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Blow through meter on n/a engine

Post by Jtab » Sun Aug 01, 2021 11:19 am

Can I use a blow through meter on a n/a engine? I'm looking for a new meter and I'd like to future-proof it in case I ever go forced induction.

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Re: Blow through meter on n/a engine

Post by jsa » Sun Aug 01, 2021 6:16 pm

Yes.

A slot maf sensor is the go.
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Re: Blow through meter on n/a engine

Post by Jtab » Sun Aug 01, 2021 7:55 pm

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Re: Blow through meter on n/a engine

Post by jsa » Sun Aug 01, 2021 9:23 pm

Yes.
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Re: Blow through meter on n/a engine

Post by EDS50 » Mon Aug 02, 2021 1:59 pm

What is the purpose or benefit of running a blow thru meter in an N/A environment? You will not have the volume of air a blow thru meter is expecting sampled by the sample tube or housing created by an turbo/supercharger. Even the 03/04 cobras are draw thru from the factory. Im not saying it wont work but I dont feel its optimal or even recommended for an N/A engine.
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Re: Blow through meter on n/a engine

Post by cgrey8 » Mon Aug 02, 2021 2:13 pm

He's just future-proofing. Presumably he suspects he'll upgrade to a super/turbo at some point in the future, but wants to get the project and engine running in the short term.
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Re: Blow through meter on n/a engine

Post by EDS50 » Mon Aug 02, 2021 2:26 pm

I always recommend to use the correct components required by the combination being utilized. Using a blow thru meter now is not a future proof as some supercharger combinations require draw thru meters, some blow thru and most but not all turbo set ups require blow thru. Some even choose to switch to DFI and eliminate the meter all together. Its like asking which slicks should I use on my street car daily driver in case I ever go to the track. Just my opinion; I would use the correct draw thru meter while N/A and correct meter required when the combination is changed to a power adder set up.
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Re: Blow through meter on n/a engine

Post by cgrey8 » Mon Aug 02, 2021 3:03 pm

This is an interesting take and not without its merit. But it's probably not enough just to say it's the wrong tool for the job "trust me", then leave it at that. Some explanation might be in order.

What, specifically, makes it a bad choice? Simply being a blow-thru capable MAF doesn't, by itself, disqualify it. So there has to be some detail about it that you think makes this a not-ideal choice (other than the price). If this was an N/A build and plans to stay that way, he could get away with a used stock slot sensor in a piece of PVC for ~$25.

But price aside, the only thing I could come up with is that the high voltage limit wouldn't be met and thus some resolution at the low-end is lost both in lower mechanical airflow across the sensor AND in reduced voltage gamut. But this is a slot-style sensor. Simply installing the sensor in a smaller diameter enclosure would fix both of these things. So yes, I'd have to agree that this MAF in that exact housing is "not ideal" for an N/A application. It's not the end of the world, but not ideal.

Now some people might jump on the..."a smaller diameter passage will increase the resistance over a larger passage." And while that is undeniable, significant resistance only occurs at really high flowrates. And as is already stated, an N/A engine isn't going to come close to seeing a difference between a 3" vs 3.5" pipe. And a "properly sized" draw-thru meter is probably going to be a similarly smaller diameter also...the only exception being maybe the 90mm LMAF.

So that said, if the OP thinks he'll run a boosted application that will require a blow-thru setup in the future, he could try running that 3.5" tube. If it causes problems, put the sensor in a smaller diameter pipe. I run a stock GT slot meter in a piece of PCV pipe that just happens to have an Internal Diameter very near the stock GT size. I loaded my tune with the stock slot MAF curve and tweaked from there. It did require some tweaks, but overall, it was very close.

Point is, if that 3.5" housing causes issues he's not willing to live with while running N/A, there's no reason he couldn't install that HPX sensor in a smaller diameter PVC pipe, adjust the curve for the reduced diameter, and revisit the shiny 3.5" pipe when/if he ever upgrades to that boosted setup.

