is there a way to log for the effective area vs. iac tables? for all the people with upgraded throttle bodies??

 

what size is your throttle body... 90mm??

for most 90mm I just multiply the table by 1.44
is the TPIS is "not round" if so then do it by 1.48

 

its the round tpis tb

 

Is there a better way to alter this table for non-90mm TB's (ported & epoxied stock castings, BBK, etc) than shifting the values left/right? Something to calculate the correct area for each column?

 

there is, i was working on it, but my car broke, so the development been halted... PatrickG should chime in, he seems to have a good grasp of it.

 

you could do a true volume calculation using water....
get a cylinder....with a known size ....fill up the TB(might require a little tape over the Idle Hole)
dump water into cylinder...measure true volume.....
do some math..LOL

 

So you just highlight the whole table and multiple by 1.44? Does it have any affect on hot or cold starts?

For a ported stock TB, 1.2 should get you close right?

Please (explain/teach us) more on this if you could (effective area)...

 

Is the effective area not the IAC bore opening vs
counts? I would think that this tracks the internal
passage dimensions and not the throttle body main
opening?

On my ported TB I have a 1/4" dia hole in the epoxy.
So no matter how much I open the IAC plunger that's
as much as will be had.

Maybe bigger TBs also have bigger IAC passages?

 

sure no mention of me? i had this **** down a while ago lol

 

multiplying the table is worthless. anytime you mod that stock curve in the table is thrown out. the values in the effective area table are the iac steps. it says that for that given step the area is xx mm^2. if you tell the computer that a certain iac step has too large an area than it actually has the dynamic airflow will be lower than the idle desired airflow, and vice versa.

log from a cold start the iac step, dynamic airflow, idle desired airflow. in the end you want the desired and actual airflow to overlap.

the only area i have seen issues with this is no throttle going down the street with the clutch in the values wont overlap. this is just due to the fact that you have more air being forced into the TB. that wont throw the car off much though to where it will hurt. when you are on the gas though and clutch is still engaged, they line up right. we had an issue in the past with the ac being on and the airflows going appart but that was fixed with ac torque changes and the effective area table still holds true the way i initially did it. i did alter mine a little when going down the road to meet in the middle so at idle the dynamic is lower then actual and when going donw the street its the other wya around. but the values are close enough it wont hurt anything. just have to make proper changes with the idle airflow after this. the other thing that will play a role is the rpm. higher rpm will pull more air through the iac hole, until you reach a terminal velocity of air through the hole. i am almost positive in the computer calculations that it calculates this all based on rpm and if the area is right itll all work out, but im not too sure about that

 

that is the thing, depending on the side of the hole and the design of it the maximum amount of airflow drasticly changes. when i had the epoxy filling in mine it would max out very fast and on a cold start i could not get enough air in unless i drilled the tb or opened the blade more. so i just knocked out the epoxy and redid the effective area and all is good now.

 

seeing that it deals in mm^2 and that it is very small, little cracks/imperfections in the tb surface at the blade will change it a lot. there is no real way to measure it esp with the bends in the tb. also the fact that iac steps can be inconsistent and we dont know how much it really moved from 0-310 steps.

 

also make sure the ve is where you want it. every ve change will change the effective area so make sure it is dialed into 14.7 at idle and leave it there. otherwise you will have to make changes again.

im going to try and talk with my fluids professor and see if i can come up wtih a spread sheet that will figure this all out. im just not too good with some excel stuff but i know what needs to be done now and just have to double check on it