[AnArKey]

Well, I can tell you all about it now. I succesfully have a "blow through" MAF setup on my car. What this means is the MAF is mounted in the tubing between the turbo and the motor. In my case, after the intercooler, about halfway between the intercooler and the throttle body. To get this to work, you need to run a hose from the idle motor to a hose nipple between the MAF and throttle butterfly. For me, I removed my throttle body and had the traction throttle butterfly removed, one side plugged, and had a 3/4" hose nipple connection welded on there. A hose runs from there to the idle motor. Heavy duty heater hose works fine, and can take 50psi with no problem. The BOV should be somewhere before the MAF, in my case, the BOV is immediately after the intercooler. If yours is right next to the turbo, that will work fine too. The wires for the MAF will reach over there if you take off the sleaves for the wiring, to about mid way across the front of the motor (where wire bundle crosses right above the cam gears). So far, it works great. So the trick is (arrows indicate airflow):

Turbo->BOV->MAF->connection for idle motor->throttle butterfly (rear one, the one you control with the gas pedal)

Advantages:

1. HP Limitation: When on the pressure side, the MAF offers no restriction to HP, at least up to 800RWHP. Why? A vessel that starts to be a restriction at 400-450RWHP when at 0psi (stock MAF operation), can flow double with no restriction at 14.7psi, and triple at 29.4psi. So unless you make 800HP at 14.7psi, no worries.

2. Price: Costs almost nothing. Just some changes to your intercooler tubing.

3. BOV operation. Since the BOV is before the MAF, all the problems with open-air BOVs and the MAF are gone. Any air that passes through the MAF is going to the motor.

4. Accuracy: MAF systems are more accurate at metering air than speed-density (MAP) systems, like the VPC.

If anyone is interested in doing this, the intercooler tubing is up to you. Place it where you like, but I recommend AFTER the intercooler (for heat reasons). I can tell you the in side of the MAF is 3", and the out side is about 3 3/8".

I can help you with the throttle body. I'm not sure what the price will be, probably $130 I think. For that I will have the traction butterfly completely removed, one hole sealed, and the other hole enlarged and used for the hose nipple for the idle motor. Considering it's $95 for a traction removal kit anyway, I think thats a deal.

This will not be like the MAF dual pipe deal. I don't need a group for this to work, I can do them one at a time if need be.

 

[Grant]

Derek,

I was going to try a MAF bypass as soon as I got my FJO wideband working, but this may be a better idea.

The IC prevents big changes in temp that could be too fast for the sensor in the MAF to react, but the problem is oil. Everyone who used this would have to disable their PCV system (you'd be surprised how many Supra owners don't) and of course have good turbo seals.

So no additional tuning was required? Just move it and go? Have you verified it with a wideband? If its that simple I'll do it tonight

 

[AnArKey]

Pretty much Grant. Never required any tweaking, it worked great from the start. Let me be clear though, you have to make sure your idle motor gets air from somewhere between the MAF and the throttle blade. I used some red double layer coolant hose and sealed both ends as tightly as you would a intercooler connection. If you take the idle motor from open air, the idle will be crap, and probably won't run at all. When I was experimenting, I capped the idle motor and opened the throttle to idle at 1500RPMs. This way I was able to confirm it worked before hacking my throttle body. But I can tell you personally, it works.

One other thing someone mentioned by Grant which is important, you must disable or move your PCV. You can have the PCV draw from open air, that's ok. The amount of air is so small it won't effect driveability. Just don't have it going to the intake stream. Otherwise oil will get on the MAF and screw it up. If your turbo(s) go bad and leak oil on the compressor side, that can mess it up too. Since I have a brand new T78, I'm not concerned about it. But if you have a 100,000 mile set of stock turbos and know they leak oil, I'd suggest you go single or get them fixed before doing this.

 

[mistersolo]

Isn't there a air charge temperature sensor in the MAF? If there is, wouldn't the computer think that its intaking hot air, as if it were very hot outside. In this condition, it would lean out the fuel mixture. How much it would lean out, I don't know.
Just a thought- I could be very wrong.
John B

 

[AnArKey]

Yes you are right, the MAF has it's own temperature sensor. But air coming out of the intercooler isn't all that hot, not much worse than underhood air. But the temp sensor there increases the accuracy of the MAF, it doesn't reduce it. The MAF will continue to read accurately.

 

[Ranger498]

this idea sounds great do you have any pics of the set up ??
does it make the motor look clutered!???

 

[AnArKey]

Cluttered? Not at all. You can barely see the wires the way I have them snaked, and would be invisible once I get around to rewrapping them. The MAF is hard to spot unless you are looking for it, as it is just below the battery. The hose from the throttle body to the idle motor goes down under the intake manifold, and if black wouldn't stand out at all. I have red hose just because that's what the store had, but kinda like the fact it catches the eye and makes people ask, "what's that for?"

Since everyone is asking for it, I'll take some pics with my crappy camera tonight if I can. My setup is temporary, as I am getting a custom top pipe for the MAF->throttle body. For those of you who already have full hard pipes, all you would need to do is chop about 4" off of the top pipe (near the bottom of that pipe), buy a 3" coupler, and a 3->3 3/8 adapter and done. Don't forget the idle motor of course.

 

[Ranger498]

great i cant wait to see this setup !..just wanted to thank you for the info your posting too!

 

[sc300tt]

This is nice and all, but how does this in ANYWAY replace a VPC. You still can only meter up to ~500rwhp... It's not the restriction caused by the MAF that's the problem, it's the corresponding 0-5v values sent to the stock ecu for a given amount of metered air......

That's why I made the dual MAF setup