Now is it what I'd do? No. I couldn't justify that much for a sensor to enable a possible future project, particularly knowing I could run a $25 setup on the N/A engine with confidence. But it's not my money. If this is what he wants to do, I'm not aware of a technical reason why the HPX wouldn't work...yet.
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Re: Blow through meter on n/a engine

Post by EDS50 » Mon Aug 02, 2021 3:28 pm

cgrey8 wrote: Mon Aug 02, 2021 3:03 pm This is an interesting take and not without its merit. But it's probably not enough just to say it's the wrong tool for the job "trust me", then leave it at that. Some explanation might be in order.

What, specifically, makes it a bad choice? Simply being a blow-thru capable MAF doesn't, by itself, disqualify it. So there has to be some detail about it that you think makes this a not-ideal choice (other than the price). If this was an N/A build and plans to stay that way, he could get away with a used stock slot sensor in a piece of PVC for ~$25.

EDS50 wrote: Mon Aug 02, 2021 1:59 pm What is the purpose or benefit of running a blow thru meter in an N/A environment? You will not have the volume of air a blow thru meter is expecting sampled by the sample tube or housing created by an turbo/supercharger. Even the 03/04 cobras are draw thru from the factory. Im not saying it wont work but I dont feel its optimal or even recommended for an N/A engine.

My reply clearly stated that a blow thru maf in an N/A environment will not sample the volume of air forced passed the sample tube a power adder creates. I never once said "trust me" and or its "wrong".
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Re: Blow through meter on n/a engine

Post by cgrey8 » Mon Aug 02, 2021 3:34 pm

Lol, I wasn't speaking specifically at you
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Re: Blow through meter on n/a engine

Post by EDS50 » Mon Aug 02, 2021 3:40 pm

cgrey8 wrote: Mon Aug 02, 2021 3:34 pm Lol, I wasn't speaking specifically at you
8)
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Re: Blow through meter on n/a engine

Post by cgrey8 » Mon Aug 02, 2021 3:45 pm

Yeah I just reread that...and I see how that did look accusatory. My bad.
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Re: Blow through meter on n/a engine

Post by EDS50 » Mon Aug 02, 2021 4:13 pm

cgrey8 wrote: Mon Aug 02, 2021 3:45 pm Yeah I just reread that...and I see how that did look accusatory. My bad.
No worries, this is a good topic of discussion to continue. From my experience in the shop, on the dyno and at the track; I have seen, r&d'd and retuned numerous cars/combinations that have had issues with blow thru meters in N/A environments with the same intentions of anticipated upgrades. The idle maf voltage can be extremely low creating a maf error which is corrected via chip or tuner when using a stock ecm. Same can be said for the maf lower clip limits as well as the transfer tuning depending on sensor type and environment such as tube dimension sensor placement and fore and aft radial bends. Tube material plays into the equation as well in regards to turbulence and velocity since some materials are smother for air than others. Yes, I am over dramatizing and complicating the question at hand by the op but my thoughts merit consideration. Being that ive been there and done that 10x over and have had success with all 3 variations of maf, I would recommend using the correct draw thru configuration maf for the current n/a combination and re-cross the bridge when plans for the power adder come to fruition. If it were injectors in question or some other component the discussion would be different but the maf is one of the single most important sensors in an efi combination and is worth keeping as correct as possible which aids in ease of tuning. Just my .02
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Re: Blow through meter on n/a engine

Post by cgrey8 » Tue Aug 03, 2021 7:10 am

EDS50 wrote: Mon Aug 02, 2021 4:13 pm...The idle maf voltage can be extremely low creating a maf error which is corrected via chip or tuner when using a stock ecm. Same can be said for the maf lower clip limits as well as the transfer tuning depending on sensor type and environment such as tube dimension sensor placement and fore and aft radial bends...
That's what I was trying to get at by saying the HPX can be moved to a smaller diameter enclosure. However neither of these are related to whether the MAF supports a blow-thru application or not. These are more related to the flowrate capacity of the meter. Even a high-flow draw-thru MAF would have these same issues.
EDS50 wrote: Mon Aug 02, 2021 4:13 pm...Tube material plays into the equation as well in regards to turbulence and velocity since some materials are smother for air than others. Yes, I am over dramatizing and complicating the question at hand by the op but my thoughts merit consideration...
I'm sure there is some very minor difference between the laminar flow characteristics of plastic vs metal. But those differences are so trivial, I'm not sure anybody would ever notice anywhere but a lab where someone was specifically looking for them.

