I have read every thread in this forum from today to 8-15-06 (yes it has taken me awhile) and I havent found what I am looking for.

For what I had known and what I have found:
-a stock head at .442" of lift (1.6 rockers) flows 190 cfm @ 28"
-a stock head at .415" of lift (1.5 rockers) flows 187 cfm @ 28"
-a stock runner flows 203 cfm @ 28"
-a stock base and runner flows 199 cfm @ 28"
-a stock MAF flows 529 cfm
-a MAF with no screens flows 711 cfm
-a stock TB flows 668 cfm
-a stock TB with air foil flows 709 cfm


For the questions:
-Has anyone flowed the stock air cleaner assy before and after gutting it?
-The stock runner and base are obviously flowing more than the flow at max lift so I'm guessing the largest restricition is the plenum. Is this correct?

 

thats some valuable information.

with that info id say that the heads are a huge restiction.
well maybe not HUGE.

 

There is a cummulative effect. The total flow will be less with all the parts assembled. I have seen a post showing the cfm of the air filter assembly on the Trans Am to the throttle body. It was a restiction. I don't recall the exact number.

The one on the Camaro is much better. However the one on the Trans Am is easy to fix with new parts. The Camaro has to be opened up at the neck. So where are you going with your research? Maybe we can cut to the chase and give you some answers.

 

I'd like to know why you picked the plenum as the biggest restriction,,, after all, you have no flow data for it. The cross sectional area inside the plenum is huge, much larger than any one runner.

The entire TPI system, taken as a whole, is the restriction. You have restriction in the throat of the air lid (Camaro), the MAF w screens, the runners, the intake manifold, and the heads.

 

I know there will be a cumulative effect but thats not the point I'm going for here. I want to narrow down the most restrictive part of the intake tract.

I wanted to know if the stock camaro air cleaner assy is more restrictive than the MAF without screens or the TB with an air foil.

I also wanted to know if the plenum was indeed the lowest flowing part of the manifold. I know it has a large cross sectional area but I wanted to know if you were to bolt together the plenum, runners, and base how much more the air flow would decrease. The decrease may come from 90* anlges with harsh cast bends or it may out flow the runners/base and not decrease the flow at all. I was just looking for an answer.

 

You should have more concern about the length of the intake tract itself. Take a look at the other intakes, SuperRam, Miniram, StealthRam, all shorter. The SuperRam has a larger plenum mostly to accomodate larger engines.

I dont know how believeable those numbers are you posted though, I cant see base and runners flowing only 4cfm less than the runners alone. Also, its hard to put a number on the MAF and TB thats useful since there are 8 runners wanting air but at intervals, best way at that point is to see what results there are from changing these parts. Its pretty well known that working on the intake base itself will yield the largest gains.

 

the only hope a tpi unit has for making HP is high velocity. with a LTR there's no chance passed 5500... maybe to 5700. i do belive that at upper rpms the plenum can not hold the right amount of charge for those long runners. thus the flat curve pass 5000.

 

Mad Max: Its easy to flow the MAF, TB, and air cleaner on a superflow and know what they flow. It will tell you which of the three is the most restrictive and then you can fix that first. Thats what I want to know. Other runners are shorter and I would want to decrease my runner length if I were going to put a cam in that was suited for higher RPM. The stock system was tuned according to the cam and the low RPM aspirations it has. The runner length was selected according to the 2nd wave theory and it works very well.


I will not sacrifice any torque, period, for hp so decreasing runner length is not going to work. I just want to know what the lowest flowing part of the intake tract and the intake manifold are. Im trying to modify my car in progression from worst flowing component to best and since I wont change my heads or my cam it doesnt make sense to replace something that flows more than them.

Does anyone have the flow info for the plenum and the air cleaner?

 

Start with the inlet tract from filter to TB. Leave the TB and MAF alone, for now. The MAF is too big of a hurdle to deal with and will not give you the gains you want without a lot of mess. As for wave theories, GM was totally inconsistent with cam selection, CI, and gearing so they werent exactly making anything work together ideally. They made an intake and threw some other stuff on around it.

Unless you plan on gearing the car properly, keeping your TPI torque and wanting to go fast is a contradiction of desires.

 

So, any plans to upgrade the exhaust or have you done that already?

 

right now I have a 89 IROC-Z with a 350. I currently have a Holley air foil, 180* T-stat, Banks Y-pipe and Banks cat back with the Banks 4th gen rear section, and a set of RE 730s.

I have a 203* fan turn on switch, a set of CC 2055s, and some K&N filers waiting and I am planing on checking my timing this spring and setting it to 6* as Ive heard it sometimes came from the factory with 0* and Im also planning on removing the screens from the MAF.



Is the base more restrictive than the lid?