Friction Air Flow Intl. VS Startup Air Flow Intl.
05-22-2014, 06:09 PM
#1
Friction Air Flow Intl. VS Startup Air Flow Intl. I am wondering what the difference in these two tables is. I was taught to modify these two tables to make start up easier in a cammed bolt on fourth gen Camaro. I have compared many similar tunes from the repository at hptuners.com and almost none of them even modified these tables at all. I know different people tune different ways but I am wondering if someone can shed a little light on this subject. Thanks in advance.
05-23-2014, 08:49 AM
#3
This is a good subject for discussion and I hope a lot will chime in with their experiences. Cams want some extra air to fire up and this is a good way to give it. I use the Friction Air table a lot over the Startup Air table because it seems to work better. Then I set the decay faster and shorten the delay.
I have never really gotten a grasp on the Park Airflow table doing what I want. By description you should be able to park the IAC high enough to do the job but it is influenced by other tables and learned push to positions.
I have never really gotten a grasp on the Park Airflow table doing what I want. By description you should be able to park the IAC high enough to do the job but it is influenced by other tables and learned push to positions.
Last edited by 67SS509; 05-23-2014 at 12:10 PM.
05-23-2014, 09:30 AM
#4
Would these types of tables be what causes the engine to rev up on a start before coming down to a proper idle? RAF table has been set using the proper procedure but every time I start the car it revs up the the high teens and takes 15-20 seconds before it will come down to correct desired idle.
05-23-2014, 07:45 PM
#5
Would these types of tables be what causes the engine to rev up on a start before coming down to a proper idle? RAF table has been set using the proper procedure but every time I start the car it revs up the the high teens and takes 15-20 seconds before it will come down to correct desired idle.
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05-24-2014, 12:38 PM
#9
Would these types of tables be what causes the engine to rev up on a start before coming down to a proper idle? RAF table has been set using the proper procedure but every time I start the car it revs up the the high teens and takes 15-20 seconds before it will come down to correct desired idle.
05-24-2014, 02:20 PM
#10
Even with all the tuning options available, alot will still drill a hole in their tb to compensate for not knowing how to tune startup. That is why you see those tables untouched.
Startup is exactly as it states, and friction airflow is a transitional airflow that decays over the amt of time set in the friction airflow delay table into the RAF or base idle airflow table. You can set the delay and decay to anything you want, but alot of times you dont have to touch but the airflow tables to get most combos dialed in.
Startup is exactly as it states, and friction airflow is a transitional airflow that decays over the amt of time set in the friction airflow delay table into the RAF or base idle airflow table. You can set the delay and decay to anything you want, but alot of times you dont have to touch but the airflow tables to get most combos dialed in.
05-24-2014, 04:25 PM
#11
Even with all the tuning options available, alot will still drill a hole in their tb to compensate for not knowing how to tune startup. That is why you see those tables untouched.
Startup is exactly as it states, and friction airflow is a transitional airflow that decays over the amt of time set in the friction airflow delay table into the RAF or base idle airflow table. You can set the delay and decay to anything you want, but alot of times you dont have to touch but the airflow tables to get most combos dialed in.
Startup is exactly as it states, and friction airflow is a transitional airflow that decays over the amt of time set in the friction airflow delay table into the RAF or base idle airflow table. You can set the delay and decay to anything you want, but alot of times you dont have to touch but the airflow tables to get most combos dialed in.
05-24-2014, 04:28 PM
#12
Because making an even larger hole to compensate is better than actually getting the tune correct?
What size should you stop at? 1/2"?
The hole gm put in the blade is very very small and the normal hole you have to drill to get a decent cam idling is large.
There were and still are quite a few aftermarket tbs that dont have a hole and they tune just fine along with stock 97-04 vettes...
What size should you stop at? 1/2"?
The hole gm put in the blade is very very small and the normal hole you have to drill to get a decent cam idling is large.
There were and still are quite a few aftermarket tbs that dont have a hole and they tune just fine along with stock 97-04 vettes...
05-24-2014, 05:00 PM
#13
So you want to compare a cable throttle body with an IAC and a hole in the blade with an ETB that regulates idle speed by opening and closing the blade.....ok. If there is no need for a hole in any throttle body why did the GM engineers put one (i don't care how small it is) in stock cable TBs? It should be painfully obvious why there is not one in ETBs.
05-24-2014, 05:19 PM
#14
They both use the same tables. There were some companies that put holes in their DBW tbs also. Just making a comparison. The vette TBs have an air bypass besides the throttle blade fyi.
Gm doesnt give reasons why they do anything, and you sure arent either. You are just saying they did and apparently condoning drilling an even larger hole in the blade to keep a cammed car running.
Gm doesnt give reasons why they do anything, and you sure arent either. You are just saying they did and apparently condoning drilling an even larger hole in the blade to keep a cammed car running.
05-24-2014, 06:03 PM
#15
They both use the same tables. There were some companies that put holes in their DBW tbs also. Just making a comparison. The vette TBs have an air bypass besides the throttle blade fyi.
Gm doesnt give reasons why they do anything, and you sure arent either. You are just saying they did and apparently condoning drilling an even larger hole in the blade to keep a cammed car running.
Gm doesnt give reasons why they do anything, and you sure arent either. You are just saying they did and apparently condoning drilling an even larger hole in the blade to keep a cammed car running.
And prove where this mysterious air bypass you speak of is in a 97-04 Vette TB.
05-24-2014, 06:11 PM
#16
Look at a picture of a C5 tb and you will know where it is. Even the TB on your truck has one.
The idle stop screw adjustment to get voltage where it is needed while keeping the tps at 0% is alot better way to get what you want done. It allows the exact same airflow dynamics to happen that would normally happen when you open the tb with the cable anyway. You talk about it like its bad. Do you know what a larger hole will do to airflow dynamics when the throttle blade is opened?
I have no idea why gm chose that size hole etc so I am not going to follow you down the rabbit hole on that one.
Just because I said you arent proving why it is there come back at me with the same thing? Come on. Like I said before, what size hole should you stop at then? Until the IAC counts are less than 100? And like I said, there are aftermarket TBs out there without holes in the blades and they do just fine.
Proof enough?
The idle stop screw adjustment to get voltage where it is needed while keeping the tps at 0% is alot better way to get what you want done. It allows the exact same airflow dynamics to happen that would normally happen when you open the tb with the cable anyway. You talk about it like its bad. Do you know what a larger hole will do to airflow dynamics when the throttle blade is opened?
I have no idea why gm chose that size hole etc so I am not going to follow you down the rabbit hole on that one.
Just because I said you arent proving why it is there come back at me with the same thing? Come on. Like I said before, what size hole should you stop at then? Until the IAC counts are less than 100? And like I said, there are aftermarket TBs out there without holes in the blades and they do just fine.
Proof enough?
05-24-2014, 06:42 PM
#18
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I think I played with these a little after the cam swap,
to get it enough air to catch reliably. But I couldn't tell
you much about where I ended up or why, it's been
too long since.
It's just another couple of "*****" that will get you past
the initial warmup, to where running airflow can handle
things.
to get it enough air to catch reliably. But I couldn't tell
you much about where I ended up or why, it's been
too long since.
It's just another couple of "*****" that will get you past
the initial warmup, to where running airflow can handle
things.
05-24-2014, 06:53 PM
#20
Here is a hint, it is a filtered fresh air source for the PCV system. Now I guess you'll justify it by saying the PCV system is an idle air control.