Now what is far more crucial are transitions. As you go from one diameter to another or one material to another, any lips or sharp edges will create flow disturbances and those could definitely cause performance issues at the high end of flow. You ideally want perfectly smooth transitions. That's not always possible for the average Joe nor their priority. So you do the best you can smoothing things out as much as practically possible. But I also agree when money is on the line and hundredths of a second matter, those details become very relevant and spending more time and money concocting something better is definitely justifiable. Thus it makes sense that you would care about such things.
EDS50 wrote: Mon Aug 02, 2021 4:13 pm...I would recommend using the correct draw thru configuration maf for the current n/a combination and re-cross the bridge when plans for the power adder come to fruition...
I too am advocating the same move, but I think my distinction in all this is that you still seem to be suggesting that there's something specific to blow-thru vs draw-thru MAFs that makes blow-thru MAFs not function as well in a draw-thru scenario. But all the scenarios I've heard up to this point are referencing the max flow measuring capacity aspects. And those have to do more with sizing your parts correctly. And again, I don't disagree with that hence my suggestion of "resizing" the diameter of the meter into something that works better for N/A.

What I'm still trying to get to the root of is if there's something specific to a MAF being blow-thru capable that changes it's characteristics enough to warrant not using it in a draw-thru scenario, even if its max flow capacity is appropriate for the application?

It's my understanding that the biggest difference between the two is the temperature ranges they are capable of operating at. A MAF works by heating a highly calibrated mass, usually a wire of some kind, while measuring the temperature of the wire. The MAF controller is trying to maintain a very specific temperature. It measures airflow by measuring the amount of current required to keep the wire at a very specific temperature (also taking into account ambient temp). The more airflow across the wire, the more current is required to maintain the temp and thus how it is able to report a mass-airflow. Draw-thru only MAFs do this with a lower temp than blow-thru MAFs mainly because doing so is cheaper to manufacture. But as a result, they don't work in blow-thru applications where the boosted air temps can get way higher than ambient temps will ever be. The higher air temps confuse the sensor and make it more difficult for it to determine just how much air is flowing particularly in high airflow conditions such as WOT.

This is where I'm not sure whether I'm right or wrong. Does a MAF's ability to operate correctly in a blow-thru environment disqualify it for duty in a draw-thru scenario (N/A or boosted)? I don't think it does. The disqualifying aspect of blow-thru MAFs on N/A engines has to do with their airflow measuring capacity (at least those are the reasons I've heard so far). They are usually way oversized for the task of being an N/A engine's MAF. But in the case of a slot-style MAF, you can redeploy them in a smaller enclosure if you were so inclined to purposefully reduce their capacity.
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Re: Blow through meter on n/a engine

Post by EDS50 » Tue Aug 03, 2021 10:33 am

I would concentrate on functionality and application. With tuning capabilities blow thru will "work" in an N/A environment as long as its properly placed in the intake tract and the correct housing/sensor is used. Ill wait to get into more specifics regarding which meter is recommended to use and why if/when the op chimes in on what his/her future plans are as this topic is easily google searched and beat to death.

Here is a copy and paste from Lasota Racing in the mean time:

Draw through vs. Blow through MAF 1988-2010)
There are two ways of configuring a mass air meter for a centrifugally supercharged or turbocharged vehicle. Here are the pluses and minuses of each setup.

Draw Through
A draw through mass air meter (MAF), i.e. ahead of any blower /turbo, is more affected by bends in the pipes near the MAF. You CANNOT use reducers near the MAF. Remember that the Mass air meter relies on laminar airflow to get a good signal. A draw though meter must use a bypass valve for a supercharger – it bleeds off boost and recirculates pressurized air from the blower and keeps metered air in the system. It must be done this way because the air has already been metered. If a bypass is dumped to atmosphere it will result in huge rich spikes that will kill driveability. With a turbo, you use a BOV recirculated.

