopped trying it 10 years ago or more. Its nearly been eliminated from this area from what I can tell.
I am not surprised though that somebody on LS tech still uses it. Just like atmospheric pcv venting. This place is like the 1980's stood still
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Ha 1980s stood still. Damn. condecending asshat much. I was trying to council some restraint on your part but you just flew past it and douche soldiered on. You know i saw that why we all dont miss kingtalon thread awhile back and i thought damn that was harsh but now i get it. Everything i wrote still stands. I can make it work and have many many times. If you couldnt make it work then you arent as talented as you seem to believe. You keep saying you cant figure it out and customers will continue to take there vehicles to those who can. Carry on. I will fall in line with the rest of ls1tech and just ignore your posts. (have you noticed nobody really addresses anything you write these days). Easy enough. I bow to your most infinite and up to date wisdom.
I really love the 80s stood still thing. Ha you truly are the court jester of ls1tech.
I really love the 80s stood still thing. Ha you truly are the court jester of ls1tech.
Moot point since you can't. I can go on and on about the benefits of MAF over VE but there's no point because A) you'll just argue, mostly in strawman form, and B) not worth the time because it's been discussed ad nauseum on here. To each his own, and this is a maf thread.
Launching!
Joined: Aug 2015
Posts: 206
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From: Duvall, WA
I ran a blow-through MAF setup with a "card" style MAF (probably manufactured by Hitachi) on a Ford 4.2L V6 before I switched my Mustang over to the LS platform. I was running with a GT3582R at about 12-13 psi of boost, and the engine made about 450 whp, which isn't bad when you consider what those boat anchors make stock. The car was basically a daily driver. MAF placement was indeed important, because the setup worked better when the MAF was in a long run of straight tubing with no bends nearby, but the layout of the intake manifold on that engine lent itself fairly well to that. It worked well enough for what it was, and I have no qualms about doing it again if I ever want to build an FI setup around Ford EEC-IV/V era stuff (which does NOT have provisions for a MAP sensor, so speed density is not an option).
Everything is a tradeoff. No matter which way you go with a MAF on a forced induction setup, you have to size the thing big enough to meter airflow at full blast, so you're trading some low end resolution for that. However, if all of the injector data is right and there are no other problems with the system, it's super easy to tune the fueling. If you go with draw-through, you tend to need to have the MAF in a larger tube size, and you have to take BOV/BPV placement into consideration. Speed density isn't particularly difficult to tune, but it IS tedious, and it's going to be more sensitive to setup changes than a MAF. There's no such thing as a free lunch.
Everything is a tradeoff. No matter which way you go with a MAF on a forced induction setup, you have to size the thing big enough to meter airflow at full blast, so you're trading some low end resolution for that. However, if all of the injector data is right and there are no other problems with the system, it's super easy to tune the fueling. If you go with draw-through, you tend to need to have the MAF in a larger tube size, and you have to take BOV/BPV placement into consideration. Speed density isn't particularly difficult to tune, but it IS tedious, and it's going to be more sensitive to setup changes than a MAF. There's no such thing as a free lunch.
Last edited by lemming104; Sep 17, 2019 at 10:09 AM.
Launching!
Joined: Jan 2002
Posts: 299
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From: Detroit, Murder City
I have literally forgotten how many times I have done a blow-through forced induction MAF setup. They all drove great when the hardware was appropriately chosen for the system and there was no contamination issue. Many of them were precise enough to pass emissions. If you want to critique transient fueling, the first thing you need to do is refine the rest of the airflow model that compliments the filtered MAF reading (VE, manifold filling, etc...) Anecdotal evidence about what one tooner couldn't make run right is irrelevant.
I have literally forgotten how many times I have done a blow-through forced induction MAF setup. They all drove great when the hardware was appropriately chosen for the system and there was no contamination issue. Many of them were precise enough to pass emissions. If you want to critique transient fueling, the first thing you need to do is refine the rest of the airflow model that compliments the filtered MAF reading (VE, manifold filling, etc...) Anecdotal evidence about what one tooner couldn't make run right is irrelevant.