Hi,
I am thinking of replacing the stock inlet tube between the MAF and throttle body in my 5,3 Tahoe 04.

I know after scanning with HPT that a CAI does nothing to lower the inlet temps, since the stock unit give an inlet temp of just 0 to 3 degres over ambient.

But looking at the stock MAF to throttle body pipe, it looks as if a smoth pipe should flow better. When scanning at WOT I se 96 Kpa when ambient pressure is 102.

Has any one scanned before and after replacing said pipe, or even has dyno numbers?

//

 

I'm glad to see someone taking a scientific approach to this issue. Have you tried using a heat reflective wrap around the intake tube?

Is using pressure drop the best way to figure out flow rate? Would higher CFM mean more of a pressure drop or less?

I bet all the CAI manufacturers would love it if we all believed that their smooth tubes provided better flow than the stock tube with all those 'clunky' Helmholtz chambers dangling off it.

The popular wisdom says that smoother must flow better but does it? Well, it's probably cheaper to build a smooth tube than a convoluted one.

I don't claim to understand the physics behind all this but I wonder why GM engineers employ Helmholtz chambers in their intake tubes. Would they go to the trouble and expense of manufacturing them if they didn't offer some benefit to engine performance? Why are some of the aftermarket suppliers (eg, Volant & Outlaw) using a variation of this technology?

Based on a little internet research, it appears that Helmholtz chambers help by dampening intake noise and to compensate for weak spots in a particular engine's torque curve. If you look at Outlaw's marketing, they claim an increase in power within a certain RPM range. (an increase over what, I don't know)

And I agree with you; It would be nice to see a dyno sheet comparison between smooth and stock intake tubes. (using the stock air filter box)

 

Hi,
I am sure the Helmholtz chambers are there for noice control.
I have read that some CAI systems are loud!

So no one actually know if there is any restriction to flow in the stock pipe?


Br//

 

i just replaced mine today with some 4" pvc pipe. i'm going to data log tommorrow and see what happens. if it works i'll take picks. i painted it all up and made it look nice. when i put it on i tightened it all up and fired it up. well i decide to spray some brake cleane around it to see if it leaked and as i did so i remember, oh yeah this stuff eats paint as i watch the paint bubble . i wiped it off as best i could but you can see where it meesed it up some.

 

Well.... come on 4.8T, spill it. It's tomorrow now.

I'm interested in seeing some before & after scans from intake work myself. CAI sounds interesting, but the majority opinion seems to be for these trucks they're not worth much performance.

I think if there's a real difference then it should be reflected in the scans.

Mike

 

well i almost forgot about this thread. i logged with and with out the intake tube on there. with the 4" pvc the maf spiked at like 1 lb higher. but thats just it, it spiked up down up down the flow was all wiggly but with the stock intake on there it was more smooth. while it didn't spike as high in airflow it was smoother. i wish someone could flow these things and see what kind of cfm they can flow. i mean would just a better filter and a modified box be good enough. i'll post logs if a i can find them again. not sure how to do a screen shot.

 

I have my intake tube wrapped in header wrap then I fiberglassed over the header wrap for a smoother appearance. I have logged with EFI Live and the IAT are only +or- 2 degrees ambient temp. So honestly wrapping the tube does nothing. One thing I did notice is that it might actually trap in heat at startup for awhile.... This is using a modified stock airbox.

 

You do know that your IAT sensor is in the MAF, right?

 

Airaid claims that their intake tube flows just over 400 cfm more than the stock tube. The Helmholtz chamber I know for fact reduces noise, but I'm not sure about helping the torque curve.

 

but 400cfm more than what? i read that too. but does the stock one floe like 300-400 cfm then it would be good to get it but if it flows like 800 or so cfm already then most people would see nothing out of it.