Too Much Air Flow? Is it Possible?

[DWestfall]

This past weekend I installed a BHAF on my truck. I couldnt even get the tires to break loose after that. One other problem. From a standing start it takes off slower than before, revs up to 3300 RPM, Defuels, then shifts into second and continues to pull hard. Why does it fall on its face so bad? It is like it cant shift fast enough into second. I put stock air box back on, now I can smoke tires and doesnt fall on its face. This was on the 100HP setting of the xzilliraider box. I always thought that more air the better? Is it the cp3 not keeping up? Can someone explain the air flow dynamics of this one? Is there a cure for this when using a BHAF? Thank You.

 

[Alan Reagan]

What did you do with the IAT sensor?



You can't get too much air flow. Air flow is based on the displacement of the engine. In this case, it will take 5. 9 liters per two revolutions.



Fueling is based on throttle position, air temp and manifold pressure. If there is no boost being built, the engine will not fuel and you will have the symtoms you described. All you did was change the amount of work the engine was having to do to get air.

 

[DWestfall]

I put the IAT sensor in the rubber boot along with the filter minder. It acted as if the turbo was spooling up slower, which with the BHAF it should have been opposite. Boggles me.

 

[Goodys1ton]

DWestfall

Sounds like you were having the problem I was with the torque management system. I had no idea what defueling was until I went for a ride in a 2nd gen with the RAD device. First ride was with the device off letting the truck manage the torque and it fell on its face. Second trip was with the RAD on and holy cow, it was like a different truck. I still haven't got my device fully hooked up yet. When I got the RAd 2 device it had tire claibration on it and after reading the directions I got, stated the tire calibration could be used. So I sold my True speed calibrator and installed the device. To make a long story short, I had the wrong directions, the 2003 autos can not use the tire calibration but only the RAD portion with the speed eliminator. BD is sending me another box so I can hook it up correctly to get the torque management taken care of. But so far the speed eliminator works great. I dynoed over the weekend and I could take my truck to 3250 RPM's. In the past I was only able to hit 2950-3000 RPM's.

 

[BCarmicle]

What exactly is the IAT sensor? I had been running my truck with only the TST hooked up and then hooked my EZ to determine the difference in performance and got a P0112 code. THen took the EZ off and tried to clear the code and it is still there.



Goodys1ton,



Keep us updated on the RAD device. I can feel mine falling on its face and would like to get that taken care of.



Brandon

 

[Alan Reagan]

IAT is the Intake Air Temperature sensor.



Back to the turbo not spooling up... ... . either the engine is defueling because it is getting bad sensor input or somehow you are loosing boost pressure which is causing the MAP sensor to not allow the engine to fuel. The BHAF shouldn't cause that problem. You aren't getting too much air. The more air you get, the faster you can build pressure which once the MAP sees that, it will allow faster fueling.



I can't imagine the BHAF causing this. I'm with you... . baffled. So you put the stock box back on and everthing is normal? And no codes?

 

[JHardwick]

In this case, it will take 5. 9 liters per two revolutions.

I thought it was per revolution

 

[DWestfall]

Here is another one to stump you. My mileage dropped a ton. I normally get 14. 5 - 16 MPG towing 4000K @ 71 -74 MPH Hand Calculated. My mileage dropped to 12 MPG same 235 mile stretch of road, xzillliraider set at 0. Yes I put air box back on and it runs like it used to. Tonight I got 14. 5 MPG on a 200 mile round trip. Could the end of the IAT sensor have been dirty? I used WD40 around the hole I drilled in the boot, to get that sensor in. Would that have made a differance? I will check for codes when I get up in morning. Thanks for all your help on sorting this out.

 

[Tim]

I thought it was per revolution

Four stroke engine buddy. You wouldn't have any compression if you were injesting and exhausting air without compressing it and having a power stroke. :-laf



That said it's not 5. 9 liters anyway... boost is involved which will increase volumetric efficiency above 100% most of the time.

 

[Alan Reagan]

Four stroke engine buddy. You wouldn't have any compression if you were injesting and exhausting air without compressing it and having a power stroke. :-laf



That said it's not 5. 9 liters anyway... boost is involved which will increase volumetric efficiency above 100% most of the time.