A draw through meter is a long distance from the engine. Add in an intercooler and there may be an unacceptable delay in what the mass air meter reads and how the engine responds. On a turbo vehicle, the turbos natural ‘spin down’ will create backwash through the MAF that cannot be tuned around. In worst cases, you must convert to blow through to get rid of this.

As previously mentioned, on a draw through setup you need to recirculate the bypassed air when using it with a turbo or centrifugal supercharger. Designing a decent bypass can sometimes be tough - you need to route the return air line as far away from the MAF as possible, and even situate the pipe so it is blowing air at an angle away from the MAF. And maybe add an air shield inside the pipe. With an intercooler, you'd need to most likely add two bypasses, one ahead of the IC and another after the IC. This can result in a plumbing nightmare. Bypasses must be big enough to handle all the air. Bypass problems will result in horrible drivability that usually cannot be tuned around - if you suspect a bypass problem, graph a log of MAF volts where the problem occurs. If it looks like a seismograph during an earthquake - that's your problem. Naturally if you run a twin screw or roots style blower, or are NA, your only option is draw through and on those systems, they work just great.

Blow Through
A blow through MAF is less affected by bends. You cannot use a draw through style (tonsil) MAF in blow through. This includes factory MAFs from 1988-2004 vehicles. You need to use a 2005-2010 style slot MAF as they are a lot more forgiving of bends and much better suited for blow through. A blow through setup vents after the blower, but before the MAF, so the unmetered air can be dumped to atmosphere with a bypass for a supercharger and a BOV for a turbo They do not require extra plumbing to bypass the air. Don't use a BOV with a supercharger as the springs are too heavy. Venting to atmosphere makes plumbing much easier.

Overall, blow through systems work well. When properly designed, they do NOT reduce the range of the MAF. Contrary to internet misinformation, a properly designed blow through system will be easier to tune and live with than a draw through setup.

The BEST alternative for a blow through MAF is to use an '05 Mustang style slot MAF, and in 3, 3.5 or 4" tube. The larger the tubing the more range the MAF has, but it also has less low end resolution. Using a 'performance' style MAF such as a Professional Mass Air Systems HPX MAF will increase range even further. Note: that even with a Diablosport MAF.ia the '05 style MAFs will NOT output to battery voltage. Using the HPX will negate this disadvantage as will going to larger diameter tubing for higher HP vehicles.

It's not a great idea to use an HPX MAF setup in a 4" tune on a lower HP car, it doesn't have any advantages, it just adds range at the expense of low-end resolution. Always plan your MAF setup so that you will be using 80% of the theoretical range of the MAF.

Using an '05 style MAF in an earlier vehicle will require some additional parts, a MAF flange welded into the pipe and a late model pigtail. These are available from LaSota Racing.
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Re: Blow through meter on n/a engine

Post by cgrey8 » Tue Aug 03, 2021 11:00 am

Excellent information.

I should have, but I completely forgot to consider that blow-thrus work better with turbulent flow (and bends). I have to admit, I don't know what they do differently to compensate for this, but knowing what their tactic to dealing with this would be valuable.

I was also not aware that the stock slot style MAFs were blow-thru tolerant. As I mentioned earlier, I'm using a slot style MAF for my N/A engine and I'm obviously not using it for its blow-thru capabilities. I'm using it because of it's tolerance for bends (turbulence). One of the things I struggled with for years was to get my old C&L to work in all possible scenarios. But there were just some cases where it would either measure MORE air than actual or less than actual...and of course these were during driving load conditions where overly rich/lean conditions cause annoying driveability quirks. After replacing the C&L with the slot-style MAF, those issues all but went away.
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Re: Blow through meter on n/a engine

