Blow through MAF

[MerkXRTurbo]

I have just begun collecting the parts to do a TT Yamaha V6 swap in my Merkur XR4Ti. If all goes as planned, I will eventually be using a stand alone fuel system but I am planning on getting it running with a modified SHO EEC (I have access to a TwEECer).

The major delima I have with using the stock system is using twin turbos with a MAF. I REALLY do not want to route two intakes through the same filter , but I will temporarly if I have to. The what came to my mind next was to put the MAF sensor right before the TB, using it as a blow through MAF. I do know that people have complications when they try to blow through the VAM on the turbofords... some have been succesful, while others haven't. Anybody have any ideas or experience blowing through a MAF? Can it handle the heat (the car WILL be intercooled)? Anything I'm not factoring in?

 

[Matt W]

I don't see a problem running the meter in a blow-through setup. ATI (Procharger) has many of their kits running like this using stock electronics. If you intercooler setup is as efficient as it *should* be your charge temps should not be that much higher than ambient. Setting up two turbos to draw through one MAF would be a plumping nightmare in comparison to running one blow-through MAF. That's how I plan on doing it although I'm not sure if I'm going with twins or a larger single.

Matt

 

[UnderPSI]

You can blow thru a maf with no problems. They work very well that way.

 

[Axianator]

You can blow thru a maf with no problems. They work very well that way.

The thing to note here is that most factory draw-through MAFs do not take well and/or are not engineered to be used in a pressurized, blow-through configuration. Consequently, one must also factor MAF metering type(s) (blow-through or draw-through) into their thought process when searching or shopping for the right MAF for their setup.

 

[UnderPSI]

The thing to note here is that most factory draw-through MAFs do not take well and/or are not engineered to be used in a pressurized, blow-through configuration. Consequently, one must also factor MAF metering type(s) (blow-through or draw-through) into their thought process when searching or shopping for the right MAF for their setup.

A MAF measures air going through it, it can't tell if the air is pressurised or not. Have been through several turbo builds using a stock MAF as a blow thru without problems. It might need to be clocked for pest performance though.

 

[SHOSIG]

Don't know about sea-level, but some ATI Procharged Mustangs have idle issues with the factory MAF here in Colorado. The ideal set up would be to have a draw thru set up,but on a TT application there really is no other choice but for a blow thru setup.

 

[UnderPSI]

Don't know about sea-level, but some ATI Procharged Mustangs have idle issues with the factory MAF here in Colorado. The ideal set up would be to have a draw thru set up,but on a TT application there really is no other choice but for a blow thru setup.

Were at in Colorado? Northern Utah is fairly high, the problems I have seen have been fixed by clocking the MAF. Assuming the MAF is correct for the injector size etc.

 

[Axianator]

A MAF measures air going through it, it can't tell if the air is pressurised or not. Have been through several turbo builds using a stock MAF as a blow thru without problems. It might need to be clocked for pest performance though.

While you are correct in your statements about MAF metering characteristics, it is not correct to state (or imply) that all factory draw-through MAFs will function or meter properly when they are subjected to a setup different from the one they were intended for (such as a "different than stock" blow-through configuration). To do so would lump all factory MAFs (and their metering characteristics) into one group and imply that all are capable of being used in a blow-through setup, when this is not always the case. The most common reason for this (which may or may not be curable by reorienting or "clocking" the MAF) is altered airflow around the sample tube induced by the pressurized aircharge from the compressor, often resulting in false or improper airmass sample readings from the sensor.

Assuming the MAF is correct for the injector size etc.

Just a few quick FYI's to clear up any misconeptions:

- MAFs are not calibrated to (or based on) injector size
- MAFs are calibrated based on airflow at a given voltage
- injector size calculations are handled seperately by the EEC

 

[Axianator]

A MAF measures air going through it, it can't tell if the air is pressurised or not. Have been through several turbo builds using a stock MAF as a blow thru without problems. It might need to be clocked for pest performance though.