The volume of the cylinders doesn't change with pressure. Just the mass of air being put into that volume. That's why when doing the turbo calculations, pounds of air (mass) versus volume are used to give a true picture of how much air is being moved. For the flow calculations, mass is converted back to volume to determine the volume in liters/min or cubic ft/min for how much the filter has to be able to flow.

 

[JHardwick]

Four stroke engine buddy. You wouldn't have any compression if you were injesting and exhausting air without compressing it and having a power stroke. :-laf

I understand the difference in a four and two stroke, but tell me how the volume changes after compressing and before exhausting? If you lost the compression stroke and only had an intake and exhaust stroke, turned the motor over 1 rev, it would displace 5. 9L of volume.



A 5. 9L engine displaces 5. 9L of volume per revolution ... ... ..... buddy.

 

[RGramlow]

It takes two revolutions,because on the first one only the intake stroke is completed on 1-5-3 cylinders, and 6-2-4 are on exhaust stroke, so that means that they are not bringing any air in, so that means that it takes two revs to get the job done.

 

[JHardwick]

It takes two revolutions,because on the first one only the intake stroke is completed on 1-5-3 cylinders, and 6-2-4 are on exhaust stroke, so that means that they are not bringing any air in, so that means that it takes two revs to get the job done.

LOL, okay, okay ... ... ... ..... lets take the head off the motor completely and crank it over 1 time. What is the volume displaced by all 6 cylinders?



5. 9L does not describe how the engine works; firing order, 2/4 stroke. It only refers to the displacement per rev.

 

[hasselbach]

LOL, okay, okay ... ... ... ..... lets take the head off the motor completely and crank it over 1 time. What is the volume displaced by all 6 cylinders?



5. 9L does not describe how the engine works; firing order, 2/4 stroke. It only refers to the displacement per rev.

I think what he meant was its injesting 5. 9 per 2 revolutions. But at 30 psi, its actually taking about 4 to 5 times that amount per two revolutions.

 

[RustyJC]

5. 9L does not describe how the engine works; firing order, 2/4 stroke. It only refers to the displacement per rev.

5. 9L describes the swept volume per revolution or the theoretical displacement per cycle (2 revolutions).



Rusty

 

[Alan Reagan]

I think what he meant was its injesting 5. 9 per 2 revolutions. But at 30 psi, its actually taking about 4 to 5 times that amount per two revolutions.

Right on. It's every 2 revolutions that it takes the full volume in. Even compressed it is the same volume, only at a different pressure. But you are right. That's why they measure the compressed air mass, not volume. You have to take into consideration temperature and ambient pressure at the start. Volumetric efficiency is about 85% so after all the calculations, multiply the mass of air by 85% and you can see how much actually went in there in pounds.

 

[JHardwick]

I think we are kind of on a tangent here, but ... .



With a bore and stroke 4. 02"x4. 72" we can calculate each cylinder at 59. 907 cubic inches. In a 6 cylinder configuration like ours, we multiply 59. 907 x 6 and get 359. 447 cubic inches or 5. 890 cubic litre. The engine will displace 5. 9L per single rev.



Things like turbo charging, super charging, naturally aspirated, head design, cam design all effect mass air flow, but the engine will only displace 5. 9L of volume every rev.



Back to the original post, too much air is only bad if you can't get enough fuel to achieve the proper air/fuel ratio.

 

[hasselbach]

Apples and oranges. There is a difference as to how much is swept volume within the motor, vs. how much is consumed or moved through the motor...

 

[RustyJC]

Apples and oranges. There is a differece (sic) as too (sic) how much is swept volume within the motor, vs. how much is consumed or moved through the motor...

Ummm... . did you happen to notice the term THEORETICAL displacement? Theoretical displacement = swept volume.



Rusty

 

[hasselbach]

Ummm... . did you happen to notice the term THEORETICAL displacement? Theoretical displacement = swept volume.



Rusty

didn't notice that, but thanks for pointing out the spelling errors. .