Post by EDS50 » Tue Aug 03, 2021 12:22 pm

In my experience, not all draw/blow thru work well with bends in front of the meter. Placement and clocking is key with sample tube housings as the air can rush around the sample tube depending on the placement of the housing and bend radius in front of the housing. Placing or clocking the meter sample tube favoring the bend is beneficial. Using a univer housing that eliminates the sample tube and samples from the housing 360 degrees is optimal in my opinion. Slot style work better than sample tube housings as well. Power adder combos and intercoolers/after coolers, igloos style intakes and air to water intercoolers and such add another degree of difficulty because of the intake tract and the right style of blow off/surge valve has to be utilized.
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Re: Blow through meter on n/a engine

Post by jsa » Tue Aug 03, 2021 4:28 pm

cgrey8 wrote: Tue Aug 03, 2021 7:10 am The disqualifying aspect of blow-thru MAFs on N/A engines has to do with their airflow measuring capacity (at least those are the reasons I've heard so far). They are usually way oversized for the task of being an N/A engine's MAF. But in the case of a slot-style MAF, you can redeploy them in a smaller enclosure if you were so inclined to purposefully reduce their capacity.
Keep in mind that on turbo applications mass flow off boost is 'effectively' the same as n/a. The turbo has to come on boost before mass flow exceeds n/a quantities. Idle and light cruise are similar mass flows for n/a and turbo.

So if it is oversized (poor low flow resolution) for n/a, it is not the right choice for turbo either.

Study the hpx and n/a oem slot transfer functions. It will become apparent that at least some of the hpx have enhanced low flow resolution.

As always, select the right part to achieve the best working outcome.
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Re: Blow through meter on n/a engine

Post by Jtab » Tue Aug 03, 2021 5:59 pm

EDS50 wrote: Tue Aug 03, 2021 10:33 am I would concentrate on functionality and application. With tuning capabilities blow thru will "work" in an N/A environment as long as its properly placed in the intake tract and the correct housing/sensor is used. Ill wait to get into more specifics regarding which meter is recommended to use and why if/when the op chimes in on what his/her future plans are as this topic is easily google searched and beat to death.

Here is a copy and paste from Lasota Racing in the mean time:

Draw through vs. Blow through MAF 1988-2010)
There are two ways of configuring a mass air meter for a centrifugally supercharged or turbocharged vehicle. Here are the pluses and minuses of each setup.

Draw Through
A draw through mass air meter (MAF), i.e. ahead of any blower /turbo, is more affected by bends in the pipes near the MAF. You CANNOT use reducers near the MAF. Remember that the Mass air meter relies on laminar airflow to get a good signal. A draw though meter must use a bypass valve for a supercharger – it bleeds off boost and recirculates pressurized air from the blower and keeps metered air in the system. It must be done this way because the air has already been metered. If a bypass is dumped to atmosphere it will result in huge rich spikes that will kill driveability. With a turbo, you use a BOV recirculated.

A draw through meter is a long distance from the engine. Add in an intercooler and there may be an unacceptable delay in what the mass air meter reads and how the engine responds. On a turbo vehicle, the turbos natural ‘spin down’ will create backwash through the MAF that cannot be tuned around. In worst cases, you must convert to blow through to get rid of this.

As previously mentioned, on a draw through setup you need to recirculate the bypassed air when using it with a turbo or centrifugal supercharger. Designing a decent bypass can sometimes be tough - you need to route the return air line as far away from the MAF as possible, and even situate the pipe so it is blowing air at an angle away from the MAF. And maybe add an air shield inside the pipe. With an intercooler, you'd need to most likely add two bypasses, one ahead of the IC and another after the IC. This can result in a plumbing nightmare. Bypasses must be big enough to handle all the air. Bypass problems will result in horrible drivability that usually cannot be tuned around - if you suspect a bypass problem, graph a log of MAF volts where the problem occurs. If it looks like a seismograph during an earthquake - that's your problem. Naturally if you run a twin screw or roots style blower, or are NA, your only option is draw through and on those systems, they work just great.

Blow Through
A blow through MAF is less affected by bends. You cannot use a draw through style (tonsil) MAF in blow through. This includes factory MAFs from 1988-2004 vehicles. You need to use a 2005-2010 style slot MAF as they are a lot more forgiving of bends and much better suited for blow through. A blow through setup vents after the blower, but before the MAF, so the unmetered air can be dumped to atmosphere with a bypass for a supercharger and a BOV for a turbo They do not require extra plumbing to bypass the air. Don't use a BOV with a supercharger as the springs are too heavy. Venting to atmosphere makes plumbing much easier.