While you are correct in your statements about MAF metering characteristics, it is not correct to state (or imply) that all factory draw-through MAFs will function or meter properly when they are subjected to a setup different from the one they were intended for (such as a "different than stock" blow-through configuration). To do so would lump all factory MAFs (and their metering characteristics) into one group and imply that all are capable of being used in a blow-through setup, when this is not always the case. The most common reason for this (which may or may not be curable by reorienting or "clocking" the MAF) is altered airflow around the sample tube induced by the pressurized aircharge from the compressor, often resulting in false or improper airmass sample readings from the sensor.

Assuming the MAF is correct for the injector size etc.

Just a few quick FYI's to clear up any misconceptions:

- MAFs are not calibrated to (or based on) injector size
- MAFs are calibrated based on airflow at a given voltage
- injector size calculations are handled seperately by the EEC

 

[SHOSIG]

With this you can run two MAFS and set them up as a draw thru......just found it:

http://www.mass-air.com/Products.htm

 

[SuperchargedSHOguy]

Use the mega-squirt-n-spark if you want to run with out a MAF

 

[Mr Anonymous]

While you are correct in your statements about MAF metering characteristics, it is not correct to state (or imply) that all factory draw-through MAFs will function or meter properly when they are subjected to a setup different from the one they were intended for (such as a "different than stock" blow-through configuration). To do so would lump all factory MAFs (and their metering characteristics) into one group and imply that all are capable of being used in a blow-through setup, when this is not always the case. The most common reason for this (which may or may not be curable by reorienting or "clocking" the MAF) is altered airflow around the sample tube induced by the pressurized aircharge from the compressor, often resulting in false or improper airmass sample readings from the sensor.

Just a few quick FYI's to clear up any misconceptions:

- MAFs are not calibrated to (or based on) injector size
- MAFs are calibrated based on airflow at a given voltage
- injector size calculations are handled seperately by the EEC

AMEN!

 

[UnderPSI]

While you are correct in your statements about MAF metering characteristics, it is not correct to state (or imply) that all factory draw-through MAFs will function or meter properly when they are subjected to a setup different from the one they were intended for (such as a "different than stock" blow-through configuration). To do so would lump all factory MAFs (and their metering characteristics) into one group and imply that all are capable of being used in a blow-through setup, when this is not always the case. The most common reason for this (which may or may not be curable by reorienting or "clocking" the MAF) is altered airflow around the sample tube induced by the pressurized aircharge from the compressor, often resulting in false or improper airmass sample readings from the sensor.

Altered airflow around the MAF? Not sure about that, but airflow thru the MAF is easy enough to handle. As long as you have enough pre and post MAF charge pipe, I haven't had a problem In several turbo builds. On Mustangs anyways. Turbulence is bad.

=Just a few quick FYI's to clear up any misconceptions:

- MAFs are not calibrated to (or based on) injector size
- MAFs are calibrated based on airflow at a given voltage
- injector size calculations are handled seperately by the EEC

They work together, with a stock EEC a MAF that has been calibrated to run the the EEC with a certain injector size, say 36lbers, is going to show less voltage at a given airflow, some MAFs do this with different electronics and some do it with a different size sample tube. With a stock EEC, you have to lie to it so that it does caculate properly. So in lamens terms, it is safe to assume that a MAF is calibrated for injector size. Because the EEC will run like shit with larger injectors unless you use a MAF that has been properly calibrated to show a certain voltage according to the size of injector you have at any given amount of airflow.

So why all the tech shit, honestly? It's a lot easier to say "MAF calibrated for XXlb injectors", and everybody knows what I'm talking about.

 

[NotSoSlowSHO]

It's a lot easier to say "MAF calibrated for XXlb injectors", and everybody knows what I'm talking about.

Not when you are talking about motors with different numbers of cylinders and injectors. A MAF may be "calibrated" for a certain injector, but that calibration also takes into account a certain numer of total injectors.

