Thread: Adding a 2nd MAF?

Could someone please offer to buy James twin-m90 plates and finish it? That would be different ....

Twin M90 plates? I might be interested...

Originally Posted by Explicit_Spade

What experience do you have to come to this conclusion? There are plenty of twincharged (supercharger/turbo combination) set-ups that work.

Those are run in series, turbo, supercharger, engine. To the best of my knowledge no one has ever successfully run them the way you are suggesting. What would be the purpose of two mafs, just the novelty of it? Ive heard the LS7 mafs are impossible for a 3800 to outflow, if you're worried about that try one of them.

LOl man if your not going to listen to me, listen to Jeff. You need to sit down and THINK about what your saying and trying to do.

A Actual twin charge is blower feeding the engine, then the turbo is feeding the blower. The only way the air can escape is into the motor all on 1 line, it cant go backwards.

Your trying to side feed the turbo which gives it 2 options, go to the lim or back up the blower and out the tbody. Air isnt going to sit there compressed when in the end you have 2 inlet/outlets that at any time WILL be used.

all of this is a moot point since the series two piece of s*** is a short deck High angularity engine and has horrible breathing at the top end even with the symmetrical Port heads
this thing was designed for low and mid-range torque.
Trying to get more power out of it up top is pretty f****** useless

i still can't understand what you're controlling with the second MAFF. once the air enters the first MAFF / SC plenum, it's fixed volume all the way through. you can't force more air through the turbo or SC then you're drawing into the SC in the first place. You have to maintain constant volume through the system at any given instant.

Originally Posted by Explicit_Spade

What experience do you have to come to this conclusion? There are plenty of twincharged (supercharger/turbo combination) set-ups that work.

Plenty of experience. The fatal design flaw I see in the parallel super/turbo arrangement is that it takes 40-60hp to turn the supercharger at 7-8psi now you are going to add more on top of that lets say you shoot for 15 psi now you have the supercharger working against an added 7psi this takes more power to turn, then what about your poor turbo? You take off and the supercharger instantly shuts the valve on the turbocharger outlet so it isn't just pushing boost through the turbo back out and through the MAF that doesn't know which direction that the air is flowing (to a point), but knows theirs airflow. So this valve is shut and the motor is pushing out all that exhaust and turning all of that turbine goodness. The impeller is picking up speed at the same time and starts producing boost, but it's not against a hungry engine, but a blockage. So what happens now? Well as the air flows in it has nowhere to go and just kinda pushes back against the wheel and starts to slow the impeller and the turbine. This is going to try to finally overcome the blockage but is going to be hard on the turbo. Who's to say that it just doesn't stall at a given speed and never gets up enough rpm's to set up it's own feedback loop and build enough pressure to overcome the valve? Then if you were to vent the tube before the valve so there's no blockage you now have metered air not entering the engine, so now you have to pas the tube back onto the supercharger before the MAF or before the inlet of the supercharger after the maf, so then it becomes a controls nightmare. Now, I can program a PLC and use ladder logic all the time but how do you get around these items? I've looked at this six ways to Sunday and I don't see it working or being viable as a parallel system. I have thought about all kinds of different combinations of supercharger and drive ratio and a lot of other things and I just don't see it. Please show me one instance of a Parallel supercharger/turbocharger combination that works.

Jeff

If a turbo is lagging that bad, it is too big for the application.

As long as there is exhaust flow, the turbo will be pushing air, therefore as the supercharger spins faster with RPMs, so will the turbo.

I'm going to put this on hold, and end up buying blueguy's ported blower. I might come back to this concept at a later time.

Yeah you aren't thinking this through.

But to answer your question on how to use 2 MAF's with one input you would need to take the output of each and sum them into a single channel. So you would need to design a circuit that takes 2 frequencies in and sum them into a single output to the PCM. This could be accomplished with a few 555 timer IC's and some thinking.

Jeff

Thinking things through and overthinking them are two different things.

You wouldn't want to do it that way, because they'll be flowing differently and twice as much as was being accounted for. The reading would never be right if I did 2 to 1 and based off the sum. Speed Density tuning would be much more accurate.

It wouldn't necessarily be the sum directly but in essence it would still be the sum. The total going into the engine would be split between the 2 sensors the result would still be about the sum of both sensors unless you were out range of them. Still 100cfm+200cfm=300cfm. You would have to break it down into grams per second and frequency and it would be the sum +/- some number as a fudge factor. It could be easily done but I don't want to overthink it...

You definitely are not thinking this through. I am no where near being an engineer and even I understand this is basic fluid dynamics. When the "lower" throttle body would open the compressed air from the SC is going to blow out that opening and cause compressed air to slam backwards into the turbo. Even if the turbo goes into boost you are going to cause confused air. This will never work.

maf sensors measures temp/density/mass of airflow.
they cannot distinguish the direction the mass is traveling.

Dual intakes and throttle bodies


Forgot where I seen this

Yes, but they are both in the upper intake. Lots of vehicles use dual TB's, but none use them via one in the upper intake and one in the lower intake.

No I'm saying start with this. We're all talking sbot doijg a 3800 in a different way. Well that's another possibility

Would this style of manifold cause problems if you went with twin turbos? Little bit off topic, but would you be able to feed one bank "into" itself and let them both act "independent" in terms of air moving through?

Just curious, honestly.

So many nay sayers... I'll do this someday just to prove it can be done. And it will be SD tuned on MS3Pro

Originally Posted by WarStryker13

Would this style of manifold cause problems if you went with twin turbos? Little bit off topic, but would you be able to feed one bank "into" itself and let them both act "independent" in terms of air moving through?

Just curious, honestly.

I've seen it done. You want to run the turbo to the opposite bank. Exhaust from bank 1 should push the turbo to bank 2.

Show me one parallel flow turbo/supercharger setup. Just one.

you would make more power with direct exhaust injection.jpg