Overall, blow through systems work well. When properly designed, they do NOT reduce the range of the MAF. Contrary to internet misinformation, a properly designed blow through system will be easier to tune and live with than a draw through setup.

The BEST alternative for a blow through MAF is to use an '05 Mustang style slot MAF, and in 3, 3.5 or 4" tube. The larger the tubing the more range the MAF has, but it also has less low end resolution. Using a 'performance' style MAF such as a Professional Mass Air Systems HPX MAF will increase range even further. Note: that even with a Diablosport MAF.ia the '05 style MAFs will NOT output to battery voltage. Using the HPX will negate this disadvantage as will going to larger diameter tubing for higher HP vehicles.

It's not a great idea to use an HPX MAF setup in a 4" tune on a lower HP car, it doesn't have any advantages, it just adds range at the expense of low-end resolution. Always plan your MAF setup so that you will be using 80% of the theoretical range of the MAF.

Using an '05 style MAF in an earlier vehicle will require some additional parts, a MAF flange welded into the pipe and a late model pigtail. These are available from LaSota Racing.
I read that article before making this post, but it focuses more on the operation of blow-through verses draw-through and venting excess pressure. I also came across a thread on this site where someone was trying to learn why sensors are categorized as draw- or blow-through, but it never reached a definitive answer.

I don't know what my future plans are. A turbocharger sounds awesome, but that's years out if ever, which is why I'm looking for a quality sensor that can grow with my build.

It sounds like an oem slot sensor is a cheap solution for now. I have a C&L 73mm that came with my mass air conversion, but it really doesn't work well with my intake. I'm using an oem mass air intake from a 1995ish F250 with a 351, if memory serves, and I don't think the C&L appreciates the sharp turn through the filter. I'm currently running a meter from a 1996 V6 Explorer; I think the small diameter is choking performance, so I'm looking for an alternative.

I appreciate the replies and insight. Thanks to all for your time and wisdom.

- Joe
1993 F250 460cid. Mass air conversion. CBAZA T4M0. Quarterhorse tuned with binary editor.

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Re: Blow through meter on n/a engine

Post by EDS50 » Tue Aug 03, 2021 7:25 pm

If possible try clocking the meter housing so tge sampling tube is more in line with the bend thats coming into the front of it. It will help straighten out idle and overall driveability once the sampling tube and outer radius of the bend are lined up better. Thats what we used to do with the cold air intakes on the fox body and sn95 cars. The C&L meters are not bad and usually utilize the factory maf 55mm sensor if its off a foxbody. Not sure on what exact maf combination you are currently using but you can use the factory maf curve and injector settings for the sensor/ecm you are using and fine tune from there with whichever calibration tube is in the meter. I think I still have all of the c&l flow bench curves from lee bender.
1992 Mustang LX - 25.1c Chassis, Vortech Blown Dart 333 on Meth, Lentech Trans, TRZ Backhalf, A9P Tune, Moates QH/SL v1.9, BE, EA, TunerView

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Re: Blow through meter on n/a engine

Post by Jtab » Tue Aug 03, 2021 9:49 pm

EDS50 wrote: Tue Aug 03, 2021 7:25 pm If possible try clocking the meter housing so tge sampling tube is more in line with the bend thats coming into the front of it. It will help straighten out idle and overall driveability once the sampling tube and outer radius of the bend are lined up better. Thats what we used to do with the cold air intakes on the fox body and sn95 cars. The C&L meters are not bad and usually utilize the factory maf 55mm sensor if its off a foxbody. Not sure on what exact maf combination you are currently using but you can use the factory maf curve and injector settings for the sensor/ecm you are using and fine tune from there with whichever calibration tube is in the meter. I think I still have all of the c&l flow bench curves from lee bender.
Would that be the shorter side of the bend?

