throttle body data

[etm351]

Anyone have and throttle airflow data for any of the aftermarket throttle bodies on the hemi's? Or how would be the best way to go about calculating it.

[06300CSRT8]

Which throttle body you running? And NA or boosted?

For anything other than the BBK or API throttle bodies, stock flow numbers are what should be used. The ported stockers DO NOT flow any more CFM than stock, a lot of debates were had around this topic and even some dynos were done showing some gains, but were later disproved. Even if you believed in the gains seen, they were in the margin of error of a back to back dyno run (5-7whp).

Cant speak for the BBK, but API published airflow CFM gains over the stock 80mm throttle body on their website. Per their testing with no filter and no cold air tube attached, "819cfm at Wide Open Throttle a full 178cfm over a stock 80mm throttle body" is what they claim for their 90mm throttle body. Being that its simply a tube and volume should be the same, I would guess BBK is similar. That equates to a 27.7% increase at wide open. However, I would not simply multiply the entire throttle body airflow table by 27.7%, closer to idle and mid throttle, the increase isn't as dramatic, maybe half of that.

And of course, all this goes out the window if you have a positive displacement blower with the throttle body IN FRONT of the blower. The rotors pulling the air through the throttle body makes the stock airflow values much too low, even with a stock 80mm throttle body sitting in front of a whipple or TVS blower, the values need to go up quite dramatically, in the order of 15-20% as a baseline.

In my experience with my whipple 2.9, I picked up 15whp swapping from the stock 80mm to the API 90mm, zero changes to the tune. I noticed my AFR go leaner by about .1-.2 points on the dyno. That's right on par with the old 10cfm per 1whp rule.

[etm351]

it is an api 90mm on a 2011 6.4l with a cam.

[etm351]

is there something you can log to calibrate the throttle body data to where it would be with a magneson blower, i have an srt8 09 model with a magneson and i am using the factory flow data for the stock throttle body which it has, if i change the data then it doesn't want to idle smooth. I see airflow calculations what is the best way to dial in so it is correct with the calculation the ecm has.

[06300CSRT8]

You have no way to arrive at a differential versus stock flow rates, it is going to be purely touch and feel. Are you saying the car had a magneson with stock throttle body, stock flow rates, and it idled ok? Then why would you want to change it?

As noted earlier, the idle area flow rates are not drastically different, in the design of the throttle body from Arrington they reused the stock mechanism and sensors, therefore the throttle blade angle that is preset into the design mimics the factory angle, so airflows should be minimally different. I would start with a 5% change from 0 to 0.5volts and then interpolate to the 3.9 volt cell of 27.7% additional airflow (assuming you are installing an API 90mm to the magneson). Screen shot attached of a 2013 6.4L tune from Whipple themselves for stock throttle body.

Whipple TB Airflow.JPG

[06300CSRT8]

Don't chase your tail here either, remember the PCM, through the airflow/torque factors, first determines how much airflow it needs based on the torque requested. From there it will find the throttle angle (voltage) needed to arrive at that airflow, and move to that spot, this is the throttle body airflow table. Therefore, changing only the throttle body airflow table will not result in the motor actually getting more air in, instead the PCM will just move the throttle body to the new voltage you have now programmed in that supposedly provides the same original airflow. If you get this wrong and tell it the wrong spot, the starting point the PCM moves the throttle blade to will need adjustments, all handled in the torque adaptives (proportional, derivative, and integrals). If you are too far off, itll be in a constant state of adjustment and not idle smoothly.

If you monitor and log the TPS voltage, you can watch it try to adjust. If you have the time, I would reinstall the stock throttle body, log the TPS voltage, rpms, and airflow rates. This will be what the motor actually needs to idle properly. Install the bigger throttle body with no changes, and as the idle fluctuates, find the spots where the rpms are closest to your desired idle rpm, and take note of that TPS voltage. You now safely assume your new throttle body flows the airflow as noted from the stock log at that new voltage, and build your TB table from there.

[06300CSRT8]

Lastly, timing table becomes crucial for a good idle, swapping throttle bodies and allowing more air in at idle will change the required timing to idle properly. More air typically means less timing advance is needed, otherwise itll idle too high. You may have to deal with this in your PT Timing table but first flattening out the timing requested (stock is all over the place) and taking out timing until it settles down. Stick with the TB calibration first, move here after if you cant get it to smooth out.

[etm351]

the 90mm isn't on a 6.4l and the magneson is on a 6.1 i know i kinda threw out 2 questions at once but what you say makes sense.

on the magneson car with a stock throttle body if i change the throttle body airflow it will not idle down to commanded so i guess that would be a sign of too much air flow at that voltage.

i will try the small changes you seguested on the 6.4 with the 90 mm. I had to change the tables selection so it would use the ve mode not sure if it is working yet the 6.4l ecm seems to be a little different than the 5.7 or 6.1

[etm351]

what is the scale on that screen shot i assume lb/min ?

[06300CSRT8]

lb/hr