Discussion on Bigger Throttle Body - What to Change for NGC3 CAN LX Platform

[06300CSRT8]

Being that I finally got my car to idle nice and stable without any surging, I am about to take some next steps and try to let her breath a bit more. I have a ported 87mm throttle body on it now, BUT it has been hashed out to death on my forums that the ported throttle body at no spot in its entire length is any bigger than the stock 80mm since it uses the stock butterfly and therefore doesn't flow anymore than stock. I am looking to install a true 90mm throttle body.

Through looking at various tune samples, it looks as though the stock throttle body airflow table for base Whipple tunes is already raised up, presumably due to the huge airpump added just aft of the throttle body which is increasing the effective flow rate of the throttle body. Example at 0.3 volts on the stock manifold/throttle body without a twin screw behind it, the tune says 126 lbs/hr flow for stock, Whipple says 153lbs/hr. Can anyone else confirm this?

This creates a dilemma for me on a base line point to start to increase the throttle body airflow. API, the maker of my throttle body, claims the 90mm TB flows 819CFM at peak, "178CFM more than stock" implying stock is 641CFM. Using STP to convert, 641 / 0.75 = 8,547 lbs/hr. Stock throttle body table is pretty close at 8,412 lbs/hr at peak, seems like their data is lining up.

Overall their 90mm throttle body should flow about 25-27% more at peak, and I am guessing it is a non-linear curve to the flow increase getting closer to 0 volts.

What do you guys think? Take a stab at increasing the Whipple values or maybe just install and see how it acts? Also, I noticed a distinct relationship between the Throttle Body Airflow, Airflow>Electronic Throttle>Desired Throttle both the Large Range and Small Range. ALL three of these tables in a stock NGC3 CAN tune are 100% inverses of each other. Now I assume this should be kept this way, but looking a little deeper and thinking about this, not sure they HAVE to be. Looks like the desired throttle is pedal voltage. Just because I put the pedal to 0.70 volts doesn't mean I want the throttle body to give me 544 lbs/hr of flow, even though at 0.70 volts on the TPS means that's what the throttle body would flow. Maybe at 0.70 volts with my right foot I want just slightly more than idle power, something like 200 lbs/hr, and so should scale the desired throttle this way.

Confusing I know...just thinking out loud.

[06300CSRT8]

After the swap and not changing the tune at all, the idle is now a touch less stable than it was prior. I can see the timing getting pulled as the rpms in general are higher than commanded, and so it is trying to pull down the rpms. This to me means the throttle body is flowing too much air, more than I have told the PCM it actually flows, and so it is trying to adjust. Next step is to up the throttle body airflow table to tell it about the higher airflow, see if it stabilizes a bit more.

I found in CMR two very interesting tables called Desired Airflow Drive and Desired Airflow Neutral, both of which HP has added to the editor. However, upon opening my tune the entire table (ECT vs RPM) is all zero's, so either these tables aren't used or they are adders to another table versus being an all in airflow desired. I will test adding some values in there and report back. Low hopes they are going to be of any use.

[PurpleRam]

What do you guys think? Take a stab at increasing the Whipple values or maybe just install and see how it acts? Also, I noticed a distinct relationship between the Throttle Body Airflow, Airflow>Electronic Throttle>Desired Throttle both the Large Range and Small Range. ALL three of these tables in a stock NGC3 CAN tune are 100% inverses of each other. .

Confusing I know...just thinking out loud.

Small range/Large range what's the 3rd table you are talking about ?

[PurpleRam]

Stock throttle body table is pretty close at 8,412 lbs/hr at peak,

Stock 80mm TB depending on who you talk to can flow as much as 900CFM @ 28hg which would be 12000 Peak......I've never hit 900cfm on the bench with one 875 was the best stock, , I've hit 1025cfm with a fastman #805 TB and 1095cfm with a #801 TB

I was looking at an 06SRT Maggy that for a while had me baffled as to why it just never ran right.....Came across this thread last night ......I never I mean Never thought to look at this table in this way I keep thinking it was Throttle volts & RPMs , not Throttle Volts & LB/H never mind that fact that next to the add block it has lb/h so I looked at it a different way this morning....and it showed 7936@ 3.9 on the ECM35035 table, it's the only one I've seen that way went and checked about 30 different tunes between 04-08 and they are all 8412.3 @ 3.9....it has me baffled as to why anyone would go lower then stock on this table. so I copied and pasted #s from a stock 06C300 I had and AHHHH moment realized......thing pulls like it should now.

[GeForce1986]

it takes much changing on some tables but i will gladly tune your tb for you just send me your tune and what cai you run and what manifold then i will adjust it for you