Do you think I'm better off using the c&l verses using the Explorer meter that runs pretty well as is?
1993 F250 460cid. Mass air conversion. CBAZA T4M0. Quarterhorse tuned with binary editor.

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Re: Blow through meter on n/a engine

Post by EDS50 » Wed Aug 04, 2021 12:07 am

I would target the outer side of the bend. Air will always rush towards the farthest bend. I would stick with what you are currently using. The c&l would depend on which sensor and sample tube its equipped with. I see your using cbaza so the c&l might be wirth a try with the corrrct sensor. Also what size injectors are you using?
1992 Mustang LX - 25.1c Chassis, Vortech Blown Dart 333 on Meth, Lentech Trans, TRZ Backhalf, A9P Tune, Moates QH/SL v1.9, BE, EA, TunerView

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Re: Blow through meter on n/a engine

Post by cgrey8 » Wed Aug 04, 2021 7:06 am

Personally, I'd prefer the stock Explorer MAF over the C&L although neither are exactly great.

The C&L uses the very old edge-detection sensor used on the Fox bodies from the factory. And like you, I had some trouble with getting my C&L 73mm to work well. I tried clocking and while that did make differences, it just moved the problems around, but didn't actually fix anything.

The famous LMAF samples right from the middle of flow. Here's a picture of a Stock 55mm MAF, LMAF, and some random other MAF that appears to also use that old edge-sensor:
Image

I can't remember what the Explorer MAF's construction is, but I think it is a variant of that far-right MAF which means it's only marginally better than the older style MAF.

Looking on eBay, I can't find that seller that sells the used slot MAF sensors WITH the pigtail for you to splice onto your wiring harness. Although you can still find the sensor itself for ~$15:
https://www.ebay.com/itm/174052228130?e ... ondition=4

You might need to call some salvage yards and see if you can find a place that'll sell you both a sensor and the pigtail. Otherwise, you'll have to buy a pigtail connector too...which new will run about twice the price of the sensor on eBay:
https://www.ebay.com/itm/132790353984?h ... Sw8sBbpWyx

So maybe my estimate of $25 for a slot conversion is outdated?

_____Edit
I found the seller selling the used sensors along with the connector...price now closer to $27:
https://ebay.us/s9fTe7
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89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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Re: Blow through meter on n/a engine

Post by cgrey8 » Wed Aug 04, 2021 8:02 am

BTW, this was my setup back in 2012 when I converted away from the C&L to the slot MAF...
C&L_installed.jpg
C&L_installed.jpg (98.07 KiB) Viewed 1598 times
As you can see here, the MAF has a filter mounted right on the end and a bend immediately after. Add to that, the filter is butted right up against the battery, a wheel well below it, and when the hood is shut, the hood right above. So only the backside of the filter is unobstructed for incoming air thus causing the airflow into the sensor to not exactly be straight. And much of that air is air that's come through the radiator AND washed right past the passenger-side header, although at non-WOT conditions, I'm sure a good bit of the air is actually being pulled through the gap between the hood and fender. You can also see the slot sensor pigtail has already been installed on the wiring harness. Since the slot style MAF has an integrated ACT sensor, I abandoned the stock ACT sensor you can see mounted in the end of the cone filter. But if your ACT is mounted in your lower intake, you should probably NOT do this.


Here's the PVC pipe with the slot cut and an indention Dremeled into it to fit the rubber gasket that comes with the slot sensor:
PVC_Pipe.jpg
PVC_Pipe.jpg (68 KiB) Viewed 1598 times


Sensor installed with some silicone to hold it in place:
Pipe&Sensor.jpg
Pipe&Sensor.jpg (25.29 KiB) Viewed 1598 times


End view. It may be hard to see, but I smoothed the ends of the pipe so there's not a sharp edge leading into the airflow:
Pipe&Sensor_EndView.jpg
Pipe&Sensor_EndView.jpg (23.46 KiB) Viewed 1598 times


And here it is installed:
SlotSensor_Installed.jpg
SlotSensor_Installed.jpg (76.27 KiB) Viewed 1598 times
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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