This becomes an issue when looking at MAFs that could be used on our Yamaha V6, that originally were designed for a V8

 

[UnderPSI]

Not when you are talking about motors with different numbers of cylinders and injectors. A MAF may be "calibrated" for a certain injector, but that calibration also takes into account a certain numer of total injectors.

This becomes an issue when looking at MAFs that could be used on our Yamaha V6, that originally were designed for a V8

I agree, how do you setup your car for say a 90mm L MAF? Can a Tweecer handle that?

 

[NotSoSlowSHO]

Tweecer can handle pretty much anything you can throw at it.

As long as you have the right callibration files.

On my Titanium '89 I have a lincoln Mark-8 80mm MAF, with a bunch of ither intake and exhaust work. it is tuned with the tweecer.

My Red '89 is a totally different toy. It is a Eaton M90 blower project.

Eaton M90 blower
Pro-M 80mm MAF
42# injectors
High flow fuel pump
Adjustable regulator

Still VERY under construction, but it will be tuned with the Tweecer.

 

[UnderPSI]

Tweecer can handle pretty much anything you can throw at it.

Super!

 

[Axianator]

Altered airflow around the MAF?

Read my post just a little more closely and you'll see that I said "altered airflow around the sample tube", not the MAF. Just as reorienting or "clocking" the MAF can alter the airflow characteristics around the sample tube (and consequently, the airmass readings back to the EEC), so can running a factory draw-through MAF as a blow-through MAF in a pressurized configuration.

They work together, with a stock EEC a MAF that has been calibrated to run the the EEC with a certain injector size, say 36lbers, is going to show less voltage at a given airflow, some MAFs do this with different electronics and some do it with a different size sample tube. With a stock EEC, you have to lie to it so that it does caculate properly. So in lamens terms, it is safe to assume that a MAF is calibrated for injector size. Because the EEC will run like shit with larger injectors unless you use a MAF that has been properly calibrated to show a certain voltage according to the size of injector you have at any given amount of airflow.

You're missing the point here - injector sizing (whether it be calculated flow rate or the total number of injectors for a particular setup) plays no part in how a MAF is calibrated. As such, it is not safe to assume that a MAF is calibrated for a particular injector size (or number of injectors) since this is simply not the case. When a prototype MAF sensor is calibrated for an OEM calibration, the electronics are setup to report back a certain voltage to the EEC for a given air mass based on the temperature delta between the two reference hotwires. Nowhere in this calibration process are the aforementioned injector variables (size or count) considered.

If you need further proof of the above, then I would encourage you to look up the application listing for the F1ZF MAF that was used on our '89-'95 V6 SHOs. You will see that this same MAF sensor (utilizing the same electronics package and programmed transfer function) was used in several other factory applications where the engine size and/or number of injectors did not match our own.

So why all the tech shit, honestly?

The reason why I choose to make these "technical" distinctions (and the reason why I've made them numerous times in the past) is simple - rather than allow everyone to believe every piece of marketing hype that dribbles from the mouths of the aftermarket parts companies and chip makers, I believe people should be made fully aware of how the EEC and it's various subsystems interact with each other, if nothing but to be better-equipped to make more intelligent decisions regarding their engine modifications and tuning calibrations.

 

[SinisterSHO]

So why all the tech shit, honestly?

Because he can.

 

[Mr Anonymous]

Companies selling aftermarket MAF sensors use the "calibrated for x injectors" fallacy in order to sell their products to the uneducated masses, as it's a relatively easy way to match off-the-shelf parts with a given vehicle for the ignorant consumer.

MAF sensors simply provide data to the PCM. It's up to the PCM logic to determine what to do with that data.

In the real world, any MAF other than stock should be calibrated in the PCM tuning in order to obtain the best results and also to avoid problems. To just install a MAF and assume that because it's allegedly "calibrated" for x injectors that it will work perfectly is foolish.