Ok, I was in a bit of a debate tonight over the real gains found with an aftermarket air intake, like the one I did.

This pertains only to the 89 2.8er as I know there were major changes to this motor over the 80;s.

My first question(s) is (are) this...

1) Who can find me a GM source of info that says exactly how much air our 2.8ers actually consume on a stock engine, normal every day hwy/city driving.

2) Who can find me a GM source of info that says how much air the stock firebird air intake with the stock filter provides in comparison to what the engine consumes during normal every day hwy/city driving.

Here is the reason.

His arguement is that the stock air intake provides sufficient air intake for the engine and is not too restrictive for the air demands of the smaller engine. This makes sence, the engine is rather tiny... He therefore feels an aftermarket air intake system is a waste of money.

So all you fact finders, highly opinionated people and moderators see what you can find.

Thx.

:lala:

 

It is not that the stock intake cannot provide enough air, it is that it has alot of detrimental features that kill performance.

Here are a few formula's, in combination they may help you out.

1. Airflow rate.
C.I.D> (Cubic in Displacement) X RPM X .5 X Volumetric efficiency devided by 1728 = XXXXX CFM
That will give you what the engine "can" or "will" use at given RPM. There really is no set value for Ve, it changes constantly. depending on humidity, temp, elevation, air filter location, air filter type ect ect.

To find the volume of air that the stock intake can provide you need the availible area is has.

2. Velocity can be found by calculated CFM devided by section area. dementions of a "slice" of the intake.

Personally I have no doubts at all that the stock intake can provide enough air to sustain well into the 400 HP range. The thing has massive static volume. But if it did not have the sharp bends that it has, it would be much better design.

 

Forgot.
As far as the air filter thing goes, you can call the manufacturers and ask for velocity and or pressure loss numbers of the actual filters in question.

But unless you talk to an engineer and or designer, everyone else will be clueless.

 

Right, thanks for the info and the opinion.

 

This is what I have found out.
The stock heads only flow about 117cfm with a .45'' open valve @ 28'' of water on the intake.
When you put the intake manifold and plenum on there the numbers go down about %10.
The 2.8 With 80% VE @ 5500rpm eats 240cfm or about 19lb/min at 48'F.
Your VE is inversly porportionl to RPM's, to about 2500 rpms your VE will be about 90% the higher you go the less you have.
Cam grind, P&P, P&P finish, TB size, Valve size, air filter and more change your VE.
What do you want it for?
Just for an air filter selection thing or are you looking into forced induction?

 

Just looking for information on air requirements of the engine as compared to air provided (and efficency thereof) from the stock air intake box assembly.

Reason is a guy I was talking with was quite adamant that any change from stock airbox is a waste of money. He was insistant on cramming that down my throat.

Therefore I am just looking into what the actual air needs for the engine are (on average) and if there really is any advantage to an aftermarket air box or custom air setup aside from the athetically pleasing and personal preference of the setup.

Bottom line, looking for justification for the air box mod I did.

Thanks for the info btw.

 

Given formulas above, you can calculate the most the engine WILL take. Just by RPM methods. Again, Ve changes radically.

I am not exactly sure what you are looking for?
air box flow? if that is the question, the TPI/2.8 air boxes are virtually the same. So if it can flow enough for a V8, the V6 would be a no brainer.

If it is the actual upper intake manifold, I cannot help you. You would need to cut one up and measure it to get its availible volume. Then you can use those numbers to calculate velocity X volume.

If it is the inlet tube from the air box to the throttle body, take ID of tube X3.14X length will give you the static cubic volume it can hold.

If it is the intake system... whooa boy. Measure everything above, PLUS middle intake and lower manifold plus the head before the valve.

You and your freind got into a debate about aftermarket "Air boxes" That would be the air filter housing.

Most the aftermarket ones do is take air from a different area, preferably a cooler source, and they remove internal baffling, to increase overall flow. Both of these are a good concept and solid theory in increasing power output.

Weither or not they are "worth the money" is all in the owner of the car. Granted a 150 Hp engine will not see the gains advertised for a Big V8. And again the gains are truely minimal.

So the arguement is in your favor, yes aftermarket airboxes are gains in power. minimal at best, but they do provide more air.

EDIT:1
Stock engine, no the airboxes are not THAT restrictive. They provide "enough" air to the engine to provide decent power. Have you ever seen an aftermarket forced induction engine try to suck air through a "stock" air box? No, because it would implode the damn thing. Stock is called stock for a reason. Stock means minimal power from the engine.

 

I got in a great argument about this with my....I suppose friend even though he drives a galant when he bought some stupid intake, a razor intake or some stupid gay thing. He thought with that he's looking at like a 20hp gain, wish we had been talking face to face so I could smack him good and hard.

I took away the air canister on my 3.1 and didn't notice a difference cept for a cool suckin sound. I also went K&N and the only real benefit from that was I can recharge the filter instead of buying a new one, and I got a cool lil sticky thing that says K&N that never touched my car because I won't put stickers on it....anyway...I don't think any of those intakes you see do much except make it so your engine takes in colder air and allows it to take in more should the need arise...

 

Ok.

That was my thoughts on the intake. It doesn't provide an increase in performance to speak of, but it does increase the efficiency of the air intake, limits turbulence and it kinda looks cool.

In regards to the more air being needed should the need arise, the guy who I was argueing with said the engine is designed to use X amount of air, it will always take in X amount of air regardless of what air box system is in place.

My theory was that the aftermarket, or custom air intakes would provide a more steady flow or solid flow of air to the engine, which perhaps would let the engine combust a little more efficiently and provide a little more fuel effiency or maybe a slight better responce.

There is also the idea that GM had limitations to parts surrounding the engine due to budget restrictions and misc reasons, so the stock intake and engine may not have the potential it was capable of off the factory floor.

Thanks again for the info guys.

 

The Dual intake, or TPI intake was measured by an old board user. He found it to be highly free flowing up to 5000'ish rpm range.

He also contacted K&N, and discussed with them air filters. Bottom line from about 15'ish emails....

Clean K&N vs Clean Paper = SAME
Dirty K&N vs Dirty Paper = K&N Better

Keep the intake you have, remove the "baffles" inside. If you wish, cut some of the bottom out.

Same person who tested the intake tested both of these mods. Removing baffles showed very minimal gain, but seemed to rev better. Cutting out the bottom showed nothing.

 

Here is the intake I have now. ..